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Geology of Casino porphyry copper-molybdenum deposit, Dawson Range, Y.T. Godwin, Colin Inglis 1975

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GEOLOGY OF CASINO PORPHYRY COPPER-MOLYBDENUM DEPOSIT, DAWSON RANGE, Y.T. by COLIN INGLIS GODWIN B.A.Sc, Univers ity of B r i t i s h Columbia, 1962 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Geological Sciences We accept th i s thesis as conforming to the required, standard: THE UNIVERSITY OF BRITISH COLUMBIA APRIL 1975 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of \ _ ' K <2i-Vfc>yixL The University of British Columbia Vancouver 8, Canada Date j C R w u k fil^ F _ r , FRONTISPIECE: Patton H i l l , ear ly September 1970, view looking south across Casino Creek. Patton Gulch i s to the r ight of the h i l l c re s t , a i r s t r i p i s to the l e f t . Horizon marks the Yukon Plateau. ia ABSTRACT Casino porphyry copper-molybdenum deposit ia in the Dawson Range, midway between Dawson City and Whitehorse, Y . . T . Kid-Cretaceous g r a n i t i c rocks of the Klotassin batholith. forra the backbone of the Dawson Range and have intruded the Yukon Hetamorphic Complex of Paleozoic or earlier age. A 70 E.y. old volcanic u n i t , the Casino complex, intruded the Klotassin batholith, and is oogenetic with Casino deposit. Hear the deposit extrusive volcanic rocks are unknown but formation of a subvolcanic plug of feldspar porphyry was followed by an explosive event that formed a steeply plunging, conical breccia pipe. This permeable pipe, about 2,000 f t . (670a.) by 1,200 f t . (400m.) at the surface localized hydrothermal fluids that formed large concentrically zoned alteration patterns during upward and outward perco-lation. A p o t a s 3 i c alteration facies core, about 1,500 f t . (500m.) in diameter, is centered approximately on the breccia pipe, and is characterized by secondary magnetite, biotite and potassium feldspar. This core i s surrounded by phyllic (quartz, sericite, sulphide) alteration that extends about 1,000 f t . (330m.) into adjacent rocks of the Klotassin batholith. Chalcopyrite and molybdenite are concentrated in the phyllic zone along the potassic alteration side of a pyrite halo. Peripheral, weakly developed zones of argillic (clay-carbonate minerals) and propylitic (chlorite) alterations are present. This characteris-tic location of economically significant minerals within a zonal distribu-tion of alteration minerals provides an important exploration guide for porphyry-type deposits in the area. Breccia formation and hydrotherrnal zoning appear interrelated and probably result from escape of netal-bearing saline solutions from "wet" magmas derived from an underlying Benioff zone associated with subduction of an oceanic plate. Supergene enrichment, preserved because the area is unglaciated, probably occurred mainly in the Paleogene and resulted in an increase in the grade of copper ib by an average factor of 1.7 through precipitation of chalcocite i n a subhori-zontal enriched zone. Copper added to this zone was extracted from up to 500 f t . (l70a.) of overlying capping rock. Controls f o r enrichment processes include grade of original hypogene copper, favourable breccia occurrence and alteration, and presence of pyrite. A plate-tectonic model relates the genesis of Upper Cretaceous to Tertiary porphyry-type deposits to the evolution of the western and central Canadian Cordillera. Existence of two Benioff zones i s assumed from definition of two distinct younging trends of intrusive centres. The f i r s t Benioff zone, ini t i a t e d west of the Queen Charlotte Islands near the Middle Triassic, continued a c t i v i t y u n t i l the early Tertiary when 50 m.y. old granitic rocks and associated porphyry deposits near the eastern boundary of the Coast Crystalline Belt were formed. The second Benioff zone, i n i t i a t e d near the earliest-Cretaceous, extended under the western margin of the North America plate and produced stocks and associated porphyry deposits that become younger from west to east across the Intennontane Belt. Intrusive a c t i v i t y associated with both Benioff zones ceased at about the same time, 50 m.y. ago, implying that they became imbricated. As a result, the North America plate overrode the Insular plate. Doubling of these plates i s reflected i n the late Mesozoic and Tertiary u p l i f t and erosion of the Coast Crystalline Belt. n CONTENTS I INTRODUCTION 1.1 SIGNIFICANCE OF THE CASINO DEPOSIT 1.2 SCOPE OF THESIS -1.3' LOCATION AND ACCESS 1.4 CLIMATE AND VEGETATION 1.5 PHYSIOGRAPHY 1.6 HISTORY 1.7 ACKNOWLEDGEMENTS II GEOLOGY OF CASINO DEPOSIT AND SURROUNDING AREA 2.1 INTRODUCTION 2.2 YUKON METAMORPHIC COMPLEX (Y.META) 2.2.1 Regional Setting 2.2.2 Casino Area 2.3 2.3.1 2.3.2 ULTRAMAFIC ROCKS Regional Sett ing Casino Area (U. SERP) Page 2.4 KLOTASSIN BATHOLITH 22 2,4.1 Regional Setting 22 2,4.2 Casino Area 23 2.4.3 Fine-Grained Quartz D i o r i t e (F.QZDR) 23 2,4.4 Leucocratic Granodiorite (L.GRDR) 26 2.4.5 Hybrid Granodiorite (Loca l ly Agmatite)(H.GRDR) 27 2,4.6 Klotassin Granodiorite (K.GRDR) 28 2,4.7 Quartz Monzonite Porphyry (P.QZMZ) 34 2.4.8 Inequigranular Quartz Monzonite (I.QZMZ) 35 2.4.9 Fine-Grained Quartz Monzonite (F.QZMZ) 36 2.4.10 Porphyry Dyke (P.DYKE) 37 2.4.11 C r y s t a l l i z a t i on of Klotass in BathoTith 41 2.4.12 Emplacement of Klotass in Batho l i th 44 2.5 CASINO COMPLEX 47 2.5.1 Regional Setting 47 2.5.2 Casino Area 47 2.5.3 Patton Porphyry (P.PPXX) 51 2.5.4 Tuff Breccia (T.BRXX) 54 2.5.5 Tuff (TUFF) 57 2.5.6 Cobble Breccia (C.BRXX) , 59 2.5.7 Undivided Volcanics (C.VOLC) 61 2.5.8 Origin of the Casino Breccia Pipe * 65 2.6 RADIOMETRIC AGE DETERMINATIONS 71 2.6.1 Samples Studied 71 i v Page. 2.6.2 Radiometric Ages 7 2 2.6.3 Discussion of Model Age and Geological Evidence for Age 7 ^ 2.6.4 Igneous and Metallogenic Events near 70 and 100 m.y.'s 7 7 in Canadian Co rd i l l e r a . , III MINERALIZATION AND ALTERATION OF THE CASINO DEPOSIT 79 3.1 INTRODUCTION 7 5 3.2 HYPOGENE ALTERATION AND ZONING 7 9 3.2.1 Introduction 7 9 3.2.2 Quant i f icat ion of Hypogene A l te ra t i on Zoning **2 3.2.3 Hypogene A l te ra t i on Zones at Casino ^3 3.2.4 Potassic A l te ra t ion Facies (7) 90 3.2.5 P h y l l i c A l te ra t ion Facies (4 to 6, mainly 5) 1 0 4 3.2.6 A rg i l l i e A l te ra t ion Facies (2 and 3) 1 1 0 3.2.7 PropyTit ic A l te ra t ion Facies (1) - 1 1 4 3.2.8 Summary of Zoning and Or ig in of Hypogene A l te ra t ion ^ 4 3.3. SUPERGENE ALTERATION 1 2 4 3.3.1 Supergene A l te ra t ion Zones 124 3.3.2 Environment and Age of Supergene Formation ^ 4 ^ V Page. IV IMBRICATE SUBDUCTION ZONES AND THEIR RELATIONSHIP WITH 143 UPPER CRETACEOUS.TO TERTIARY PORPHYRY DEPOSITS IN CENTRAL CANADIAN CORDILLERA 4.1 INTRODUCTION 143 4.2 DEDUCTIONS FROM PORPHYRY DEPOSITS AND INTRUSIVE ROCKS RELEVANT TO A PLATE TECTONIC MODEL 144 4.3. AN IMBRICATE SUBDUCTION MODEL 162 4.4 DISCUSSION 169 4.5 CONCLUSIONS 173 V SUMMARY. AND CONCLUSIONS BIBLIOGRAPHY 175 184 vi LIST OF APPENDICES Page A Field Mapping and Dr i l l Logging Techniques Developed for this 195 Study B Activities Casino Area, Y.T.: 1911 to 1974 202 C Point Counting Techniques and Tabulations for Rocks, Casino Area, 205 Y.T. D Rock Type Information from Dr i l l Holes for the 4,000 and 3,500 214 Foot Elevations, Casino Deposit Area, Y,T. E Dr i l l Hole Plan, Casino Deposit Area, Y.T. 216 F 125 400 Foot Square Cel ls , Casino Deposit Area, Y.T. 218 G Hydrothermal Energy in Magmas in Regard to the Formation and 220 Emplacement of Breccia H Cell Variables (Appendix F) Examined at Casino, Y.T. 232 I Hypogene Alteration Facies Averaged from Dr i l l Holes over the 234 200 Root Bench Intervals Centred at the 4,000 and 3,500 Foot Elevations, Casino Deposit Area, Y.T. J Qualitative Analysis of Alteration Minerals Using X-Ray 236 Diffraction K X-Ray and Thin Section Descriptions of Alteration Facies, 239 Casino Deposit, Y.T. L Proposed Outlines of Open Pits, 1970, Casino Deposit, Y.T. 244 LIST OF TABLES 2.1 Units in the Casino Area,, Y.T, 15 2.2 Eight Phases of the Klotassin Batholith 25 2.3 Depth Zone Class i f icat ion of Klotassin Granitic Units 45 2.4 Five Lithologies of the Casino Complex 50 2.5 Potassium-Argon Analytical Data 73 LIST OF TABLES (cont) Page 3.1 Mode and Degree of Dispersion of M inera l i zat ion 85 3.2 Si l icate-Carbonate A l te ra t ion Facies in Porphyry Deposits 86 3.3 Sulphide, Oxide and Native Mineral Assemblages in Porphyry 87 Deposits 3.4 Correlat ion Matrix of Variables f o r Geochemical, Magnetic, 91 L i tho log ic and Hypogene A l te ra t ion Facies at Casino 3.5 Calculat ions Concerning Source Magma, and Volume and 119 Concentration of Copper in Derivative Hydrothermal F lu id 3.6 Mineralogy of Supergene Zones, Casino, Y.T. 126 3.7 S t a t i s t i c a l Summary of Supergene Enrichment and Hypogene 128 Assay Data from D r i l l Holes 3.8 Correlat ion Matrix Comparing Assay Data from the Supergene 138 Oxide Zone to Assay Data from the Supergene Sulphide Zone 3.9 Correlat ion Matrix Comparing Assay Data from the Supergene 140 Sulphide Copper and Supergene Enrichment Zones to Assay Data from the Hypogene Zone 4.1 Potassium Argon Model Ages, Distance Relat ionships, and Metal 147 Character i s t ics of Porphyry Deposits of Canadian Co rd i l l e ra 4.2 Analyt ica l Data from Intrusive Rocks Associated with Porphyry 154 Deposits in West Central B r i t i s h Columbia 4.3 Potassium Argon Radiometric Ages and Distance Relationships of 159 Gran i t i c Rocks in the Insular and Coast C r y s ta l l i ne Belts 4.4 Explanation of Data Constraints fo r Figure 4.7 165 C l Fine-Grained Quartz D i o r i t e , Klotassin Batho l i th : Point Count 207 Data from Stained Slabs C.2 Leucocratic Granodior ite, Klotassin Batho l i th : Point Count Data 207 from Pol ished, Stained Slabs C.3 Hybrid Granodior ite, Klotassin Batho l i th ; Point Count Data from 208 Polished and Stained Slabs C.4 Klotassin Granodior ite, Klotassin Batho l i th ; Point Count Data 208 from Polished and Stained Slabs v i i i LIST OF TABLES (cont) Paje C.5 Quartz Monzonite Porphyry, K lotass in Batholith? Point Count 209 Data from Pol ished, Stained Slabs C,6 Inequigranular Quartz Monzonite, K lotass in Batho l i th ; Point 209 Count Data from Polished and Stained Slabs C.7 Fine-Grained Quartz Monzonite, K lotass in Batho l i th ; Point Count 210 Data from Polished and Stained Slabs C.8 Porphyry Dyke, Klotass in Ba tho l i th : Point Count Data of 210 Phenocrysts from Stained Slabs C.9 Porphyry Dyke, Klotass in Ba tho l i th : Composition Summary 211 C.10 Patton Porphyry, Casino Complex: Point Count Data of Phenocrysts 211 from Thin Sections C . l l Patton Porphyry, Casino Complex: Composition Summary 212 C.12 Tuff Breccia, Casino Complex: Sunmary of Point Count Data 213 from Thin Sections C.T3 Tuff, Casino Complex: Summary of Point Count Data from Thin 213 Section COG 117 G.l Data for Postulated Conditions: I, II and III 222 • G.2 Ves iculat ion Energy 224 G.3 Height and Ve loc i ty from Ava i lab le Energy 225 G.4 Volume af ter Adiabatic Expansion from Condition II to 228 Condition III G.5 Energy in Expansion from Condition I I to Condition III 229 G.6 Ve loc i ty from Avai lable Energy 231 J . l X-Ray Interpretation of Mineral Textures 238 K.l X-Ray Data and Thin Section Descriptions fo r Specimens 240 Representative of the Potassic A l t e r a t i on Facies (7) K.2 X-Ray Data and Thin Section Descriptions fo r Specimens 241 Representative of the P h y l l i c A l t e r a t i on Facies (4 to 6, mainly 5) K,3 X-Ray Data and Thin Section Descriptions for Specimens 242 Representative of the A rg i l l i e A l t e r a t i on Facies (2 and 3, mainly 3) ix LIST OF TABLES (cont) Page K.4 X-Ray Data and Thin Section Descriptions for Specimens 243 Representative of the P r opy l i t i c A l te ra t ion Facies (1) LIST OF FIGURES 1,1 2.1 2.2 2,3 2.4 2.5 2.6 2.7 2.8 2.9^ 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2,17 2.18 Location Casino deposit, Y.T. Regional geology Casino general geology Fine-grained quartz d i o r i t e Leucocratic granodior ite Hybrid granodior ite Klotass in granodior ite Quartz monzonite porphyry Inequigranular quartz monzonite Fine-grained quartz monzonite Porphyry dyke Mean values of g r an i t i c rocks in Klotass in ba tho l i t h , Casino area, Y.T. Variations in An content (ar ithmetic average and range) i n g ran i t i c rocks of Klotass in ba tho l i th , Casino area, Y.T. L ithology, Casino deposit area Patton porphyry ( t r iangu lar diagram) Patton porphyry of Casino complex (sketch of th in sect ion) Ttrff^ breccia of Casino complex (sketch of th i n section) Tuff breccia ( t r iangular diagram) Tuff of Casino complex (sketch of th in section) 2 14 in pocket 33 33 33 33 39 39 39 39 42 43 48 52 64 64 56 64 X LIST OF FIGURES (cont) 2.19 Cobble breccia of Casino complex (sketch of th in section) 64 2.20 Cobble breccia of Casino complex (sketch of th in section) 64 2.21 Isotopic ages for Casino complex, K lotass in bathol i th and 74 Yukon Metamorphic Complex 3.1 Model fo r mode and degree of dispers ion of mineral izat ion in 84 porphyry deposits 3.2 Model showing zoning of s i l i cate-carbonate a l te ra t i on fac ies in 86 porphyry deposits 3.3 Model for sulphide, oxide and native mineral assemblages 87 3.4 A l te ra t ion grade from d r i l l data at 4,000 and 3,500 f t . 92 elevations 3.5 Hypogene a l te ra t i on f a c i e s , Casino, Y.T. 93 3.6 Cross section C-D (near section 36+00S), Casino deposit, Y.T. in -p©€-k-etG/KWs 3.7 Ver t i ca l sections showing hypogene and a l t e ra t i on zoning and in peek-et^al^t^^i breccia pipe out l ine in Casino deposit, Y.T. 3.8 Contours showing percentages of surface rock with potassic 94 a l te ra t i on f a c i e s , Casino, Y.T. 3.9 Contours showing percentages of surface rock containing magnetite 95 and/or hematite, with 4th order trend of aeromagnetic values (gammas), Casino, Y.T. 3.10 Contours showing percentages of surface rock containing tour-. 96 maline with magnetite and/or hematite, with 4th order trend of aeromagnetic ranges (gammas), Casino, Y.T. 3.11 Contours showing percentages of surface rock containing p y r i t e , 97 Casino, Y.T. 3.12 Contours showing percentages of hypogene copper, Casino, Y,T. 98 3.13 Contours showing percentages of hypogene molybdenite, Casino, Y.T. 99 3.13A General change in hydrothermal solut ions at Casino, Y,T. 122 3.14 Part i t ioned bimodal p robab i l i t y p lot of 125 values of elevation 131 at centre of c e l l s , Casino, Y.T. xi LIST OF FIGURES (cont) Page 3.15 Machine contours of topography, Casino, Y,T, 132 3.16 Contours showing thickness of leached capping, Casino, Y.T, 133 3.17 Contours showing percentages of oxide copper, Casino, Y,T. 134 3.18 Contours showing average copper grades (% x 1000) of 135 zone, Casino, Y.T. 3.19 Contours showing enrichment values, Casino, Y,T, 136 .4.1 Dated Porphyry Type Deposits and Gran i t i c Rocks, and 146 Tectonic Elements of Canadian Co rd i l l e r a 4.2 Histogram of K.Ar Ages for Porphyry Deposits, Canadian 149 Co rd i l l e ra 4.3 Potassium Argon Model Ages of Int rus ive Rocks Associated 151 with Porphyry Deposits Versus Distance from Eastern Margin of Coast C ry s ta l l i ne Be l t 4.4 K-h Plots of K-Values, which are % K 2 0 at Given % Si02, 153 Against Depth to Bern*off Zone (h) 4.5 Percent KoO and Ratio of K 20 to P^O plus CaO Versus 157 Distance from Eastern Margin of Coast C r y s ta l l i ne Belt 4.6 Potassium Argon Model Ages of Intrus ive Rocks Versus 161 Distance from Fairweather - Queen Char lotte Fault 4.7 Basic Data and Assumptions Used i n Construction of 164 Figure 4.8 4.8 Plate Tectonic Model of the Development of Imbricate 168 Subduction Zones and Related Intrus ive Rocks in the Central and Western Canadian Co rd i l l e ra 5.1 Generalized D i s t r ibut ion of Hypogene A l t e ra t i on Zones, 178 Casino, Y.T, 5.2 Generalized D i s t r ibut ion of Supergene Zones, Casino, Y.T. 180 G.l P«T Project ion Showing Melting Relationships of a Granodior- 221 i t e Magma Ascending to an Epizonal Environment G,2 Expansion of Water at the Top of a Magma Column into a 227 Propagated Crack ^ x i i LIST OF PLATES FRONTISPIECE? Patton H i l l , ear ly September 1970 1.1 Patton H i l l , mid-August 1970 5 1.2. Base camp, August 1970, view looking north down Canadian 8 Creek 1.3 Canadian Creek, view looking West, upstream to head of creek 8 2.1 Typical ourcrop of Klotassin batho l i th g r an i t i c un i t with 16 heavy l ichen cover 2.2 Quartz-biotite-muscovite paraschist of Yukon Metamorphic 20 Complex 2.3 Orthoc lase-b iot i te orthogneiss of Yukon Metamorphic Complex 20 2.4 Aug i t i te of ultramafic rock un i t 24 2.5 Fine-grained quartz d i o r i t e of Klotass in bathol i th 29 2.6 Leu.cocratic granodiorite of Klotass in batho l i th 29 2.7 Hybrid granodiorite of Klotass in batho l i th 30 2.8 Klotass in granodior ite of Klotass in batho l i th 30 2.9 Quartz monzonite porphyry of Klotass in batho l i th 31 2.10 Inequigranular quartz monzonite of Klotass in bathol i th 31 2.11 Fine-grained quartz monzonite of Klotass in bathol i th 40 2.12 Porphyry dyke unit of Klotass in batho l i th 40 2.13 Patton porphyry of Casino complex 53 2.14 Tuff breccia of Casino complex 53 2.15 Tuff breccia of Casino complex 55 2.16 Tuff breccia of Casino complex 55 2.17 Tuff of Casino complex 58 2.18 Cobble breccia of Casino complex . ^58 2.19 Cobble breccia of Casino complex 60 x i i i LIST OF PLATES (cont) Page 2.20 Cobble breccia of Casino complex 60 2.21 Fracture cleavage in inequigranular quartz monzonite of 66 Klotassin bathol i th 2.22 Fracture cleavage in inequigranular quartz monzonite 66 3.1 Potassic a l te ra t i on fac ies in Klotass in granodiorite 101 3.2 Potassic a l t e ra t i on fac ies in t u f f breccia 101 3.3 Phy l l i c a l t e ra t i on fac ies in inequigranular quartz monzonite 108 3.4 P h y l l i c a l t e ra t i on fac ies in f ine-grained quartz monzonite 108 3.5 A r g i l l i c a l te ra t i on fac ies in Patton porphyry 112 3.6 A r g i l l i c a l te ra t i on fac ies in Patton porphyry 112 3.7 P r opy l i t i c a l te ra t i on fac ies in f ine-grained quartz monaonite 116 (?) 3.8 P r o p y l i t i c a l t e ra t i on fac ies in Klotass in granodiorite (?) 116 3.9 Supergene a l te ra t i on zones defined in cuttings from rotary 125 hole R8 A. l Base camp, August 1970, view looking southwest across the 197 top of Canadian Creek 1 CHAPTER I INTRODUCTION 1.1 SIGNIFICANCE OF THE CASINO DEPOSIT This thes is i s a geological invest igat ion of the Casino deposit, a large tonnage, low grade porphyry copper-molybdenum deposit in Yukon Te r r i t o r y , Canada (Figure 1.1). The deposit, on property held by Casino S i l v e r Mines L t d . , was the f i r s t large porphyry-type copper-molybdenum deposit discovered in Yukon Ter r i to ry . I n i t i a l estimates of ore reserves based on a prel iminary open p i t design (Appendix L) are described by Menzies (1970) as fo l lows: "Using a cut o f f of 0.275% Cu-equivalent for hypogene or primary ore, and 0.30% Cu-equivalent fo r the supergene zone, mineable reserves were calculated to be 179,000,000 tons grading 0.37% Cu and 0.039% M0S2, or 0.45% Cu-equivalent. The waste to ore r a t i o i s 1.67 to 1.0." Other s i g n i f i c an t features of the deposit are: (1) associat ion of copper minerals with the l a te s t - Cretaceous, stlbvolcanic Casino complex, that intruded the mid-Cretaceous Klotass in ba tho l i th , (2) a supergene zone enriched in copper that was preserved because the region of the deposit was not subjected to continental g l a c i a t i on , and (3) zoning of ore and a l te ra t i on minerals in a manner s im i l a r to many porphyry-type deposits. 2 DAWSON • or II | L x J CASINO KM .25 i MI20 » 10 o IvIAYO wAREA OF Rivir PlGUREi^ *GA RMACKS' . Aishihik Lake BURWASH O Highway .25 2 0 \WHITEHORSE "7 B RITl S H \ C 0 L U M B I A T FIGURE1.1: LOCATION CASINO DEPOSIT, Y.T. 1.2. SCOPE OF THESIS Motivation fo r the study was twofold. F i r s t of a l l , i t had to be p rac t i ca l to contr ibute to onsite economic evaluation and planning during the 1970 development program on the property. Secondly, the study was designed to provide a uniform base of documented data important to aspects of genesis of the Casino deposit, and to comparisons with other deposits. Because there are only l im i ted outcrops and d r i l l holes in the Casino area, the problems of co l l e c t i n g deta i led data were pa r t i cu l a r l y challenging and required special techniques, many of which were developed s p e c i f i c a l l y fo r th i s project. Most important were procedures used in detai led mapping and d r i l l hole logging out l ined in Appendix A. F ie ld work was done in December 1969 and from May to November 1970. During th i s period a surface area about one-mile square over the property was mapped in d e t a i l , and an area nine miles by four miles around the deposit was mapped reg iona l l y . Detail obtained during the study in the v i c i n i t y of the deposit also included logging of diamond d r i l l core and cuttings-from rotary d r i l l i n g . Three papers based la rge ly on th i s research have been published. A prel iminary paper based on the f i e l d methods and geology developed in 1969 and 1970 was published by P h i l l i p s and Godwin (1970). Blanchet and Godwin (1972) described techniques of computer and manual analysis of geological data, p a r t i c u l a r l y d r i l l hole data, from prophyry deposits. The t h i r d paper (Godwin, 1973) inquired into the mechanism of breccia formation during the development of porphyry copper deposits. 4 1.3 LOCATION AND ACCESS The Casino deposit i s in the Dawson Range 187 a i r miles northwest of Whitehorse, Yukon Ter r i to ry (Figure 1.1). I t i s near l a t i t ude 62°43' north and longitude 138°49' west a . The area i s r e l a t i v e l y inaccess ib le and i s o l a ted . There are no nearby towns. The Alaska Highway passes with in 75 miles to the southwest; the Whitehorse - Mayo - Dawson C i ty road i s about 65 miles to the east. Barge transportation i s ava i lab le from Dawson and heavy equipment can be shipped up the Yukon River to within 12 miles of the property to a landing near the junct ion of Br i tannia Creek with Yukon River (Figure 2.1). A 12-mile " tote t r a i l " extends south-southwest from th i s landing to the property. In the winter of 1969-1970 a 140-mile winter road was reopened from Burwash on the Alaska Highway, to the property. During the summer of 1970 access was mainly by wheeled a i r c r a f t , up to DC-3 i n s i z e , which landed on a gravel a i r -s t r i p on the property (Frontispiece and Figure 2.2). The deposit occurs near the prominent, rounded dome of Patton H i l l which i s about 4,500 feet in elevation (Plate 1.1). Casino Creek i s the main drainage to the southwest. This creek turns westerly into Donjek and White R ivers , and eventually flows into Yukon River. Patton Creek jo ins Canadian Creek which -flows to the north into Br i tannia Creek. A group of t r a i l e r s and buildings served as the main camp, in 1970. This camp, located near the junct ion of Patton Creek and Canadian Creek, i s connected with the a i rpor t to the southwest by a rough two-^mile-long road. a: 1:50,000 National Topographic Survey map sheets 115-J10 and 115-J15 wi th in the 1:250,000 (1 inch to 4 miles) Snag map sheet (115-J). 5 * PLATE 1.1: Patton H i l l , mid-August 1970, view looking west across Casino Creek. Bulldozed roads are mainly for access to d r i l l s i t e s . Note sharp tors in background. 1.4 CLIMATE AND VEGETATION Mean annual temperature i s in the range of 21° to 24° Fahrenheit. From the beginning of June un t i l the end of August temperatures ra re ly exceed 85° and general ly do not f a l l below 30°. Showers are frequent although annual p rec ip i t a t i on to ta l s only 14 inches. About half of th i s p rec ip i t a t i on f a l l s as snow that mantles the area during a l l but four months of the year. Freeze-up may be expected about mid-September; spring break-up occurs in l a te May. ; As a consequence of th i s subarctic c l imate, much of the area i s underlain by permafrost. The northern slope of Patton H i l l , in pa r t i c u l a r , i s permafrost ground marked by loca l areas of polygonal ground, downslope s t r i p i n g , and an absence of t rees. The top of Patton H i l l and the higher ridges in the map area are about 4,500 feet in elevation and are almost bare. So i l s support only grasses, mosses, and plants cha rac te r i s t i c of the rather a r i d , northern i n t e r i o r c l imate. Proceeding downward from the ridges to the va l leys dwarf b i r ch , s l i d e a lder , wil low and moss become increas ingly vigorous. Below t imber l ine, 3,500 to 4,000 feet in e levat ion, spruce i s prevalent with minor groves of b i rch and aspen that become more abundant in the lower, more protected va l ley bottoms of Canadian and Casino Creeks. 7 1.5 PHYSIOGRAPHY The Casino p r o p e r t y occurs i n the Dawson Range, a n o r t h w e s t e r l y t r e n d i n g i n t e r i o r mountain b e l t o f w e l l rounded monadanock h i l l s and r i d g e s t h a t r i s e t o 1,000 f e e t o r so above the 4,000 f e e t peneplanat ion e l e v a t i o n o f K l o n d i k e P l a t e a u . T h i s p l a t e a u extends northwestward i n t o A l a s k a where i t i s c a l l e d the Yukon-Tanana U p l i f t ( W a h r h a f t i g , 1965). The K l o n d i k e P l a t e a u , bounded on the n o r t h e a s t by T i n t i n a Trench and the southwest by N i s l i n g R i v e r ( F i g u r e 1.1) i s a s u b d i v i s i o n o f Yukon P l a t e a u (Bos tock , 1949). The Yukon P l a t e a u escaped almost a l l g l a c i a t i o n d u r i n g the P l e i s t o c e n e ( P r e s t , e t a l . , 1968) . In the v i c i n i t y o f C a s i n o , p e r i g l a c i a l f e a t u r e s are common and i n c l u d e the p r e v i o u s l y mentioned p a t t e r n e d ground, minor a l p i n e g l a c i e r s t h a t are c u r r e n t l y marked by s m a l l c i r q u e - s h a p e d v a l l e y s and a few smal l t e r m i n a l m o r a i n e s , and a l t i -p l a n a t i o n t e r r a c e s ( P l a t e s 1.2 and 1 . 3 ) . Tors can be seen i n the c e n t r a l , d i s t a n t r i d g e o f P l a t e 1.1 (see a l s o the same r i d g e on the l e f t hand s i d e o f P l a t e 1 . 3 ) . These r e s i d u a l p i n n a c l e s might be p e r i g l a c i a l f e a t u r e s r e l a t e d t o f r o s t s h a t t e r i n g o f g r a n i t i c rock and subsequent downslope movement by creep and s o l i f l u c t i o n . They a l s o c o u l d be r e l a t e d t o s e l e c t i v e bedrock decompos i t ion d u r i n g p r e g l a c i a l , warmer c o n d i t i o n s . Indeed, t h e i r o r i g i n might be r e l a t e d t o a combinat ion o f e f f e c t s from both types o f envi ronments . The o r i g i n o f t o r s i s s t i l l h i g h l y c o n t r o v e r s i a l and a summary o f v i e w p o i n t s i s a v a i l a b l e i n Embleton and K i n g (1968). 8 PLATE 1.2: Base camp, August 1970, view looking north down Canadian Creek. F lat sections at sky l ine are a l t i p l ana t i on terraces. - Ripper-furrow sampling trenches are apparent in foreground. PLATE 1.3: Canadian Creek, view looking west, upstream to head of creek. Ridge with tors on l e f t side of photo are those in the central d i s tant ridge of Plate 1.1. 9 1.6 HISTORY The Klondike gold rush of 1898 l i k e l y prompted the f i r s t prospecting in the Casino area. The "Discovery" gold placer claim was staked on Canadian Creek in Ap r i l 1911 by J . B r i t ton and C. Brown (Cairnes, 1917). At the c lose of the 1915 f i e l d season Cairnes ( i b id . ) investigated placer mining operations on claim nos. 71, 72 and 73 above Discovery, that were owned by C. Mann, Nicola Hansen and P. Larsen, and recognized the mineral "wolframite" ( i den t i f i ed as f e rbe r i t e in 1940) in samples of concentrate. This probably led to the f i r s t known recording of a lode mineral claim in th i s area in 1917 by D. Mann (Mining Recorders' f i l e s , Dawson C i t y , Yukon Te r r i t o r y ) . The f i r s t mineral claim to cover Patton H i l l appears to have been the "Alma" claim staked by P. Larsen in 1922 (Mining Recorders' f i l e s , Dawson C i t y , Yukon Te r r i t o r y ) . Cairnes (1912) reco-ynized the source of the gold and tungsten to be the Casino complex. His descr ipt ion of the complex can now be seen to be that of a porphyry deposit: "The small t r ibuta ry stream...heads in a round h i l l about a mi le in diameter [Patton H i l l ] which i s composed large ly of pegmatitic and porphyr i t i c rocks. The pegmatitic rocks are an extreme phase of the g ran i t i c t e r r a i n , while the porphyry, although possibly genet ica l l y re lated to the g ran i t i c intrus ives i s more recent, and"has extensively invaded them. The whole pegmatite-porphyry h i l l i s highly minera l i zed, c h i e f l y with a yel lowish iron ochre which i s l a rge ly the decomposition product of i ron-containing minerals, including py r i t e , magnetite and hematite. Some py r i t e , magnetite, and hematite are s t i l l in evidence, but near the surface, they are for the greater part leached out leaving the iron ochre f i l l i n g the various cav i t i e s which they formerly occupied. The central portion of th i s h i l l for a width of perhaps 1,500 feet i s composed of a pa r t i c u l a r l y quartzose pegmatitic rock, the quartz being associated mainly with hornblende, fe ldspars, and related minerals. This pegmatite i s intersected in a l l d i rect ions by ramifying veins and str ingers of quartz, so that the ent i re central mass of the h i l l i s la rge ly composed of quartz. I t i s evidently from th i s h i l l that the gold and wolframite now found in the gravels a few hundred feet below has been de r i ved . . . " 10 S i lver-bear ing galena veins found by prospector J . Meloy in the ear ly nineteen f o r t i e s were the cause of exploration e f fo r t s concentrated near the head of Casino Creek (Figure 2.2) un t i l 1967. B. Hestor (1963) noted t ha t ' t he area had porphyry deposit po ten t i a l , but his observations did not become general ly known. G. Harper and A.R. Archer, in June and September 1967 respect ive ly , independently recognized the porphyry deposit potent ia l of the area. Archer ' s evaluation led to the development, from 1968 to 1973, by Brameda Resources L t d . , of a large tonnage, low grade copper-molybdenum deposit. During the summer of 1974,R. Carlson and A. Sweeney re-opened the gold placer area on Canadian Creek and worked about 10,000 yards of gravel . Very l i t t l e attent ion was paid to the Dawson Range area, in sp i te of published encouragements, by Bostock (1955) and Aho (1966), u n t i l the staking rush in the f a l l of 1969 that was prompted by news of the Casino discovery. Bostock (1955) had stated quite d i r e c t l y that th i s unglaciated area l y ing northwest of Carmacks (Figure 1.1) was being neglected and elaborated: "The d i f f i c u l t y seems to be that the advantage of the lack of g l a c i a l d r i f t cover i s more than o f f se t by a very continuous mantle of deep residual s o i l and the fact that a large part of the outcrops, that do e x i s t , are in a ro t ten, crumbly s ta te , so that the general character of the surface of the region i s discouraging to lode prospectors. The region has, however, been exceedingly f r u i t f u l fo r gold placer mining and th i s f ac t with i t s favourable geology suggests that i t i s worthy of more attent ion than i t i s gett ing. Geochemistry has given prospectors a new tool that i s usable nearly anywhere and may be the answer to the d i f f i c u l t i e s of hunting for lode deposits in the unglaciated region. In th i s respect the region i s almost v i r g i n and so promises i n i t i a l d i scover ies . " Appendix B is a more complete calendar of a c t i v i t i e s in Casino area from 1911 to the present as determined from numerous references. 11 1.7 ACKNOWLEDGEMENTS Financial support for th i s study was provided by Brameda Resources L t d . , grant GSI-70 to the l a te Dr. J.A. Gower from the National Advisory Council on Research in the Geological Sciences, and grants from the National Research Council of Canada and the Geological Survey of Canada to the Univers i ty of B r i t i s h Columbia potassium argon laboratory, then under the supervis ion of the l a te Dr. W.H. White. The wr i te r was supported f i n a n c i a l l y by Brameda Resources L t d . , and teaching assistantships and un ivers i ty fel lowships from the Univers i ty of B r i t i s h Columbia. In add i t ion, the Department of Geological Sciences provided funds for much of the d ra f t i ng , typing and reproduction involved in the preparation of the f i n a l manuscript. Advice and encouragement from the la te Drs. J.A. Gower and W.H. White, o r i g i na l supervisors of th i s research were instrumental in s t imulat ing the w r i t e r ' s i n teres t in the Casino deposit. Drs. A . J . S i n c l a i r (chairman of the w r i t e r ' s thesis committee), P.A. Christopher, T.H. Brown, W.K. F letcher and K.C. McTaggart made suggestions for improvement of the o r i g i na l manuscript and ass isted in various ways during the research and preparation of the the s i s . Numerous members of the Department of Geological Sciences and Geophysics helped with d iscuss ion, advice, and analyses. In pa r t i cu l a r , Mr. J .E. Harakal and Mrs. V. Bobik assisted with the'potassium and argon analyses. The wr i te r thanks Brameda Resources Ltd. for permission to use data from the Casino deposit in th i s study and acknowledges pa r t i c u l a r l y the cooperation of Dr. J.M. Carr and Mr. R.H. Hindson. Appreciation i s also extended to Mr. P1H. Blanchet and the l a t e Mr. J.A. 12 Wood of Chapman, Wood and Griswold L td . , who guided the development of the scheme for geological logging of d r i l l holes. The wr i te r also owes much to the enthusiasm and ins ight of Mr. M.P. P h i l l i p s with whom he worked c lo se ly during deta i led mapping and logging on the Casino property. 13 CHAPTER II GEOLOGY OF CASINO DEPPS IT AND SURROUNDING AREA 2.1 INTRODUCTION Regional geology of an area centred on the Casino deposit, and modified from Tempieman-Kluit (1973), i s shown in Figure .2.1. The oldest rocks in the area are metamorphic rocks of the Yukon Metamorphic Complex. These were intruded successively fay ultramafic rocks of Permian and/or T r i a s s i c age, g r an i t i c rocks of the Klotassin bathol i th of mid-Cretaceous age and by rocks of the fo l l ow ing , possibly c o r r e l a t i v e , units of latest-Cretaceous to Early Tert ia ry age: N i s l i ng Range A l a sk i t e , Mount Nansen Group, Casino volcanics and Casino complex. Units younger than Casino volcanics are blank on Figure 2.1. Table 2.1 describes the general nature of these units in the Casino map area. Geographic d i s t r ibut ions of a l l units are shown in Figure 2.2. Locations of samples studied in de ta i l are also shown in Figure 2.2. "Geo log i ca l napping in the area was hampered by a s ca rc i t y of outcrop. The residual nature of much of the f l o a t , however, o f f se t t h i s disadvantage to some extent (Appendix A). Regional mapping of geology in Figure 2.2 was based mainly on observations of f l o a t and the minor outcrops along ridge crests and creek banks. Plate 2.1 i l l u s t r a t e s a typ ica l outcrop cons ist ing of Y. META ll4Q*OtfW LEGEND N.ALAS C.GRAN K.GSNT U.SERP Y.META CASINO VOLCANIC ROCK NISLING RANGE ALASKITE COFFEE CREEK GRANITE KLOTASSIN GRANITIC ROCK SERPENTINIZEO U L T R A -MAFIC ROCK YUKON METAMORPHIC COMPLEX + * " GEOLOGIC CONTACT: / DEFINED, INFERRED • < 1 > B HI • < » I 138'OO'W 6 2 ' J O ' N FI6URE2.I: REG-IONAL GEOLOGY 15 TABLE 2.1  UNITS IN THE CASINO AREA, Y . T . UNIT (Average AVERAGE age: K . A r . AGE: K . A r . ABBREV-. ERA PERIOD i n m.y.)a LITHOLOGY i n m . y . a IATIONS0 Mesozoic l a t e s t - Casino volcanic r o c k s , undefined C.VOLC Cretaceous Complex cobble breccia - C.BRXX (70.3) t u f f - TUFF t u f f breccia - T.BRXX Patton prophyry 71.2 P.PPXX Mesozoic mid- Klotassin porphyry dyke 99.3 P.DYKE Cretaceous Batholith f i n e - g r a i n e d quartz •99:9 F.QZMZ (99.3) \ ^ J monzonite inequigranular quartz 102.3 I.QZMZ monzonite quartz monzonite porphyry 102.6 P.QZMZ Klotassin g r a n o d i o r i t e 98.3 K.GRDR hybrid g r a n o d i o r i t e H.GRDR ( l o c a l l y agmatite) l e u c b c r a t i c g r a n o d i o r i t e 99.7 L.GRDR f i n e - g r a i n e d quartz - F.QZDR d i o r i t e Upper Permian (?) u l t r a m a f i c , Paleozoic and/or serpentinized - U.SERP (?) T r i a s s i c (?) Protero- Yukon s c h i s t - ) zoic (?) Metamorphic gneiss - ) V M C T A and/or Complex q u a r t z i t e - ) i.nt1A Paleo- marble - ) zoic (?) a: see Figure 2.21 and Table 2.5 for a n a l y t i c a l e r r o r and minerals analysed, b: used on geological maps, sections and t a b l e s . 16 PLATE 2.1: Typical outcrop of Klotass in batho l i th g ran i t i c unit with heavy l ichen cover. Few blocks are ac tua l l y in place but have been moved p r i n c i pa l l y by f ro s t act ion. P icture taken at s i t e of specimen COG 263, leucocrat ic gran-od i o r i t e . 17 blocky rubble, moved by f ro s t ac t ion , and obscured with cream and black l i chen . Geological mapping in the Casino deposit area was also hindered by the lack of outcrop. Consequently, the surface geological map in Figure 2.2 was prepared mainly from deta i led f l o a t mapping along bulldozed r ipper furrows, roads and d r i l l s i te s (Plates 1.1 and 1.2, and Appendix A: Plate A . l ) . Much data on the Casino complex, however, is from the logging of 36,922 feet of s p l i t diamond d r i l l core from 49 holes, and from the logging of cuttings representing 17,481 feet of rotary d r i l l i n g in 35 holes. 2.2 YUKON METAMORPHIC COMPLEX (Y.META)3 2.2.1 Regional Sett ing The Yukon Metamorphic Complex consists of reg ional ly metamorphosed rocks that include metasedimentary and metavolcanic un i t s . These rocks occupy the majority of the area of Figure 2.1 and the Yukon C ry s ta l l i ne Platform (Figure 4.1), and are continuous with the Birch Creek Schist of Alaska. Unt i l recent ly th i s unit has been termed the Yukon Group and, general ly, has been thought to be of Precambrian age since Cairnes ' (1915) f i r s t desc r ip t ion . However, limestones associated with-metasedimentary rock jus t south of Yukon River at the Alaska Boundary (Figure 1.1) contain c r ino id oss ic les that ind icate a Paleozoic age (Douglas, et a l . , 1970). Tempieman-Kluit (1973) notes that: "The reg iona l ly metamorphosed rocks [Yukon Metamorphic Complex] of Yukon Plateau have y ie lded radiometric ages of 180 to 200 m i l l i o n 18 years (Tr ias s ic ) at several l o c a l i t i e s . This and the fac t that Laberge Group (Early and Middle Jurass ic) rocks postdate metamor-phism gives a r e l i a b l e minimum age and indicates the rocks are T r i a s s i c or o lder . " 2.2.2 Casino Area Yukon Metamorphic Complex underlies about 20 percent of Figure 2.2. Within t h i s map area two major screens of metamorphic rock occur. One trends westerly from the east side of the map and passes about a mi le south of the Bomber ad i t . The other trends easter ly toward the base camp from the western border of the map. Metamorphic rocks also occur near the northern boundary of the area. This i s the southern border of a metamorphic terrahe that extends, almost unbroken, to the T int ina Trench (Figure 1.1). Fragments of f o l i a t ed Yukon Metamorphic Complex are contained in pipe-breccia at several l o c a l i t i e s with in the Casino deposit. This, coupled with the angular, d i s -oriented metamorphic blocks surrounded by the hybrid granodior ite (Figure 2.2) of the Klotass in ba tho l i th , establishes that the Casino complex and Klotass in batho l i th are younger than the Yukon Metamorphic Complex and the metamorphism responsible for i t s major f o l i a t i o n . Because of l im i ted outcrop no e f f o r t was made to subdivide and map separately the d i f fe rent units in th i s complex. The fo l lowing l i t ho l o g i e s were dist inguished read i ly and are, in decreasing order of abundance: 1. Quartz-biotite-muscovite paraschist (Plate 2.2). F o l i a t i o n , defined by mica layers , i s commonly crenulated re su l t ing in d i s t i n c t l ineat ions on planar surfaces. Quartz veins are abundant and commonly pa ra l l e l f o l i a t i o n . 2. Orthoc lase-b iot i te orthogneiss (Plate 2.3). Orthoclase porphyroblasts are d i s t i n c t i v e and generally augen-shaped. 19 3. Dark grey, g raph i t i c , f ine-grained quar tz i te . This unit i s found only l o c a l l y and i s known mainly from smal l , platy blocks of f l o a t . 4. Rare, wh i t i s h , medium-grained marble. A potassium-argon age of 93.0 m.y. was obtained for b i o t i t e separated from or thoc la se -b io t i te orthogneiss (Plate 2.3, Figure 2.21, and Table 2.5). This age d i f f e r s from the 180 to 200 m.y. metamorphic ages noted previous ly, but corresponds c lose ly to the 100 m.y. age of the Klotass in batho l i th (Figure 2.21'and Table 2.5). The locat ion of the sample taken f o r dating (Figure 2.2:C0G 261) i s near the granitic-metamorphic contact suggesting that th i s age was " re set " by the thermal event represented by int rus ion of Klotass in g r an i t i c rocks. 2.3 ULTRAMAFIC ROCKS (U.SERP) 2.3.1 Regional Sett ing Highly serpentinized ultramafic rock lenses, that are several hundred feet th ick and up to a mile long, form a zone along the northern contact of the Klotassin batho l i th near the head of Coffee and Independence Creeks (Figure 2.1). High magnetic values over th i s zone and along i t s extensions west-northwest and east-southeast (Geo!. Surv. Can., 1969) suggest that th i s unit i s more extensive than the known outcrop pattern would ind icate. S imi lar high aeromagnetic responses (Geol. Surv. Can., 1967 and 1969) occur over the ultramafic body noted near the north end of Figure 2.2 and at interva l s PLATE 2.3: Orthoclase-b iot i te orthogneiss of Yukon Metamor-phic Complex (specimen COG 261). Specimen, r i ght ha l f of p la te , has potassium feldspar stained yellow with sodium c o b a l t i n i t r i t e . Disk is 5 mm. in diameter (magnification x 3.6). 21 along the northern Klotass in batho l i th - Yukon Metamorphic Complex contact (Figure 2.1).- This ultramafic unit has been correlated with greenstones and per idot i tes in the southwestern corner of Figure 2.2 and tenta t i ve l y has been assigned a Permian and/or Tr ia s s i c age by Tempieman-Kluit (1973). 2.3.2 Casino Area The serpentinized ultramafic lens at the north end of Figure 2.2 i s about two-thousand feet wide, and i s characterized by brown colour, res i s tant weathering, and l i t t l e vegetation. The rocks are mainly dark green serpent in i te with two to f i v e percent opaque minerals. The fo l lowing rock types, however, were dist inguished in th in sections ' of weakly serpentinized specimens: 1) dunite composed mainly of medium-grained o l i v i n e (average grain s i ze 1.2 mm.). 2) aug i t i t e cons ist ing pr imar i ly of medium-grained augite (average grain s i ze 3 mm.), commonly with rims of t remol i te and a minor amount of o l i v i n e (Plate 2.4). 3) hornblendite composed mainly of medium-grained hornblende (average grain s i ze 2 mm.) with abundant b i o t i t e and a minor amount of t remol i te. Strong serpent in izat ion, l e n s - l i k e shapes, and the indicated l i nea r trend to occurrences along the west-northwest Klotass in bathol i th - Yukon Metamorphic Complex contacts suggest that these bodies are of the alpine type. One might speculate that the ultramafic rocks were emplaced along major f a u l t zones which l a t e r contro l led the emplacement of the Klotassin batho l i th 22 by forming i t s northern boundary. Age of the ultramafic unit was not established in the Casino area. If,, as seems l i k e l y , the b i o t i t e i s a re su l t of metamorphism by Klotass in g r an i t i c rocks, then the ultramafic unit i s o lder than mid-Cretaceous. The wr i t e r , therefore, accepts Tempieman-Kluit's (1973) assigning of th i s un i t to the Permian or T r i a s s i c . 2.4 KLOTASSIN BATHOLITH 2.4.1 Regional Sett ing Figure 2.1 shows the 20 mile wide, west-northwest trending g ran i t i c be l t ca l l ed the Klotassin batho l i th that forms the core of the Dawson Range (Figure 1.1) and the d iv ide between the Yukon and Klotass in r i ve r s (Figure 2.1). Limits of the ba tho l i th , outside of Figure 2.1, have not been defined accurately. The Casino map area of Figure 2.2 i s near the northern contact of the batho l i th with Yukon Metamorphic Complex. The bathol i th intruded Yukon Metamorphic Complex, and agmatite and skarn are found at some contacts. Intrusive contacts are broadly conformable with f o l i a t i o n in the adjacent metamorphic rocks. Gran i t i c rocks range in composition from quartz d i o r i t e to quartz monzonite. The most abundant rock in the bathol i th and in the Casino area i s c a l l e d , here, Klotass in granodior i te, an equigranular, medium-grained hornblende granodior ite. Tempieman-Kluit (1973) has proposed a T r i a s s i c age fo r the Klotassin 23 ba tho l i th . He also has defined a g r an i t i c unit ca l l ed "Coffee Creek Granite" (Figure 2.1: marked C.GRAN) that he believes to be of Tert ia ry age. The wr i te r argues in Section 2.6 that the Klotassin batho l i th i s mid-Cretaceous in age and includes the Coffee Creek Granite un i t . 2.4.2 Casino Area Intrusive rocks of the Klotass in batho l i th in the area of Figure 2.2 are divided into eight units (Table 2.2) that are d i s t i n c t i v e in the i r f i e l d occurrences, textures and mineralogies. Although r e l a t i v e ages, from oldest to youngest, are shown in Table 2.2, the sequence is somewhat uncertain because contacts are not well exposed in the map area and potassium-argon ages are ind i s t ingu i shable. Gradations between the phases outl ined in Table 2.2 m ay e x i s t , but they are not pronounced enough to hinder f i e l d mapping of d i s t i n c t i v e un i t s . A l l units can be i den t i f i ed read i ly in hand specimen. Average compositions are shown in Figure 2.11, a quartz-orthoclase - plagioclase t r i angu la r p lot recalculated from modal data in Appendix C. Modes were obtained by point counting grains in polished and stained slabs as out l ined in Appendix C. A deta i led descr ipt ion of each phase fo l lows. 2.4.3 Fine-Grained Quartz D io r i te (F.QZDR) Fine-grained quartz d i o r i t e i s known only in the northeastern part of the map area (Figure 2.2). This rock (Plate 2.5) i s t y p i c a l l y dark grey, 24 PLATE 2, Surface l a r i t y ; i s 5 mm. 4: Aug i t i te of ultramafic rock unit (specimen COG 293) i s etched with hydrof luor ic acid to emphasize granu-borders to p late. Disk 6). etching has also caused whiter in diameter (magnification x 3. 2 5 TABLE 2.2 EIGHT PHASES OF THE KLOTASSIN BATHOLITH Name Appen-Average Age Abbrev- dix C: . (K.Ar. in m.y.)" i a t i o n c Table(s) Figure P late(s ) 1. Fine-grained quartz d i o r i t e not det. 2. Leucocratic grano- 99.7 d i o r i t e 3. Hybrid granodiorite not det. ( l oca l l y agmatite) 4. .Klotassin granodiorite 98.3 5. Quartz monzonite 102.5 porphyry 6; Inequigranular quartz 102.3 monzonite 7. Fine-grained quartz 99.9 monzonite 8. Porphyry dyke 99.3 F.QZDR C.l L.GRDR C.2 H. GRDR K.GRDR P.QZMZ I. QZMZ F.QZMZ P.DYKE C.3 • C 4 C 5 C.6 C.7 C.8 & C.9 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.5 2.6 & 2.1 2.7 2.8 2.9 2.10 2.11 2.12 a: numbers equivalent to those of Figure 2.11. Sequence i s from o ldest to youngest, b: see Figure 2.21 and Table 2.5 for mineral analysed and errors in ana ly s i s , c: used on geological maps, sections and tab les. d: quartz-orthoclase-plagioclase t r iangular p lo t ; see also Figure 2.11 fo r summary plot of a l l uni ts . 26 and inequigranular with an average grain s i ze s l i g h t l y less than 1 mm. (range 0.3 to 1.8 mm.). - Large orthoclase grains are l o c a l l y p o i k i l i t i c . Point count data from polished and stained slabs are l i s t e d in Table C l (Appendix C). Averages for th i s unit are 18 percent quartz, 7 percent orthoclase, 53 percent plagioclase and 22 percent mafic minerals (approximate hornblende to b i o t i t e r a t i o i s 3). Orthoclase content i s highly var iab le in the range 2 to 18 percent. Modes of quartz and fe ldspars , reca lcu lated to 100 percent, are plotted in Figure 2.3. Plotted values span the quartz d i o r i t e - granodior ite boundary and the mean plots near the boundary at 23 percent quartz, 9 percent orthoclase and 68 percent p lag ioc lase. The name quartz d i o r i t e was chosen fo r t h i s un i t to emphasize the d i s t i n c t i v e d i f ferences from granodior ite un i t s . The texture is seen to be hypidiomorphic - granular in th in sect ions. Quartz i s anhedral and i n t e r s t i t i a l to e a r l i e r formed subhedral p lag ioc lase, hornblende and b i o t i t e c r y s t a l s . Plagioclase laths are l o c a l l y a l igned. Plagioclase c rys ta l s average An 45 but are normally zoned with a small compo-s i t i o n a l range from core to r im. Accessory minerals include one percent apat i te and a trace of sphene. The b i o t i t e potassium-argon age f o r t h i s un i t i s 99.9 + 3.0 (Figure 2.21, arid Table 2.5). 2.4.4 Leucocratic Granodiorite (L.GRDR) Leucocratic granodior ite occurs mainly to the north and east of base camp (Figure 2.2). This rock (Plate 2.6) i s c ha r a c t e r i s t i c a l l y very pale grey 27 (colour index 8) , equigranular and medium-grained with an average grain s i z e of 1.7 mm. Local ly the unit contains layers of mafic minerals. Honey-coloured sphene, accounting f o r about one percent of the rock, i s conspicuous. Point count data from polished and stained slabs are l i s t e d in Table C.2 (Appendix C). Averages for th i s un i t are 18 percent quartz, 20 percent orthoclase, 54 percent p lag ioc lase, and 8 percent mafic minerals (about equally b i o t i t e and hornblende, but var iable within ind iv idua l maf i c - r i ch l a ye r s ) . Modes of quartz and fe ldspars , recalculated to 100 percent, are p l o t t e d ' i n Figure 2.4. A l l values p lot within the granodior ite f i e l d about a mean at 19 percent quartz, 21 percent orthoclase and 60 percent p lag ioc lase. Hypidiomorphic granular, granophyric and p ro toc la s t i c and layered textures are evident in th in- sect ions . B i o t i t e in the mafic layers i s commonly bent. In the paler layers plagioclase laths (averaging An 50 and l o c a l l y a n t i p e r t h i t i c ) are c lose ly clustered and l o c a l l y are broken. Anhedral quartz and potassium feldspar (a minor portion i s microcl ine) are i n t e r s t i t i a l to e a r l i e r formed subhedral p lag ioc lase, hornblende and b i o t i t e . Contacts of potassium feldspar with plagioclase lathes are commonly myrmekitic. Sphene and apat i te are abundant accessory minerals each accounting f o r about one percent of the rock. Potassium-argon dating of b i o t i t e gave a model age of 99.7 +_ 3.0 m.y. (Figure 2.21 and Table 2.5). 2.4.5 Hybrid Granodiorite (Local ly Agmatite) (H.GRDR) Hybrid granodiorite i s known only in the northeastern part of the map 28 area (Figure 2.2). This granodiorite (Plate 2.7) i s c h a r a c t e r i s t i c a l l y pale pink, equigranular to s l i g h t l y prophyr i t i c and has an average grain s i ze of 3 mm. (range: 1 to 10 mm.). The unit includes abundant agmatite where granodior ite surrounds randomly oriented blocks of sch i s t of the Yukon Metamorphic Complex. The "hybr id " pref ix c a l l s attent ion to the p robab i l i t y of contamination by and ass imi lat ion of some metamorphic rocks. Point count data from polished and stained slabs are l i s t e d in Table C.3 (Appendix C). Averages fo r th i s unit are 19 percent quartz, 15 percent orthoclase, 51 percent p lag ioc lase, and 15 percent mafic minerals (mainly b i o t i t e ) . Modes of quartz and fe ldspars, recalculated to 100 percent, are p lotted in Figure 2.5. A l l values p lot within the granodior ite f i e l d about a mean at 22 percent quartz, 17 percent orthoclase and 61 percent p lag ioc lase. Hypidiomorphic - granular, ca tac l a s t i c and trachytoid textures are evident in th in- sect ions . Catac las t i c textures are concentrated along narrow crushed zones. Plagioclase twin lamellae are commonly broken and bent. Fractured quartz grains with undulatory ext inct ion and sutured edges are common. Anhedral quartz and potassium feldspar are i n t e r s t i t i a l to ear ly plagioclase and b i o t i t e c r y s ta l s . Plagioclase averages An 50.and i s weakly zoned. Accessory apat i te accounts fo r about one percent of the rock. 2.4.6 Klotass in Granodiorite (K.GRDR) Klotass in granodiorite i s the most abundant g r an i t i c rock in the map area (Figure 2.2). This rock (Plate 2.8) i s pale grey, equigranular, and medium-grained with an average grain s i ze of 1.6 mm. Conspicuous, subhedral, 2 9 PLATE 2.5: Fine-grained quartz d i o r i t e of Klotass in batho l i th (specimen COG 148). Specimen, r i ght ha l f of p l a te , has potassium feldspar stained yellow. Disk i s 5 mm. in diameter (magnification x 3.6). PLATE 2.6: Leucocratic granodiorite of Klotass in batho l i th (specimen COG 263). Specimen, r i ght ha l f of p la te , has potassium feldspar stained yellow. Disk i s 5 mm. in diameter (magnification x 3.6). PLATE 2.7: Hybrid granodiorite of Klotass in batho l i th (specimen COG 300). Specimen, r i ght ha l f of plate has potassium feldspar stained yellow. Note inc lus ion in lower l e f t hand corner of p late. Disk i s 5 mm. in diameter (magnification x 3.6). PLATE 2.8: Klotassin granodiorite of Klotass in batho l i th (specimen COG 262). Specimen, r ight ha l f of p la te , has potassium feldspar stained yel low. Disk is 5 mm. in diameter (magnification x 3.6). 31 PLATE 2.9: Quartz monzonite porphyry of Klotass in batho l i th (specimen COG 264). Specimen, r ight ha l f of p l a te , has potassium feldspar stained yellow. Disk i s 5 mm. in diameter (magnification x 3.6). PLATE 2.10: Inequigranular quartz monzonite of Klotass in batho l i th (specimen COG 151). Specimen, r ight ha l f of p l a te , has potassium feldspar stained yel low. Disk i s 5 mm. in diameter (magnification x 3.6). 32 hornblende crys ta l s c h a r a c t e r i s t i c a l l y exceed the abundance of b i o t i t e in t h i s un i t . The Klotassin granodiorite contains abundant xenol i ths and commonly i s cross-cut by pink a p l i t e dykes and simple pegmatites cons i s t ing mainly of quartz and orthoclase. Float of a p l i t e and pegmatite i s p a r t i c u l a r l y abundant near the a i r s t r i p . The apparent concentration in th i s area probably i s not due to an abnormally great abundance of dykes and veins, but i s more l i k e l y a re su l t of accumulated res i s tant a p l i t e and pegmatite l e f t behind a f te r erosion of granodiorite that was weathered and decomposed to sand. Point count data from polished and stained slabs are l i s t e d in Table C.4 (Appendix C). Averages for th i s un i t are 24 percent quartz, 15 percent ortho-c lase, 40 percent plagioclase and 20 percent mafic minerals (approximate hornblende to b i o t i t e ra t i o i s 1.2). Modes of quartz and fe ldspars , r eca l cu -lated to 100 percent, are plotted in Figure 2.6. Most of these values and the corresponding arithmetic mean (30 percent quartz, 19 percent orthoclase and 51 percent p lag ioc lase)p lot in the granodiorite f i e l d but a few plot i n the quartz monzonite f i e l d . Hypidiomorphic granular and granophyric textures are evident in th in sect ions. Quartz and potassium feldspar are anhedral and i n t e r s t i t i a l to e a r l i e r formed, subhedral p lag ioc lase, hornblende and b i o t i t e . Minor amounts of potassium feldspar are p o i k i l i t i c and enclose e a r l i e r subhedral p lag ioc lase, hornblende and b i o t i t e c r y s ta l s . Plagioclase i s normally zoned with a compo-s i t i o n close to An 47. Myrmekite rims on plagioclase are common where the laths are in contact with l a te potassium feldspar. Accessory apat i te and sphene account for less than one percent of the rock. 33 1 0 0 % Q U A R T Z 1 0 0 % Q U A R T Z 1 0 0 % O R T H O C L A S E MODE: QUARTZ* IB-/. ORTHOCLASE* 7 V . P L A G I O C L A S E : 5 3 v. HORNBLENDE*- t 6 V . BIOTITE" J f . OTHER: 1 0 0 % P L A G I O C L A S E C O L O U R I N D E X : 2 2 A N > « K A R A G E * N O T D E T E R M I N E D H O R N B L E N D E I B I O T I T E " . 3-2 O 1 0 2 0 3 0 1 0 0 % O R T H O C L A S E -M O D E ' : Q U A R T Z * I S " / . O R T H O C L A S E ; 2 0 V . P L A G I O C L A S E : 54 • / . H O R N B L E N D E : 3 V . B I O T I T E : 3 ' / . O T H E R : 2 • / . 70 ao 00 too 1 0 0 % P L A G I O C L A S E C O L O U R I N D E X : 8 A N : 5 0 * K A R A G E * a i : K O M Y . . H O R N B L E N D E / B I O T I T E ' 1-0 FIGURE 2.3: F I N E - G R A I N E D Q U A R T Z " DIORITE F I G U R E 2.4:LEUC0CRATlC G R A N O D I O R I T E • S p e c i m e n m o d e 9 A r i t h m e t i c a v e r a g e 1 0 0 * Q U A R T Z 1 0 0 % Q U A R T Z 1 0 0 % O R T H O C L A S E M O D E : O U A R T Z M 9 V . O R T H O C L A S E : 1 5 * / . P L A G I O C L A S E : 5 t v . H O R N B L E N D E : 4 V . B I O T I T E : 9 . ; . O T H E R * 2 - / . 60 7 0 6 0 0 0 1 0 0 1 0 0 % P L A G I O C L A S E C O L O U R I N D E X : 15 A N : 50 K A R A G E : - N O T D E T E R M I N E D H O R N B L E N D E ' B I O T I T E * . .5 / \ Q U A R T Z -D I O R I T E 1 2 0 3 0 4 0 5 0 6 0 7 0 6 0 O O I C O 1 0 0 % O R T H O C L A S E 1 0 0 % P L A G I O C L A S E , M O D E : Q U A R T Z ' 2 4 V . O R T H O C L A S E : 1 6 ' / . " P L A G I O C L A S E : 4 O V . H O R N B L E N D E : I O V . B I O T I T E : ft*/. O T H E R : 2 V . C O L O U R I N D E X : 2 0 A N : 4 7 K A R A G E : HB;g&.6 8 .9 f i ;B l :1D1&05MY HORNBLENDE / B I O T I T E - 1 2 FIGURE2.5 :HYBRID G R A N O D I O R I T E FIGURE2.6:KL0TASS!N G R A N O D I O R I T E 34 Potassium-argon dating of samples from two l o c a l i t i e s one mi le apart gave s im i l a r ages at each s i t e (for b i o t i t e and hornblende), and between s i tes (Figure 2. 21, and Table 2.5). The average of four age determinations i s 98.3 + 4.2 m.y. 2.4.7 Quartz Monzonite Porphyry (P.QZMZ) - Quartz monzonite porphyry occurs to the northeast and east of base camp (Figure 2.2). The rock (Plate 2.9) i s medium grey (colour index 19) and contains 70 percent medium- to coarse-grained phenocrysts (3 to 5 mm.) composed predom-inant ly of plagioclase hornblende and b i o t i t e . A f ine-grained (averages 0.3 mm.) matrix i s composed mainly of potassium feldspar and quartz, and a minor amount of b i o t i t e . Point count data from polished and stained slabs are l i s t e d in Table C.5 (Appendix C).. Averages for th i s un i t are 21 percent quartz, 21 percent orthoclase, 39 percent plagioclase and 19 percent mafics (approximate horn-blende to b i o t i t e r a t i o i s 1.2). Mafic mineral content ranges, however, from 10 to 34 percent. Modes of quartz and fe ldspars, recalculated to 100 percent, are plotted in Figure 2.7. Plotted values span the granodior ite-quartz monzonite boundary but the mean plots within the quartz monzonite f i e l d at 26 percent quartz, 27 percent orthoclase and 47 percent p lag ioc lase. In th in section the texture i s hypidiomorphic granular and porphyr i t i c . Phenocrysts consist predominantly of subhedral plagioclase laths that are general ly moderately, normally zoned (average An 47) but l o c a l l y have strongly corroded and a l b i t i z e d borders. Other phenocrysts are subhedral hornblende, 35 and b i o t i t e . The matrix consists of subhedral c rysta l s of p lag ioc lase, b i o t i t e and hornblende, with anhedral c rys ta l s of quartz and potassium fe ldspar. Clusters of b i o t i t e laths associated with minor amounts of hornblende and opaque minerals occur and are about the same s ize as phenocrysts. Accessory apat i te accounts fo r about one percent of the rock. Potassium-argon dating of oogenetic b i o t i t e and hornblende provided an average model age of 102.6 + 3.5 m.y. (Figure 2.21 , and Table 2.5). 2.4.8 Inequigranular Quartz Monzonite (I.QZMZ) Inequigranular quartz monzonite occurs in the northeastern and southern portions of Figure 2.2, and on the south side of Patton H i l l where i t i s highly a l tered and l o c a l l y i s mineral ized. The rock (Plate 2.10) i s character-i s t i c a l l y pale pink and coarse-grained. Commonly, 30 percent of the rock consists of large, pink grains of orthoclase up to 13 mm. in length. The remaining 70 percent of the rock i s medium-grained (averages 2.5 mm.). Grain boundaries of the large orthoclase grains are ragged and intergrown with surrounding grains. The nongenetic term " inequigranular" was chosen because of the large range in grain s i ze s , noteably, between large orthoclase and small plagioclase c r y s ta l s . Point count data from polished and stained slabs are l i s t e d in Table C.6 (Appendix C). Averages for th i s un i t are 26 percent quartz, 26 percent orthoclase, 34 percent p lag ioclase, and 14 percent mafics (approximate horn-blende to b i o t i t e r a t i o i s 0.5). Modes of quartz and fe ldspars , recalculated to 100 percent, are plotted in Figure 2.8. Plotted values and corresponding . 36 ar ithmetic mean are a l l with in the quartz monzonite f i e l d . Hypidiomorphic - granular and mortar textures are evident in th in sect ion. Potassium feldspar i s e i ther i n t e r s t i t i a l to or p o i k i l i t i c a l l y encloses e a r l i e r formed subhedral p lag ioc lase, b i o t i t e , hornblende and opaque c r y s t a l s . Potas-sium feldspar i s also l a t e r than medium-grained anhedral quartz grains. However, some smal ler, i r regu la r quartz grains e i ther within or at potassium feldspar boundaries may be l a te stage. Plagioclase c rys ta l s are zoned normally with an average composition of An 33. Large plagioclase grains commonly have corroded borders and myrmekite where in contact with potassium feldspar. One specimen (COG 291), from a tongue of th i s unit between f ine-grained quartz d i o r i t e , hybrid granodior ite and serpentinized u l t rabas ic rocks (northeast corner of Figure 2.2), exhib i ts mortar texture characterized by broken plag ioc lase, bent b i o t i t e , and recrysta l1 ized ca tac l a s t i c quartz concentrated along larger grain boundaries. Apatite and sphene occur in trace amounts. Potassium-argon age dating of b i o t i t e provided a model age of 102.3 +3.6m.y. (Figure 2.21 and Table 2.5). 2.4.9 Fine-Grained Quartz Monzonite (F.QZMZ) Fine-grained quartz monzonite occurs to the east and north of Patton H i l l (Figure 2.2). In the v i c i n i t y of the deposit i t i s a l tered and minera l -ized with sulphides. The unit also occurs in two areas south of Bomber ad i t . This rock (Plate 2.11) i s pale pink with an average colour index of 8. The un i t looks a p l i t i c because of the f i ne grain s i ze (averages 0.7 mm.). Point count data from polished and stained slabs are l i s t e d in Table 37 C.7 (Appendix C ) . Averages for th i s unit are 32 percent quartz, 30 percent orthoclase, 30 percent p lag ioc lase, and 8 percent mafic minerals (almost en t i r e l y b i o t i t e ) . Modes of quartz and fe ldspars, recalculated to 100 percent, are plotted on the.t r iangu lar diagram of Figure 2.9. Plotted values are a l l with in the quartz monzonite f i e l d and the corresponding mean plots c lose to the centre of the f i e l d . Hypidiomorphic granular and trachytoid textures are evident in t h i n -sect ions. Most specimens consist of subhedral plagioclase and b i o t i t e laths surrounded by anhedral orthoclase, quartz and b i o t i t e . P lagioclase c ry s ta l s have corroded boundaries that l o c a l l y are myrmekitic in contact with potassium feldspar. They are strongly normally zoned (determinations averaged An 39 but measured zones range from An 54 to An 16). Potassium fe ldspar i s micro-c l i n e and par t l y myrmekitic. Strained quartz and kink-banded b i o t i t e occurs l o c a l l y . Where there i s a trachytoid alignment of p lag ioclase l a th s , anhedral quartz and potassium feldspar are i n t e r s t i t i a l to and p o i k i l i t i c around ear ly subhedral p lag ioc lase, hornblende and b i o t i t e c r y s t a l s . Apat i te and sphene occur i n trace amounts. Potassium-argon dating of b i o t i t e gave a model age of 99.9 +3.0 m.y. (Figure 2. 21, and Table 2.5). 2.4.10 Porphyry Dyke (P.DYKE) Porphyry dykes of granodiorite composition occurs throughout the map area but are most common east and northeast of base camp (Figure 2.2). The dykes intrude Yukon Metamorphic Complex, ultramafic rocks and Klotass in g ran i t i c rocks. Dykes are steeply i n c l i n ed , with very i r r egu la r margins 38 that l o c a l l y are f iner-gra ined than central portions. This rock (Plate 2.12) i s c h a r a c t e r i s t i c a l l y medium grey with medium-grained (average 1.4 mm.) pheno-c ry s t s , occupying 37 percent of the rock, surrounded by a f ine-gra ined (average 0.2 mm.) matrix. Prominent, euhedral hornblende phenocrysts are d i s t i n c t i v e . Hornblende i s four to f i v e times as abundant as b i o t i t e in the phenocrysts but in the matrix b i o t i t e i s more abundant than hornblende. Point count data are l i s t e d in Tables C.8 and C.9 (Appendix C). Average overa l l composition of the rock i s 12 percent quartz, 14 percent orthoclase, 46 percent plagioclase and 29 percent mafics. Modes of quartz and fe ldspars , recalculated to 100 percent, are plotted fo r the phenocrysts, matrix and to ta l rock in Figure 2.10. Phenocryst composition plots in the quartz d i o r i t e f i e l d , matrix composition plots in the quartz monzonite f i e l d near the granodior ite border, and the tota l rock composition plots i n the granodior ite f i e l d . Porphyr i t ic texture i s also obvious in th in sect ion. Phenocrysts are mainly subhedral, strongly zoned plagioclase c rys ta l s (average An 50) that l o c a l l y have corroded and myrmekite edges. Euhedral to anhedral hornblende phenocrysts are common and some are p o i k i l i t i c enclosing small p lag ioc lase, b i o t i t e and quartz c r y s t a l s . B i o t i t e phenocrysts are minor and subhedral. Quartz phenocrysts are rare and exh ib i t mosaic ext inct ion and anhedral, embayed boundaries. Potassium feldspar phenocrysts are rare also and are anhedral and p o i k i l i t i c enclosing small p lag ioc lase, hornblende, b i o t i t e and quartz grains. The matrix i s a fe l ted mixture of subhedral p lag ioc lase, b i o t i t e and hornblende, and anhedral opaques, potassium f e l d -spar and quartz ( l o c a l l y myrmekite). Potassium feldspar i s much more 39 1 0 0 % Q U A R T Z 1 0 0 % Q U A R T Z O 10 SO 30 40 1 0 0 % O R T H O C L A S E MODE: QUARTZ/ 21'/. ' O R T H O C L A S E ! 21*1. PLAGIOCLASE:39 "/• HORNBLENDE 5 11V. BIOTITE; B V . O T H E K 1 V . 6o TO eo 00 IOO 1 0 0 % P L A G I O C L A S E COLOUR INDEX: 19 AH: 47 K AR A G E ! HBtOO;Bi:105MY. HORNBLENDE / BIOTITE* 1 £ • P H E N O C R Y S T S : 7 0 V . M A T R I X : 3 0 V . 0 10 20 30 1 0 0 % O R T H O C L A S E MODE: QUARTZ-26V. ORTHOCLASE : 2&V. PLAGIOCLASE: 34* ' . HORNBLENDE: ,4V. BIOTITE: OTHER: 2 V . 40 50 60 70 oo wq 1 0 0 % P L A G I O C L A S E COLOUR INDEX: 14 AN. 33 K AR A G £ > BI:102MT HORNBLENOE I BIOT1TET O f f F I G U R E 2 7 : Q U A R T Z M O N Z O N I T E P O R P H Y R Y F I G U R E 2 . 8 : I N E Q U I G R A N U L A R " Q U A R T Z MONZONtTET • S p e c i m e n m o d e • A r i t h m e t i c a v e r a g e 1 0 0 % Q U A R T Z 1 0 0 % Q U A R T Z .. • P h e n o c r y s t s A M a t r i x . • T o t a l QUARTZ DIORITE O IO 20 30 1 0 0 % O R T H O C L A S E MODE: QUARTZ '32 " ' . O R T H O C L A S E : 30V . PLAGIOCLASE: 3CV. HORNBLENDE: T R A C E BIOTITE: 8*/. OTHER: T R A C E 50 60 70 60 50 100 1 0 0 % P L A G I O C L A S E COLOUR INDEX: B AN:39 K AR AGE> B I : » 9 M Y HORNBLENDE / BIOTITE: 0 1 0 0 % O R T H O C L A S E MODE: OUARTZ ' 2 0 V . ORTHOCLASE : B V . PLAGIOCLASE: 4 1 V . HORNBLENDE: 23 V . BIOTITE: 5 V . OTHER: 3 V . 1 0 0 % P L A G I O C L A S E COLOUR INDEX: 31 AN: 5 0 K AR A G E : H S : 9 3 . 3 MY HORNBLENDE / BIOTITE: 4.6 P H E N O C R Y S T S : 3 6 V . M A T R I X : 6 4 V . F I G U R E Z . 9 : F I N E - 6 R A I N E D Q U A R T Z M O N Z O N I T E F I G U R E 2 . I 0 : P O R P H Y R Y . D Y K E 40 PLATE 2.11: Fine-grained quartz monzonite of Klotass in bath-o l i t h (specimen COG 243). Specimen, r i ght ha l f of p la te , has potassium feldspar stained yellow. Disk i s 5 mm. in diameter (magnification x 3.6). PLATE 2.12: Porphyry dyke unit of Klotassin batho l i th (specimen COG 13). Specimen, r ight ha l f of p la te , has potassium feldspar stained yel low. Disk i s 5 mm. in diameter (magnification x 3.6). 41 abundant in the matrix than as phenocrysts. Potassium-argon dating of hornblende gave a model age of 99.3 + 3.6 m.y., an age coincident with the average of the Klotass in batho l i th (Figure 2.21, and Table 2.5). 2.4.11 C r y s t a l l i z a t i o n of Klotassin Bathol i th Potassium-argon ages for g ran i t i c rocks of the Klotass in batho l i th i n the area of Figure 2.2 are mid-Cretaceous (average: 99.3 m.y.) and are ind i s t ingu ishable from each other in a s t a t i s t i c a l sense (Figure 2.21, and Table 2.5). Nevertheless, a time sequence in the formation of the various Klotass in g ran i t i c rocks may be inferred from the quartz - orthoclase -plagioclase plot of Figure 2.11 where a c lear trend ex i s ts from f ine-gra ined quartz d i o r i t e ( 1 ) a to f ine-grained quartz monzonite (7), a common trend of d i f f e r e n t i a t i o n . Variat ions in the An-content of plagioclase with in the various g r an i t i c units (Figure 2.12) are compatible with the sequence inferred from the tr fangular diagram. Fine-grained quartz d i o r i t e (1) i s c h i l l e d at An 45 representing an average magma composition. Successive units are f i r s t of a l l more c a l c i c ( leucocrat ic granodior ite - An 50, to porphyr i t ic quartz monzonite - An 47), and then more sodic ( inequigranular quartz monzonite - An 33, and f ine-grained quartz monzonite - An 39). The l a te stage porphyry dykes (8) do not f i t into the trends i l l u s t r a t e d in Figures 2.11 and 2.12. a: numbers 1 to 8 in brackets refer to Figure 2.11. 42 100% QUARTZ QUARTZ DIORITE 100% ORTHOCLASE 1 FINE-GRAINED QUARTZ DIORITE 2 LEUCOCRATIC GRANODIORITE 3 HYBRID GRANODIORITE 4 KLOTASSIN GRANODIORITE 100% PLAGIOCLASE 5 QUARTZ MONZONITE PORPHYRY 6 INEQUIGRANULAR QUARTZ MONZONITE 7 FINE-GRAINED QUARTZ MONZONITE 8 PORPHYRY DYKE FIGURE 2.11: MEAN COMPOSITIONS OF GRANITIC ROCKS IN KLOTASSIN BATHOLITH/CASINO AREA, Y.T. 70 6 0 < LU 5 0 CD < LfJ or 4 0 LU CL, 3 0 « 5 0 | y y 1- - - 5 0 iL r- idea 4 5 ^ A 1—;•-4 7 -f s \ \ \ y / / 5 0 la / *• \ \ \ T ^ 33 ^ Hf' j y y 1 3 9 UNIT F.QZDR L.GRDR H.GRDR K.GR DR RQZMZ I.QZMZ FQZMZ P. DYKE FIGURE 2.12: VARIATIONS IN AN CONTENT (ARITHMETIC AVERAGE AND RANGE) IN GRANITIC ROCKS OF KLOTASSIN BATHOLITH, CASINO AREA, Y.T. 44 2.4.12 Emplacement of Klotass in Bathol i th Buddington (1959) describes c r i t e r i a for a th ree- fo ld c l a s s i f i c a t i o n of plutons according to t he i r depth environments (pressure, temperature, and wallrock mobi l i ty ) of emplacement. These zones in order of progressively deeper emplacement are the "epizone", "mesozone", and "catazone". Features of the Klotass in batho l i th are t ran s i t i ona l between the mesozone and epizone Because the borders of the bathol i th (Figure 2.1) are not marked by metamor-phic aureoles, and the northern contact generally i s concordant with f o l i a -t ion of the Yukon Metamorphic Complex, a mesozonal c l a s s i f i c a t i o n i s ind icated. However, textural c r i t e r i a of g ran i t i c units in Casino area, out l ined i n Table 2.3, suggest characters appropriate in part f o r the epizone and in part fo r the mesozone. Thus, the Klotass in batho l i th l i k e l y was emplaced in the t r an s i t i ona l zone between the epizone and mesozone, implying that i t was emplaced at a depth of four to f i v e miles into the • Yukon Metamorphic Complex which was at about 300 degrees centigrade. The va r i e t i e s of g r an i t i c rock that define the trends in Figures 2.11 and 2.12 occur together only in the northeastern corner of Figure 2.2. The fo l lowing sequence of events i s suggested f o r th i s small part of the Klotass ba tho l i th . Quartz d i o r i t e magma intruded, to a depth of four to f i v e mi les , r e l a t i v e l y cool (300° centigrade) Yukon Metamorphic Complex rocks and produced f ine-grained quartz d i o r i t e (1) along the margins of the magma chamber. Upon slower cooling and crysta l s e t t l i n g of the same magma under the now s o l i d hood, a medium-grained,layered, leucocrat ic granodior ite (2) formed. At about the same time hybrid granodiorite (3) was f o r c e f u l l y 45 TABLE 2.3 DEPTH ZONE CLASSIFICATION OF KLOTASSIN GRANITIC UNITS Unit Fine-grained quartz d i o r i t e ( l ) a Leucocratic granodior ite (2) Hybrid quartz monzonite (3) Klotassin granodiorite (4) Porphyr i t ic quartz monzonite (5) Inequigranular quartz monzonite (6) Fine-grained quartz monzonite (7) Porphyry dyke (8) Textural C r i t e r i a F ine-granular i ty Granophyric Depth Zone indicated Epizonal (?)",' Mesozonal Epizonal Complexly nonconformable Epizonal (?) i n t ru s i on ; l o c a l l y porphyr i t ic Cross-cut by l a te stage ap l i te s Epizonal (?), and pegmatites Mesozonal (?) Porphyr i t ic Coarse-granularity F ine-granular i ty Mi orographic; f ine-grained margins; porphyr i t i c . Epizonal (?) None Epizonal (?), Mesozonal (?) Epizonal (?) a: numbers 1 to 8 in brackets re fe r to Figure 2.11 . 46 intruded into f ine-grained quartz d i o r i t e (1) and into the Yukon Metamorphic Complex. This unit (3) i s coarser-grained than the f ine-gra ined quartz d i o r i t e (1) because i t cooled more slowly than e a r l i e r units (perhaps because rocks were hotter than during i n i t i a l magma emplacement). Intrusion of hybrid granodior ite (3) also produced p rotoc la s t i c textures in the leuco-c r a t i c granodior ite (2) and ca tac l a s t i c textures in the granodior ite (3) surrounding the engulfed sch i s t blocks of the agmatite area. Small c i r c u l a r bodies (about 1,000 feet in diameter) of Klotass in granodior ite (4) in f ine-grained quar t z -d io r i te (1) indicate that the granodior ite (4) intruded the quar tz -d io r i te (1). Granodiorite (4) i s in contact with and l i k e l y intruded the e a r l i e r leucocrat ic granodiorite (2) and Yukon Metamor-phic Complex. Porphyr i t ic quartz monzonite (5) also intruded Klotass in granodior ite (4) and f ine-grained quartz d i o r i t e (1) i f the c r i t e r i a of small c i r c u l a r intrusions used above is correct. Inequigranular quartz monzonite (6) i s in contact with Klotassin granodior ite (4), re la t ionsh ip unknown, but i t does extend f i n g e r - l i k e into porphyr i t ic quartz monzonite (5), and between the f ine-gra ined quartz d i o r i t e (1) - hybrid granodior ite (3) contact. Mortar texture in the inequigranular quartz monzonite (6) " f i nger s " ind icate forcefu l i n t rus ion . The coarse-grain s i ze of th i s unit indicates slow cool ing of a un i t , probably in a hot environment resu l t ing from preceding plutonic events. F i n a l l y , the f ine-grained quartz monzonite (7) was introduced into a somewhat cooled bathol i th re su l t i ng in a f i ne r grain s i ze . 47 2.5 CASINO COMPLEX 2.5.1 Regional Sett ing The Casino complex i s correlated with the "Casino vo l can i c s " . The Casino volcanic unit i s an informal unit defined by Templeman-Kluit (1973) and i s thought by him to be co r re la t i ve with the Mount Nansen Group ( re-defined from Bostock, 1936). In Figure 2.1 these units are seen to intrude the Klotassin batho l i th along the trend of the Dawson Range (Figure 1.1). Casino volcanic rocks are exposed best at Mount Cockf ield (about th i r teen miles southeast of Patton H i l l ) where breccias and flow rocks aggregate 1,000 feet in thickness, the maximum known for the un i t , and are intruded by dykes and breccia pipes. . A tentat ive Tert iary age has been assigned the Casino volcanics by other workers (e.g. Templeman-Kluit, 1973). Potassium-argon ages reported in section 2.6 are near 70 m.y., latest-Cretaceous according to the time scale proposed by Obradovich and Cobban (1974) that places the boundary between Cretaceous and Tert iary periods.at 65 m.y. 2.5.2 Casino Area The Casino complex occupies about ten percent of the area of Figure 2.2 and has been studied in deta i l only in the v i c i n i t y of the Casino deposit (Figure 2.13). Extrusive volcanic rocks are not known and only breccia pipes, P.PPXX 'Wl. goo t [woo i Legal lnoot " 0 0 1 •QO I 1 1 0 0 1 •#090» 1 4 0 0 1 \* X * L ..•>-"'' \*jC. 'BRXX.V^-V NSS^ -jJSS N^QC^ MOOt MOO t I.QZMZ SRX F.QZMZ L E G E N D SECTION LINE * CONTACT, LITHOLOGY, SURFACE ^ CONTACT, BRECCIA AND P. PPXX AT 4,000 FT ELEVATION CONTACT, BRECCIA AT • 3,500 FT. ELEVATION CASINO COMPLEX [Pp? qV| BRECCIA, UNDIVIDED ( & R X O fevfiofl COBBLE BRECCIA (C.BRXX) I'.'.Ij.'H TUFF (TUFF) F ^ ^ q l TUFF BRECCIA (T. BRXX) S^ t«*J PATTON PORPHYRY (P. PPXX) K L O T A S S I N B A T H O L I T H \r. OZUl I F INE - 4 R A I N E D O U A R T Z M O N Z O N I T E I I.QZMZ j I N E O U I S R A N I J L A N OUARTZ MONZONITE) I K . 9 R 0 N j K L O T A t S I N S N A N O O I O N I T C • FIGURE 2.13= LITHOLOGY, CASINO DEPOSIT AREA fe 49 plugs and dykes are recognized. The Casinc complex i s c l e a r l y i n t ru s i ve and younger than the Klotass in batho l i th because the complex contains breccia fragments of g ran i t i c rocks from the Klotass in ba tho l i th . Further-more, the radiometric ages from the Casino complex are much younger than those from the Klotassin ba tho l i th . It must be noted, however, that the potassium argon age for the Casino complex might r e f l e c t a younger minera l -i z i ng event superimposed on the Klotassin batho l i th . Such a minera l i z ing episode would in a l l l i ke l ihood.be associated with a magmatic event of the same age (cf. White et a l . , 1968). Rocks of the Casino complex in the area of Figures 2.2 and 2.13 are divided into four un i t s , that are d ist inguishable read i ly in the f i e l d , and one undefined unit (Table 2.4). Age re lat ionsh ips in the v i c i n i t y of Casino deposit have been established as fo l lows. Patton porphyry i s the oldest rock because a l l other rock units in the complex contain fragments of the porphyry. The t u f f and t u f f breccia units might be contemporaneous fo r the t u f f d i f f e r s only in having a f iner-gra ined matrix and a prominant flow texture. The cobble breccia i s composed of rounded and spherical cobble-sized fragments of t u f f breccia in a t u f f -b recc i a matrix. This re la t i onsh ip makes the cobble breccia the youngest rock and suggests mul t ip le brecc iat ion events. An i r r egu l a r , conical breccia pipe i s defined by the three un i t s : t u f f , t u f f b recc ia , and cobble breccia. On the surface (Figure 2.13) th i s breccia pipe i s 2,000 feet long in an east-west d i rec t ion and 1,200 feet wide. A narrowing at depth, evident from the contacts at the 4,000 and 3,500 foot leve l s (Figure 2.13 and Appendix D) and cross-sections (Figures 3.5 and 3.7), 50 TABLE 2.4 FIVE LITH0L0GIES OF THE CASINO COMPLEX Name Average Age: K.Ar. in m.y. a Abbreviation* 3 Appendix C: Table(s) Figure(s) P late(s) Volcanics, undefined cobble breccia t u f f t u f f breccia not det. not det. not det. not det. Patton porphyry 71.2 C.VOLC. C.BRXX TUFF T.BRXX P.PPXX C.13 C.12 2.1 9 & 2.20 2.18 2.16 & 2.17 C IO & C . l l 2.14 & 2.15 2.18, 2.19 & 2.20 2.17 2.14, 2.15 & 2.16 2.13 a: fo r mineral analysed and errors in analysis see Table 2.5 and Figure 2.21. Mean age for Casino complex i s 70.3 + 2.4 m.y. b: used on geological maps, sections and tables. c: may include other units of Casino complex; young r e l a t i v e age i s not implied by pos it ion in tab le. 51 i l l u s t r a t e s the approximate conical shape of the brecc ia. The axis of the cone plunges steeply to the south. During ear ly work on the property a unit named Meloy quartz d i o r i t e ( P h i l l i p s and Godwin, 1970) was dist inguished in d r i l l hole logging but was not recognized in surface mapping. Subsequent petrographic examination suggested that th i s unit owes i t s d i s t i n c t i v e appearance to hypogene a l t e r a t i o n , in p a r t i c u l a r , the development of hydrothermal b i o t i t e , and that the rock was in fact f ine-grained quartz monzonite. Consequently, the ear ly terminology has been dropped. 2.5.3 Patton Porphyry (P.PPXX) Patton porphyry occurs i r r e gu l a r l y around the periphery of the main breccia pipe at Casino and i s known at the surface only around the northwest-ern margin of the pipe (Figures 2.2 and 2.13). The porphyry (Plate 2.13) i s characterized by d i s t i n c t i v e phenocrysts (4 mm. in average diameter) that account fo r about f i f t y percent of the rock and cons ist of abundant p lag io -c la se , and minor amounts of b i o t i t e , hornblende, quartz and opaque minerals. Phenocrysts of hornblende generally are d i f f i c u l t to recognize in hand specimen due to pa r t i a l a l t e r a t i o n . Although potassium feldspar phenocrysts occur very r a r e l y , sodium c o b a l t i n i t r i t e s ta in ing indicates abundant potassium feldspar in the matrix. Point count data are summarized in Tables C.10 and C l l (Appendix C), . and Figure 2.14 from thin-sect ions of r e l a t i v e l y unaltered specimens. However, composition of the matrix i s only approximate because of i t s m ic roc ry s ta l l i ne 52 100% QUARTZ 0 - 1 0 20 30 40 50 60 70 80 SO 100 100% ORTHOCLASE 100% PLAGIOCLASE MODE: QUARTZ: 15% COLOUR INDEX: 23 ORTHOCLASE: 15% AN: 42 PLAGIOCLASE: 9^5? K AR AGE BI: 71.2 MY HORNBLENDE: 8% HORNBLENDE/BIOTITE: 1,1 BIOTITE: 77-. PHENOCRYSTS: 53% OTHER: 5% MATRIX: . 47% FIGURE2.14: PATTON TOPPHYRY. POINT COUNT DATA IN TABLES C I O AND C.LI (APPENDIX 0. 53 PLATE 2.13: Patton porphyry of Casino complex (specimens: P2-320, l e f t , and COG 300, r i g h t ) . Specimen r i ght ha l f of p l a te , has potassium feldspar stained yellow with sodium c o b a l t i n i t r i t e . Disk i s 5 mm. in diameter (magnification x 3.6). See Figure 2.15. PLATE 2.14: Tuff breccia of Casino complex (outcrop near 4,000 S - 2,200 E). Note un i -form appearance. See Plates 2.15 and 2.16, and Figures 2.16 and 2.17. 54 texture and superimposed a l t e r a t i on . Compositions of phenocrysts and matrix are markedly d i f f e ren t in Patton porphyry. Phenocrysts have an overa l l composition of dac i te ; the matrix composition i s quartz l a t i t e , and the weighted average composition i s rhyodacite. A sketch of Patton porphyry, as i t appears in th in sect ion , i s shown in Figure 2.15. A mic roc ry s ta l l i ne matrix surrounds euhedral, s l i g h t l y zoned plagioclase l a th s , large anhedral, embayed quartz gra ins, and l o c a l l y kink-banded, subhedral, s l i g h t l y c h l o r i t i z e d b i o t i t e l a th s . Euhedral horn-blende phenocrysts, recognized by t he i r diagnostic diamond-shaped cross-sections,are t o t a l l y replaced by c h l o r i t e and opaque minerals. 2.5.4 Tuff Breccia (T.BRXX) Tuff b recc ia , the major unit of the main breccia pipe at Casino (Figure 2.13), i s white, where f re sh , and pale brown, where weathered (Plate 2.14). D i s t i n c t i v e , commonly very angular quartz fragments in a t u f f - s i z e d matrix give the rock a d i s t i n c t i v e appearance (Plates 2.15 and 2.16). Fragments up to one inch across are common whereas larger fragments are rare. Composition of fragments appear to be f ine-grained quartz monzonite of the Klotassin ba tho l i t h , but a l te ra t i on makes pos i t i ve i d e n t i -f i c a t i o n d i f f i c u l t . Triangular cav i t i e s up to 10 cm. long in the matrix of the t u f f breccia are a cha rac te r i s t i c feature. Thin-sections show the fragmental nature of the rock (Figure 2.16) but a l te ra t i on i s s u f f i c i e n t l y intense, in some cases, to make a c lear d i s t i n c t i on between fragments and matrix d i f f i c u l t (Plate 2.15). For th i s reason the PLATE 2.15: Tuff breccia of Casino complex (specimen P10-267) Note greenish fragment; outl ines are large ly obscured by a l t e r a t i on . Disk is 5 mm. in diameter (magnification x 3 6) See Plates 2.14 and 2.16, and Figure 2.16. PLATE 2.16: Tuff breccia of Casino complex (specimen P16-245) Note angular, fractured outl ines of many quartz grains Disk i s 5 ran. in diameter (magnification x 3.6). See Plates 2 14 and 2.15, and Figure 2.16. 56 100% QUARTZ TOTAL 100% ORTHOCLASE 100% PLAGIOCLASE 387 MODE: QUARTZ: . ORTHOCLASE PLAGIOCLASE: ]AC LITHIC : 5% : W, } = : W. ) VISUAL ESTIMATE FIGURE2.I7:TUFF BRECCIA. POINT COUNT DATA IN TABLE Cl? APPENDIX 0 . 57 summary of point count data in Table C.12 (Appendix C) i s par t ly incomplete and otherwise very approximate in nature. Tuff breccia i s 40 percent fragments that are mostly close to 1.2 mm. in diameter. The fragments are mainly quartz, some are fe ldspar, and in rare cases they are l i t h i c in nature. These fragments are surrounded by an ash-sized matr ix, 0.08 mm. in average grain diameter. The composition of the matrix i s not known because of thorough a l te ra t i on and f i ne grain s i z e ; i t i s assumed, however, to be more-or-less the same as the coarser f r ac t i on but perhaps containing less quartz. The overa l l composition of th i s breccia appears to be about 40 percent quartz and 60 percent fe ldspar, a composition corresponding to that of a r h yo l i t e or granite (Figure 2.17), assuming a high proportion of fe ldspar to be orthoclase. The fragmental character of th i s t u f f breccia unit i s not obvious in a l l specimens because of pa r t i a l ob l i t e r a t i on of fragment out l ines by a l t e ra t i on (Plate 2.15). Nevertheless the fragmental character of th i s un i t i s apparent in the f ractured, angular outl ines of quartz grains (Plate 2.16), occurrence of angular cav i t i e s and overal l p i pe - l i ke geometry i l l u s t r a t e d in Figures 2.13, 3.5 and 3.7). P h i l l i p s and Godwin (1970) describe th i s un i t as a microbreccia. P r io r to t he i r work i t had been ca l led a "quartz-eye" porphyry. 2.5.5 Tuff (TUFF) Tuff and t u f f breccia units are int imately re lated as shown in the cross-sect ion of the breccia pipe in Figure 3.5. Tuff i s a pale rock (Plate 2.17) very s im i l a r to t u f f breccia with the exception that i t has a 58 59 s l i g h t t rachy t i c texture and fev/er quartz fragments. The fragmental or microbreccia character of the rock i s only apparent in th in section (Figure 2.18). One mm. diameter fragments, accounting for about 20 percent of the rock, Table C.13 (Appendix C), are surrounded by a very f i ne ash-sized matr ix. On the assumption that fragments and matrix have the same composition, the rock i s composed of about 25 percent quartz, and 75 percent feldspar and other minerals. This composition i s s im i l a r to that of the t u f f breccia (Figure 2.17). Consequently, the two units are probably nearly equivalent chemically and are d ist inguishable only on a textura l basis. 2.5.6 Cobble Breccia (C.BRXX) Cobble breccia occurs near the edges of the main breccia pipe as i l l u s t r a t e d in Figures 2.13 and 3.3. It crops out only near 4030 S, 1800 E (Figure 2.13)and i t s general appearance at th i s l o c a l i t y i s that of a cobble "conglomerate" (Plate 2.18). Cobble breccia general ly has well rounded, almost sphe r i ca l , cobble-s i ze fragments in a t u f f breccia matrix (Plates 2.19 and 2.20). Local ly fragments are pebble-size and boulder-s ize. Spher ic i ty and angular i ty also vary widely. Rock types represented by the fragments include: sch i s t of the Yukon Metamorphic Complex, inequigranular quartz monzonite and f i n e -grained quartz monzonite of the Klotass in ba tho l i th , and Patton porphyry and t u f f breccia of the Casino complex. Sketches of th in sections (Figures 2.19 and 2.20) show the s i m i l a r i t y of the matrix to t u f f brecc ia ; the f ractured, angular out l ines of quartz 60 PLATE 2.19: Cobble b r e c c i a of Casino complex (specimen 4,030 S - 1,800 E). Note dark t o u r m a l i n i z e d fragment and l i m o n i t e a f t e r s u l p h i d e s concentra ted as blobs ( e s p e c i a l l y a t fragment boundar ies ) and d i s s e m i n a t i o n s . Disk i s 5 mm. i n diameter ( m a g n i f i c a t i o n x 1.7). See P l a t e s 2.18 and 2.20, and F igures 2.19 and 2.20. ; C o b b l e b l " e c c i a of Casino complex (specimen COG 302) Fragments i n c l u d e Patton p o r p h y r y , t u f f and t u f f b r e c c i a , Black area 1 S t o u r m a l i n i z e d . Disk i s 5 mm. i n d iameter (mag-nification x 3.6). See P l a t e s 2.18 and 2.19, and F igures 2.19 and 2. ^ u. 61 grains, in pa r t i cu l a r , support the comparison. The overal l composition, depending upon degree of fragment contamination, i s s im i l a r to t u f f breccia (Figure 2.17). Cobble breccia i s c l e a r l y in t rus i ve through both Yukon Metamorphic Complex and Klotassin batho l i th . Several periods of brecc iat ion are suggested by the occurrence of t u f f breccia fragments surrounded by a t u f f breccia matrix. Whether the net d i rec t ion transportation of fragments was up or down i s unknown because of the absence of marker un i t s . f 2.5.7 Undivided Volcanics (C.VOLC) The undivided volcanic un i t includes a var iety of volcanic rocks not dist inguished from each other during the regional mapping. In Figure 2.2 these rocks occur as plugs and dykes; flow rocks may occur but have not been i d e n t i f i e d . This unit l o c a l l y consists of rocks s im i l a r to t u f f and t u f f breccia but more commonly cons ist of porphyry. The porphyry i s generally paler in qbtour than the Patton porphyry and i s characterized by short, stubby, doubly-truncated quartz c r y s t a l s , and less abundant sanidine. Pervasive a l te ra t i on of th i s un i t i s common. Disseminated py r i te i s ub iqu i t -ous, and minor amounts of epidote, c a l c i t e , c l ay , s e r i c i t e and tourmaline also occur. LEAF 62 OMITTED IN PAGE NUMBERING. 63 CAPTIONS FOR FIGURES 2.15, 16, 18, 19 AND 20. FIGURE 2.15: Patton porphyry of Casino complex (specimen 2800S - 2200E) as sketched from a th in sect ion. Generally f lanks the main breccia pipe. See Plate 2.13. FIGURE 2.16: Tuff breccia of Casino complex (specimen PI6-140) as sketched from a th in sect ion. This un i t i s part of breccia pipe. See Plates 2.14, 2.15 and 2.16. FIGURE 2.18: Tuff of Casino complex (specimen COG 117) as sketched from a th in sect ion. This unit i s part of the main breccia pipe. See Plate 2.17. FIGURE 2.19: Cobble breccia of Casino complex (specimen PI4-286) as sketched from a th in sect ion. This un i t i s part of the main breccia pipe. See Figure 2.20 and Plates 2.18, 2.19 and 2.20. FIGURE 2.20: Cobble breccia of Casino complex (specimen PI6-214) as sketched from a thin sect ion. Note fragment of.Patton porphyry (P.PPXX). This unit i s part of the main breccia pipe. See Figure 2.19 and Plates 2.18, 2.19 and 2.20. 64 FIGURE 2.15. , F IGURE E.I6. FIGURE 2 .19 . FIGURE 2.20. 65 2.5.8 Origin of the Casino Breccia Pipe A suggestion has been made (Tempieman-Kluit, 1973) that volcanic rocks of Mt. Cock f ie ld , 13 miles to the southeast, are time equivalents of the Casino breccia pipe. Cer ta in l y , the breccia pipe resembles the neck of a volcano. Extrusive equivalents of the Casino complex are not known in the immediate v i c i n i t y of Patton H i l l but had they been present they could have been removed by erosion. The o r i g i n of breccia pipes i s f a r from c lea r . In 1891 Daubree proposed the word "diatreme" fo r pipes or volcanic necks formed by a d r i l l i n g process that u t i l i z e d the explosive energy of gas-charged magmas. Since then, most wr i ters seem to agree that breccia pipes are formed by an explosive mechanism (White et a l . , 1957; Carr, 1960) in conjunction with gas-f lux ing (Shand, 1916), f l u i d i z a t i o n (Reynolds, 1954), rock bursting and stope cave f i l l i n g (Gates, 1959; Cu r t i s , 1954; Perry, 1961; Norton and Cathles, 1973), and a t t r i t i o n on movement. The wr i t e r (Godwin, 1973) proposed that shock brecc iat ion might account f o r some of the features of breccias in the porphyry environment. An endo-genetic mechanism capable of creating a shock wave was assumed. It was noted that features associated with breccia bodies in the porphyry environment that ind icate a shock wave d e f i n i t e l y occured were not found, however, features that ind icate that a shock wave might have occurred are common. In the Casino area, features, other than the breccia i t s e l f , thought to be i nd i ca t i ve of shock include f racture cleavage (Plates 2.21 and 2.22), kink-banded b i o t i t e (Figure 2.15), and strained quartz (Figure 2.19). There i s the added p o s s i b i l i t y that f racture cleavage represents " s p a l l " produced by shock 66 PLATE 2.21: Fracture cleavage in inequigranular quartz monzon-i t e (specimen PI5-215) of Klotassin batho l i th near contact with the main, eastern Casino breccia pipe. Note mu l t i p l e , pa ra l l e l fractures concentrated in quartz grains. See Plate 2.22. Disk is 5 mm. in diameter (magnification x 3.0). PLATE 2.22: Fracture cleavage in inequigranular quartz monzon-i t e (specimen PI5-215) of Klotassin batho l i th near contact with the main Casino breccia pipe. Note pa ra l l e l f ractures v i s i b l e from macro (Plate 2.21) to microscopic scale above. 67 metamorphism or , at l ea s t , sharp f ronted, very high stress disturbances. Other interpretat ions have been made, notably by A l len (1971), Si 11itoe and Sawkins (1971), and Norton and Cathles (1973). Thus, o r i g i n of the Casino breccia pipe could be connected with an explosive event perhaps caused by hydrothermal so lut ions. The close spat ia l re la t ionsh ip between breccias and porphyry copper deposits i s well documented (Lowell and Gu i lber t , 1970). A descr ipt ion of what i s enta i led in an explo-s ion, however i s e s sen t i a l . An explosion i s an extremely rapid transfer of stored or potent ia l energy. Once explosion has been i n i t i a t e d the immediate re su l t i s develop-ment of a reaction zone around the s i t e of i n i t i a t i o n , by propagation of a compressive wave ca l l ed an explosive wave. Two d i s t i n c t types of explosive wave are recognized, def lagrat ion and detonation. Deflagration waves propagate at low ve l o c i t i e s of a few centimeters per second to a few meters per second. They have low shattering power unless strongly confined. Detonation waves propagate at a high ve loc i t y that i s always higher than the ve l oc i t y of sound in the medium through which the wave i s t r a v e l l i n g . High pressures are developed. A detonation wave i s , in f a c t , a shock wave. Hydrothermal explosions are the resu l t of energy released by the rapid expansion of hot water. Muff ler et a l . (1971) explained the o r i g i n of craters in Yellowstone Park by hydrothermal explosions. These craters , up to 4,000 feet in diameter and 200 feet deep, are produced when water contained in near surface rock at temperatures as high as 250°C. flashes to steam _3 y i e l d i ng 1.5 to 4.0 c a l . cm of energy that v i o l en t l y disrupts the confining rock. They note that " th in sections of breccia show no features that can be at t r ibuted to shock...". 68 In a deeper confining environment, the s i tua t ion might be d i f f e r en t . Carr (1960) and Ca r g i l l (1972, pers. comm.) note that in some porphyry copper environments dykes of porphyry merge upward into breccias that include fragments of both porphyry and country rock. Maars, i n the Hopi Butte area are f i l l e d with tu f f -b recc i a that grade downward to lamprophyre dykes (Shoemaker et a l . , 1956; Wil l iams, 1936). Curt i s (1954) describes andesite dykes from Ca l i f o r n i a that change progressively upward from non-vesicular andesite to to microvesicular andesite to andesite brecc ia. In Appendix G the w r i t e r examines the amount of hydrothermal energy that could be ava i l ab le in the porphyry environment, to determine!if the ava i lab le energy i s s u f f i c i e n t to comminute and transport rock, thus forming breccia rock. A fu r ther purpose of these energy considerations i s to invest igate the p o s s i b i l i t y that diatreme formation may be, in part , a shock phenomenon. The f i r s t approach in Appendix G (sect ion.G. l ) considers the maximum energy that might be ava i lab le at the instant a magma c r y s t a l l i z e d and, as a consequence, vesciculates exsolving a l l i t s water. Work, in th i s environ-ment, i s done rap id ly by volume expansion. Calculat ions in Table G.2 suggest that from one gram of water the work energy i s 57.7 c a l o r i e s , and from one cubic centimeter of rock exsolving 8 percent water the work energy i s 11.5 c a l o r i e s . Suppose that th i s work from ve s i c i cu l a t i on i s absorbed in crushing the rock and giv ing i t motion. Assume, furthermore, that the rock i s cons id-ered incompressible so that no energy i s used i n changing the volume of the rock. The energy required to comminute quartz under s t a t i c conditions so there are equal weights of larger and smaller pa r t i c l e s around one centimeter i s 0.5 ca lor ies per cubic centimeter (cf. Muff ler et a l . , 1971). The energy ava i l ab le f o r motion i s , thus, about 11 ca lor ies per cubic centimeter. From 69 ca lcu lat ions in Table G.3 (Appendix G), i f no other energy absorption occurred, th i s energy could l i f t one gram of rock 6,160 feet v e r t i c a l l y above i t s s ta r t ing point and impart to the rock an i n i t i a l ve l oc i t y of 0.303 km./sec. This ve l oc i t y i s about one-sixteenth the ve loc i t y of sound in rock (approx-imately 5 km. per second). Therefore, i t i s highly un l i ke l y that the above vesc icu lat ion mechanism w i l l produce a shock wave .in the system. There seems l i t t l e doubt, however, that energy i s ava i lab le to f racture and move rock^ — probably explos ively by comparison of the maximum ava i lab le energy above (11.5 ca lor ies per cubic centimeter) to the maximum value (4.0 ca lor ies per cubic centimeter) calculated by Muff ler et a l . (1971) to have produced the craters at Yellowstone. The second approach in Appendix G (section G.2) considers the energy that might be ava i lab le from the expansion of water, co l lec ted at the apex of a magma, into a crack propagated in country rock ahead of the magma and co l lected water. The crack is formed by pressures and attendant wedging act ion of upward r i s i n g magma (Figure G.2: Appendix G). The expansion of the water vapour in such a crack releases energy that might be s u f f i c i e n t to form a shock wave in the vapour. Transmission of the stress from th i s wave f ront across an interface to a medium with much more r i g i d i t y produces the unusual feature described by Rinehart (1960) where the stress of the transmitted pulse is approximately twice the stress of the inc ident wave. The stress along the crack surface i s , therefore, l i k e l y to be extreme and rupture and transport of material probably takes place. Crack propagation and water expansion could eas i l y be a r epe t i t i v e and, thus, represent an e f fec t i ve " d r i l l i n g " process for diatreme development. It seems l i k e l y that the Casino breccia-pipe represents the subvolcanic 70 neck of a volcano emplaced through the Yukon Metamorphic Complex and the Klotass in ba tho l i th . Emplacement of a plug (?) of Patton porphyry was followed by development of the Casino breccia pipe cons i s t ing of t u f f b recc ia , cobble breccia and t u f f . The breccia-pipe emplacement was explos ive. Energy for the explosion came from a hydrothermal source derived by ve s i cu l a -t ion of a r h y o l i t i c magma. Energy considerations suggest that the character of the explosion was def lagrat ion but l o c a l l y shock waves could have developed. Regardless, the ca lcu lat ions in Appendix G show that energy and a mechanism for breccia formation are ava i lab le in the emplacement of wet, g ran i t i c magmas. 71 2.6 RADIOMETRIC AGE DETERMINATIONS 2.6.1 Samples Studied Ten samples from the Casino area have been dated by the potassium-argon method. Samples include: two from the mineral ized zone of the Casino complex, seven g ran i t i c rocks from the Klotassin ba tho l i t h , and one sample of gneiss from the Yukon Metamorphic Complex. The two samples from the mineral ized Casino complex were d r i l l core from the hypogene zone where r e l a t i v e l y unaltered b i o t i t e was ava i l ab le . Samples of g r an i t i c rocks and gneiss were co l lected in the f i e l d with the aid of a sledge hammer to avoid, as much as poss ib le, the deeply weathered coatings on outcrops. One sample (FJ67-122-1) was co l lected by Findlay (1969) and analysed by the Geological Survey of Canada. The remaining nine samples were analysed in the potassium argon laboratory of the Univers i ty of B r i t i s h Columbia. Techniques employed in separating b i o t i t e and hornblende, and analyses of potassium and argon contents of these minerals are described in deta i l by White et a l . (1967). In b r i e f , b i o t i t e i s co l lected roughly from crushed rock, in the overflow from a ve r t i c a l hyd roc la s s i f i e r . Hornblende i s concen-trated from the residue in the bottom of the hydroc la s s i f i e r by heavy media separation using bromoform. B i o t i t e i s cleaned using gravity*separat ion in bromoform. Hornblende and b i o t i t e are cleaned further with the aid of hand magnets, electromagnetic separation and hand p ick ing. Potassium analyses are run on a quadruplicate s p l i t with a Baird-Atomic KY or KY-3 series flame photometer. Argon analyses are determined with an AEI MS-10 mass spectrometer 72 modified to permit rap id , s t a t i c , i sotop ic r a t i o measurements on a small quantity of gas released by fusion of b i o t i t e or hornblende by an induction furnace. 2.6.2 Radiometric Ages Potassium-argon ages from rocks in the Casino area are l i s t e d in Table 2.5 and shown graphical ly in Figure 2.21. The Casino complex, dated at 70.3 a + 2.4 b m.y. c l ea r l y represents the youngest event recorded in the samples studied. The 70.3 m.y. date, although near the Cenozoic-Mesozoic boundary at 65 m.y. (Obradovich and Coleman, 1974), i s Late Cretaceous, in contrast to the Early Tert iary age assigned by previous wr i ters (e.g. Templeman-K l u i t , 1973). The Klotass in batho l i th su i te in the Casino area has an average mid-Cretaceous age of 99.3 a + 3.6 b or + 6.4 C m.y. (Figure 2.21). The ca l cu la t i on of th i s average age includes the age obtained from gneiss of the Yukon Metamorphic Complex because the sample of gneiss was taken near the contact with Klotass in granodior ite (Figure 2.2) and i t s radiometric age was reset at the time of emplacement of the batho l i th for elsewhere Yukon Metamorphic Complex dates (age of metamorphism?) are T r ia s s i c or Jurass ic (175 to 187 m i l l i o n years, Tempieman-Kluit, 1973). A l l age r e su l t s , whether from hornblende or b i o t i t e are with in two standard deviations of the mean for the Klotass in ba tho l i th . Analyses by the Geological Survey of Canada of a: ar ithmetic mean of 10 age determinations (Figure 2.21). b: average ana ly t i ca l error or + associated with an age determination i s the summation of errors based on resu l t s obtained on inter!aboratory standards and ca l i b r a t i on s . In general, these l im i t s range between 3 and 4 percent of the associated apparent.age for the analyses car r ied out in th i s study ( J . Harakal, 1974, pers. comm.). c: two standard deviations of 10 age determinations (Figure 2.21). TABLE' 2.5 POTASSIUM-ARGON ANALYTICAL DATA > rad c  4 U Ar total 4 0 Ar,rad. (10 _ 5cc STP/g) ( 4 0 Ar rad.) 40 K) (40 Ar) Apparent age Specimen No.a Unit Rock Type Mineral %K t Sb (4°K>x 10-3 (36 Ar) x 105 (36 Ar) x 103 and Assianed error CP-2-69 Casino Complex Patton Porphyry Bigtite 6.55 + .07 0.828 1.883 4.246 3.249 . 1.666 71.2 + 2.6 m.y. CP-25-69 Casino Complex Secondary Biotite Biotite 7.23 + .03 0.817 2.026 4.140 3.122 1.581 69.5 + 2.2 m.y. COG 13 Klotassin Batholith Porphyry Dyke Hornblende 0.620 + .005 0.783 0.250 5.967 1.687 1.285 99.3 + 3.6 m.y. COG 151 Klotassin Batholith Inequigran-ular Quartz Monzonite Biotite . 6.42 + .03 0.959 2.673 6.151 10.348 6.635 102.3 + 3 m.y. COG 243 Klotassin Batholith Fine grained Quartz Monzonite Biotite 6.18 + .01 0.959 2.509 5.998 . 10.361 6.481 99.9 + 3.0 m.y. COG 261 Yukon Meta-morphic Complex Biotite Gneiss Biotite 6.72 + .04 0.955 2.537 5.578 10.467 6.114 93.0 + 3.0 m.y. COG 262 Klotassin Batholith Klotassin Granodiorite Biotite Hornblende. 6.80 + .03 0.602 + .002 0.948 0.838 2.786 0.241 6.052 5.919 8.275 2.395 . 5.282 1.691 100.7 + 3.0 m.y, 98.6 + 3.0'm.y. COG 263 Klotassin Batholith Leucocratic Granodiorite Biotite 6.39 + .01 0.945 2.591 5.991 7.824 4.963 99.7 + 3.0 m.y. COG 264 Klotassin Batholith Quartz Monzonite Porphyry Biotite Hornblende 6.64 + .06 0.752 + .006 0.952 0.711 2.834 0.307 6.306 6.025 8.594 ' 1.167 5.693 0.988 104.8 + 4 m.y. 100.3 + 3 m.y. GSC 67-45d Klotassin Batholith Klotassin Granodiorite Hornblende - - - - - 99.0 + 6.0 m.y. GSC 67-46d Klotassin Batholith Klotassin Granodiorite Biotite - - - - - - 95.0 + 5.0 m.y. a: b: c: for location see Figure 2.2. Potassium analyses by J.E. Harakal and V. Bobik using KY or KY-3 flame photometers; S 1s one standard deviation of quadruplicate analyses. Argon analyses by J.E. Harakal and C. Godwin using MS-10 mass spectrometer; constants used 1n model age calculations: Xe => 0.585 x 10-1°/year XB = 4.72 x 10- 1 0/year, 4 0 K/K = 1.181 x 10' 4. Analyses of sample FJ 67-122-1, Wanless et a l . , 1970, p.27, Geological Survey of Canada. CO or < >-o CD < O CL O h -o CO 65 +-70 75 4-80 85 90 4-95 4-100 105 +-I 10 CASINO COMPLEX >-ce X a. ce o a. cn i C J a. o CC < a z o o Ul CO cn to i -in OJ a. o KLOTASSIN BATHOLITH UJ z o — N W ° CM tr N O < o < — N 3 O ui tr z < — z> o Ul z o N O * § s >- ° CO o H id O Z - CM Ho" 3 o: CM O ID - CM Z w Ul H Ct to o <o — CM IS z o < — CC 15 Ul >-o >-CC >-X a. CC o CL NOTES1 a= ar i thmet ic mean b' average analyt ica l e r r o r c; two standard d e v i a t l o m YUKON METAMORPHIC COMPLEX co </> Ul Z o 10 CM <S o O 99.3°. s.e* 99.3°i 6.4C 99.9 105.? c -F I G U R E 2.2I: IS0T0PIC AGES FOR CASINO COMPLEX, KLOTASSIN BATHOLITH AND YUKON METAMORPHIC COMPLEX 75 sample FJ67-122-1 (Wanless, et a l . , 1970) show good agreement with analyses by the geochronology laboratory of the Univers i ty of B r i t i s h Columbia and are included in the ca lcu la t ion of the average age. 2.6.3 Discussion of Model Age and Geological Evidence for Age Templeman-Kluit argues that the model age of 100 m.y. for the Klotass in batho l i th does not represent a true age of emplacement. He considers the model age to : " ind icate a thermal event that modified the Klotass in ba tho l i t h " and c i te s two l ines of evidence suggesting that the granodior i te of the Klotass in batho l i th i s ear ly Mesozoic or older ( i b i d . , p. 34): "The rock [granodior ite] post-dates depos i t ion, but not the l a s t regional shearing and r e c r y s t a l l i z a t i o n , of the enclosing metamorphic rocks. This shearing and metamorphism on the l im i ted radiometric data presently ava i lab le i s probably of Late T r i a s s i c age. Therefore, the granodiorite i s T r i a s s i c or o lder. The second l i n e of reasoning is s t ra t i g raph i c ; a large proportion of the boulders in the Laberge conglomerate with in and very close to A i sh ih ik Lake map-area are of hornblende granodior ite and f o l i a t ed granodior ite and granodiorite invaded by pink quartz monzonite that is 1 i t h o l o g i c a l l y l i k e the hornblende granodior ite. As the Laberge i s Early Jurass ic and younger the granodior ite must be T r ia s s i c and/or o lder. Two potassium-argon ages outside the project a r e a ' . . . one on granodior ite boulders from the Laberge conglomerate and one on hornblende granodior ite l i k e that of the Klotass in Batho l i th , also support a T r i a s s i c or older age." Intrusive-metamorphic rock contacts, however, general ly pa ra l l e l f o l i a t i o n , and he notes (p. 34) that: "The contact between granodior i te and metamorphic rocks seen on a large is land in A i sh ih ik Lake dips s teeply, and i s pa ra l l e l with the f o l i a t i o n of the int rus ive and metamorphic rocks . " His f i r s t l i n e of evidence suggests that the Klotass in batho l i th i s the same age as, or older than, the regional metamorphism and implies that 76 the thermal event of the batho l i th may coincide with the thermal event of the metamorphism. In the Casino area, however, the Klotass in batho l i th i s younger than the regional metamorphism because g r an i t i c rocks cross-cut and d i so r ient the fab r i c of the metamorphic rocks. For example, blocks of s ch i s t in the agmatite zone in the northeast corner of Figure 1.2 are engulfed by hybrid quartz monzonite. Radiometric ages are in accord with th i s re la t ionsh ip . The age from gneiss (sample COG 261) near the grano-d i o r i t e contact is concordant with the granodiorite and discordant with Jurass ic radiometric dates from elsewhere in the Yukon Metamorphic Complex. Tempieman-Kluit's second l i n e of reasoning concerning the 199 m.y. potassium argon age on hornblende of a granodiorite boulder from the Laberge conglomerate i s no more compelling because the Laberge conglomerate area i s more than 100 miles southeast of the Casino area. The 199 m.y. o ld boulder corre lates with the 140 to 223 m.y. old Ruby Creek Batho l i th that occurs in the A i sh ih i k Lake area (Figure 1.1) east of the sample s i t e f o r the conglomerate. If the Ruby Creek Bathol i th i s twice as old but 1 i t ho l og i ca l l y s im i l a r to the Klotassin batho l i th the granodiorite boulder age i s resolved. Indeed, Tempieman-Kluit's observations at A i sh ih ik Lake (above) suggest that the thermal r e c r y s t a l l i z a t i o n of the Yukon Metamorphic Complex and intrus ion of the Ruby Creek Bathol i th may be synchronous. The assignment of a Ter t i a ry , Eocene (?) age (Templeman-Kluit, 1973) to the Coffee Creek granite (Figure 2.1) seems doubtful mainly because mega-scop i ca l l y th i s granite resembles the mid-Cretaceous inequigranular quartz monzonite (Figure 2.2) that has an absolute age of 101.3 m.y. (Figure 2.21 and Table 2.5). The Coffee Creek granite i s more equigranular than the 77 inequigranular quartz-monzonite, but both are medium- to coarse-grained rocks with abundant quartz, orthoclase and minor amounts of b i o t i t e . Occurrence of Coffee Creek gran i te, shown in Figure 2.1, has no known, well defined contacts with rocks of the Klotassin ba tho l i th . Therefore, on the basis of l i t ho l o gy , texture and d i s t r i bu t i on , i t seems l i k e l y that the Coffee Creek granite belongs to the mid-Cretaceous Klotass in batho l i th su i te . Because of previous arguments the c i r c u l a r intrus ions of Coffee Creek granite into the Yukon Metamorphic Complex (Figure 2.1) are further evidence of the intrus ion of the Klotassin batho l i th into the older metamorphic terrane. 2.6.4 Igneous and Metallogenic Events near 70 and 100 M.Y.'s i n Canadian Co rd i l l e ra Evidence presented in the foregoing section leads to the conclusion that the Klotass in batho l i th i s about 100 m.y. old and the Casino complex i s about 70 m.y. o l d . The 100 m.y. age fo r the Klotass in batho l i th corresponds with the age of numerous other in t rus i ve bodies throughout the Canadian c o r d i l l e r a . From a l l a va i l ab le , r e l i a b l e potassium-argon ages, Christopher (1973) shows that a concentration occurs near 98 m.y. Examples of plutons of about th i s age have a widespread geographic d i s t r i b u t i o n . White et a l . (1968), defined the l a t e -Lower Cretaceous (c i rca 100 m.y.) as an important time fo r the formation of mineral deposits in B r i t i s h Columbia although his evidence was only the Boss Mountain mine occurrence. A number of deposits and showings in both B r i t i s h Columbia and Yukon Ter r i to ry are now known to be of s im i l a r age. Examples are 78 the Lost Creek molybdenum deposit, southern B r i t i s h Columbia, and the tungsten skarns in the Selwyn Range in the Yukon and Northwest T e r r i t o r i e s , Skarns at the contact of Yukon Metamorphic Complex rocks and Klotass in g r an i t i c rocks (Figures 1.2 and 2,1) are of th i s age. These skarns are c a l c - s i l i c a t e rocks of complex mineralogy, but commonly contain p y r i t e , p y r r ho t i t e , minor amounts of cha lcopyr i te , and traces of molybdenite and s chee l i te . The 70 m,y. age for the Casino deposit corresponds c l o se l y to ages of numerous porphyry deposits and re lated intrus ives in the Canadian c o r d i l l e r a . Table 4.1 and Figures 4.1 and 4,2 ind icate that a number of porphyry deposits occur in the range from 60 to 85 m.y. These deposits, with the exception of Casino, a l l occur with in the Intermontane Belt (Figure 4.1). A northwesterly extension of th i s be l t fo r less than 100 miles pa r a l l e l to the tectonic trend would include the Casino deposit. The Omineca Be l t , adjacent to and east of the Intermontane Belt (Figure 4.1), y i e l d s s im i l a r ages only from metamorphic rocks such as the 69 m.y. potassium argon age from the Mai ton Complex (Wanless, et a l . , 1967, 1970 and 1972) and 61 m.y. potassium argon dates from the Shuswap Complex (Wanless et a l . , 1968). A 67 m.y. potassium argon age (Wanless et a l . , , 1972) has a lso been obtained from sch i s t in the Yukon C r y s t a l l i n e Platform (Figure 4.1). The Coast C r y s t a l l i ne Be l t , adjacent to and west of the Inter-montane Belt (Figure 4.1), y i e ld s 64 to 70 m.y. potassium argon ages only from g ran i t i c rocks not knov/n to be associated with m ine ra l i za t i on . Casino deposit, therefore, correlates in age with other porphyry deposits with in the Intermontane Be l t , The Casino deposit i s of the "s imple ' 1 type ( c f . , Sutherland Brown, 1969) and l i k e other simple porphyry deposits seems to re la te to a Late Cretaceous to ear ly Tert iary metallogenic epoch (Christopher, 1973) that had been defined previously for central B r i t i s h Columbia by Carter (1970) and for south-central Alaska by Reed and Lanphere (1969). 79 CHAPTER III MINERALIZATION AND ALTERATION OF THE CASINO DEPOSIT 3.1 INTRODUCTION Recent studies of a large number of porphyry-type deposits have resulted the common recognit ion of large sca le , systematic mineral d i s t r i bu t i on and s t ructura l patterns (e.g. Lowell and Gu i lbe r t , 1970) related to minera l i zat ion Such zoning at the Casino deposit i s apparent f o r assemblages of opaque and s i l i cate-carbonate a l te ra t i on minerals. These patterns are discussed in r e l a t i on to geology, assay information, whole rock and s o i l geochemical data, and the resu l t s of airborne and ground magnetic surveys. Mapping techniques used to describe the a l te ra t i on are unique i n some respects, and are described in Appendix A (cf. Blanchet and Godwin, 1972). Hypogene and supergene a l t e r a -t i on zones are discussed separately. 3.2 HYPOGENE ALTERATION AND ZONING 3.2.1 Introduction Hypogene zoning at Casino i s re lated to universal models that group the 80 mineral assemblages formed by hydrothermal a l te ra t i on into s i l i cate^carbonate minerals, su lphide-oxidemative minerals, and mode of occurrence. This sect ion deals with d i s t i n c t i on s between various a l t e ra t i on zones and t he i r re la t ionsh ips to s i g n i f i c an t geo log ica l , geochemical and geophysical var iab les . Such d e f i n -i t i o n and comparison are s i gn i f i c an t not only to the genesis of the deposit but also to explorat ion of the Casino deposit or other s im i l a r deposits. The p o s s i b i l i t y that a l te ra t i on zoning could form regular patterns at Casino was suggested by apparent gross metal zoning i n the area and the recog-n i t i o n that the deposit was of the porphyry type. A generalized metal zoning was indicated at Casino by the presence of gold?-tungsten placer deposits near Patton H i l l (Figure 2.2, Canadian Creek), and by the occurrence of l ead -z inc -s i l v e r veins at a greater distance from Patton H i l l (Figure 2.2, Bomber a d i t ) . The porphyry deposit character was recognized from surface exposures of a l tered breccia,, porphyry and leached capping containing l imon i te - r i ch boxwork textures that indicated the former presence of disseminated and vein sulphides. Ear ly diamond d r i l l holes in the Patton H i l l area confirmed th i s i n terpretat ion by reveal ing the presence of a supergene zone below the capping, and a hypogene zone containing the sulphide minerals, p y r i t e , cha lcopyr i te, molybdenite and bornite as disseminations and veins in varying but economically important amounts. A l te ra t i on typ i ca l of porphyry deposits was also apparent in the d r i l l core. Quartz-sulphide veins surrounded by a l terat ions envelopes were common. Some sections were notably "bleached", due to abundant secondary s e r i c i t e and c lay minerals, compared to darker sections that were e i ther less a l tered or a ltered by the development of secondary b i o t i t e and magnetite. The major problem in studying zonal patterns associated with the Casino deposit was the absence of good surface outcrops. Detai ls of systematic changes 81 in veins and cross^cutting vein systems have recognized usefulness in the study of zoning patterns in porphyry type deposits (Meyer and Hemley, 1967; Drummond and Kimura, 1969). To make such a study excel lent exposures such as those in an open p i t or in underground workings are required. At Casino, because adequate exposures were not present, the best data were from 36,922 feet of s p l i t diamond d r i l l core from 49 d r i l l holes. The remaining information had to be gleaned from 17,481 feet of rotary d r i l l chips,from 35 d r i l l holes and from rubbly surface outcrops or f l o a t . A second problem, common to most studies, was that a l te ra t i on had to be defined and described cons i s tent ly in the f i e l d . I t was found that with equip-ment no more sophist icated than a binocular microscope, needle, pencil magnet and acid bo t t l e , the a l t e ra t i on assemblages of an outcrop or specimen could be i den t i f i ed in base camp. However, where supergene a l te ra t i on e f fect s were present i n the rocks they required pa r t i c u l a r l y careful interpretat ion when determining the probable o r i g i na l hypogene a l te ra t i on fac ies or sulphide-oxide-native mineral assemblages. Consistency in recording information (1) from the ent i re deposit and (2) o r i g inat ing from several geologists was aided in part by using mapping techniques out l ined in Appendix A and in part by development and use of the "Geolog System" (Blanchet and Godwin, 1972). The "Geolog System" uses an 80-column format for recording coded geological features. Codes and columns aid consistency and interpretat ion because codes enable an observation to be made quick ly and columns serve as a check l i s t so an observa-t ion i s always made. The 80-column format, of course, i s su i tab le for key-punching for computer appl icat ions. A l te ra t ion features that were described rout ine ly were selected from a model modified from that of Lowell and Gui lbert (1970). 82 Comparisons of 39 var iables (12 a l t e r a t i o n , 9 l i t h o l o g i c a l , 7 geochemical and 11 geophysical) were made by quantifying these var iables f o r 125 square c e l l s , each 400 feet to the s ide, that blanket the area over and about the Casino deposit (Appendix F). These var iables are described in Appendix H. In add i t i on , assay data from d r i l l holes with in the 125 c e l l s were compiled as percent copper, percent molybdenite, and copper equivalent (%Cu + 2 x %MoS2). A l l data were recorded in a computer f i l e and access was f a c i l i t a t e d by use of various computer programs that provided the fol lowing output: 1. histograms, p robab i l i t y p l o t s , means and standard deviat ions of raw and transformed (log 10 and arcsine) data. 2. contoured maps showing the d i s t r i bu t i on of var iables over the 125 c e l l s . 3. co r re la t ion coe f f i c i en t s between most pairs of va r iab les . 4. trend surface printout-maps of selected var iab les . S i gn i f i can t computer output i s presented in the fol lowing sect ions. Quantita-t i v e treatment of a l t e ra t i on was based on the models described below. 3.2.2 Quant i f icat ion of Hypogene A l te ra t ion Zoning Lowell and Gui lbert (1970) proposed three idea l ized models to describe the generalized d i s t r i bu t i on of various features of hypogene minera l i zat ion i n and around porphyry copper-molybdenum deposits. These models are concerned with: (1) d i spos i t i on and in tens i ty of ve in , envelope, and disseminated or pervasive minerals, (2) zoning of s i l i c a t e - carbonate mineral f a c i e s , (3) zoning of sulphide - oxide - native mineral assemblages. Representation of 83 zonal patterns was modified somewhat to permit quant i tat ive treatment by numer-i c a l symbols that progress in a l l models from a peripheral 0 or 1 to a centra l 8 or 9, Other s l i g h t changes were made to incorporate suggestions by Rose (1970), Meyer and Hemley (1967), and Meyer et a l . (1968). Blanchet and Godwin (1970) suggested that at the Casino deposit mode of occurrence of s i l i c a t e -carbonate minerals might zone analogously to opaque minerals. Consequently, the fo l lowing three features were examined and recorded in a systematic fash ion, wherever poss ib le: 1. degree of dispersion of s i l i c a t e - carbonate and sulphide - oxide -native mineral assemblages (Figure 3.1 and Table 3.1), 2. a l t e ra t i on fac ies based on the occurrence of s i l i c a t e - carbonate minerals (Figure 3.2 and Table 3.2), 3. mineral assemblages based on the occurrence of sulphide, oxide and native minerals (Figure 3,3 and Table 3.3). The approach used to record these features in a quant i tat ive manner i s described in Tables 3.1, 3.2 and 3.3 respect ive ly , and corresponding Figures 3.1, 3.2 and 3,3. Because the locations of cer ta in geometric forms of "ore deposits" are known with respect to other a l t e ra t i on zones a comprehensive knowledge of, zoning can provide useful information to guide deta i led explorat ion. 3.2.3 Hypogene A l te ra t ion Zones at Casino Figure 3.5 shows hypogene a l te ra t i on zones based on surface mapping. The pattern i s somewhat obscured by superimposed supergene a l t e r a t i on . Data for 84 i ll«n - VtlM Figure 3.1. Model fo r mode and degree of dispers ion of minera l i zat ion in porphyry deposits ( a f te r Lowell and Gu i l be r t , 1970). 1 indicates a very low degree of dispers ion of a mineral - that i t occurs in veins almost e n t i r e l y . 9 ind icates a very high degree of dispers ion - that i t occurs pervas ively or very wel l disseminated i n the wal l rock. See Table 3.1 f o r de f i n i t i on s and d e t a i l s . 85 TABLE 3,1 MODE AND DEGREE OF DISPERSION OF MINERALIZATION (AFTER BLANCHET AND GODWIN, 1970), V, E, D and P re fer to the modes of occurr-ence; ve ins, envelopes, disseminations and pervasive, respec*-t i v e l y . See Figure 3.1 for model. MODE OF OCCURRENCE OF OPAQUE MINERALIZATION Veins and macro-veins including stockwork and gouge. Veins, veinlets, fracture f i l l ings & minor dissem-inations. Veinlets and soma disseminations. Veinlets with Moderate disseminations. Veinlets and dissem-inations more or less equal. Disseminations and moderate veinlets. Disseminations with some veinlets. Mostly dissemination with minor veinlets or micro-veinlets. Disseminations. I DEGREE OF I: DISPER-j SION v l v D << V 2 E < V or P « V 2 < V 3 E = V or P < V D < V 4 E > V or P <_ V D = V 5 E or P = V D > V 6 P < E or P > V D > V 7 P = E or P > V D » V 8 P > E or P » V D 9 P MODE OF OCCURRENCE OF SILICATE-CARBONATE MINERAL ASSEMBLAGES veins veins and moderate envelopes or minor pervasive envelopes and veins equal or veins and moderate pervasive envelopes with some veins or pervasive with moderate veins envelopes or pervasive equal to veins pervasive with some envelopes or moderate veins pervasive and envelopes or with some veins pervasive with some envelopes or minor veins pervasive 86 / \ / / • > - — _ \ t \\\\ F r t i h Rock ,2/3,4/5/6, ! ' / / / I// /' Propylitic MonlmorlHoHKc Inlertnadiott Argllli*. KF -Stoblff Seriellic I Phyllte) onced Aigillic V / A / \ WW Ml/ I - P o t O I M C - C M o r I - P o t o » » l c Figure 3.2. Model showing zoning of s i l i ca te -carbonate a l t e r a t i o n fac ie s i n porphyry deposits (after Lowell and Gu i lbe r t , 1970). Note that numbers increase inwards toward the deep core, as in Figure 3.1. Compare a lso with Figure 3.3. See Table 3.2 f o r de t a i l s and d e f i n i t i o n s . TABLE 3.2 SILICATE-CARBONATE ALTERATION FACIES IN PORPHYRY DEPOSITS (Blanchet and Godwin, 1972). See Figure 3.2 fo r model. A l t * ration r»ci . . Quarts Q Z M u i -cevit* Serlcite] MU,MS C U / i CY Kaolin ktontrrcc-l Chlorite C L Epidot* E P Carbon' att»» Froah Rock Propyllrte Montmorillonlde lnt«rm«d iat« KT - StabW Sorlcitic (•Phyllic) Advanced Argillic Po*-»»»ic •Chlori-Potia»ic* SJicic (Quarts Flooding) and/or and/or and/or and/or \ l t y • /j 1 U U ( •> s ? Ori j .B t ' 0 I I /I \ \ S \ \ / • / I I I y ',' ' y y)\ '"A y V X y J J < '/ " A B y y y*\ Z E S i d . H I . . A B - A l b i t . Z E - Z . o U l . ( . ) \ \ /; •[ 1 T O tovirm»lin» • J p p 3 pyrophyllit* AH« 1 • r.hydrlto commonly present fe moderate » f f infrc^ucr.ily present I. minor • y 87 i I I . i I i 1 A V / ^ 3-N 5-V-I I I I / I J i » i A I-i I *-' • / • • A ! +4f l ' ! 1 i 4~yL - P e r i p h e r a l Shell - L o « Pyri le Shell - P y r i u Shell -Low Cradt Core - D e e p Core • - D e e p Ring Figure 3.3. Model f o r sulphide, oxide and native mineral assemblages i n porphyry deposits (a f ter Lowell and Guibert, 1970). Note that numbers increase inwards toward the deep core, as in Figures 3.1 and 3.2. See Table 3.3 f o r de ta i l s and d e f i n i t i o n s . TABLE 3.3 SULFIDE, OXIDE AND NATIVE MINERAL ASSEMBLAGES (Blanchet and Godwin, 1972), See Figure 3.3 fo r model. M i n e r a l i z a t i o n Zones P y r i t e P Y C h a l c o -pyri te C P Molyb-denite Wol f rami te CoveLlite Digenite W T . C V . D G Chalcoc i te C C Hematite Magnet i te G a l e n a -Sphalerite CK (Gold-S i lver occurrence! P y r r h o t i t e Native Copper Shroud P e r i p h e r a l Shel l Low P y r i t e Shel l Deep Ring P y r i t e Shel l O r e Shell L o w - G r a d e C o r e Deep C o r e i i /./A / / / / / / , s / / / \ \ \ / / / / ) / / / / / / / ' J J\ y y\ / i i yi i i /i /y\ i /// 1/ A v i i / (diagnostic U ahtir.ti.int i ir" cquer.t". y p r e s t n c i : substantial Jus-iatly i>reien: .v moderate j sometimes ^resynt 5; m i n o r > ::.£ rec:uer.:lv present trace to :ru:Jo: = / / / / . ! 88 the northern and northwestern parts of the map area are not as r e l i a b l e as information fo r the remainder of the area because th icker overburden to the north decreased the effectiveness of the f l o a t mapping technique used (c f . Appendix A). A l t e ra t i on zoning at depth was described from d r i l l hole information (Appendices: E and I ) , Each hypogene a l t e ra t i on mineral was described f i r s t of a l l by i t s mode and degree of dispersion (Table 3.1) and by i t s abundance over every f i f t e e n foot assay interva l i n d r i l l core and rotary chips or over a shorter in terva l i f a d i s t i n c t change i n a l t e r a t i on was detected. In general, mode of dispers ion of minera l i zat ion was seldom ava i lab le from rotary chips. An estimate of the dominant s i l i cate^carbonate a l t e r a t i on fac ies fo r the interva l under consideration was then recorded on the basis of mineralogy. A volume basis was used to e s tab l i sh which fac ie s was dominant because in some cases several fac ies were represented i n a given in terva l of cutt ings or core. For example, an in te rva l cons i s t ing mainly of pervasive a r g i l l i c a l te ra t i on cut by minor quartz veins with quartz-s e r i c i t e envelopes (phy l l i c a l te ra t ion ) would be described as a r g i l l i c f ac i e s . Even with th i s degree of general izat ion simple overa l l patterns were not recognizable on deta i led (one inch to 100 feet ) cross-sect ions. However, averaging of the s i l i cate-carbonate a l t e r a t i on assemblage numbers (Table 3.2 and Figure 3.2) weighted by the i r respective lengths of occurrence over a bench interva l of 200 f ee t , gives numbers referred to here as " a l t e r a t i on grade". The resu l t ing pattern of numbers representing a l t e r a -t ion grade was eas i l y contoured. Appendix I gives a sample ca l cu la t i on of a l t e ra t i on grade for a bench interva l and l i s t s these averages fo r the 200 foot benches centred at elevations of 4,000 feet and 3,500 fee t . Figure 3.6 89 shows the averages of these benches along cross^section CrvD, Figure 3,4, an overlay on Figure 3.5, shows the contours of a l t e ra t i on grade at the 4,000 and 3,500 foot elevations of bench centers. Numbers representing a l t e ra t i on grade (Figures 3.4, 3.6 and 3.7) correspond only approximately to numbers used to define sil icates-carbonate a l t e ra t i on fac ies (Figures 3.2 and 3.5, and Table 3.2) because the former are averages of the l a t t e r , Contours of a l t e ra t i on grades of 6.5 and 7 (Figures 3.4 and 3,7) enclose areas of a l t e ra t i on dominantly of potassic fac ies ( 7 ) a , Contours of a l t e r a -t ion grades of 4 to 6,5 enclose areas of a l t e ra t i on representing p h y l l i c fac ies (4, 5 and 6 ) a . Areas less than a l te ra t i on grade 4 contain mainly a r g i l l i c (2 and 3 ) a , p r opy l i t i c ( l ) a , or fresh rock ( 0 ) a . The procedure used fo r averaging the quant i tat ive a l t e ra t i on f ac ie s data to obtain the a l t e ra t i on grade i s mathematically ident ica l to procedures used in obtaining weighted assay values. This i s an empirical smoothing technique designed to show generalized var iat ions and patterns. I t cannot be thought of as a quant i tat ive interpretat ion method but i t s advantages l i e i n the speed with which i t can be applied to even a l im i ted amount of quant i ta t i ve data and the app l icat ion of such simple patterns to explorat ion. Furthermore, many of the computer programs that ex i s t f o r the treatment of assay data can be applied read i l y to such a l te ra t i on data. Concentric zoning i s suggested in Figure 3.5 but i s pronounced in Figure 3.4 that also shows several rad ia l trends away from the a l te ra t i on core. Figure 3.7 shows the a l te ra t i on patterns and breccia pipe occurrence in cross-sections across Figures 3,4 and 3,5, The p r inc ipa l a l te ra t i on a: numbers re fer to a l te ra t i on fac ies (Figure 3,2 and Table 3.2), 90 fac ies defined at Casino are potassic a l te ra t i on ( 7 ) a , p h y l l i c a l t e ra t i on (mainly 5 and 6) , a r g i l l i c a l t e ra t i on (mainly 3 ) , and p r o p y l i t i c a l t e r a t i on (1). Subsequent sections describe the mineral assemblages in these a l t e r a -t i on fac ies at Casino and the i r re lat ionsh ips to (1) geochemical, magnetic, l i t h o l o g i c and mineral occurrence var iables (Table 3.4 and Figures 3.8 to 3.11), and (2) assay values f o r copper and molybdenum (Table 3.6 and Figures 3.12 and 3.13). 3.2.4 Potassic A l te ra t i on Facies (7) Potassic a l te ra t i on fac ies at Casino contains the fo l lowing minerals in approximate order of decreasing abundance: b i o t i t e , quartz, potassium fe ldspar , s e r i c i t e , magnetite and/or hematite, tourmaline, anker ite (?), and gypsum. Gypsum occurs along fractures and might be e i ther an a l t e ra t i on of anhydrite or a primary deposit from migrating groundwater. Potassic a l t e ra t i on i s recognized most read i ly i f magnetite i s present because hand specimens def lec t a pencil magnet r ead i l y , B i o t i t e with f e l t e d texture or pseudomorphic a f te r hornblende normally defines the occurrence of th i s f ac ie s and pale green s e r i c i t i c a l te ra t i on of plagioclase i s general (Plate 3.1). Where the rock i s not a l tered by supergene processes t o ta l sulphide content i s low consist ing mainly of pyr i te with lesser amounts of chalcopyr i te and molybdenite, and trace amounts of sphaler i te and bornite. As a r u l e , sulphides and oxides are very f i n e l y disseminated throughout the rock (P late 3,1) although magnetite-hematite-pyrite veins several inches wide are found l o c a l l y TABLE 3 .4 CORRELATION MATRIX Or S E L E C T E D V A R I A B L E S FOR GEOCHEMICAL, MAGNETIC, L I T H O L O G I C , AND HYPOGE'lE A L T E R A T I O N F A C I E S A T C A S I N O . M j t r l x I s b a s e d o n 1 2 5 o o i e r v a t i o n s f r o m 1 2 5 c e l t s o f A p p s n d l x f . ! f tfce c o r r e l a t i o n c o e f f i c i e n t i s 0 . 2 2 5 , t h e h y p o t h e s i s t h a t t h e t w o v a r i a b l e s a r e i n d e p e n d e n t a t t h e 1 p e r c e n t l e v e l i s r e j e c t e d ; i f tr-.e c o r r e l a t i o n c o e f f i c i e n t i s 0.3.-6 t h o h y p o t h e s i s i s r e n t e d a t t h e 0 . 1 p e r c e n t l e v e l . T h e r e f o r e , i f >0.30t, 2 l i n e s a r e d r a w n u n d e r t h e c o r r e l a t i o n c o e f f i c i e n t , Jn<t i f >0.T?5anj <o.306, 1 l i n e i s d r a w n . C o r r e l a t i o n c o e f f i c i e n t s d e t e r m i n e d b y " T R I P " r o u t i n e , U n i v e r s i t y o f B r i t i s h C o l u m b i a t o r p u t i n g C e n t r e , M a r c h 1 9 7 1 . S o i l T u n g s t e n S o i l S i l v e r S o i l C o l d R o c k C o p p e r P o c k r - ' o l y h d e n u r a P o c k L e a d P o c k 2 i n c G r o u n d R j n ^ e A i r b o r n e V a l u e ' A i r b o r n e R a n g e D i s t a n c e f r o m f a i n A i r b o r n e H i g h P e r c e n t I . Q Z M Z >z 2 P e r c e n t F . Q Z H Z jjj P e r c e n t P . P P X X —1 P o r c e n t BP.XX P e r c e n t A r g i l l i c ( 2 ) P e r c e n t P h y l l i c ( 5 ) P e r c e n t P n y l l i c ( 6 ) P e r c e n t P o t a s s i c ( 7 ) P e r c e n t o T o u r r . a l 1 n e c r T e r c e n t \t : : . * n n e t i t e a n d / o r •*r H e r r a t i t e T e r c e n t T o ' j r m a l -i n e w i t h M a g n e t -i t e a n d / o r H e m a t i t e P e r c e n t -P y r i t e 1 . 0 0 0 0 . 0 3 5 - 0 . 0 7 1 0 . 0 4 9 0 . 0 9 6 - 0 . 0 2 3 - n . 1 1 5 0 . 0 2 2 0 . 0 2 4 0 . 1 0 4 - 0 . 1 9 7 - 0 . 0 4 4 - 0 . 1 7 7 - 0 . 1 8 5 0 . 0 9 . 1 - 0 . 1 2 2 - 0 . 0 0 2 ( 1 . 0 7 6 - 0 . 1 6 5 0 . 0 6 7 IS) ut t/i c 1 . 0 0 0 0 . 1 2 1 - 0 . 0 0 3 0 . 1 6 6 0 . 0 2 0 • - 0 . 0 5 0 0 . 1 2 4 0 . 2 3 7 - 0 . 1 . 1 9 0 . 1 9 8 -n_._2_« - 0 . 2 1 7 0 . 2 2 2 0 . 2 5 3 0 . 0 3 6 0 . 0 5 9 0 . 2 1 1 0 . 2 3 4 0 . 1 8 2 35 MAGNETICS 1 II c f es O a. UTHGIOGY ii S S S E V. *-» 3 o o *> o a. a. a. I— H I * 1 . 0 0 0 0 . 0 2 7 0 . 0 5 4 n . o i l - 0 . 0 2 3 n . ? 3 9 0 . 2 7 5 0 . 1 9 2 - 0 . 3 3 4 . 0 . 0 6 3 - 9 . 1 6 1 - 0 . 0 4 8 0 . 1 8 7 0 . 1 8 4 - 0 . 0 H 6 0 . 0 9 6 0 . 2 1 6 0 J 3 8 _ 0 . 2 9 7 1 . 0 9 O 0 , 4 1 7 0 . 1 8 0 0 . 5 9 5 [ M 0 9 0 . 4 9 7 0 . 1 3 1 - 0 . 5 1 4 - J V 3 9 0 - 0 . 1 9 3 0 . 1 3 7 0 . 1 9 8 - 0 . 0 0 0 - " . 3 7 0 - 0 . 1 1 6 0 . 6 3 5 - 0 . 1 4 1 0 . 6 6 6 1 . 0 0 0 0 . 1 2 0 0 . 2 0 1 0 . 1 f .6 0 . 3 7 2 0 . 2 0 1 ; - 0 . 3 2 2 0 . 0 1 4 " • 2 3 1 0 . 2 2 7 0 . 0 7 9 - 0 . 2 1 4 - 0 . 0 9 2 0 . 3 4 5 0 : 2 1 7 0 . 3 P 4 1 . 0 0 0 0 . 6 0 5 0 . 0 2 4 - 0 . 0 3 0 - 0 . 0 9 2 - 0 . 0 4 3 - 0 . 0 8 2 0 . 1 4 5 0 . 0 6 1 0 . 1 9 3 0 . 0 2 2 - O . 0 8 7 0 . 0 2 3 0 . 0 7 6 0 . 0 7 3 0 . 0 7 0 1 . 0 0 0 0 . 1 8 3 0 . 1 6 4 - 0 . 0 9 4 - 0 . 1 1 8 - 0 . 2 6 3 0 . 0 5 3 0 . 0 0 9 0 . 2 4 0 - 0 . 0 2 7 - 0 . 1 6 3 - 0 . 1 5 1 " • 3 7 3 - 0 . 0 9 3 0 . 3 3 9 i.c*> ' W . l;ooo 0 . 2 9 2 O . ; 0 9 1.QW1 --IK56J3 - 0 . 7 P J . - 0 , 5 ° ? 1.090 • 0 . 3 4 4 - 0 . 3 7 8 -0,0.31'' '•«» 0 . 0 5 3 n ^ j ) . 0 . 1 0 5 ' -0.101 -_0.3°7 1 . 0 0 0 0 . 1 2 3 0 . 1 1 0 0 . 1 4 ? : n . 3 ? 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ELEVATIONS, CASINO Y.T. poo s . gooo s • Uzoo i J3600 8 l«O00 8 14400 9 4800 8 S E C T I O N L I N E C O N T A C T , A L T E R A T I O N F A C I E S P O T A S S I C F A C I E S P H Y L L I C ( 6 ) F A C I E S i.:.;^:.!::! P H Y L L I C IS) F A C I E S A R O I L L I C ( 3 ) F A C I E S Kiftt%ft1 P R O P Y L I T I C ( I ) F A C I E S I F R X | F R E S H R O C K FIGURE 3.5 i H Y P O G E N E A L T E R A T I O N F A C I E S C A S I N O , Y.T. 3600 S 4 600 S 400 . 200 800 1200 FT I L E G E N D <J3 -F=> F CENTRE OF 1 0 0 FT. SQUARE CELL WITH PERCENTAGE OF AREA OF SURFACE ROCK (WITHIN CELL) ALTERED TO POTASSIC FACIES. r^" MACHINE CONTOURS OF PERCENTAGES OF 7 0 0 SURFACE ROCK ALTERED TO POTASSIC FACIES. CODED AS FOLLOWS: 1 0 0 0 = 1 0 Z 5 5 0 « 5 5 Z 2 5 0 » 2 5 1 7 0 0 = 7 0 Z 1 0 0 = Wl 8 5 0 = S5Z AREA GREATER THAN 20 PERCENT BREC-CIA ON HARKED SIDE OF LINE. 701 J FIGURE 3.8: CONTOURS SHOWING PERCENTAGES OF SURFACE ROCK WITH POTASSIC ALTERATION FACIES, CASINO, Y.T. aoo s 2000 s 2400 S 3600 S 4800 S eoo 1200 FT HO L E G E N D w " CENTRE OF 100 FT. SQUARE CELL WITH PERCENTAGE OF AREA OF SURFACE ROCK (WITHIN CELL) CONTAINING MAGNETITE AND/OR HEMATITE. y MACHINE CONTOURS OF PERCENTAGES J" (xlO) OF SURFACE ROCK CONTAINING MAGNETITE AND/OR HEMATITE. vtV ITH ORDER TREND SURFACE' CONTOURS OF AEROMAGNETIC VALUES AT CELL CENTRES. AREA GREATER THAN 20 PERCENT BREC-CIA ON MARKED SIDE OF LINE. FIGURE 3.9: CONTOURS SHOWING PERCENTAGES OF SURFACE ROCK CONTAINING MAGNETITE AND/OR HEMATITE, WITH ITH ORDER TREND OF AEROMAGNETIC VALUES (GAMMAS), CASINO, Y;T. 800 S 100 50 0 100 200 300 M 400 800 L E G E N D <* / / CENTRE OF 400 FT. SQUARE CELL WITH PERCENTAGE OF AREA OF SURFACE ROCK (WITHIN CELL) CONTAINING TOURMALINE WITH MAGNETITE AND/OR HEMATITE. MACHINE CONTOURS OF PERCENTAGES (xlO) OF SURFACE ROCK CONTAINING TOURMALINE WITH MAGNETITE AND/OR HEMATITE. .a* 4TH ORDER TREND SURFACE CONTOURS OF THE RANGE OF AEROMAGNETIC VALUES WITHIN CELLS. AREA GREATER THAN 20 PERCENT BREC-CIA ON MARKED SIDE OF LINE. FIGURE 3.10: CONTOURS SHOWING PERCENTAGES OF SURFACE ROCK CONTAINING TOURMALINE WITH MAGNETITE AND/OR HEMATITE, WITH ITH ORDER TREND OF AEROMAGNETIC RANGES (GAMMAS), CASINO, Y.T. 1 0 ^ ^ 5 0 ^ 0 _ i ? P 2 200 500 U 4 0 0 200 j 4C0 S 0 0 1200 FT I L E G E N D t o i* CENTRE OF 000 FT. SQUARE CELL WITH PERCENTAGE OF AREA OF SURFACE ROCK (WITHIN CELL) CONTAINING PYRITE. / MACHINE CONTOURS OF PERCENTAGES OF fm SURFACE ROCK CONTAINING PYRITE, / CODED AS FOLLOWS: . 500 = 5% 350 = 35% 150 = 15? 450 = 45% 250 = 25% 550 = 55% ///^ .AREA CONTAINING 15 PERCENT PYRITE. TCN^ PYRITE HALO. • AREA GREATER THAN 20 PERCENT BREC-CIA ON MARKED SIDE OF LINE. FIGURE 3.11: CONTOURS SHOWING PERCENTAGES OF SURFACE ROCK CONTAINING PYRITE, CASINO, Y.T. 100 50 0 100 200 500 U • -100 800 1200 FT I L E G E N D UD CO DRILL HOLE LOCATION. MACHINE CONTOURS OF PERCENTAGES OF HYPOGENE COPPER CODED AS FOLLOWS: 800 = .082 110 = ,11% wo = .m 170 = .17% 230 = .23% ITH ORDER TREND SURFACE CONTOURS OF %- PERCENTAGE-HYPOGENE COPPER. AREA GREATER THAN 20 PERCENT BREC-CIA ON MARKED SIDE OF LINE. FIGURE 3.12: CONTOURS SHOWING PERCENTAGES OF HYPOGENE COPPER, CASINO, Y.T. 100 50 0 400 200 200 300 U •loo eoo L E G E N D S DRILL HOLE LOCATION. ^ MACHINE CONTOURS OF PERCENTAGES OF y HYPOGENE MOLYBDENITE CODED AS FOLLOWS; 800 = .008% 350 = .035% 140 = ,014% 390 = .039% • 250 = .026% ./ Q°l° OF PERCENT HYPOGENE MOLYBDENITE. 4TH ORDER TREND SURFACE CONTOURS J AF AREA GREATER THAN 20 PERCENT BREC-CIA ON MARKED SIDE OF LINE. FIGURE 3,13: CONTOURS SHOWING PERCENTAGES OF HYPOGENE MOLYBDENITE, CASINO, Y.T. Ld O o o 100 PLATE 3.1: Potassic alteration facies in Klotassin granodiorite (P23-856). Disseminated sulphides are concentrated with secondary, felted biotite which is partly after hornblende. Left side: polished core; disk 5 mm. in diameter (x3). Right side: thin section observed with crossed nicols (x25). PLATE^3.2: ^  Potassic alteration facies in tuff breccia (3200 S, 1800 E). Magnetite is abundant as veins and disseminations, and is accompanied by yellow j a r o s i t e after sulphides. Polished surface of hand specimen; disk 5 mm. in diameter (x3). 101 102 (Plate 3,2), Where th i s fac ies i s a ltered by supergene processes, potassium fe ldspar, b i o t i t e and magnetite are replaced in whole or in part by k a o l i n i t e , c h l o r i t e and hematite respect ive ly . X-ray and th in sect ion data from specimens representative of potassic a l t e ra t i on fac ies are in Table K.l (Appendix K) and i l l u s t r a t e the usefulness of the two laboratory techniques together in studying hydrothermally a ltered rock. In x-ray charts from oriented mounts of crushed whole rock (Appendix H) peaks from quartz (20 = 20.85°), orthoclase (29 = 27.4°) and plagioclase (29 = 21.9°) generally occur due to the presence of these minerals in the o r i g i na l rock. Secondary and primary orthoclase and quartz, of course, j produce ind ist inguishable peaks. In the supergene environment orthoclase breaks down read i l y to c lay and, consequently, potassic a l t e ra t i on can be marked in such cases by a strong kao l i n i t e response (29 = 24.9°). A low pTagioclase response indicates e i ther l i t t l e primary plagioclase or i t s conversion to other minerals. Rocks of the potassic a l t e ra t i on zone when invest igated by x-ray d i f f r a c t i o n give r i s e to a pronounced peak f o r b i o t i t e and/or muscovite (29 = 17.8.°)./ The d i s t i n c t i o n between b i o t i t e and muscovite i s made most read i l y in th in section and, in some cases, by colour of hand specimen. Minor amounts of l a te c h l o r i t i z a t i o n of b i o t i t e are common and x-ray peaks are d i s t i n c t (29 = 25.2°). Much of th i s c h l o r i t e i s of supergene o r i g i n . The r e l a t i v e l y low sulphide content in the potassic a l te ra t i on zone i s emphasized by the absence of j a r o s i t e (29 = 17.2°) in specimens that have undergone supergene a l t e r a t i o n . The potassic a l t e ra t i on zone (Figures 3.4 and 3,5) i s a dominant central feature of the Casino deposit and c lose ly coincides with the main breccia body (Figure 2.13). This re lat ionsh ip i s also apparent in Figure 3.8 where 103 the contour outlining 20 percent or more breccia nearly coincides with the circular potassic alteration pattern. The overall correlation coefficient (r) between percentage of area mapped as breccia and potassic alteration is 0.288 (Table 3.4), which is significant at less than the one percent level. This correlation would have been even better i f only the main, eastern breccia occurrence had been considered. Figure 3.7, shows cross-sections of the hypogene alteration pattern as well as the general coincidence of a potassic alteration core with the breccia or breccia contacts. Breccia and potassic alteration zones are both centrally located in the zonal arrangement related to significant copper-molybdenum mineralization at Casino. Because of the presence of abundant magnetite in rocks that have undergone potassic alteration, one would expect a magnetic high to coincide with or at least be more or less centred on the zone of potassic alteration. Such a pattern is obvious from a comparison of Figures 3.8 and 3.9. In Figure 3.9 the coincidence between fourth order trend surface of aeromagnetic values, and mapped presence of magnetite and/or hematite shows the same spatial relationship to the eastern breccia occurrence as does potassic alteration (Figure 3.8). In fact, the airborne magnetic high anomaly is superimposed almost exactly on the potassic alteration pattern. It is not surprising, then, that the close dependence between potassic alteration and magnetic values is also suggested by Table 3.4 where correlation coefficients relating magnetic data to potassic alteration are all significant at less than the 0.1 percent level. Details of these correlations are as follows. First of a l l , the aeromagnetic values at cell centres correlate closely (r - 0.749) with percent of cell area mapped as potassic alteration. Secondly, the ranges of ground and airborne magnetic values in the cells correlate with percent of cell area mapped as potassic alteration (r = 0.629 104 and r ~ 0,350 respectively), These relationships indicate that there are relatively strong local changes in the magnetic field associated with potassic alteration. Finally, as the distance from the centre of the aeromagnetic high centred over the eastern breccia pipe increases the percent potassic alteration within a cell decreases (compare Figures 3,8 and 3.9), and the corresponding correlation coefficient is negative (r = -0.654). Percent tourmaline with magnetite and/or hematite (Figure 3,10) is an empirical, easily derived variable that correlates strongly with potassic alteration (r = 0,596) and unifies well those variables closely related to potassic alteration by its close correlations with: geochemical values in gold (r = 0.341), copper (r = 0.428), molybdenum (r =-0.477), lead (r = 0.237) and zinc (r = 0.372), magnetic variables (r = 0.379, 0.508, 0.453, -0.612), and occurrence of breccia (r = 0.44.6), tourmaline (r = 0.367), and magnetite and/or hematite (r = 0.767). 3.2.5 Phyllic Alteration Facies (4 to 6, mainly 5) Rocks of the phyllic alteration facies at Casino are dominated by occurrence of quartz with sericite or muscovite. Tourmaline is abundant, and hematite and magnetite are present but become more abundant as the zone of potassic alteration is approached. Clay minerals are common, but probably are due in large part to supergene processes. A white or "bleached" appearance is the most characteristic feature of this facies, and is particularly useful in distinguishing phyllic facies from the darker coloured biotite-bearing 105 potassic facies, Phyllic alteration facies clearly is concentrated in a zone peripheral to the central potassic facies zone (Figure 3.4). This relationship was not obvious in the original mapping results (Figure 3.5) at Casino for several reasons. First, because the central potassic alteration is nearly coincident with the hill crest of Patton Hi l l , the fringing phyllic zone is on the flanks of the h i l l . Consequently, downslope dispersion of phyllic alteration float results in an enlarged area of apparent phyllic alteration. Secondly, the northern part of Figure 3.5 contains deep overburden so that reliability of float mapping -in this area is poor. Finally, supergene alteration can produce sericite as well as clay minerals (Titley, 1973), thus, the widespread phyllic alteration facies in Figure 3.4 that was thought to be hypogene in origin may be, in part, of supergene origin. The likelihood that supergene sericite occurs is emphasised by comparison of the overlay Figure 3.4 (prepared from dr i l l hole information) with Figure 3.5. Similarly, the alteration zones projected to the surface from unweathered dr i l l core (Figures 3.4 and 3.7) enclose a smaller phyllic alteration zone than is mapped in Figure 3.5. X-ray and thin section data from specimens representative of phyllic alteration facies are in Table K.2 (Appendix K). Phyllic alteration is divisible into phyllic (5) and phyllic (4) in Table K.2, however, three divisions were made in the field and were numbered in decreasing order of intensity: phyllic (6), phyllic (5) and phyllic (4). Phyllic (6) facies is confined mainly to. the periphery of the main, eastern breccia body, and to adjacent inequigranular quartz monzonite. This facies was mistakenly identified in the field as advanced argillic facies 106 (Phillips and Godwin, 1970) because of its characteristic whiteness (thought to be partly due to abundant clay minerals), and the presence of quartz, muscovite, and tourmaline (Plate 3.3). Data in Table K.2 (Appendix K), however, indicates that this unit is intensely sericitized and is better described as phyllic (5) of high to .extreme intensity, because the high clay content and/or pyrophyllite, indicative of advanced argillic alteration, does not occur. Phyllic (5) facies is the most abundant phyllic facies mapped in Figure 3.5. Quartz and sericite are abundant as alteration products of potassium and plagioclase feldspars, and mafic minerals (Plate 3.4). Tourmaline is common. Clay minerals are likely largely supergene. Dissem-inations and vein-lets of pyrite, chalcopyrite and less abundant molybdenite are common throughout the phyllic (5) zone. Original sulphides in the capping have been leached leaving boxwork cavities that are f i l l e d , lined, or fringed with indigenous jarosite. Jarosite and, consequently, sulphides are more abundant in the phyllic facies than in the potassic facies (compare jarosite in Tables K.l and K.2: Appendix K). Phyllic (4) or potassium feldspar stable (?) facies was not observed in significant amounts in surface mapping (Figure 3.4), but it was noted in drill holes (Plate 3.4). In this facies potassium feldspar crystals are hard to scratch with a sharp needle compared to softer, pale green sericitized plagioclase. The relationship of fresh potassium feldspar to altered plagio-clase is very apparent in thin section. Significant correlations of phyllic (5) and phyllic (6) facies to geochemical, magnetic and geological variables are underlined in Table 3.4, Phyllic (6) is associated closely with inequigranular quartz monzonite (r = 1 0 7 PLATE 3 3- P h v l l i c alteration facies in inequigranular quartz monzon-ite (4400'S, UOO E). Specimen is strongly bleached. White areas are mainly quartz and sericite. Left side: polished slab; disk 5 mm. in diameter (x3). Right side: thin section observed with crossed nicqls (xlOO). '• ' • PLATE 3.4: Phyllic alteration facies in fine-grained quartz monzonite (P9-191). Specimen is altered to quartz and sericite -, some original K-feldspar is unaltered. Bluish area is tourmalinized and black streaks contain chalcocite. Left side: polished core; disk 5 mm. in diameter (x3). Right side: thin section observed with crossed nicols (xlOO). 108 109 0.422) as indicated earlier, Phyllic (5) has a strong negative correlation (r - "0,370) with whole rock copper. Superficially this is a surprising result for 5 later, phyllic facies is shown to contain most of the copper in the deposit. The apparent paradox is easily explained by surface leaching that has replaced sulphides by jarosite. The acid environment necessary to produce jarosite (Blanchard, 1968) also results in leaching of copper. Consequently, surface data used in the cell correlation study in some instances give correlations much the opposite of what would be expected. The signifi-cant negative correlations of phyllic (5) alteration to ground magnetic range (r = -0.259) and aeromagnetic value (r = n0.299) indicate that the phyllic facies is characterized by a relatively flat and low magnetic response. An apparently discontinuous pyrite halo is indicated in Figure 3.11. Leaching of surface pyrite, however, makes difficult accurate definition of pyrite distribution and the possibility of an annular zone of pyrite cannot be discounted. Comparison of pyrite distribution with Figure 3.4 and 3.5 clearly shows that the halo is outside the potassic core and is confined mainly to the phyllic (5) and phyllic (6) zones. Furthermore, pyrite appears to be concentrated around the periphery of the main breccia body. The good correlation in Table 3.5 of percent pyrite to percent breccia in a cell (r = 0.246) does not negate the above observation but emphasises the coin-cidence of pyrite with the western occurrence of breccia (Figure 3.11). Comparison of Figures 3.11 and 3.12 show that hypogene copper assay values are highest along the inside margin of the pyrite halo, and Figures 3.4 and 3.5 place these high assays within the phyllic facies. Consideration of the contoured molybdenum assays in Figure 3 V 13 indicates a belt of higher assays in a pattern similar to copper assay values. 110 In summary, the phyllic zone is marked by a distinctive bleached appearance and a mineralogy dominated by sericite and quartz, Magnetic expression over this zone is not pronounced but the occurrence of hematite and magnetite increases toward the potassic core. The phyllic alteration zone contains a pyrite rich zone that defines a discontinuous halo about the peri-phery of the main breccia occurrence. Highest copper values occur immed-iately inside this halo. Molybdenite occurs in a similar fashion to copper. Location of the pyrite halo and phyllic alteration facies are extremely important exploration guides for copper and molybdenum sulphides. 3.2.6 Argillic Alteration (2 and 3) Argillic alteration is poorly developed (cf. Table K.3 - Appendix K) and of limited occurrence in Figure 3.5. A bleached appearance (Plates 3.5 and 3.6) with abundant clay characterizes this facies. White kaolinitic clay defines argillic alteration facies 3. Swelling, montmorillonitic clays, commonly with carbonate, define argillic alteration facies 2. Supergene development of clay minerals complicates identification of argillic facies in surface rocks. Furthermore, clay minerals, in hand specimen, are difficult to identify but generally their presence is indicated when dampening with the tongue produces a tackiness and argillaceous odour. Clay alteration of feldspar crystals is indicated locally by a "pock marked" surface on drill core caused by erosion of grains softened by water circulated in drilling. Additional field criteria are the common presence of minor amounts of carbonate I l l PLATE 3.5: Argillic alteration facies in Patton porphyry (P24-228). Clay alteration is very strong. Left side: polished core; disk 5 mm. in diameter (x3).' Right side: thin section observed with plane polarized light (x25). PLATE 3.6: Argillic alteration facies in Patton porphyry (P26-607). Clay alteration is strong. Greenish tinge is due to chlorite. Car-bonate is apparent in thin section. Left side: polished core; disk 5 mm. in diameter (x3). Right side: thin section under crossed nicols (xlOO). 113 or chlorite and the absence of abundant sericite and quartz. X-ray and thin section data are necessary to identify argillic altera-tion positively. Abundant kaolinite (29 = 24,9°), especially wi.th montmor-illonite (29 = 5.7°) or i l l i t e (29 = 19.9°), indicates argillic facies i f sericite and quartz of the phyllic facies, and epidote, chlorite, albite and carbonate of the propylitic facies are present in only minor amounts. These latter minerals generally are identified best in thin sections but x-ray data commonly are required to indicate the occurrences of minerals that are too fine-grained to identify otherwise (Plates 3,5 and 3.6), Specimens illustrating argillic alteration (Table K.3: Appendix K) overlap the mineral compositions of both phyllic alteration (sericite) and propylitic alteration (chlorite, carbonate, and epidote). Sulphide minerals are dominantly pyrite but are not generally abundant. Correlation coefficients underlined in Table 3.4 suggest that surface argillic alteration was identified more commonly in fine-grained quartz monzonite (r =0.238) that occurs distantly and separately (Figure 2.13) from the inequigranular quartz monzonite (r. = -0.321). Argillic alteration (alteration grade less than 4) is peripheral to the core defined by phyllic and potassic alteration in Figure 3.4. Because the maqnetic range varies strongly in the core area a significant negative correlation exists in Table 3.5 between argillic facies and magnetic range (r = -0.328). Geochemical values of silver in soil correlate positively (r = 0.258) and strongly with the occurrence of argillic alteration facies. 114 3.2.7 Propylitic Alteration (1) Propylitic alteration facies occurs rarely in surface rocks near the periphery of Figure 3.5. This facies is characterized by abundant chloriti-zation of hornblende and/or biotite with accompanying carbonate and minor quantities of clay minerals, albite and epidote (Plates 3.7 and 3.8). Chlorite is readily identified in hand specimen, in thin section or by x-ray diffraction. Strong x-ray peaks for chlorite (29 = 2.52°) are apparent in Table K,4 (Appendix K). Carbonate, epidote, albite and clay were observed in some thin sections of this facies (Table K.4: Appendix K), Minor veinlets of sulphides, dominantly pyrite, are common. Correlation coefficients relating propylitic alteration to other variables were not obtained because of the limited occurr-ence of this facies in Figure 3.5. 3.2.8 Summary of Zoning and Origin of Hypogene Alteration The existence, at Casino, of a systematic pattern of alteration grade, decreasing outwards from a central core is apparent in Figures 3.4 and 3.7. A corresponding change in facies from potassic to argillic is indicated in Figure 3.5. These patterns are similar to the idealized bulk alteration zones described by Lowell and Guilbert (1970) from empirical evaluation of geological characteristics of 27 major porphyry deposits (Figures 3.1 and 3.2), This sequence of alteration zones observed on a deposit scale is identical with the sequence observed on a centimeter scale progressing outward from the walls 115 PLATE 3.7; Propylitic alteration facies in fine-grained quartz mon-zonite (?) (P25-586). Quartz vein, and abundant carbonate and chlorite is apparent. Left side: polished core; disk 5 mm. in diameter (x3). Centre: thin section observed with plane polarized light (x25). Right side: thin section observed with crossed nicols (x25). PLATE 3.8: Propylitic alteration facies in Klotassin granodiorite (?) (P25-309). Biotite is weakly chloritized and specimen is cut by a carbonate veinlet. Polished surface of dr i l l core; disk is 5 mm. in diameter (x3). -117 of small veinlets within porphyry systems (cf, Meyer et al,, 1968), The pattern at Casino consists of a core of potassic alteration surrounded.successively by phyllic, argillic and"propylitic alteration. The potassic and phyllic zones dominate the pattern, and are. central and coincident with areas enriched in copper and molybdenum. Development of the argillic and propylitic zones are comparatively weak. Minerals that characterize these zones are: (1) potassic facies: potassium feldspar, biotite, magnetite, molybdenite and chaicopyrite, (2) phyllic facies: muscovite (and sericite), chalcopyrite and molybdenite, (3) argillic facies:- clays, sericite and chlorite, (4) propylitic facies: chlorite, carbonate, epidote,clay and sericite. Rock types altered by hydrothermal solutions include granodiorite (Patton porphyry, Casino complex), quartz monzonite (fine-grained and inequigranular quartz monzonite, Klotassin batholith) and rhyolite (?) (tuff and tuff breccia, Casino complex). The origin of such hydrothermal alteration patterns is controversial. Basic requirements in the formation of zoned mineral assemblages include sources for hot water, metals and other components of alteration, and a mechanism or interplay of processes such as changes in environmental factors of pressure, temperature and chemical composition that produce distinctive mineral assemblages. These factors are examined below in a framework consistent with data for the Casino deposit. In Chapter 4 the writer develops the argument for a genetic relationship between subduction and porphyry deposits. This implies that the metals of these deposits originate in part, at least, at a Benioff zone and are,released from a subducted oceanic plate that may be "wet" and anomalously rich in the desired metals. The way metals migrate upward is unknown but generation of magma on the top of a subducted plate and upward movement of such magmas are generally accepted processes (e,g. 118 Gilluly, 1971), A "wet!! magma originating at a Benioff zone and migrating upward is compatible with the explosive nature of the Casino breccia pipe (Section 2.5.8). How much magma, water, copper, molybdenum, etc., are involved in the formation of a deposit like Casino? Estimations shown in Table 3,5 are based on assumptions (1) estimated orebody size, based on Figure 2.13, and grade, based on Section 1.1, (2) the copper in the deposit originated from a magma with an enhanced copper content comparable to average oceanic clays (250 ppm: Parker, 1967), and (3) the source magma contained 8 percent water (to be consistent with assumptions for breccia formation in Section 2.5.8). The assumption of a source enriched in copper (12.5 times average value for felsic granites and granodiorite: Parker, 1967) is in accord with conclusions from many studies of the regional distribution of ore deposits (Noble, 1970) and has been discussed by Krauskopf (1971). The conclusions from Table 3.5 seem reasonable. The required source magma is only one-hundred times larger than the deposit provided 80 percent of the copper is partitioned from the magma into the hydrothermal fluid and all the , copper is precipitated from the fluid. The copper concentration in the hydrothermal fluid is 2,500 ppm. and apparently high but comparable to estimates used by Rose (1970). The source magma, therefore, provides the energy to hydrothermal fluids that produce the intense fracturing and local development of breccia that are characteristic of porphyry deposits. Movement of magmatic hydrothermal solutions upward and outward from the core of the shattered rock leads to alteration and mineral zonation. The magmatic origin for hydrothermal alteration is currently debated. A magmatic hydrothermal source is in accord with the classical approach summarized by Holland (1972) with oxygen and hydrogen isotope values for secondary biotite in porphyry systems (Sheppard, 119 TABLE-3.5 CALCULATIONS CONCERNING SOURCE MAGMA, AND VOLUME AND CONCENTRATION OF COPPER IN DERIVATIVE HYDROTHERMAL FLUID 1. Weight of deposit (Wdep) = Volume of deposit9 (LxWxH) x specific gravity or: WORE = 1000m. x 1000m. x 1000m. x 106 cm? x 2.7 cjm. = 2.70 x 1015gm. m' cm? rock 2. Weight of copper (Wr,u) = W0RE x %Cu in orebody.Say % Cu^ 0.20%b then: WCu = 2.70 x 1015gm. x 0.20 x 10"2 = 5.40 x 10 1 3 gm. Cu 3. Weight of source magma (W$M) = Wcu -J-weight of copper liberated from source magma (Cu|_). Say source magma contains 250 ppm? Cu and retains 50 ppm. Cu; Cuj_ = 250-50 = 200 ppm., Q n d : WSM = 5.4 x 10 1 3 gm.Cu = ?_ 7 x 1 Q17 g m > .2 x 10"4 Cu = 100 times larger than orebody (e.g. block measuring 10,000 m. x 10,000 m. x 1000 m.) 4. Weight of water (W ) in magma if magma contains 8% water0' Ww = 2.7 x 10 1 7 x 8 x 10"2 = 2.16 x 10 1 6 gm. water 5. Concentration of copper in water (Cuw) " W Q u -t-W"W or: Cuw = 5.4 x 10 1 3 gm.Cu = 2,500 ppm. Cu. 2.16 x 10 1 6 gm. a: 1000 m. square area encloses the deposit area (see Figure 2.13). b: overall grade for copper will be less than orebody grade (section 1.1). c: 250 ppm. is 12.5 times average copper content for felsic granites and granodiorite and equals the average copper content of deep sea clays (Parker, 1967, p. D13). d: Appendix G (cf. Burnham, 1967) and section 2.5.8. 120 et al., 1971; Taylor, 1974), and with lead and sulphur isotopes, values in some alteration minerals (Doe et al., 1968; Stacey et al,, 1968; Kulp et al, 1957; Field, 1966a, 1966b). The magmatic source does not deny the possible import-ance of a meteoric water component in certain alteration zones (Sheppard et al., 1969; Taylor, 1974), but is incompatible with a strictly centripetal source of hydrothermal solutions. Estimates of depth or pressure and temperatures prevailing during hypogene alteration at Casino are difficult in light of the absence of data collected for this purpose. Nevertheless, a crude depth estimate of 2.2 km (616 bars), based on average rate of denudation for North America (about 0.003 cm/year: Holmes, 1965, p. 514) over the 70 m.y. interval since the deposit formed, is bracketed by the estimated figure of 5,000 to 10,000 feet depth for shallow porphyry systems suggested by Lowell and Guilbert (1970). Biotite geothermometry by Beane (1974) indicates that secondary biotite coexisting with magnetite and potassium feldspar is commonly formed in the range from 350°C to 550°C. Thus, a reasonable temperature for the core at Casino is about 400°C. The absence of pyrophyllite in the phyllic zone at Casino suggests that the temperature in this zone is less than 350°C on the basis of Figure 3.13A (Meyer et al., 1968; cf. Drummond and Kimura, 1969). Regional tempera-tures might be as low as 150°C on the assumption of depth and a twice normal geothermal gradient. Thus, a horizontal section through the Casino deposit during the formation of hypogene alteration zones would be isobaric at about 600 bars with temperatures varying from about 400°C in the potassic core, to less than 350°C in the phyllic zone to perhaps as low as 150°C in the outer zones. Cooling of outward migrating hydrothermal solutions is discussed by Rose (1970) who concludes that mechanisms of cooling include throttling 121 (irreversible adiabatic expansion), mixing with meteoric or other cold water and, doubtfully unless fluid flow is extremely slow, heat exchange with wall rocks. Mass transfer calcuations by Helgeson (1970) indicate that mineral zoning in porphyry deposits is consistent with increasing acid attack from the core outwards with approximately constant activity of potassium ion. Consequently, the potassium to hydrogen ion ratio generally would decrease outwards. Decrease in this ratio is also predicted by'Korzhinskii (1965, 1970) where infiltration and diffusion of a hydrothermal solution produces an "acid wave". This acid wave is a manifestation of an "acid-base filtration effect" where acidic components move faster than basic components in a perco-lating solution. Possible support for this mechanism is found by Olade and Fletcher (1975) from porphyry deposits of the Highland Valley, B.C., where some trace elements such as Zn, Mn, and Sr are commonly depleted in the core, presumably by the acid wave, but redeposited in the periphery of the deposits as the wave is netralized by reactions with wall rock. Combination of temperature gradient considerations and potassium- . hydrogen ion ratio variations is summarized by the path in Figure 3.13A. This path reflects the changes in bulk alteration at Casino from potassium feldspar in the core,to sericite followed by clay, progressively outward. The proposed path is analogous to that proposed by Drummond and Kimura (1969) for alteration adjacent to different stages of veins at the Endako, B.C., porphyry molybdenum deposit. A change in opaque mineral assemblage from a magnetite rich ore in the potassic core to a sulphide rich ore in the surrounding phyllic zone might be related to a process that decreases the fugacity of oxygen (see fugacity 122 101 10 2 10 3 i o 4 - 10 5 m KCl/ m HCl Figure 3.13A: General change (a to b) in hydrothermal so lut ions at Casino, Y.T. 7-ALT = potassic a l t e r a t i o n , 5-ALT = p h y l l i c a l t e r a t i on , 3-ALT = a r g i l l i c a l t e r a t i o n . System: 0.5 m. KC1 in H2O, at 10 bars pressure, and quartz or C r i s t o b a l i t e present (modified from Meyer et a l . , 1968). 123 diagrams in Helgeson et al., 1969, pp, 237-243) and increases the concentration of sulphide ion in a hydrothermal fluid. Such a change might be related to the reduction of sulphate ion by sulphide ion caused by precipitation of magnetite as shown by the following equation: 8H+ + Fe + 2 + S04 = S"2 + 8Fe + 3 + 4H20 Ferrous ion might be supplied to the solution by destruction of primary biotite (e.g. bleached biotite of Patton porhyry ?). Magnetite (FeO-FegO^) precip-itation would consume two ferric ions for every ferrous ion used and, con-sequently, the equation would proceed to the right increasing the concentra-tion of sulphide ions. The effect of reduction of sulphate on the fugacity of oxygen is shown by: S0 4" 2 - 202 + S"2 or: fugacity 0 2 = Agg^ -2 where: . a is the activity of the species. Thus, oxygen fugacity decreases with decrease in sulphate and increase in sulphide ions. Progression of the first equation by precipitation of magnetite, therefore, changes the solution toward sulphide saturation. Outward flow of this solution might lead to occurrence of sulphides outside the magnetite rich core." 124 3.3 SUPERGENE ALTERATION 3.3,1 Supergene Alteration Zones Supergene zonal patterns are evident in dr i l l holes because of abrupt changes in mineralogy, colour, and assay values. The following zones, from the surface downward, were intersected normally: 1. cap (CAP) or leached zone, characterized by a boxwork that resulted from 1 eaching of sulphides, and now is filled with indigenous, earthy limonite composed principally of jarosite. 2. supergene oxide (SUO) zone characterized by copper oxides or copper carbonates and sulphates. 3. supergene sulphide (SUS) zone characterized by chalcocite replacement of chalcopyrite and/or pyrite. Relationships of these zones to each other, to topography, and to lithology are shown in Figure 3.6, a general cross-section of the Casino deposit. A distinctive mineralogy for each zone is outlined in Table 3.6. Colour variation between zones are apparent in Plate 3.9' of rotary hole R8. The cap is bleached and sulphides are leached, consequently, there is no panned concentrate after removal of magnetite. The supergene zone has sulphides that appear black due to the presence of chalcocite, in part as coatings on grains of qther minerals. Assay values also are sharply higher in this zone. A heavy mineral concentrate obtained from dr i l l cuttings of the hypogene zone by panning is paler in colour due to an absence of chalcocite. Presence or absence of chalcocite was the field criteria used for defining the boundary between the supergene and hypogene zones. In general, the boundary was equally 125 m mm m Latin m cum IBt L I B U IB.' JGIBH ID: :CIEE IB. nr r n u e i i i :CIBB IB. 'DIBB iBL ' L i l i l !BL ;•! i : mm ¥ -VDtm K TJnii tatr :nniH &HL TEBI URL . n c i Hie rem m :rrm :Ddw IB y 1 41 J IBL !L"n@i IL mm H l r f C B B a s , l U L i i i i r r n i i EaEli, -L<L HK;JX m i IIL ;nn ii> "CD BfflLTIH an 'Tci o G 5 IS PLATE 3.9: Supergene alteration zones defined in cuttings from rotary hole R8. Bleached capping (CAP) with minor sulphide mineralization is distinct from darker enriched (ENR) and hypogene (HYP) zones. Black, chalcocite coatings on pyrite grains are readily observed in column of panned heavy concen-trates (magnetite removed). Grade increase in copper is apparent in enriched zone. 126 TABLE 3.6 Mineralogy of Supergene Zones, Casino, Y.T. A. Supergene Capping (CAP) cl 1. jarosite 2. goethite 3. hematite (after magnetite) 4. ferrimolybdite B. Supergene Oxide SU0) 1 . a tenorite' 2. neotocite 3. malachite 4. azurite 5. chalcanthite 6. brochantite 7. native copper 8. hematite C. Supergene Sulphide (SUS) 1. chalcocite 2. covellite 3. digenite (identified microscopically) a: in approximate order of abundance. 127 apparent due to an abrupt decrease in copper assays downward. Table 3,7 is a'statistical summary of supergene and hypogene data from 20 to 35 holes in the Casino Deposit. Because these holes extend beyond the proposed mining area the grades are lower than published reserves (Section 1.1), The following conclusions are apparent from this table.; 1. the cap is leached of copper and depleted in the mineral molybdenite; although not shown in this table, the molybdenum content is nearly constant indicating l i t t l e overall mobility of the element despite the fact i t has been oxidized completely. 2. supergene oxide and sulphide zones are enriched in copper to about the same degree. 3. supergene oxide and sulphide zones are not enriched appreciably in molybdenum. 4. regarding the supergene oxide and sulphide zones as a single enriched zone, the overall enrichment ratio relative to the hypogene zone is about 1,7 for copper, 1.0 for molybdenite, and 1,6 for copper equivalent9 (from arithmetic means). If the assumption is made that copper from the leached cap was transported downward and deposited entirely in the enriched zone, the original thickness of the cap can be calculated readily from: lc x Dc = le x Ee> where: t = original cap thickness calculated from arithmetic data, Dc = cap depletion in copper t = thickness of enriched zone, and E e = enrichment zone enrichment in copper. a: copper equivalent = copper assay + 2 x molybdenite assay. 128 TABLE 3.7 STATISTICAL SUMMARY OF SUPERGENE ENRICHMENT AND HYPOGENE ASSAY DATA FROM DRILL HOLES A r i t h m e t i c Values V a r i a b l e No. o f Standard Logarthmic Values Hoi es Mean D e v i a t i o n Geometric Mean A. Leached capping zone 1. t h i c k n e s s i n f e e t 25 230.6 112.8 207.0 2. grade i n percent copper 25 0.046 0.036 0.035 3. grade i n percent molybdenite 25 0.008 .0.007 0.005 • 4. grade i n copper e q u i v a l e n t 3 25 0,061 •'0.042 0.047 B. Supergene oxide zone 1. t h i c k n e s s i n f e e t 21 80.8 62.7 57.9 2. grade i n percent copper 21 0.213 0.167 0.162 3. grade i n percent molybdenite 20 0.021 0.020 0.015 C. Supergene s u l p h i d e zone 1. t h i c k n e s s i n f e e t 25 206.2 98.5 171.8 2. grade i n percent copper 35 0.268 0.122 0.232 3. grade i n ^ p e r c e n t molybdenite ' 35 0.023 0.020 0.015 D. Enrichment zone'3 1. t h i c k n e s s i n f e e t 25 247.1 104.6 209.0 2. grade i n percent copper 25 0.252 0.125 0.213 3. grade i n percent molybdenite 25 0.023 0.021 0.017 4. grade i n p e r c e n t copper e q u i v -a l e n t 3 25' 0.298 0.160 0.246 5. v a l u e 0 i n f e e t , percent copper e q u i v a l e n t ' 1 25 82.42 63.68 51.39 E. Hypogene zone 1. grade i n percent copper 25 0.147 0.082 0.122 2. grade i n percent molybdenite 25 0.022 0.022 . 0.013 3. grade i n percent copper e q u i v a l e n t 3 25 0.191 0.110 0.155 F. Enrichment zone to hypogene zone r a t i o s 1. r a t i o f o r copper - 1.72 1.75 2. r a t i o f o r molybdenite - 1.04 1.31 3. r a t i o f o r copper e q u i v a l e n t 3 - 1.56 - 1.59 a: Copper e q u i v a l e n t equals percent copper plus two times percent m o l y b d e n i t e , b: Enrichment zone equals supergene o x i d e p l u s supergene s u l p h i d e zones, c: Value equals copper e q u i v a l e n t times f e e t o f enrichment. 9 129 Using arithmetic values from Table 3,7 the calculated value for original cap thickness (t ) is: t (0.147 - 0.046) = 247.1 (0,252 n 0.147), or: t = 257 feet. The arithmetic average of the present cap thickness is 231 feet. Consequently, on the average, very l i t t l e cap rock (about 26 feet) has been removed by erosion. Of course, there are some obvious assumptions in the foregoing calculations. For example, an implicit assumption is that copper was more-or-less evenly distributed throughout the original hypogene mineral deposit and has been adequately sampled by the 25 to 35 dri l l holes. This is not unreason-able in view of the characteristically uniform distribution of grade in many porphyry-type deposits. Furthermore, 100 percent capture of downward moving copper is assumed in the zone of enrichment. This is the weakest part of the argument but i t does seem likely that a very high proportion of copper would be retained in the system. The major reason is the presence of a very large pyrite zone surrounding the copper-molybdenite deposit, and i t is largely the presence of pyrite that fixes copper in the zone of supergene sulphide enrichment. By the time erosion had cut down to the copper-molybdenite deposit, escaping ground waters would be released through the surrounding pyrite halo and it is unlikely that much would escape. These calculations, of course, provide approximate but realistic figures although one must not rely on their exactness. One may conclude, then, that on the average, there is almost enough cap thickness to account for the enrichment, in the supergene oxide and supergene sulphide zones. Migration of some copper solutions is demonstrated elsewhere, however, the major portion of the land surface on Patton Hill must be close to the original surface at 130 the onset of supergene alteration. Some portions of Patton H i l l , particularly toward Casino Creek are deeply incised suggesting that the topography in this area does not represent the original surface. Statistical analysis in Figure 3.14 of the distribution of elevation values shows two well-defined lognormal distributions. In Figure 3.15 the separated two populations and those values that are a mixture of the two, plot distinctly as follows: 1. the population of lower elevations covers a strip beside Casino Creek and Canadian Creek. 2. the population of higher elevations covers the top part of Patton Hi l l . 3. a zone of mixed populations occur between the two populations above. Since the top part of Patton Hill is nearly original surface by the criteria of cap grade, reconstruction of the population of elevations related to this area closely represents the original surface at the time supergene enrichment commenced. The second, lower elevation, population has been down cut by Canadian and Casino Creeks; events that clearly lowered the base level of ground water flow with concommittant lowering of the water table. The down-cutting is distinguished by one population. Perhaps i t is not surprising, then, that only one major blanket of'supergene enrichment is known. Cap thickness averages 231 feet, but ranges from 100 to 510 feet. Figure 3.16 is a contour plot of cap thickness. Area A, of shallow cap thickness, is related to the downcutting of Casino Creek. The axis of Area B which outlines where the cap thickness is greater than 275 feet has the following relationships when Figure 3.16 is compared to, other maps: 1. i t is not related to topography (Figure 3.15) in any obvious way, 2. it is generally within the phyllic alteration zone although i t FIGURE 3.14: BIMODAL PROBABILITY PLOT OF 125 VALUES OF ELEVATION AT CENTRE OF CELLS, CASINO, Y.T. O r i g i n a l d a t a and machine-drawn contours a r e shown i n F i g u r e 3.15. 100 £0 0 IQO 2 0 0 3 0 0 M 400 200 j 4 0 0 ^ " " 8 0 0 J200 FT I L E G E N D i , n ELEVATION ( F T . ) AT CENTRE OF 1 0 0 F T . SQUARE C E L L . f>nJ MACHINE CONTOURS OF TOPOGRAPHY (ELEVATION IN FT. X 1 0 " 1 ) AREA A > 1 3 6 0 F T . IN ELEVATION. AREA B < 1 2 6 0 F T . IN ELEVATION. FIGURE 3 . 1 5 : MACHINE CONTOURS OF TOPO-GRAPHY, CASINO/ Y . T , ELEVATION POPULATIONS A AND B ARE DEFINED IN FIGURE 3 . 1 1 . 12400 S 13200 S 3200 S L E G E N D , " A " DRILL HOLE LOCATION WITH THICKNESS OF LEACHED CAPPING IN FEET. MACHINE CONTOURS OF THICKNESSES OF ST LEACHED CAPPING IN FEET. ' / / / / , ZONE A, CAP < 150 FEET THICK. .: \^S< ZONE B, CAP > 275 FEET THICK. '///// AXIS OF ZONE B. FIGURE 3.16: CONTOURS SHOWING THICKNESS OF LEACHED CAPPING, CASINO, Y.T.V 1200 5 100 50 0 100 200 300 U 400 600 1200 FT L E G E N D O J 4== DRILL HOLE LOCATION. MACHINE CONTOURS OF PERCENTAGES (xlOOO) OF SUPERGENE OXIDE COPPER INDICATED FROM DRILL HOLE DATA. '///// ZONES A AND B: OXIDE COPPER>0,22Z 4000 S 4400 S 4600 S FIGURE 3.17: CONTOURS SHOWING PERCENTAGES OF OXIDE COPPER, CASINO, Y.T. 1600 S 1 0 0 50 Q ' 100 200 300 !• 400 sop j 400 800 FT L E G E N D £ 2800S & DRILL HOLE LOCATION. J MACHINE CONTOURS OF AVERAGE COPPER GRADE (% x 1000) OF ENRICHMENT ZONE (SUPERGENE OXIDE AND SUPERGENE SULFIDE ZONES). '////, ZONES A AND B: ENRICHED ZONE C0PPER>0.27% 4100 S 4800 S FIGURE 3.18: CONTOURS SHOWING AVERAGE COPPER GRADES (Z x 1000) OF ENRICHMENT ZONE, CASINO, Y.T. 100 50- 0 100 200 L E G E N D OT 75o' DRILL HOLE LOCATION KITH ENRICHMENT VALUE (THICKNESS OF ENRICHMENT ZONE IH FT. X COPPER EQUIVALENT (Cu2 + 2 x KoS 2i5)) IN FT. PERCENT COPPER EQUIVALENT. S MACHINE CONTOURS OF ENRICHMENT VALUES, CODED AS FOLLOWS: 1000 = 10 105 = 105 350 = 35 135 = 135 600 = 60 180 = 180 750 = 75 y///, ZONES A, B, AND C,>105 ZONE D,<75 IN CORE AREA. || | | | | PYRITE HALO (FIGURE 3,11). FIGURE 3,19: CONTOURS SHOWING ENRICHMENT VALUES, CASINO, Y.T. 137 locally crosscuts the edge of the potassic core. This is clear in comparison with Figures 3.4 and 3.5. The importance of phyllic alteration is also implied by comparison to Figure 3.10 where zone B of Figure 3.16 is peripheral to the tourmaline with hematite and/or magnetite zone which closely coincides with the central potassic alteration zone (Section 3.2.4), 3. i t crosses the breccia pipe contact but is clearly thicker in the breccia unit, as 'can be seen in comparison to Figure 3.6. In summary, the thickest cap zone outlined by area B is developed in phyllic alteration and breccia rock type because these features probably reflect high permeability. Permeability due to fracturing may also be important. Supergene oxide copper grades are shown in Figure 3.17. Two high grade zones are labelled A and B. Zone A is on a steep slope where surface and subsurface drainage is easterly into Casino Creek. Zone B is at the head of a southerly draining creek.. This coincidence of relatively high grade oxide copper zones with slopes draining to creeks suggests that the supergene oxide zone is an oxidation of the top part of the supergene sulphide zone brought about by a relatively recent drop in the surface of the water table. The occurrence of similar enrichment grades in both supergene oxide and supergene zones (Tables 3.7 and 3.8) also supports this conclusion. Figure 3.18 is a contour map of copper grades in the supergene sulphide zone. Enrichment greater than 0.27 percent copper shows two areas of concen-tration: 1. area A which roughly coincides with thicker leached cap, especially i f cap removal by Casino Creek (area A, Figure 3.16) is ignored. 2. area B which coincides with areas of high concentration of pyrite 138 TABLE 3.8 CORRELATION MATRIX COMPARING ASSAY DATA FROM THE SUPERGENE OXIDE ZONE TO ASSAY DATA FROM THE SUPERGENE SULPHIDE ZONE. 25 observations, all assay data were log 10 transformed. If the correla-tion coefficient is 0.505 the hypothesis that the two variables are independent at the 1 percent level is rejected (Dixon and Massey, 1951). If the correlation coefficient is>0.618 the hypothesis that the two variables are independent at the 0.1% level is rejected. Therefore, if>:0.518 the correlation is very good, and' the coefficient is underlined twice, if> 0.505 and<0.618 the correlation is good and the coefficient is under!ined once. SUPERGENE OXIDE SUOa Copper % SUOa Molyb % SUOa CuEc % Copper % 0.675 0.560 0.674 iii a. Cl I •ZD Z3 Molyb % 0.737 0.609 0.742, CuEc % 0.705 0.585 0.705 SUO = supergene oxide zone Moly = M0S2 CuE = copper equivalent - copper % + 2 x Moly % SUS = supergene sulphide zone 139 halo indicated by Figure 3,11, Figure 3,19 shows contour of supergene enrichment zone value which is equal to copper equivalent times enrichment zone thickness. Relationships apparent in this figure help to clarify general controls of supergene alter-ation. Areas of high enrichment value, A, B and C, all coincide with the pyrite halo defined in Figure 3.11. Areas A, B and C (A and B particularly) also coincide with areas of thicker cap defined in Figure 3.16. All these areas are well drained by present streams suggesting that the base-level in these areas may have been more quickly downcut here than elsewhere, thus promoting supergene enrichment. Downweathering likely is enhanced by highly fractured areas which also reflects a higher permeability. Area D, with low enrichment value, is centred on the zone of sil i c i f i e d tourmaline with hema-tite and magnetite (also potassic alteration facies); because this zone was relatively impermeable l i t t l e enrichment developed; Table 3,9 shows that stronger supergene enrichment correlates with higher copper values in the hypogene zone, The major controls for high supergene zone grades are; high hypogene zone grade, favourable permeability which is related to breccia and to the phyllic zone or the outside edge of the potassic zone, coincidence of pyrite rich rocks to promote chalcocite replacement, and rapidly downcutting frac-tured areas to lower the ground water table. 140 TABLE 3.9 CORRELATION MATRIX COMPARING ASSAY DATA FROM THE SUPERGENE SULPHIDE COPPER AND SUPERGENE ENRICHMENT ZONES TO ASSAY DATA FROM THE HYPOGENE ZONE - 25 observations, all assay data were log 10 transformed. If the correla-tion coefficient is >0.505 the hypothesis that the two variables are . independent at the 1 percent level is -rejected (Dixon and Massey, 1951). All correlation coefficients in the table below are significant at the 1 percent 1evel. SUPERGENE SULPHIDE ENRICHMENT SLISa Copper % ENRb Copper % ENRb Molyc % ENRb CuEd % Copper/, 0.740 0.698 • ' 0.558 0.690 I. Molyc % 0.758 0.731 0.863 0.766 o £ CuEd % 0.778 0.740 0.660 0.746 TT. a: SUS = supergene sulphide zone b: ENR .= enriched zone = supergene oxide +. supergene sulphide zone c: Moly = MoS2 d: CuE = Copper equivalent = copper % + 2 x Moly % . . 141-3.3.2 Environment and Age of Supergene Formation It is not obvious when supergene alteration in the Casino area formed. Nor is it clear whether or not i t is forming under present semi-arid arctic environmental conditions. It is known, however, that supergene enrichment is occurring at present in the tropical rain forests of New Britain (Titley, 1973) where enrichment factors of two to four are developed with supergene alteration zones some 450 feet thick. In New Britain important environmental factors include: major relief, high rainfall of about 350 inches per year, warm climate, rapid uplift causing lowering of the water table as base level is lowered, and mineralized rocks with high primary permeability due to strong fracturing. The Casino deposit formed about 70 m.y. ago, just before the Tertiary Period; i t was fractured, mineralized, altered and emplaced in an area that was to become uplifted and denuded. On the basis of the plant record,- Dorf(1969) has concluded that Tertiary climates changed from consid-erably warmer conditions in the early Tertiary to cooler conditions in Late Tertiary times. Thus, in the early Tertiary the climate was much warmer and wetter than now. This is indicated by the occurrence of subtropical types of trees, including palms, as far north as southern Alaska, while fossil leaves of the magnolia and fig trees have been found in early Tertiary deposits of Alaska (Moore, 1958). A radical change to an arid and cool climate in Alaska probably occurred in the Oligocene between 30 and 35 m.y.-on the basis of leaf margin curves9 from Tertiary floras of Alaska (Violfe and Hopkins, 1967). The onslaught of this cooler climate and the initiation of glacial a: Leaf margin curves are drawn by plotting percent of species of flora with entire margined (smooth, without teeth) leaves against age. Axelrod and.Bailey (1969) suggest, however, that because Wolfe and Hopkins (1967) did not take into account leaf size their above evidence for rapid lower-ing of temperature is incomplete. 142 conditions was probably not conducive to supergene leaching and enrichment. McConnell (1905) suggested that supergene bleaching occurred at least as far back as the Pliocene in the white channel gravels of the Klondike Gold Fields just south of Dawson, Y.T. He argues that ground water circulation was required to leach the greater part of the iron from the gravels and that climatic conditions since the Pliocene, including the present, would have frozen the ground water with the gravels as soon as they were deposited to preclude ground water circulation with consequent leaching. In conclusion, the conditions most favourable for supergene leaching and concentration probably existed in the Tertiary until the mid-01igocene. It is suggested, therefore, that the Casino supergene alteration occurred during this time. The supergene oxide zone, however, as noted previously, may have formed more recently, and probably is gradually destroying the supergene sulphide zone at the present time. 143 CHAPTER IV IMBRICATE SUBDUCTION ZONES AND THEIR RELATIONSHIP WITH UPPER CRETACEOUS TO TERTIARY PORPHYRY DEPOSITS IN CENTRAL CANADIAN CORDILLERA, 4.1 INTRODUCTION Genesis of porphyry-type deposits has been related to models of plate tectonics by a number of writers (Si 11itoe, 1972 and 1972a; Sawkins, 1972; Hodder and Hollister, 1972; Touray, 1973). The circum-Pacific distribution of porphyry copper-molybdenum deposits in igneous belts located either along continental margins or in island arcs has been linked to partial melting of wet oceanic crust descending along Benioff zones (Mitchell and Garson, 1972). Geological and geophysical data from the South American Cordillera indicate subduction of the East Pacific plate beneath the continental South America plate (James, 1971; Clark, 1974; Dewey and Bird, 1970) with concomitant development of belt-like 'metallogenic provinces roughly parallel to the western coast of South America (Si H i toe, .1972 and 1972a). Models incorporating plate tectonic theory have been developed to explain'the complex evolution of the Canadian Cordillera. Thus, Monger et al. (1972) postulated that plates, of oceanic and arc origin, were subducted northeasterly down a series of zones in a way' that explained the tectonic framework shown in Figure 4.1 (notably, the narrow, northwest trending, elongate belts and the changes in structural and stratigraphic character of 144 these belts from west to east, Many porphyry deposits occur along the northwest trend of the Intermontane Belt. However, these deposits appear to be superimposed on more than a single, recognizable, major tectonic subdivision, For example, the Casino deposit is like a number of similar-aged porphyry deposits in the Intermontane Belt, but it occurs in the Yukon Crystalline Platform (Douglas, et al., 1970). Thus, the strong resemblance between the deposits in different crustal settings implies a subcrustal origin, and the linearity of the deposits fits a plate tectonic model. 4.2 DEDUCTIONS FROM PORPHYRY DEPOSITS AND INTRUSIVE ROCKS RELEVANT TO A PLATE TECTONIC MODEL. Distribution of porphyry deposits in the Canadian Cordillera is shown in Figure 4.1. Potassium-argon model ages of these deposits (Table 4.1), plotted as a histogram (Figure 4.2), show a pronounced concentration of porphyry deposits in the age range 45 to 85 m.y. This time interval is dominated by a large number of porphyry-type deposits that are either within the Intermontane Belt or along the eastern margin of the Coast Crystalline Belt. Figure 4.3 shows potassium-argon ages of porphyry deposits plotted versus the distance from the eastern margin of the Coast Crystalline Belt (Figure 4.1: line a-b). The resulting plot indicates that these porphyry deposits can be separated into (1) group A (Table 4.2 and Figure 4.3) that are dominantly molybdenum, 50 m.y. old deposits that cluster very close to the eastern margin of the Coast Crystalline Belt, and (2) groups B, C and D (Table 4.2 and Figure 4.3) that plot with a general trend about a straight 145 FIGURE 4,1; DATED PORPHYRY TYPE DEPOSITS AND GRANITIC ROCKS, AND TECTONIC ELEMENTS OF CANADIAN CORDILLERA. A-B; Fairweather - Queen Charlotte Fault. C-D: Denali-Shakwake-Fraser Suture. E-F; TesTin-Pinchi Suture. G-H: Tintina-Rocky Mountain Lineament. 1; Insular Belt. 2; Coast Crystalline Belt. 3: Intermontane Belt. 4; Omin-eca Crystalline Belt. 5: Yukon Crystalline Platform. 6: Eastern Marginal Belt. Line a-b marks eastern boundary of Coast Crystalline Belt. Line c-d is tangent to Queen Charlotte Fault. Numbered crosses are dated intrusive rocks (Table 4.3 and Figure 4.5). Other numbered symbols refer to dated porphyry deposits (Table 4.1 and Figures 4.2 and 4.3). 147 TABLE 4.1 POTASSIUM ARGON MODEL AGES, DISTANCE RELATIONSHIPS, AND METAL CHARACTERISTICS OF PORPHYRY DEPOSITS OF CANADIAN CORDILLERA. D i s t a n c e (km) . from E'rn Margin f 9 o f Coast C r y s t a l -Number Deposit Name m.y. Symbol' l i n e Complex M e t a l ( s ) 1 Chi 11iwack 2 0 a , 26.1 C> D _ Cu 2 Cork - Cu.Mo 3 111iance R i v e r 34,4 a 179 Mo 4 Mt. Washington 3 5 a - Cu, Mo 5 C o r r i g a n Creek 3 8 a - Cu, Mo 6 F a i t h ,Gem . 3 g a - Cu, Mo 7 Catface • 48* 4 8 a Cu, Mo 8 Red Mountain Mo 9 Big Onion 48.7 a , 4 8 . 8 a ' b log9 Cu ' 10 Mt. P r i e s t l y Mo "11 T r a i l Peak 48.9 a 1 7 4 9 Cu 12 Ridge ' 49.0 a , 4 9 . 3 ^ 49.5 C 'P 4 9 . 5 a ' b 09 Mo 13 Berg 2 0 9 h Cu ,Mo 14 Mt. Reed 2 6 f ? ) h Mo, W 15 Red B i r d 1 7 9 Mo 16 Lucky Ship 4 9 ,9 a 3 1 g Mo 17 Tof i n o 5 0 r h 2 6 ( ? ) h Mo 18 Mt. Haskin 50.1 c 7 50.4 a 'P ' 5 0 - 5 « h Mo 19 Newman ( B e l l Cooper) 1569 Cu 20 Old Fort 1549 Cu 21 B e l l Molybdenum 5 1 . 1 a , b 5 1 . 6 a ' 3 5 1 . 8 a , D i p 9 3 9 0 Mo '22 B.C. Molybdenum Mo 23 Gran'isle 1 5 6 9 Cu 24 Val 1ey 52.0 a 0 Mo 25 Morr i s o n 5 2 . l a , 5 2 . 5 a , D 162 9 Cu 26 Roundy Creek °o Mo 27 Kay 53. 2 a O 9 Mo 28 Mt. Tomlinson 53.8 a 1209 Mo 29 Ajax 54.0 a ' I49 Mo 30 Goosly 56.2? 61. ?. 1 0 8 g 92, Cu, Mo 31 Maggie Cu 32 Adanac 62.0 C 611 Mo 33 Rey Lake 6 7 a K Cu 34 Muber (Molymine) 6 9 - 5 c b 70.0 ' 999 Mo 35 C a s s i a r Molybdenum o(?r Mo 36 Sunsets Creek 70.0 a , 70.3 ' 759 Cu, Mo 37 Casino - Cu, Mo 148 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 G l a c i e r Gulch Rocher de Boule Jan T r o i t s a B e r g e t t e Lennac Lake Huckleberry Bear (Laura) Ox Lake Coles Creek Boss Mountain Endako I s l a n d Copper Brenda L o r r a i n e Tachek Creek S t i k i n e Copper Mountain Bethlehem 70.8 a 71.9 d Mo, Cu, Cu, Cu, Cu, Cu Cu, Mo, Cu, Cu, Mo Mo Cu Cu, Cu Cu Cu, Cu Cu Mo Mo Mo Cu Mo Mo Mo Mo Mo W Mo, W a. C a r t e r , 1974. b. a n a l y s e s averaged. c. C h r i s t o p h e r , 1973. d. F i g u r e 2.19 and Table 2.5. e. H a r a k a l , 1974, pers. com. f. numbers o r symbols on .Figures 4.1, 4.2 g. measured on C a r t e r , 1974: F i g u r e 4. h . measured on C h r i s t o p h e r , 1973: F i g u r e i . measured on White, 1966: F i g u r e 10-1. j . Rowe, 1973. k. S u t h e r l a n d Brown, 1969. 1. M c M i l l a n , 1970. Motes: 1 : t o t a l number of d e p o s i t s = 56 It I i ? i i M.Y.:?5 25 4 6 3 5 2S! 28 2 7 26 25 24 23 22 21 20 1S 13 30 33 40J j47 35 39 43 46 32 34 38 42 45 31 33 37 41 44 EM: 1 0 1 A G E : DIVISION: SYMBOL: I E 2 2 0 11 RTI A R Y — i 55 I 12 1 2 75 35 105 s 115 2: numbers w i t h i n h i s t o n r a n r e f e r to d e p o s i t l i s t i n o o f Table 4.1 3: d e p o s i t s o l d e r than 85 m.y. not c o m p l e t e l y r e o r e s e n t e d . 4 4 3 4 0 0 j C 1 0 0 0 0 U P P E R I L O W E R C R E T A C E O U S . S C R E T A C E O U S g . — 4 2 . 9 . 4 3 — 5 7 3 •85 43! -; I 125 135 "T" 145 53| i T S i 155 175 185 135 205 0 0 1 155 0 1 0 0 2 0 1 0 J U R A S S i C 1 0 2 0 0 2 5 - 142.S 14! 211 F I G U R E P Ll ?• HISTOGRAM OF K.AR. AGES FOR PORPHYRY DEPOSITS.. CANADIAN C O R D I L L E R A . 150 FIGURE 4.3; Potassium Argon Model Ages of Intrusive Rocks Associated with Porphyry Deposits Versus Distance from Eastern Margin of Coast Crystalline Belt (Figure 4.1: line a-b). Symbols and deposit number as in Table 4.1 and Figures 4.1 and 4.2. Cross through symbol indicates that data point was not used to establish line. Dashed lines are drawn 2 standard errors (in Y) from, the mean line (standard error in Y is 5.3). Number of points (n) used to define line is 21. Correlation coefficient (r) for the mean line is -0.90. t n 4.0 33.0 72.0 I0S.0 I ' i O . O 174.0 D I S T A N C E ( K M . ) FROM L I N E o -1> (FIGURE 4.1} 152 line (r = -.0.90). Group B are 84••m.y. old copper-molybdenum deposits that occur near the western margin of the Intermontane Belt. From this area centres of intrusions related to porphyry deposits migrated easterly, through group C (copper-molybdenum-tungsten deposits) for about 174 km. at an average rate of 0.5 cm. per year to finally form 46 m.y. old, dominantly copper, porphyry deposits at group D. Chemical analyses for certain oxides (Carter, 1974) from intrusive rocks associated with the deposits in Figure 4.3 are listed in Table 4.2. Average K2O contents at given Si0g are plotted on Figure 4.4 (after Dickinson, 1970) against depth "h" to Benioff zone (James, 1971; Lipman et al., 1971). Although these data can be influenced locally by factors such as hypogene potassic alteration, averaged data from Table 4.2 plotted on Figure 4.4 indicate that group A intrusions at the eastern margin of the Coast Crystalline Belt may be related to a Benioff zone originally about 300 km. deep, and are associated mainly with molybdenum deposits. Groups B, C and D apparently are related to a Benioff zone about 200 km. deep, and are associated with copper and/or molybdenum deposits. Figure 4.5 illustrates the discontinuity between group A and groups B, C and D in % K2O and K2O to Na20 plus CaO ratio. In addition the content of molybdenum, and possibly tungsten, in deposits decreases from group B to the more easterly and younger group C. This change is reflected by the drop in K2O to 1^0 plus CaO ratio. Eastward younging of granitic intrusions suggests the presence of an underlying, subducting plate moving easterly from a subduction zone lying to the west of the eastern margin of the Coast Crystalline Belt (Farrar,.et al., 1970; James, op.cit.; Clark, 1974), However, the'discontinuity in *aqe, metal characteristics, percent K2O, K~0 to NaoO plus CaO ratios, and apparent 153 h ( km.) FIGURE 4.4: K-h plots of lvalues, which are %Y^0 at given %Si0 2 (e.g. K55 = 55% SiO2)? against depth to Benioff zone (h). Variation diagram was obtained from Dickinson (1970, p. 832). Groups A to D are averages obtained from intrusive rocks associated with porphyry deposits (Table 4.2). Standard errors are shown by bars. 154 TABLE 4.2 ANALYTICAL DATA FROM INTRUSIVE ROCKS ASSOCIATED WITH PORPHYRY DEPOSITS IN WEST CENTRAL BRITISH COLUMBIA. Group A: Eastern Margin Coast C r y s t a l l i n e B e l t No. a Name Age(m.y,) a S i 0 o b K ? 0 b N a 2 0 b CaO K 20 Na ?0 + CaO 13 Berg 49.3 65.02 C 4.81 c 2.94 c 1.70 c 1 .04 15 Red B i r d 49.5 73.42 6.02 2.97 1 .14 1.46 21 B e l l Molybdenum 51.1 66.98 4.65 3.76 3.08 .68 22 B.C. Molybdenum 51 .6 71.38 6.72 1.07 1.90 2.26 26 Roundy Creek 52.5 71 .16 4.58 3.22 1 .40 0.99 29 Ajax 54.0 65.78 4.25 3.97 3.53 . .57 AVERAGES": 51.3 ±- 68.96 ± 5.17 ± 2.99 ± 2.12 ± 1.17 ± .73 1.41 .40 .43 .39 .25 AVERAGE DISTANCE (Table 4.1): 10.7 km. Group B: Western Margin Intermontane B e l t No. a Name Age(m.y.) a S i O ? b K ? 0 b Na ?O b CaO K 20 Na ?0 + CaO 44 ' Hu c k l e b e r r y 46 Ox Lake . AVERAGES": . DISTANCE FOR 8 82.0 66.98 83.4 64.22 3.30 2.45 3.48 3.75 . 2.12 2.53 0.59 0.39 82.7 ± 65.60 ± .7 1.38 2.7 m.y. ( F i g u r e 4.3): 8, 2.87 ± .43 .2 km. 3.62 ± .27 2.33 ±-.21 0.49 ± .10 Group C: C e n t r a l Intermontane Gelt _K2P_ No-'1 Name AgeQn.y.)" S i 0 £ _ K ? 0 U N a J ) " CaO N a ^ V ' C a Q 36 Sunsets Creek 70.0 65.44 3.53 3.32 3.58 0.80 38 G l a c i e r Gulch 70.8 70.98 4.03 5.55 1.87 0.55 39 Rocher de Boule 71.9 64.58 2.81 3.73 4.48 0.34 40 Jan 72. . 60.86 2_.44_ 5.80 4^72 0.23 AVERAGES^: 71.2 ± 65.47 ± 3.22 ± 4.60 ± " 3.66 ± 0~48~± .5 2.09 • .27 .79 .83 .13 • DISTANCE FOR 71.2 m.y. ( F i g u r e 4.3): 60.0 km. 155 Group D: Eastern Intermontane Belt NoJ^ Name Age(m.y.) b K ?0 b Ca0 K 20 Na20"+ CaO 19 20 23 25 Newman Old Fort Grani s i e Morri son AVERAGES'^: 50.4 50.5 51.8 52.1 59.76 63.90 64.34 63.18 2.66 3.20 2.66 1 .39 4.88 4.32 4.59 3.91 3.36 3.44 2.97 • 2.45 0.32 0.41 0.35 0.22 51.2 ± .4 62.80 ± 1.04 2.48 ± .38 4.43 ± .21 3.05 ± .23 0.32 ± .04 DISTANCE FOR 51.2 m.y. (Figure 4.3): 151.0 km. a: numbers refer to Table 4.1 and Figures 4.1, 4.2 and 4.3. b: Carter, 1974, Appendix B, Table B . l . c: averaged analyses. d: error expressed as standard error of the mean. 156 FIGURE 4.5: Percent K20 and ratio of K2O to Na20 plus CaO versus distance from eastern margin of Coast Crystalline Belt (Figure 4.1: line a-b). Data are from Table 4.2. Group A is from the eastern margin of the Coast Crystalline Belt and represents dominantly molybdenum porphyry deposits. Group B is from the western margin of the Intermontane Belt and represents molybdenum and/or copper deposits. Group C is from the central Intermontane Belt and represents molybdenum-tungsten and/or copper deposits. Group D is from the eastern margin of the Intermontane Belt and represents dominantly copper porphyry deposits. Standard errors of the mean are shown by vertical bars. L E G E N D 0 25 50 75 100 125 150 175 DISTANCE FROM EASTERN MARGIN OF COAST CRYSTALLINE COMPLEX 158 depth to Benioff zone between groups A and B (Table 4.2 and Figures 4,3? 4,4 and 4.5) near the eastern margin of the Coast Crystalline Belt make i t difficult to avoid the conclusion that a second Benioff zone might have existed contemporaneously with the first, This supposition is examined below by plotting age - distance relationships for intrusive rocks in the Insular and Coast Crystalline Belt across the transect continuing southwestward from the above porphyry deposits to the western margin of the Queen Charlotte Islands. Figure 4.5, plotted from data in Table 4.3, shows potassium-argon model ages of intrusive rocks versus distance of the sample locality from a line drawn parallel to the eastern margin of the Coast Crystalline Belt and tangent to the Fairweather - Queen Charlotte Fault (Figure 4.1: line c-d). This graph can be fitted by a straight line (r = -0.91). The age of intrusions projected to the Fairweather - Queen Charlotte Fault is 165 m.y. Intrusive centres apparently migrated eastward at an average rate of 0.25 cm. per year over a distance of 300 km. where they attain an age of about 46 m.y. near the eastern margin of the Coast Crystalline Belt. The average age of group A porphyry intrusions along this boundary is similar, about 50 m.y. (Table 4.2 and Figure 4.3). Consequently, these data are consistent with a model incorporating a second Benioff zone. 159 TABLE 4.3 POTASSIUM ARGOtl RADIOMETRIC AGES AND DISTANCE RELATIONSHIPS OF GRANITIC ROCKS IN THE INSULAR AND COAST CRYSTALLINE BELTS. Number 3 Reference Age ± e r r o r D i s t a n c e (km.) Reference Number l i m i t s (m.y.) from Queen C h a r l o t t e F a u l t 1 GSC70-1 143 ± 8 HB 32 Wan!ess et a l . 1972, P- 6 2 GSC70-3 156 + 10 HB 58 Wan!ess e t a l . 1972, P- 7 3 GSC67-20 142 ± 14 HB 20 Wan!ess e t a l . 1970, P- 13 4 GSC66-14 142 ± 3 7 HR 31 Wanless e t a l . 1968, P- 19 5 GSC66-10 139 ± 7 B l 175 Wan!ess e t a l . 1968, P- 16 6 GSC67-24 104 ± 4 B l 185 Wanless et a l . 1970, P- 15 7 GSC67-23 115,+ 6 B l 176 Wan!ess e t a l . 1970, pp. 14-15 8 GSC64-5 & 6 107 B l 172 Wanless et a l . 1966, pp. 10-11 9 GSC66-16 8 7 + 1 1 HB 187 Wanless et a l . 1963, P- 20 10 GSC67-21 84,+ 4 Bl 202 Wanless e t a l . 1970, PP 13-14 11 GSC66-4 & 5 98 Hb & B l 198 Wanless et a l . 1958, pp. 12-13 12 GSC67-26 109 ±'5 B l 163 Wanless e t a l ., 1970, pp. 16-17 13 GSC67-27 & 28 95 HB & B l ' 172 Wanless et a l . 1970, P- 17 14 GSC64-11 67, + 5 B l 232 Wanless e t a l . 1966, pp. 13-14 15 GSC66-12 & 13 78PHB & B l 219 Wanless et a l . 1963, pp. 17-18 16 GSC67-33 & 34 77 Hb & B l 188 Wanless et a l . 1970, PP 20-21 17 GSC65-31 64 + 8 B l 219 Wanless et a l . 1967 , PP 32-33 18 GSC64-8 77 + 5 B l 215 Wanless , e t a l , 1966 , pp. 11-12 19 GSC64-7 77 + 5 Bl 215 Wanless et a l . 1966, pp. 11-12 20 GSC57-25 49 + 4 B l 251 Wanless et a l . 1970, P- 16 21 GSC66-15 47. + 4 Bl 314 Wanless e t a l . 1968, pp. 19-20 22 GSC66-8 & 9 46, HB & B l 49 HB & Bl 250 Wanless et a l . , 1968, P- 15 23 GSC66-6 & 7 " 298 Wanless e t a l . 1968, pp. 13-14 24 GSC65-30 44 + 4 B l . 266 Wanless e t a l . 1967, pp. 31-32 25' GSC65-32 46 ± 10 B l 250 Wanless e t a l . 1967, pp. 33-34. 26 GSC64-9 45 + 12 B l 304 Wanless e t a l . , 1966, pp. 12-13 27 GSC65-19 47 ± 5 B l 312 Wanless e t a l . , 1967, P- 23 28 GSC65-28 70, + 14 B l , 53 B l k MU 280 Wanless e t a l . 1967 , P- 30. 29 6SC66-10 & 20 252 Wanless , e t a l . , 1966 P- 13 and Wanless et. a l . 1968, pp. 22-23 a: Numbers on F i g u r e s 4.1 and 4.5 • b: analyses averaged. measured, on F i g u r e 10-1 (White, 1966) a f t e r p l o t t i n g of p o i n t s by l a t i t u d e and •longitude from r e f e r e n c e , d: mineral analysed: B l = b i o t i t e , HB = hornblende, MU = muscovite. 160 FIGURE 4,6: Potassium Argon Model Ages of Intrusive Rocks Versus Distance from Fairweather - Queen Charlotte Fault (Figure 4.1: line c-d). Symbols, location and number ()<12)-are as in Figure 4.1 and Table 4.3. Dashed lines are drawn 2 standard errors (in Y) from the mean line (standard error of Y is 14.5). Number of points (n) used to define line is 29. Correlation coefficient (r) for the mean 1ine is -0.91. 162 4,3 AN. IMBRICATE SUBDUCTIQN MODEL A single assumption provides the framework for the model presented here: that is, distance versus intrusive age trends of Figures 4.3 and 4.6 represent two paleo-Benioff zones that simultaneously ceased activity at about the same time, 50 m.y. ago. Additional assumptions have to be made to provide details for the plate-model within constraints imposed by geology which generally is known poorly in detail. Information required to construct a plate-tectonic model is summarized in Figure 4.7 and explained in detail in Table 4.4. Four guidelines for construction of Figure 4.7 may approximate only poorly the actual case. These are (1) assumptions for dips of Benioff zones (Figure 4.7: angles at points C and H), (2) definition of the time of initiation of a subduction zone by extrapolation of migration rates of intrusive centres (Figure 4.7: time of initiation of subduction zones at C and H from rates at M and R over distances BC and GH respectively), (3) calculation of apparent depth to Benioff zone, H, using granitic rocks and empirical plots by Dickenson (1970), and (4) drift rate for North America plate (Figure 4.7: point N) based on Atlantic sea floor spreading rates in Coney (1972). Figure 4.8 is, thus, a pictorial representation of a sequence of events restrained by the data and assumptions outlined above, in Figure 4.7, and in Table 4.4. Two subducting plates are envisaged. Plate 1 oceanic crust, beginning in the Middle Triassic, moved down under the "Insular plate" east of its subduction zone. Part of this plate became the Insular Belt and part of i t eventually formed the bulk of the Coast Crystalline Belt. Plate 2, beginning in the earliest-Cretaceous, oceanic crust moved beneath the margin 163 FIGURE 4.7: Basic Data and Assumptions Used in Construction of Figure 4.8. Location of key, lettered points are shown in Figure 4,8. Explanation of lettered points is detailed in Table 4.4 and in appropriate places in the text. 164 SUBDUCTION ZONE AT H SUBDUCTION ZONE AT LINE_a_-b , a> (F igure 4.!) o 3 S C A L E : HOR IZONTAL AND V E R T I C A L 50 0 •LTO4 E 3 4 0 50 zxr : I00_ 150 2 0 0 CM. _czi__r... 0 4 0 80 :3 120 M l . 165 TABLE 4.4 EXPLANATION OF DATA CONSTRAINTS FOR FIGURE 4.7 POINT A: Porphyry deposit area of Babine Lake (deposit nos. 19, 20, e t c . , Figure 4.1); age of i n t r u s i v e rocks 49 m.y. (Table 4.2 and Figures 4.3 to 4.5: group D). POINT B: Present eastern margin of Coast C r y s t a l l i n e B e l t (Figure 4.1: l i n e a~b); 162 km. west of p o i n t A (Figui-es 4.1 and 4.3); age of i n t r u s i v e rocks, 84 m.y. (Table 4.2 and Figures 4.3 to 4.5: group A ) . POINT C: Subduction zone f o r p l a t e 2; 240 km. west of p o i n t B (locate d by assuming 40° d i p to p l a t e 2 t h a t passes through p o i n t 0 ) ; age at i n c i p i e n t development of subduction zone, 135 m.y. (obtained by d i v i d i n g d i s t a n c e BC by m i g r a t i o n r a t e of i n t r u s i v e s from p o i n t B to p o i n t A (point M ) ) a . POINT D: E v e n t u a l l y becomes the eastern margin of Coast C r y s t a l l i n e B e l t ; at 135 m.y. p o i n t D i s eastern edge of " I n s u l a r p l a t e " 150 0 km. from p o i n t C. This d i s t a n c e i s perpe n d i c u l a r to l i n e s a-b and c-d (Figure 4.1) and i s the d i s t a n c e r e q u i r e d t o allow f o r west-ward movement of the North America p l a t e as i n d i c a t e d by A t l a n t i c sea f l o o r data (Coney, 19 72) f o r the per i o d 135 to 50 m.y.; see po i n t N. POINT E: Hecate S t r a i t (Figure 4.1). POINT F: Eastern margin of Queen C h a r l o t t e I s l a n d s . POINT G: Fairweather - Queen C h a r l o t t e F a u l t (Figure 4.1: l i n e c-d). POINT H: Subduction zone f o r p l a t e 1; 10 5 km. west of p o i n t G (located by assuming 35° dip to p l a t e 1 th a t passes through p o i n t S); age at i n c i p i e n t development of subduction zone 210 m.y. (obtained by d i v i d i n g d i s t -ance GH by mi g r a t i o n r a t e of i n t r u s i v e rocks from p o i n t G t o p o i n t D (point R ) ) a . POINT I : Oceanic p l a t e ; oblique subduction at H i s i n d i c a t e d by r e l a t i v e northward movement of P a c i f i c sea f l o o r w i t h respect to Horth America p l a t e - from seamount data ( I r v i n g and Yole, 19 72) and magnetic patterns on the ocean f l o o r (Atwater, 1970). POINT M: Eastward r a t e of mi g r a t i o n of i n t r u s i v e s from p o i n t B toward p o i n t A i s 0.46 cm./hr. (1/s.lope of l i n e i n . Figure 4.3). 166 TABLE 4.4. (CONTINUED) POINT N: POINT 0: POINT R: Approximate westward' 3 d r i f t r a t e of North America based on A t l a n t i c sea f l o o r spreading r a t e s i n Coney (19 72) that vary from 3 to 1 cm./yr. f o r the p e r i o d 13 5 m.y. to 49 m.y. 200 km. depth "h" below p o i n t B (Table 4.2 and Figure 4.4: group B). Eastward r a t e of mi g r a t i o n of i n t r u s i v e s from p o i n t F toward p o i n t D i s 0.2 5 cm./yr. (1/slope of l i n e i n Figur e 4.6). 300 km. depth "h" below p o i n t D (Table 4.2 and Figure 4.4:.group A). age c a l c u l a t i o n f o r t h i s p o i n t i s only approximate because assumption i n c a l c u l a t i o n may not be s t r i c t l y v a l i d . Given a v a i l a b l e data, how.ever, no other way to estimate age of t h i s p o i n t i s known. b: movement of North America p l a t e from 180 m.y. to present, as marked by the d i r e c t i o n between the White Mountain magma ser-ies,- i n New England, U.S.A., to the Azores, i n the mid-Antlan t i c (Coney, 19 72, a f t e r Morgan, 19 71) i s about at r i g h t angle to the trend of the Canadian C o r d i l l e r a . Subduction at C, however, may be oblique because r e l a t i v e movement of the "I n s u l a r P l a t e (point D) i s not known but may co n t a i n a l a r g e northward component i f paleomagnetic data from Karmutsen v o l c a n i c rocks are, c o r r e c t ( I r v i n g and Yole, 1972; c f . Symons 1971; c f . Beck and Noson, 1972). 167 FIGURE 4.8: Plate tectonic model of the development of imbricate subduction zones and related intrusive rocks in the central and western Canadian Cordillera. Most lettered points are explained by Figure 4.7 and Table 4.4. Point X represents erosion level of Coast Crystalline Belt in Prince Rupert - Terrace area. Point Y is erosion level, southern Coast Crystalline Belt. Suture C-D (Figure 4.1) crosses the Coast Range in response to this pattern of erosion. Point Z represents the bulge below Vancouver Island that is probably due to a slab of oceanic plate related to present sub-duction of the Juan de Fuca Plate (Atwater, 1970: Stacey, 1973), Primed letters (e.g. E1) indicate shifted relative positions. (+++) indicates granitic rocks formed above Benioff zone during time illustrated. Crustal thicknesses reflect type of plate. Present profile (sequence 5) modified from Wheeler et al. (1972), Stacey (1973), and Forsyth et al. (1974). 168 MIDDLE TRIASSIC ( 2 1 0 M.Y.) H.H G F . E 0~- 0-0 a INSULAR PLATE D 2. E A R L I E S T - C R E T A C E O U S ( 1 3 5 M.Y.) H G F E D\,C -Q >- C {ZZjll^ NORTH AMERICA P L A T E A 3 3. UPPER C R E T A C E O U S (84M.Y.) E D 4 . T E R T I A R Y ( 5 0 M.Y.) 5 . P R E S E N T ( 0 M.Y.) SCALE: HORIZONTAL AMD VERTICAL 50 100 150 200 KM. SO 0 E t E I J ESI 40 o n e 40 80 120 Ml. 169 of the westward drifting North America plate, Subduction of both plates was active until about 50 m.y. by which time the North America plate had collided with, and overridden, the eastern portion of the island arc. Thus, the two Benioff zones became imbricated. The doubling of plate thickness caused isostatic rebound of the merged plates and subsequent deep erosion exposed the dominantly igneous- terrane of the Coast Crystalline Belt. 4.4 DISCUSSION Data presented are mainly from the northeast trending transect from the western margin of Queen Charlotte Islands to Takla Lake (Figure 4.1: deposit 25) that is near the eastern margin of the Intermontane Belt (Figure 4.1). This is probably one of the best possible cross-sections of the Canadian Cordillera for sampling of granitic rocks. In the Intermontane Belt numerous plutons are exposed along the Skeena arch. Geology of the Queen Charlotte Islands and Hecate Strait portions of this transect apparently is simpler than that of Vancouver Island to the south and Alaska to the north because no rocks older than Mesozoic are exposed3. Probably configuration of the imbricated subduction zones about 50 m.y. ago (Figure 4.8; sequence 4) is similar to subparallel•„ imbricate paleo--Benioff zones postulated beneath western United States (L.ipman et al,, 1971) as defined by plotting K^O/Si0£ ratios in volcanic rocks against depth to a: Shouldice (1971) has suggested that the "basement" beneath the Tertiary sediments of Hecate Strait may contain, from the evidence of one oil exploration drill hole "intrusions of Paleozoic (?) age." 170 Benioff zone (h). Lipman et al. (1971) suggest that the westernmost Benioff zone emerged at one time at a trench. The eastern Benioff zone, however, is said to have been decoupled from the overlying continental plate and never emerged at the surface. It seems difficult to provide material for such a downgoing plate. A more reasonable model, presented in Figure 4.8, incorporates two plates of oceanic crust descending along zones that are similar to those documented through seismic records of present day Benioff zones near the margins of island arcs or continents (Isacks, et al., 1968; Dewey and Bird, 1970). Closure of the distance between the "Insular plate" and the North America plate started when the intervening oceanic plate became uncoupled at the western, leading edge of the North America plate (Figures 4.7 and 4.8: point C) about 135 m.y. ago, and produced the downgoing plate 2. Part of this movement is accomodated by drift of the North American Plate which is reflected in the Atlantic. Coney (1972) indicates that North. America has drifted westward from 180 m.y. to the present based on the assumption (after Morgan, 1971) that the White Mountain magma series at the eastern edge of the North America plate (New England, U.S.A.) Originated near the Azores (presently in the mid-Atlantic) 180 m.y. ago. The White Mountain magma series and the Azores moved about 1500 km. apart from 135 m.y. to 40 m.y. Some westward movement of the North America plate took place before the subduction zone developed at point. C (Figures 4.7 and 4.8). This movement probably • : caused compression along the western margin of the North America plate with consequent development of a geanticline and a parallel trough to the. east by Middle Jurassic. In this structural framework Triassic and Lower Jurassic granitic rocks in upthrust blocks of this geanticline were eroded and deposited 171 eastward, for example, in the Whitehorse trough (cf. Wheeler et al,, 1972, Figure 9, p. 20 and Figure 10, p, 22). These older granitic rocks were an integral part of the North America Plate at this time (cf. older porphyry deposits Figure 4.2) and,' therefore, are not thought, here, to be related to the Coast Crystalline complex discussed below. Figure 4.8 implies that the Coast Crystalline Belt was generated largely from processes related to subduction of oceanic plate 1. Culbert (1972) lends some support to such an origin. He notes that granitic rocks in this belt have potassium-rubidium ratios that are significantly higher than normal for continental granitic rocks. He states (ibid., p. 1097) that: "One explanation for the abnormal Coast Mountain K/Rb values is that these alkalies may have been derived in part by destruction of oceanic crust during.. ..subduction." Furthermore, he indicates (ibid., p. 1098) that all parameters involving potassium or rubidium change radically at the eastern boundary of the Coast Mountains. Such changes in chemistry are substantiated by Figure 4.5 and are readily related to the imbricate subduction model of Figure 4.8. Relative westward movement of the North America plate caused i t to collide with and over-ride the "Insular plate" (Figure 4.8: length CB over length DE). This doubling of plate thickness resulted in rebound reflected, in part, by the presently high elevations of the Coast Crystalline Belt. The rate of erosion increased as a consequence of the uplift and is thought to have occurred largely in the late Mesozoic and Tertiary (Eisbacher, .1975). Because the crustal thickness where this overlap occurred is about normal (Figure 4.8: sequence 5) the implication is that material approaching the thickness of one crustal plate has been removed leaving ubiquitous roof 172 pendants in this belt, as remnants (Roddick, 1966). Deep removal of material . is supported by the occurrence, in the Prince Rupert area, of metamorphic facies of amphibolite grade within roof pendants that indicate lithostatic pressure of greater than 6,000 bars (equivalent to approximately 17 kilometers of lithostatic pressure) (Hutchison, 1970). This level of erosion is indicated in Figure 4.8 (sequence 4, point X) as the lower part of the overriding North America plate. A study by Reamsbottom'(1974) of a pendant in the southern portion of the Coast Crystalline Belt is not as simply interpreted but indicates that pods and slices of ultramaphic rocks and their enclosing schists were metamorphosed at depths of 23 km.a It is suggested, here, that these rocks may have originated near the base of the North America plate and indicate considerable erosion. The occurrence of several massive sulphide deposits and associated rnetavolcanic rocks in the roof pendants of the Coast Crystalline Belt (Hutchison, 1970; Woodsworth, 1971) attests to early volcanic activity above plate 2 in the foreland of the North America plate (Figure 4.8: segment BC). Exact location of the suture between the North America and "Insular" plates is difficult because (1) magmatisrn continued after collision and overlap (e.g. Figure 4.8: 50 m.y. old magmatisrn at point B in sequence 4), and (2) deep erosion of the Coast Crystalline Belt in the late Mesozoic and Tertiary (Eisbacher, 1975) exposed rocks that are intensively metamorphosed so that correlation of units is difficult. Presumed flatness of the suture and the exceptionally difficult terrane of the Coast Crystalline Belt compounds the problems in the definition of this surface. Nevertheless, suture C-D (Figure 4.1) roughly divides the Coast Crystalline Belt into two. a; based on isobaric, univarient reaction: talc + forsterite + enstatite + vapour. 173 The impl icat ion of the pos i t ion of th i s suture i s that deeply eroded segments of the North America plate are east of th i s l i n e . Rocks west of the suture belong to the " Insular p l a t e " . Present conf igurat ion of the western Canadian Co rd i l l e ra was achieved when debris eroded from the Coast C r y s t a l l i ne Be l t , and the portion of the " Insular p l a te " west of the Queen Charlotte f a u l t (Figure 4.8; segment G-H) was removed by the northward moving Kula p late. According to Atwater (1970) th i s p late moved northward at a rate of 12 cm. per year and was consumed at the Aleutian Trench. Thus, the sediments deposited on th i s plate were removed rap id l y , in about a 20 m.y. period. 4. 5 CONCLUSIONS A model, consistent with presently known geology and plate tectonic theory, i s presented in Figure 4.8 to describe the evolution of much of the western and part of the central Canadian Co rd i l l e r a . The fol lowing scenario i s re lated to th i s f i gu re . A Benioff zone, i n i t i a t e d in the Middle T r i a s s i c , produced a ser ies of g r an i t i c plutons that started with Jurassic-Cretaceous rocks in the Queen Charlotte Islands and ended with Tert ia ry rocks, and associated porphyry molybdenum deposits, along the eastern margin of the Coast C r y s ta l l i ne Be l t . Near the e a r l i e s t Cretaceous, a second Benioff zone was i n i t i a t e d , perhaps by the westward d r i f t i n g of the North America p late. This Benioff zone produced: (1) Upper Cretaceous g r an i t i c plutons and coeval molybdenum-copper porphyry deposits along the western margin o f the Intermontane 174 belt, and (2) the Tertiary plutons and associated porphyry copper deposits near the eastern edge of the Intermontane Belt, Overriding of the stationary island arc by the westward drifting North America plate resulted in imbrication of the two Benioff zones, and uplift and subsequent erosion of the Coast Crystalline Belt. Remnants of the obducted North America plate include roof pendants metamorphosed at depths approaching the thickness of a crustal plate and massive sulphide deposits indicative of volcanic activity in the Coast Crystalline Belt. The model of Figure 4.8 appears to bring together a large body of data, but i t considers only the activity associated with two palo-Benioff zones. It does not analyse the evolution of the Intermontane Belt, and contained deposits, before 85 m.y. Young intrusions and porphyry deposits in the Insular Belt, similarly, have not been discussed. Complexities in correlations between events suggested in the model (based primarily on data from the transect from the Queen Charlotte Islands to Babine Lake) to events north and south of the transect are to be expected. These problems are under investi-gation. 175 CHAPTER V SUMMARY AND CONCLUSIONS The following discussion concerning the Casino area deals with (1) emplacement of the mid-Cretaceous Klotassin batholith into the Yukon Metamorphic Complex, (2) development of the latest-Cretaceous Casino complex as "wet" magmas probably derived from a Benioff zone, (3) development of hypogene zoning patterns by upward and outward movement of magmatic hydro-thermal solutions, (4) formation of supergene zones, depleted of and enriched in copper, in response to climatic conditions during the Tertiary, (5) guidelines concerning further exploration at Casino, and for similar deposits, and (6) direction of possible further studies. Intrusion of Klotassin batholith, during the mid-Cretaceous (99.3 m.y.), into the Yukon Metamorphic Complex may have been guided, in part, by fault, zones which are occupied locally by bodies of ultramafic rocks of Permian and/or Triassic age. The massif was probably emplaced within and near the western margin of the North America plate. Eight units of intrusive rocks, distinctive in field occurrence,, texture and mineralogy, have been defined in the general area surrounding the Casino deposit. Potassium-argon model ages of biotites and hornblendes from the different granitic rocks are statistically indistinguishable and average 99.3 m.y, A relative age sequence of the intrusive units has been proposed (Section 2.4.11) on the basis of a clear cut compositional trend from diorite 176 to quartz monzonite (Figure 2.11). Porphyry dykes do not f i t this trend. The batholith probably consolidated in a zone transitional between the epizone and mesozone at a depth of about four to five miles. The area was uplifted and eroded for a substantial time interval (circa 180 m.y. to 70 m.y.) before the next important tectonic event-formation of the Casino complex. Volcanic rocks of the Casino complex intruded the Klotassin batholith at several localities along the trend of the Dawson Range. In the immediate vicinity of the Casino deposit extrusive volcanic rocks are not known but breccia pipes, plugs and dykes are recognized. The latest-Cretaceous (70.3 m.y.) age of the Casino deposit clearly relates it to a number of porphyry deposits of similar age aligned along the tectonic trend of the Intermontane Belt. Disposition of these deposits as a whole can be explained simply in terms of magma generation related to the more easterly Benioff zone of an imbricate subduction arrangement that appears to have been operative at that time. Casino deposit is centred on an irregular, conical breccia pipe defined by the three units: tuff, tuff breccia, and cobble breccia. The pipe was formed in the immediate vicinity of an earlier plug (?) of Patton porphyry. At the surface this pipe is about 2,000 feet (670 m.) long in an east-west direction and 1,200 (400 m.) feet wide. It becomes smaller at depth and the axis plunges steeply to the south. Calculations of the energy that might be available in "instantaneous" adiabatic expansion of a hydrothermal solution exsolving from a wet granitic magma indicate that energy for fracturing, emplacing and moving rock in an explosive manner is available and is suffic-ient to form the Casino breccia. 177 A large-scale pattern of hypogene zoning is recognized at Casino and is generalized in Figures 5.1A and 5,IB, Figure 5.1A shows the central part of the potassic alteration facies to be centred on the northern side of the main breccia pipe. The middle of a pronounced aeromagnetic high, a response to magnetite, is also coincident with this potassic core. The potassic zone is surrounded successively by phyllic, argillic and propylitic alteration zones (Figures 3.4 and 3.5). Zoning of opaque minerals is closely related both to the breccia pipe and to the distribution of alteration facies, as can be seen in Figure 5.1. Magnetite in the core is flanked by chalcopyrite and molybdenite (represented by higher grades of copper and molybdenite) which in turn are largely enclosed by a pyrite halo. The "ore" zone is in a position common to many porphyry deposits, that is, between the potassic core and the pyrite halo and mainly within the zone of phyllic alteration facies. Causes of the zoning are complex but a dominant control was likely the high permeability of the breccia pipe. Formation of the Casino deposit appears to have taken place near a depth of 2.2 km. (616 bars) over an approximate temperature gradient of 400°C at the core to 150°C at the periphery. Hydrothermal fluids, principally of magmatic origin, changed in chemical composition during outward migration by reactions with wallrock and, possibly by fi'itration effects. These compositional changes coupled with the. effects of temperature change produced the overall pattern of alteration and ore mineral deposition. The role of meteoric water in hypogene mineral deposition is unknown. Supergene alteration zones defined in the Casino deposit are important because copper depleted from the capping has been deposited in the enriched 100 0 3 0 0 M • ••••VI AF(!0MAG"EriC HIGH, f.'.V. ^724 t (cf. FIG. 3.9) ^•/I'-A ] POTASSIC CORE. DRILL DATA. = ••:..Vj ALT. GRADE > 7 (cf. FIG. 3.4) n j j l SURFACE PYRITE 2:1 5% II (cf. f l G . 3.1 i) "7\ COPPER GRADE >.17% Zj, (cf. FIG. 3.12) SURFACE POTASSIC A I T . 2 7 C (cf. FIG. 3.3) l \ \ \ i MOLYBDEHITE GRADE > .0204 (c f . FIG. 3.13) GREATER THAN 20". BRFCCJA ON MARKED SIDE Of LINE FIGURES 5.1 A 2 B: GCfOALIZLD DI ST?. I BUT 10.1 OF IIYPOGEilE ALTERATION ZONES, CASINO, Y.T, 179 zone. The grade of copper in the enriched zone has been increased by an average factor of approximately 1.7. The following zones normally are intersected in drill holes: (1) capping or zone depleted of copper values, characterized by indigenous limonite and having a thickness of up to 500 feet (140 m.), (2) supergene oxide zone identified by the presence of copper oxides, carbonates or sulphates, and a higher grade of copper than found in either the capping or hypogene mineralization, (3) supergene sulphide zone recognized by the occurrence of chalcocite replacement of chalcopyrite and/or pyrite and higher copper assays than in the capping or hypogene zones. Contrasting the amount of copper depleted in the cap with the copper added to the enriched zone (Section 3.31) indicates that .there has been l i t t l e erosion of the capping. The importance of metal contribution from the capping is also illustrated in Figure 5.2A where deep leaching of the capping coincides with higher grades of copper in the enriched zone. The higher grades in the zone of enrichment also coincide with higher grades of copper in the hypogene zone (Figure 5.IB). Figure 5.2B indicates that development of the supergene oxide zone may be a comparatively recent development related to drainage induced by the downcutting of Casino creek and a small tributary gully. Values of "enrichment" (feet times grade of enriched zone) form a pattern similar to the enriched zone itself (compare Figure 5.2B to 5.2A). However, an additional enrichment zone occurs to the northeast and is almost coincident with the pyrite halo. This latter zone may represent chalcocite precipitation caused by the pyrite concentration within the pyrite halo. The Pal eocene, when the climate was warm and possibly subtropical was a likely period for development of a blanket of supergene enrichment, The cooler climate of the Meogene is thought to be unfavourable ISO FIGURES 5.2 A 5 B: GENERALIZED DISTRIBUTION OF SUPERGENE ZONES, CASINO, Y.T. 181 for continued development of the blanket, but downcutting by streams, such as Casino Creek, continued. Results and implications of this study provide important guidelines for mineral exploration. Perhaps the most useful, practical product of the work is the recognition of a broad, systematic, zonal pattern of hydrothermal alteration facies and the relationship of these zones to corresponding sulphide zones of economic importance. The patterns will be useful in providing guidelines for further drilling of the Casino deposit as well as providing a conceptual model in the exploration of other porphyry type deposits in the area. For example, drilling at Casino of the zone between the pyrite halo and the potassic core defined by the aeromagnetic high (or by mapping) would have ensured intersections of significant mineralization early in an explor-ation program. Mapping techniques developed for this study are designed for use in a deeply weathered, unglaciated area affected by permafrost. The techniques have proved useful and warrant continued application. In particular, the procedures used for a quantitative approach to alteration facies and the ease with which such data can be computer-contoured to provide a basis for further exp!orati on,.i s worth emphasizing. The significance to exploration, of the plate tectonic model developed in Chapter IV is more complex. The model implies that the generation of porphyry deposits may be more closely related to the location of a Benioff zone rather than to composition of the adjacent crust. In particular, the model indicates that porphyry deposits similar to those in the Intermontane Belt might occur along the tectonic "grain" beyond the belt, as is the case for Casino. A more distressing aspect with respect to exploration is that 182 because the crust intervenes between the source (Benioff zone) and the sites of ultimate formation, porphyry deposits might be dispersed somewhat randomly. However, smaller scale controls operate to produce "mining camps" or areas of concentration of mineral deposits. One of the more important controls are fracture zones, emphasizing the practical importance of the analysis of fractures, at various scales. Porphyry deposits have been formed from "wet" magmas, a view supported by the common association of breccia pipes with porphyry deposits. One could speculate that such magmas were "wet", metal-rich and saline because of their derivation from ocean floor material. This view is in accord with the classical concept of crystallizing wet magmas forming the genetic link between.plutons and their related features such as explosion breccias, "crackle" zones, and fracture cleavage, as well as the high contents in such plutons of hydrous minerals including biotite and hornblende. It also emphasizes the classic concept of magmatic hydrothermal fluids and the genetic association of many mineral deposits to igneous rocks. Further detailed studies of Casino deposit are warranted when and if the deposit becomes more exposed. Much of the author's interpretive work has been somewhat generalized in nature because of.the limitations placed on data by paucity of outcrop, supergene effects and inadequacy of dr i l l hole information. Additional detailed information is required particularly for a more thorough petrogenetic approach to alteration and sulphide zoning. Detailed studies of the age of the Klotassin. batholith are necessary to. resolve the disparity between the author's viewpoints on age and those expressed by Tempieman-Kluit (1973). Concordant hornblende-biotite potassium argon ages over a large area around the Casino deposit and compositional similarity of inequigranular quartz monzonite to the Coffee Creek Granite 183 indicate that the batholith along the trend of the Dawson Range is 100 m.y. in age. This batholith could be distinctly younger than the batholith to the south around Aishihik Lake. Alternatively, the radiometric ages near Casino might be completely reset, a view held by Tempieman-Kluit (1975, pers, comm.). This proboem can be resolved by further field and laboratory studies of the Dawson Range granitic rocks with particular attention directed to radiometric dating of oogenetic hornblende and biotite. In addition, the spatial relationship of samples to possible younger intrusive rocks could be of critical importance in interpreting results. The plate tectonic model presented here needs verification of certain aspects. In particular, more detailed geological knowledge is required to allow precise location of sutures. Equally important are additional data relating'to chemistry and radiometric ages of plutonic and extrusive equivalent rocks, to confirm the regional trends on which the model is based. Many worthwhile projects are suggested by the model, results of which could substantiate or modify the picture presented here. Such studies include (1) investigation of ultramafic bodies and their relation to the tectonic evolution of the- western margin of North America, (2) detailed chemical and stratigraphic studies to establish the origin of, and correlation between, Karmutsen and Nicolai volcanic units, (3) exhaustive, paleomagnetic studies on the Karmutsen and Nicolai volcanic units in a number of areas to define relative movements between the Insular Belt and the North America plate, and (4) examination of metamorphic grades and stratigraphy to establish the erosional history of the Coast Plutonic Belt, 184 BIBLIOGRAPHY Aho, A.E., 1966. Exploration in Yukon: Western Miner, A p r i l , pp. 127-148. A l l e n , D,6., 1971. The Origin of Sheet Fractures in the Galore Creek Copper Deposits, B r i t i s h Columbia: Can. Jour. Earth S c i , , v,8, pp, 704-711. Archer, A.R., and C.A. Main, 197V. Casino, Yukon - A Geochemical Discovery of an Unglaciated Arizona-Type Porphyry: Proc. 3rd Int. Geochem. 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The western Co rd i l l e ra - B r i t i s h Columbia and Neigh-bouring parts of the United States: Figure 10-0 i n Tectonic History and Mineral Deposits of the Western Co rd i l l e r a : Can. Inst. Min. Met. Special Volume No. 8. White, Wm. H., G.P. Erickson, K.E. Northcote, G.E. Dirom, and J.E. Harakal, 1967. Isotopic dating of the Guichon ba tho l i t h , B.C.: Can. Jour. Earth S c i . , v. 4, pp. 677-690. White, W.H., J.E. Harakal, and N.C.*Carter, 1968. Potassium-argon ages of some ore deposits in B r i t i s h Columbia; Can. Inst. Min, Met,, B u l l . , V, 61, pp. 1326-1334. White, Wm. H., R.M. Thompson, and K.C. McTaggart, 1957. The geology and mineral deposits of Highland Va l ley, B.C.: Can. Inst. Min. Met., Trans., v. 60, pp. 273-289. 194 Wil l iams, Howel, 1936. Pliocene volcanoes of the Navajo-Hopi County: Geol. Soc, Am. B u l l , , v. 47, pp. 111-171. Wolfe, J .A. , and D.M. Hopkins, 1967. C l imat ic changes recorded by land f lo ra s in northwestern North America: '_in Tert ia ry Correlations and Cl imatic Changes in the P a c i f i c , 11th Pac. S c i , Congr., pp. 67-76. Woodsworth, G .J . , 1971. A geochemical drainage survey and i t s impl icat ions fo r metal 1ogenesis, central Coast Mountains, B r i t i s h Columbia: Econ. Geo l . , v, 66, pp. 1104-1120. Yarwood, T.M., and F. Cast le, 1957. Physical and Mathematical Tables: Macmi11 an, 72 p. 195 APPENDIX A FIELD MAPPING AND DRILL LOGGING TECHNIQUES DEVELOPED FOR THIS STUDY A . l INTRODUCTION G e o l o g i c a l mapping i n the Casino area presented a number o f problems not n o r m a l l y encountered i n most o f the Canadian c o r d i l l e r a . These r e s u l t e d p r i n c i p a l l y from a combinat ion o f two f a c t o r s : (1) the area was not g l a c i a t e d by P l e i s t o c e n e c o n t i n e n t a l i c e sheets and i s , t h e r e f o r e , covered by a t h i c k l a y e r o f r e s i d u a l o v e r b u r d e n , and (.2) the r e g i o n i s c h a r a c t e r i z e d by permafrost and a s s o c i a t e d f e a t u r e s . , These f a c t o r s l e d to the n e c e s s i t y o f d e v e l o p i n g a s p e c i a l technique o f s u r f a c e mapping, a method e v e n t u a l l y m o d i f i e d and expanded t o f i t i n w i t h a. new approach t o l o g g i n g o f d r i l l h o l e s , an approach t h a t probably has more widespread a p p l i c a t i o n i n the r e c o r d i n g and a n a l y s i s o f o t h e r types o f g e o l o g i c a l i n f o r m a t i o n A.2 SURFACE MAPPING TECHNIQUES The r e s i d u a l , overburden-covered t e r r a i n i n the Cas ino area has abundant outcrops on r i d g e c r e s t s , a long road c u t s , a t d r i l l s i t e s , l o c a l l y a long some c r e e k s , and r a r e l y e l sewhere . P l a t e 3 .4 shows a t y p i c a l o u t c r o p o f j o i n t e d 196 g ran i t i c rock. Blocks of rock invar iab ly have been moved by f r o s t action and gravity f a l l . I dent i f i ca t ion of the rock type i s only possible i f the rock i s chipped with a hammer because of the pervasive coat of l i chen . F loat, where found beneath moss and shrub cover, is a r e l i a b l e ind icator of underlying bedrock in some places. In others, however, espec ia l l y on the flanks of va l leys in permafrost areas, mapping of f l o a t can be highly midleading. For example, toward the head of Canadian Creek an inc l ined terrace (possibly an a l t i p l ana t i on terrace) on the south side of the creek i s truncated abruptly by the base of a ridge (Plate A . l ) . Surface f l oa t on the terrace consists mainly of blocks with the same composition as ridge rocks. Trenches, d r i l l holes, and r ipper furrows, however, indicate that terrace bedrock i s not represented by surface f l o a t , and that the terrace cover is a shallow veneer general ly less than ten feet th i ck . The ridge rocks apparently move across the terrace from the r idge to the va l ley bottom by creep and s o l i f l u c t i o n confined to a s u r f i c i a l act ive layer above permafrost. It was found that r ipping to depths of only three feet (Plate A . l ) with a bul ldozer frequently dug up angular rock fragments d i f f e ren t from the boulders on the surface; these fragments were thought to represent nearby bedrock. These r ipper furrows were inexpensive compared to trenching and, of course, minimized ground cover disturbances. By 1973 these 1970 furrows had large ly grown over and had not caused any serious erosional problems (J.M. Carr, 1973, pers. comm.). Consequently, in the overburden covered area in the v i c i n i t y of the Casino deposit, the fol lowing techniques were employed for mapping on a scale of one inch to 100 feet . 1. A continuous furrow was ripped by D-8 bulldozer to depths of up to 3 feet along l ines spaced 400 feet apart; in areas of steep topography shallow trenches were cut. In th i s manner 240,000 l i n e feet or 45 197 PLATE A.l: Base camp, August 1970, view looking southwest across the top of Canadian Creek. Note ripper-furrow sampling trenches. Their southwest termination against the ridge with tors marks the top of a possible altiplanation terrace. Bed-rock on the terrace is only 10 feet below the surface as seen in trenches at middle background of plate. 198 l i n e miles(27 km.) were prepared. Where roadcuts existed these were used in l i e u of r ipper furrows. 2. Approximately f i v e specimens were co l lected along a l l trenches at s i te s 100 feet apart by a geologist. An attempt was made in the f i e l d to separate transported and residual f l o a t ; small fragments, for example, were thought to represent more accurately the bedrock than rounded, large boulders (espec ia l ly i f these boulders were representative of upslope r idge rocks). 3. Samples were examined under a binocular microscope and the fo l lowing features were observed and recorded rout ine ly : (a) rock type of l i k e l y underlying rock. (b) hypogene a l te ra t i on fac ies of underlying rock. (c) associated minerals, e spec ia l l y : hematite, magnetite, tourmaline, py r i t e , chalcopyr i te, cha lcoc i te and molybdenite. (d) s t ructura l re lat ionsh ips such as c lose ly spaced pa ra l l e l f ractures , and quartz veins with qua r t z - se r i c i t e envelopes, etc. Geological data were displayed in a one inch diameter c i r c l e on a map with a scale of one inch to 100 feet. Reduction of these maps produced the surface geological and a l te ra t i on patterns in the v i c i n i t y of the Casino deposit (Figures: 2.2, 2.13, 3.4 & 3.5). The r e l i a b i l i t y across the maps i s somewhat var iab le . For the regional area (Figure 2.2) r e l i a b i l i t y i s indicated by density of observations, sample l ocat ions , outcrops, and/or f l o a t . Geology in , the area of the deposit, based large ly on road cuts and r ipper furrows, i s r e l i a b l e near the crest of Patton H i l l and decreasingly so away from the h i l l , p a r t i c u l a r l y to the north near Canadian Creek where overburden depth l o c a l l y increases to f i f t een feet or more (Nordland and A l l e n , 1941). Instances where 199 th i s u n r e l i a b i l i t y appears to be s i g n i f i c an t are pointed out in r e l a t i v e sections. A.3 DRILL HOLE LOGGING TECHNIQUES During 1970, 36,922 feet of s p l i t diamond d r i l l core, from 49 holes, and cuttings representing 17,481 feet of rotary d r i l l i n g from 35 holes, were logged by the wr i te r and Mr. M. P h i l l i p s of Archer, Cathro and Associates, Whitehorse, Y.T. D r i l l i n g and sampling techniques used on the property are described in P h i l l i p s and Godwin (1970). At the onset of the program i t was apparent that a scheme of logging that would promote consistency of observation between geologists and throughout a l l holes was e s sent ia l . Logging also had to be rap id. Furthermore, observations could be aided only by simple equipment such as a binocular microscope, hand magnet, needle and acid bo t t l e . Observations were recorded in coded form on an 80-column format that was su i tab le for keypunching and subsequent computer manipulation. This logging system was the prototype for the format and codes described in de ta i l by Blanchet and Godwin (1970) for the "Geolog System". The format and codes allowed detai led and summary descr ipt ions to be made of the: 1. l i t ho l ogy , 2. supergene a l te ra t i on zones, 3. hypogene a l te ra t i on zones and mineral assemblages and occurrences. 200 A.4 COMPUTER ANALYSIS OF EXPLORATION DATA By 1971 a large amount of surface explorat ion data had accumulated for the area of the Casino deposit. L i thology, a l t e ra t i on zones, and magnetic and geochemical responses were known in d e t a i l . To s impl i f y the s t a t i s t i c a l t r e a t -ment of airborne and surface data, an area west of Casino Creek including Casino deposit was divided into 125 c e l l s , each 400 feet square. This d r i l l plan and c e l l - g r i d are shown in Appendix E and F respect ive ly. As many surface exploration parameters as possible were recorded for each c e l l . The more s i gn i f i can t parameters are l i s t e d in Table 3.4; a complete l i s t i n g i s given in Appendix H. D r i l l hole information for the 125 c e l l s i s tabulated in Appendices D and I. Only v e r t i c a l holes that lay near the centre of a c e l l were used in the s t a t i s t i c a l ca lcu lat ions thus l i m i t i n g the number of useful holes to between 25 or 35 depending upon the depth of the hole and whether or not the hypogene zone data was required. A l l holes, of course, were used in manually constructed plans and cross-sections such as f igures 3.4, 3.6 and 3.7. Computer analysis of d r i l l hole data was confined la rge ly to assay and related data from the capping, supergene enrichment, and hypogene zones. Data co l lected were keypunched and processed with the aid of the I.B.M. 360 computer at the Computing Centre, Un ivers i ty of B r i t i s h Columbia. A great deal of output was obtained from a number of programs made ava i lab le to the wr i te r through the Computing Centre of by Dr. A . J . S i n c l a i r of the Department of Geological Sciences, Un ivers i ty of B r i t i s h Columbia, Output used in th i s thesis from c e l l data input includes; , 1 , s t a t i s t i c a l information f o r ar i thmetic and transformed data, including histograms, probab i l i t y p l o t s , co r re la t ion c oe f f i c i en t s , etc. 201 2. contoured maps, 3. trend analysis pr intouts. A.5 SUMMARY Techniques used in mapping the surface geology about the Casino deposit helped overcome the problems of res idual overburden and r a r i t y of outcrops. D r i l l hole logging on an 80-column format designed for the "Geolog System" aided consistency, speed and thoroughness in describing the d r i l l holes. In a deta i led study the compilation of data for 125 ce l l s , each 400 feet square, permitted rapid graphic and simple s t a t i s t i c a l analysis of geo log ica l , geo-physical and geochemical variables to be analysed with the aid of a computer, and permitted a qua l i t a t i ve approach to studying correlat ions among geolog ica l , geochemical and geophysical var iab les. Computer output of maps, graphs, l i s t i n g s and s t a t i s t i c a l parameters f a c i l i t a t e d descr ipt ion and analysis of the Casino deposit. 202 APPENDIX B ACTIVITIES CASINO AREA, Y.T.:'.' 1911 "to 1974 Year 1911 1913 1916 1917, 1919, 1922, 1923, 1925, 1926, 1928, 1931. 1933 1940 1941 A c t i v i t y " Discovery"placer claim staked fo r gold on Apr i l 21 by Br i t ton and Brown. Upper part of Canadian placer gold. Creek staked for Cairnes examined placer deposits, i den t i f i ed "wolframite" and postulated source of tungsten from s i l i c i f i e d , pegmatitic, porphyry (Patton H i l l ) now known as part of the Casino complex. A shipment of several hundred pounds of tungsten containing 64.32 percent WO3 was made. Staking, apparently tr iggered by Cairnes 1 recognition of "wolframite" i s document-ed in ear ly lode claim records. The 1922 staking was probably the f i r s t to cover Patton H i l l . Meloy re-staked gold-tungsten placer area. Small shipments of tungsten were made during the Second World War. A l lan studied placer tungsten po ten t i a l , pa r t i cu l a r l y Meloy's ground, f o r Geolog-i c a l Survey of Canada. His estimate of s i ze was 400,000 cubic yards holding 2,000 tons of crude fe rbe r i te and minor schee l i te . The Geological Survey of Canada i den t i f i ed "wolframite" to be f e rbe r i t e . Bostock studied tungsten in placer area; he estimated Patton Gulch reserves to be 75,000 cubic yards to a nine foot depth, averaging 0.75 pound f e rbe r i t e and $1.00 per cubic yard. Reference Cairnes, 1917; L i t t l e , 1959. Cairnes, 1917; L i t t l e , 1959. Cairnes, 1917; L i t t l e , 1959. Mining Recorders' f i 1e s , Dawson C i t y , Y.T. Hester, 1963; Taylor, 1971. Bostock, 1941 L i t t l e , 1959; Craig and Laporte, 1972. 203 Year A c t i v i t y References 1941 1942 1940 to 1947 1948 Canadian Tungsten Company Ltd. and Hol l inger Exploration Company L t d . , d r i l l e d and bulk tested gold-tungsten placer area; A l len noted presence of molybdenite in addit ion to go ld, f e r be r i t e , c a s s i t e r i t e , hematite and magnetite in the placer concentrates. Yuba Consolidated Gold Fields L t d . , an a f f i l i a t e of Bralorne Mines L t d . , optioned and test d r i l l e d the go ld-tungsten placer area. Meloy in partnership with A. Brown, discovered galena veins that led to the staking of the Hel icopter showing (recorded 1943) and the Bomber showing (recorded 1947). Noranda Mines Ltd. optioned Hel icopter and Bomber showings and hand trenched in the area. Norlund and A l l e n , 1941; Gustafson, 1941. Bigelow, 1942; L i t t l e , 1959. Taylor, 1971; Mining Recorder's f i l e s , Dawson C i t y , Y.T. Western Miner, Dec. 1948, p. 153. 1949 1953 1963 BRC claims staked by H. covered Patton H i l l . Tecumseh Petroleums Ltd. placer gold-tungsten. Col ley probably invest igated Mining f i 1e s , Y.T. Recorder's Dawson C i t y , Burden, 1953; Archer & Main, Hester, 1963; Green & Godwin, 1971 1964; Galena veins investigated by Hester for Rio Tinto Canadian Exploration L t d . , and i t s a f f i l i a t e the Yukon Colsol idated Archer & Main, 1971 Gold Corporation Ltd. Hester f i r s t known to have recognized porphyry deposit potential of Patton H i l l . 1964 to 1967 1964 Proctor optioned and consolidated properties forming Casino S i l v e r Mines Ltd. (N.P.L.) in 1965. Exploration directed mainly to galena veins, e spec ia l l y the Bomber showing. A i r s t r i p constructed near Bomber showing. Dredging potent ia l of Canadian Creek placer gold-tungsten reviewed f o r Nordex Exploration Ltd. (L. Proctor) by Taylor who recommended test ing placer potential and locat ing lode gold-tungsten. Taylor, 1971; Green, 1965 & 1966; Findlay, 1967. Taylor, 1964. 204 Year A c t i v i t y Reference 1965-1966 June 1967 Sept 1967 1968 June 1969 Proctor constructed a winter road from Burwash on the Alaska Highway to the property. Harper recognized porphyry deposit potential of Casino area and commented: " . . .chalcocite and gold minera l izat ion should be looked f o r . " Archer & Main, 1971 Archer, of Archer, Cathro and Associated Archer & Main, 1971 L td . , independently recognized porphyry deposit potent ia l . Geochemical analysis of Patton H i l l rock specimens substantiated viewpoint. Control of Casino property acquired early in year by Brynelson Group who contracted Archer, Cathro and Assoc-iates L td . , to conduct a mapping and s o i l sampling program. Brameda Resources Ltd. of Brynelson Group entered into agreement with Casino S i l v e r Mines Ltd. Findlay, 1969. Brynelson, 1969. 1969 to 1970 1971 to 1972 1973 Study and evaluation of Casino property was done by Brameda Resources Ltd. with a id of consultants Archer, Cathro and Associates Ltd; announcement of grade and tonnage was released by Menzies in November 1970 (see Section 1.1). No act ive f i e l d work on property. Brameda Resources Ltd. conducted a l im i ted d r i l l i n g program on the property and in November rel inquished the i r option on i t in reutrn fo r shares in Casino S i l v e r Mines Ltd. Menzies, 1970; Archer & Main, 1971 Hallbauer, 1973. 1974 R. Carlson and A. Sweeney re-opened M. Carr, 1974, placer area on Canadian Creek to pers. comm. recover gold & tungsten. Attempts from 10,000 yards of gravel were made but were unsuccessful. 205 APPENDIX C POINT COUNTING TECHNIQUES AND TABULATIONS FOR ROCKS,.CASINO AREA, Y.T. C l POINT COUNTING TECHNIQUES ON ROCKS Modes for specimens were made by point counting grains on polished and stained slabs. Polished s labs, most of them measuring four or more inches in largest diameter, were etched in hydrof luor ic ac id . Subsequently, the potassium feldspar (herein, generally termed orthoclase) was s e l ec t i ve l y stained yellow with a sodium c o b a l t i n i t r i t e so lu t ion . In the coarser grained phases a c lear gr id was placed over the stained slab and grain types at gr id intersect ions were counted under a binocular microscope! Finer phases were analysed under a binocular microscope by counting grains at gr id intersect ions in an occular. Data from point counting are l i s t e d in the tables accompanying various rock descr ipt ions. Percentages of quartz, orthoclase, plagioclase and mafic minerals are calculated for each specimen. For purposes of t r i angu la r p l o t s , the modes in terms of quartz, orthoclase, and plagioclase content were recalculated to tota l one hundred percent. These t r iangu lar plots allow c l a s s i f i c a t i o n of the rock a f te r Johannsen (1939, v o l . T, p. 143; c f . Northcote, 1969). For convenience, potassium-argon model ages and data obtained from thin section study, such as: hornblende-biotite percentages and r a t i o s , plagioclase composition', e t c . , are noted below the ternary p lo t . 206 The r e l i a b i l i t y of mineral percentage ca lcu lat ions fo r each specimen i s expressed as two standard deviat ions. This was calculated (Chayes, 1956) using the binomial d i s t r i bu t i on i f nP i s greater than 5: 2S = 200 r 1^ " ^ • iff n v or , i f nP i s less than 5, the Poisson d i s t r i b u t i o n : 2S where: S = standard deviat ion P = p robab i l i t y of the occurrence of a mineral n - number of grains counted. The two standard deviations of the averaged percentages were calculated using the formula: N where: 2S.j =2 standard deviations for each specimen. N = number of specimens. C.2 POINT COUNTING TABULATIONS Point counting data from polished and stained slabs for Klotassin g ran i t i c units fo l low in Tab l e s .C l to C.9. Point counting data for Casino complex are in Tables C IO to C 1 3 . 207 TABLE C l FINE-GRAINED OUARTZ D I O R I T E , KLOTASSIN BATHOLITH: POINT COUNT DATA FROM STAINED SLABS S p e c i m e n COG 47 COG 5 0 a COG 6 2 a COG 87 . COG 1 0 1 b COG 107 COG 143 COG 1 4 8 a COG 149 A v e r a g e s : 9 s p e c i m e n s O v e r a l l M o d e s : P e r c e n t a g e s + 2S M a f i c F r e e A d j u s t e d M o d e s : P e r c e n t a g e s + 2 S . Q u a r t z .+ O r t h o c l a s e + ~ P l a g i o c l a s e = 100S Q u a r t z O r t h o - P l a g i d - O r t h o - P l a g i o -c l a s e " c l a s e M a f i c s Q u a r t z c l a s e c l a s e 2 0 + 2 8 ± 2 54 + 3 18 ± 2 2 5 + 3 10 + 2 6 5 ± 3 2 0 ± 3 8 + 2 4 3 + 4 15 ± 3 24 ± 3 19 + 3 57 + 4 13 + 3 • 3 ± 1 6 0 + 4 24 + 3 17 + 3 4 + 2 79 + 4 23 ± 3 ' 6 + 2 4 9 + 4 22 + 3 29 ± 3 8 + 2 63 + 4 16 ± 3 6 + 2 5 5 + 4 22 + 3 20 + 3 8 + 2 72 + 4 14 ± 3 2 t 1 52 + 4 3 2 + 3 2 1 + 3 2 + 1 . 77 + 4 20 + 3 5 + 2 5 5 + 4 20 + 3 2 5 + 3 6 + 2 6 9 + 4 16 + 2 2 + 1 5 5 + 2 27 + 2 2 2 + 2 3 ± 1 75 + 3 22 + 3 1 5 + 3 . 4 7 + 4 16 + 3 26 + 3 17 + 3 57 + 4 18 s 3 7 + 2 53 ± 4 22 + 3 23 + 3 9 + 6 6 8 + 4 a : b : t h i n s e c t i o n o u t s i d e a r e a o f F i g u r e 1 . 2 TABLE C.2 LEUCOCRATIC GRAN0DIC31TE, KLOTASSIN BATHOLITH{ POINT COUNT DATA FROM POLISHED STAINED SLABS O v e r a l l M o d e s : P e r c e n t a g e s +2S S p e c i m e n Q u a r t z COG 5 a 2 3 + 5 COG 64 1 5 + 4 COG 7 1 b 19 ± 3 COG 8 3 1 6 + 4 COG 2 6 3 c 1 5 + 4 A v e r a g e s : 5 s p e c i m e n s 18 + 4 O r t h o - P l a g i o - O r t h o -c l a s e c l a s e M a f i c s Q u a r t z c l a s e 23 + 5 4 7 ± 5 7 ± 3 2 5 + 5 2 5 + 5 17 + 4 5 9 i 5 9 + 3 16 ± 4 19 + 4 23 i 4 51 i 4 . 7 + 2 21 + 4 24 + 4 18 ± 4 61 i 5 5 ^ 2 17 + 4 19 + 4 17 + 4 57 ± 5 11 + 3 17 + 4 19 + 4 20 i 4 . - 5 4 ± 5 8 t 3 19 ± 4 21 + 4 M a f i c F r e e A d j u s t e d M o d e s : P e r c e n t a g e s ± 2 S . Q u a r t z + O r t h o c l a s e + P l a g i o c l a s e = ICO?; P l a g i o -c l a s e 5 0 + 6 6 5 + 5 5 5 + 5 64 + 5 64 + 5 60 + 5 a : t h i n s e c t i o n b : o u t s i d e a r e a c f F i g u r e 1 . 2 c : t h i n s e c t i o n a n d K / A r d a t e 208 TABLE C . 3 HYBRID GRANODIORITE, KLOTASSIN BATHOLITH: . POINT COUNT DATA FROM POLISHED AND STAINED SLABS M a f i c F r e e A d j u s t e d M o d e s : P e r c e n t a g e s ± 2 S . Q u a r t z + O v e r a l l M o d e s : P e r c e n t a g e s +2S O r t h o c l a s e + P l a g i o c l a s e = 100% S p e c i m e n O r t h o - P l a g i o - O r t h o - P l a g i o -Q u a r t z c l a s e c l a s e M a f i c s Q u a r t z c l a s e c l a s e COG 5 9 14 ± 3 11 + 2 52 + 4 2 3 ± 3 18 ± 3 14 ± 3 6 8 + 4 COG 1 3 8 a 28 + 4 16 ± 3 5 0 + 4 6 ± 2 3 0 ± 4 17 ± 3 5 3 ± - 4 COG 1 3 9 2 0 ± 3 16 + 3 5 3 t 4 ' 11 ± 2 23 + 3 18 * 3 59 ± 4 COG 3 0 0 A a 13 ± 2 11 i 2 5 6 ± 4 2 0 ± 3 16 ± 3 13 ± 3 71 ± 4 COG 3 0 0 B a 18 ± 3 19 ± 3 4 9 + 3 14 ± 2 21 ± 3 22 ± 3 5 7 ' ± 4 A v e r a g e s : 5 s p e c i m e n s 19 ± 3 15 i 3 51 + 4 15 ± 2 22 ± 3 17 + 3 61 ± 4 a : t h i n s e c t i o n TABLE C . 4 KLOTASSIN GRANODIORITE, KLOTASSIN BATHOLITH: POINT COUNT DATA FROM POLISHED & STAINED SLABS M a f i c F r e e A d j u s t e d Modes P e r c e n t a g e s ± 2 S . Q u a r t z + O v e r a l l M o d e s : P e r c e n t a g e s +2S O r t h o c l a s e + P l a g i o c l a s e = 100% O r t h o - P l a g i o - O r t h o - P l a g i o -S p e c i m e n Q u a r t z c l a s e c l a s e M a f i c s . Q u a r t z c l a s e c l a s e COG 1 2 a 2 2 + 4 19 3 31 + 4 • 2 8 + 4 3 0 + 5 26 + 5 44 ± 5 COG 1 8 a 2 3 + 5 14 + 2 4 5 + 5 2 0 + 4 . 29 + 6 . 14 4 57 ± 6 . COG 2 1 a 2 5 + 3 17 3 . 41 + 4 17 + 3 30 + 4 21 + 3 4 9 ± 4 COG 23 2 2 + 4 21 + 4- 3 3 " + 4 24 4 29 + 5 27 + 4 . 4 4 ± 5 COG 41 2 6 + 4 . 13 + 3 3 9 + 4 2 2 4 34 + 5 16 + 4 50 ± 5 COG 73 19 5 11 + 4 4 3 + . 6 27 5 26 + 6 15 + 5 59 ± 7 COG 93 21 + 4 12 + 3 3 9 + 4 28 + 4 2 9 + 5 16 4 ; • 5 5 ± 5 COG 102 22 + 4 17 * 4 4 2 + 5 19 4 • 28 + 5 21 + 5 51 ± 6 COG 115 1 6 + 3 9 ± 3 4 3 + 5 32 + 4 23 + 5 13 + 4 64 ± 6 COG 121 18 t 3 14 + 3 4 2 + 4 26 + 5 24 5 19 + 4 . 57 + 5 COG 135 2 5 * 5 12 + 4 4 5 + 6 18 5 31 6 15 + 5 54 + 7 COG 144 2 4 ± 3 19 + 3 4 6 + 4 11 + 3 27 + 4 2 2 + 3 5 1 + 4 COG 161 2 2 3 19 + 3 4 2 + 4 . 17 + 4 26 + 4 23 + 4 5 1 + 4 COG 201 26 + 4 . 12 + 3 45 + 5 17 + 4 31 5 15 + 4 54 ± 5 COG 2 0 5 2 9 + 5 12 + 4 4 0 4 5 19 + 4 26 + 6 15 + 4 4 9 ± 6 COG 2 2 7 31 + 3 24 z 3 • 34 + 3 . 1 1 2 36 ± 4 26 + 3 3 8 ± 4 COG 2 3 2 • 2 3 4 14 * 3 38 + 5 2 5 + 5 31 • 5 18 + 4 51 ± 5 COG 2 4 8 2 6 + 4 15 + 4 3 8 + • 5 . 21 + 4 • 33 ± 5 19 + 4 4 8 + 6 COG 2 5 4 2 2 3 . 14 • 3 41 4 23 3 2 9 4 19 + 4 52 + 5 COG 2 6 2 c 24 + 4 18 + 3 -42 + 4 16 + 3 29 + 4 22 + 3 4 9 ± 5 COG 2 6 6 3 0 + 4 14 + 3 46 • 5 10 • 3 33 + 5 16 + 4 5 1 + 5 C 7 - 3 6 2 2 + 5 16 + 4 . 44 • 6 18 5 28 + 6 19 + 5 5 3 + 7 A v e r a g e s : 22 s p e c i m e n s 24 + 4 15 + 3 41 + 5 2 0 + • 4 3 0 + 5 19 + 4 5 1 + 5 a : thin s e c t i o n c: thin s e c t i o n a n d K / A r d a t e 209 TABLE C .5 QUARTZ MONZONITE PORPHYRY, KLOTASSIN BATHOLITH: POINT COUNT DATA FROM POLISHED STAINED SLABS • S p e c i m e n COG 6 a COG 10 COG 42 COG 55 COG 5 7 , COG 6 5 b COG 9 1 ° COG 147 COG 2 6 4 c O v e r a l l M o d e s : P e r c e n t a g e s +2S M a f i c F r e e A d j u s t e d M o d e s P e r c e n t a g e s ± 2 S . Q u a r t z + O r t h o c l a s e + P l a g i o c l a s e = 1 0 0 ? Q u a r t z O r t h o - P l a g i o - O r t h o - P l a g i o -c l a s e c l a s e H a r i c s Q u a r t z c l a s e c l a s e 2 2 ± 3 24 ± 3 34 + 4 20 + 3 2 8 + 4 3 0 + 4 4 2 ± 4 21 + 3 22 + 3 3 9 + 4 18 + 3 26 + 4 27 + 4 - 27 + 4 2 0 ± 3 2 1 + 3 2 5 t 3 34 • 3 3 0 + 4 3 1 + 4 39 ± 4 19 + 3 18 + 3 4 7 + 4 16 - 4 2 2 + 4 2 2 + 4 56 + 4 17 • 2 1 9 + 3 52 ± 3 12 • 2 2 0 + 3 2 1 + 3 59 + 3 20 + 3 19 + 3 39 + 4 23 i 3 25 + 4 25 + 4 5 0 + 5 16 i 3 21 + 3 39 + 4 2 4 - 3 2 0 + 4 2 8 + 4 52 + 5 3 0 + 3 23 + 3 37 ± 4 10 * 2. 3 3 + 4 26 + 4 4 1 + 4 2 5 + 4 24 + 4 3 5 + 4 16 + 3 3 0 ± 4 29 + 4 41 ± 5 A v e r a g e s : 9 s p e c i m e n s 2 1 + 3 2 1 + 3 3 9 + 4 19 + 3 2 6 27 ± 4 47 + 4 a : t h i n s e c t i o n b : o u t s i d e a r e a o f F i g u r e 1.Z c : t h i n s e c t i o n and K/Ar d a t e TABLE C.6 INEQUIGRANULAR QUARTZ MONZONITE, KLOTASSIN BATHOLITH: POINT COUNT DATA FROM POLISHED AND STAINED S L A B S S p e c i m e n COG 1 5 1 c COG 279 COG 2 8 2 COG 2 8 4 a COG 2 8 8 a COG 2 9 0 a COG 2 9 1 a COG 3 C 2 a COG 3 0 8 A v e r a g e s : 9 s p e c i m e n s O v e r a l l M o d e s : P e r c e n t a o e s +2S Q u a r t z 2 6 + 4 2 8 + 5 2 5 ± 5 2 3 + 4 27 + 4 2 3 ± 6 29 + 5 26 + 5 2 8 + 5 26 O r t h o -c l a s e 29 + 4 30 + 5 21 + 4 27 + 4 28 + 5 28 t 6 22 + A 27 ± 5 2 5 + '5 26 + 5 Plagio-clase 31 + 5 3 0 ± 5 33 + 5 33 ± 5 3 5 • 5 3 3 + 7 3 9 + 5 34 i 5 3 2 + 6 34 + 5 M a f i c s 14 12 21 17 . 9 . 11 10 13 15 M a f i c F r e e A d j u s t e d Modes P e r c e n t a g e s ± 2 S . Q u a r t z + O r t h o c l a s e + P l a g i o c l a s e = TOO" 14 • 4 Q u a r t z 30 ± 5 3 1 + 5 32 + 6 2 8 + 5 30 + 5 25 + 7 32 + 5 3 0 + 5 33 + 6 3 0 ± 5 O r t h o -c l a s e 34 + 5 3 5 + 5 26 + 5 33 + 5 3 0 31 24 31 30 31 + 5 P l a g i o -c l a s e 3 6 + 5 34 + 5 4 2 + 6 2 9 + 5. 4 0 + 5 .43 + 7 44 + 6 3 9 + 6 37 + 6 3 9 + 6 a : t h i n s e c t i o n c : t h i n s e c t i o n a n d K / A r d a t e 210 TABLE C.7 FINE-GRAINED QUARTZ MONZONITE, KLOTASSIN BATHOLITH: POINT COUNT DATA FROM POLISHED AND STAINED SLABS M a f i c F r e e A d j u s t e d M o d e s : P e r c e n t a g e s ± 2 S . Q u a r t z + O v e r a l l M o d e s : P e r c e n t a g e s ± 2 S O r t h o c l a s e + P l a g i o c l a s e = 101 O r t h o - PI a g i o -S p e c i m e n Q u a r t z c l a s e c l a s e " M a f i c s Q u a r t z c l a s e c l a s e COG 8 a COG 7 9 a . -COG 82 23 ± 4 26 ± 4 42 + 4 9 ± 2 25 i 4 2 9 ± 4 46 ± 4 COG 8 3 3 7 + 3 3 6 + 3 2 1 + 3 6 + 2 4 0 + 4 3 8 + 3 2 2 + 3 COG 1 0 1 " ? K + 4 io ^  A ->/i - « o . * ~ . . . . . O r t h o - P l a g i o -r t z l    r t z 33 + 4 34 + 4 27 + 4 6 + 2 35 + 4 3 0 + 3 27 + 3 34 + 3 9 + 2 33 + 4  +   +    +  +  7  3 6  3  + 2 0  4 26  4 32 + 4 34 + 4 8 + 2 28 + 4 3 6 + 4 26 + 4 28 + 4 10 + 2 40 + 4 3 5 ± 4 27 ± 4 31 t 4 7 • 2 3 8 + 4 . 3 5 + 3 25 t 3 31 + 3 9 + 2 3 8 i 3 2 9 + 4 "30 + 4 31 • 4 TO • 2 32 + 4 3 7 + 4 3 2 - 4 26 + 4 5 + 2 3 8 + 4 3 2 + 4 30 + 4 30 + 4 8 + 2 35 + 4 37 ± 4 2 8 + 4 2 9 + 3 3 8 ± 4 34 ± 4 3 8 ± 4 3 1 + 4 33 ± 4 - - ? z L J O : j 2 8 ± 3 34 + 3 COG 2 1 8 ° • 2 9 + 4 "30 + 4 31 + 4 TO + 2    34 + 4 34 + i " ' * " ' ' ' ' " " " 34 t 4 28 + 4 3 2 + 4 3 3 + 4 COG 175 6 4  *   •      29 + 4 COG 1 7 9 a    1 - 4       29 + 4 COG .213 - - - - - ~ — COG 2 1 8 COG 2 4 3 A v e r a g e s : a : t h i n s e c t i o n b : o u t s i d e a r e a o f F i g u r e Z . 2 c : t h i n s e c t i o n and K/Ar d a t e TABLE C.8 PORPHYRY DYKE, KLOTASSIN BATHOLITH: POINT COUNT DATA OF PHENOCRYSTS FROM STAINED SLABS O v e r a l l M o d e s : P e r c e n t i n P h e n o c r y s t s ± 2 S . S p e c i m e n COG 1 3 a COG 1 6 a COG 56 COG 5 8 COG 150 COG 221 COG 2 7 0 c Q u a r t z 0 + 0 0 + 0 4 + 8 0 ± 0 • 0 + 0 18 + 8 28 + 9 O r t h o -c l a s e 0 + 0 0 ± 0 T + 3 0 + 0 0 + 0 0 ± 0 9 + 3 P l a g i o -c l a s e 57 i 7 54 + 8 5 9 + 7 6 5 + 8 6 2 + 7 56 + 10 26 ± 9 4 2 + 9 21 + 8 M a f i c s P h e n o c r y s t s 43 t 7 4 6 + 8 36 + 6 35 ± 8 38 + 7 42 + 5 44 + 6 41 + 4 3 1 + 4 39 + 5 24 + 4 3 5 + 5 A v e r a g e s : 7 s p e c i m e n s 7 ± 2 2 + 1 5 6 • 3 3 5 + 3 37 + 2 a: t h i n s e c t i o n c: t h i n s e c t i o n and K/Ar d a t e 211 TABLE C . 9 PORPHYRY DYKE, KLOTASSIN BATHOLITH: COMPOSITION SUMMAftY M a f i c F r e e A d j u s t e d M o d e s : P e r c e n t a g e s . Q u a r t z + O v e r a l l M o d e s : P e r c e n t a g e s O r t h o c l a s e + P l a g i o c l a s e = 101 O r t h o - P l a g i o - O r t h o - P l a g i o -Q u a r t z c l a s e c l a s e M a f i c s T o t a l Q u a r t z c l a s e c l a s e P h e n o - . c r y s t s " 3 1 21 13 37 12 4 8 4 M a t r i x e 9 13 25 16 63 19 2 8 53 T o t a l R o c k 12 14 46 2 9 100 17 19 64 d : f r o m T a b l e C 8 e : v i s u a l e s t i m a t e f r o m t h i n s e c t i o n s and p o l i s h e d , s t a i n e d s l a b s TABLE C . 1 0 PATTON PORPHYRY, CASIKO COMPLEX: POINT COUNT DATA OF PHENOCRYSTS FROM THIN SECTIONS V _ O v e r a l l M o d e s . P e r c e n t a g e i n P h e n o c r y s t s ± 2 S . S p e c i m e n Q u a r t z O r t h o -c l a s e P l a g i o -c l a s e B i o t i t e H o r n -b l e n d e Opaques P h e n o c r y s t s 2 8 0 0 S - 2 2 0 0 E 14 ± 3 0 t 0 64 + 4 7 + 2 9 ± 2 6 • 2 54 + 3 P 2 - 3 4 0 5 ± 2 0 + 0 63 + 4 11 ± 3 17 + 3 4 ± 2 51 + 3 COG 3 0 0 1 1 + 3 0 ± 0 65 + 4. 9 + 2 1 1 + 3 4 + 2 53 ± 3 A v e r a g e s : 3 s p e c i m e n s 10 ± 2 0 + 0 64 + 2 .- 9 + 1 12 + 2 5 + 1 53 + 2 212 TABLE C I V PATTON PORPHYRY, CASINO COMPLEX: COMPOSITION SUMMARY P h e n o -c r y s t s 3 M a t r i x b T o t a l Rock O v e r a l l M o d e s : P e r c e n t a g e s Quartz 5 10 15 O r t h o -c l a s e 0 14 P l a g i o -c l a s e 34 16 •Biotite 5 2 H o r n -b l e n d e \ O p a q -u e s 14 50 53 47 100 M a f i c F r e e A d j u s t e d M o d e s P e r c e n t a g e s . Q u a r t z + O r t h o c l a s e + P l a g i o c l a s e 100% T o t a l Q u a r t z 13 2 5 19 O r t h o -c l a s e 0 3 5 P l a g i o -c l a s e 8 7 4 0 18 63 a: f r o m T a b l e C . I O b : v i s u a l e s t i m a t e f r o m t h i n s e c t i o n and p o l i s h e d , s t a i n e d s l a b s . 213 TABLE C . 1 2 TUFF B R E C C I A , CASINO COMPLEX: SUMMARY OF POINT COUNT DATA FROM THIN SECTIONS . F r a g m e n t s : P e r c e n t a g e Whole Rock M a r t i x : P e r c e n t a g e A v e r a g e D i a m e t e r , MM. W h o l e Rock F e l d -S a m p l e 1 Q u a r t z s p a r L i t h i c T o t a l F i n e Opaque T o t a l F r a g m e n t s M a t r i x 3 2 0 0 S - 1 4 0 0 E 2 8 8 3 3 8 57 5 6 2 0 . 8 0 . 1 5 3 2 0 0 S - 1 8 0 0 E 2 2 « * - 9 — 31 -*-6 9 - * - 69 1 . 5 0 . 1 3 6 0 0 S - 1 8 0 0 E 2 3 4 9 36 57 7 64 0 . 8 0 . 0 8 4 0 0 0 S - 1 8 0 0 E 3 4 - 6 6 • -' 2 . 0 — PI 0 - 2 5 0 34 — 6 3 - » 3 0 . 8 — P 1 0 - 2 6 1 34 — 6 4 - » - 2 * '• — ' 1 . 4 — PI 6 - 1 4 0 2 0 22 3 4 5 54 . 1 55 1 . 0 0 . 0 0 5 A v e r a g e s : 7 s p e c i m e n s 2 8 11 5 38 t o 56 4 6 2 t o 6 0 1 . 2 0 . 0 8 44 TABLE C . 13 TUFF ( T U F F ) , CASINO COMPLEX: SUMMARY OF POINT COUNT DATA FROM THIN SECTION COG 117 F r a g m e n t s : P e r c e n t a g e ± 2 S . M a t r i x : P e r c e n t a g e +2S. M o d a l D i a m e t e r W h o l e R o c k W h o l e R o c k mm. F e l d s p a r p l u s . S a m p l e Q u a r t z L i t h i c T o t a l F i n e . Opaque T o t a l F r a g m e n t s M a t r i x COG 117 7 + 2 12 + 2 19 + 2 70 ± 3 11 + 2 81 s 3 1 . 0 5 \ Y 214 APPENDIX D ROCK TYPE INFORMATION FROM DRILL HOLES FOR THE 4,000 AND 3,500 FOOT ELEVATIONS, CASINO DEPOSIT AREA, Y.T. 215 APPENDIX D ROCK TYPE INFORMATION FROM DRILL HOLES FOR THE 4,000 AND 3,500 FOOT ELEVATIONS, CASINO DEPOSIT AREA, Y . T . L i t h o l o g y L i t h o l o g y S e c t i o n H o l e 4,000 f t . 3,500 f t . S e c t i o n H o l e 4,000 f t . ~3,500 f t . 0 + OON R - 2 4 N . I . a N . I . R - 2 3 N . I . N . I . P-21 N . I . F.QZMZ P - 9 F . Q Z M Z * * F.QZMZ 4 + OOS R - 2 0 I .QZMZ I . Q Z M Z 6 + OOS P - l l F.QZMZ F.QZMZ 8 + OOS P-& F.QZMZ I.QZMZ 16 + OOS R - 1 3 P . P P X X P . P P X X R - 4 BRXX F.QZMZ P - 5 F.QZMZ F.QZMZ R - 1 2 P . P P X X N . I . R - l l F.QZMZ N . I . R - 9 F.QZMZ N . I . R - 9 A F.QZMZ ' F.QZMZ R - 1 0 F.QZMZ , . F.QZMZ 2 0 + OOS R - 1 4 P . P P X X N . I . " R - 1 9 P . P P X X P . P P X X P - 1 2 Y.META F.QZMZ P - 2 6 F . Q Z M Z ( ? ) F . Q Z M Z ( ? ) 24 + OOS R-T7 . B R X X BRXX R - 1 5 A P . P P X X P . T P X X R - l 5 P . P P X X N . I . P - 2 4 P . P P X X N . I . P - 4 P . P P X X N . I . P - 3 P . P P X X N . I . P - 2 • P . P P X X N . I ; R - 2 9 F.QZMZ F.QZMZ 28 + OOS R - 1 8 CONTACT: N . I . I . Q Z M 7 / P . P P X X R - 1 6 CONTACT: P . P P X X B R X X / P . P P X X R - 3 0 BRXX N . I . R - l BRXX CONTACT: B R X X / P . P P X X P - l F.QZMZ N . I . , R - 2 5 F.QZMZ F.QZMZ P - 2 5 N . I . F.QZMZ 32 + OOS P - 4 4 BRXX P . P P X X P - 4 5 P . P P X X P . P P X X R - 5 BRXX BRXX • P - 1 3 BRXX N . I . P - 3 4 BRXX BRXX P - 4 1 BRXX N . I . P - 4 1 A BRXX N . I . R - 2 7 F.QZMZ F.QZMZ 36 + OOS R-22 N . I . N . I . P - 1 9 FQZMZ N . I . P-17 I .QZMZ I .QZMZ R-3A BRXX N . I . P - 1 0 CONTACT I .QZMZ B R X X / I . QZMZ, P - 4 6 & 46A BRXX N . I . P r 4 6 B TUFF N . I . P - l 4 .. N . I . ' BRXX P - 4 2 BRXX N . I . P - l 6 BRXX BRXX P - 3 6 BRXX I .QZMZ P - 6 N . I . N . I . P - 8 N . I . N . I . 4 0 + 3 0 S P - 2 3 . N . I . F.QZMZ P - l 5 I .QZMZ I .QZMZ R-32 BRXX N . I . R-21 BRXX N . ' I . P - 4 7 BRXX N . I . . R-26 I .QZMZ N . I . P - 4 3 N . I . . N . I . P - 1 4 BRXX BRXX P - 4 0 BRXX N . I . R-60 TUFF N . I . R-8 BRXX I .QZMZ P38 4 38A BRXX N . I . • P - 3 5 N . I . I .QZMZ P-31 N . I . BRXX P - 4 8 . N . I , F.QZMZ 44 + OOS P - 2 0 I .QZMZ I .OZMZ P - 1 8 I .QZMZ I .QZMZ P - 3 2 N . I . CONTACT: F . Q Z M Z / I . Q Z M Z P - 2 2 N . I . BRXX R-2 N . I . BRXX P - 3 7 N . I . CONTACT: F.QZMZ/BRXX P - 2 7 N . I . F.QZMZ 46 + OOS R-31 N . I . F.QZMZ 48 + OOS P - 2 9 N . I . CONTACT: F . Q Z M Z / I . Q Z M Z P - 3 9 N . I . - F.QZMZ R-28 N . I . F .QZMZ P - 3 0 N . I . F.QZMZ 52 + OOS P - 2 8 N . I . F.QZMZ a : N . I . = no i n f o r m a t i o n • b : S e e T a b l e 2 . 1 f o r e x p l a n a t i o n o f l i t h o l o g y s y m b o l -216 APPENDIX E DRILL HOLE PLAN, CASINO DEPOSIT AREA, Y.T. W)R20 poo s I leoo a I t t o o t " 0 0 t |3«00 » L E G E N D OP22 DIAMOND DRILL HOLES ^ ORI6 ROTARY DRILL HOLES > J O VERTICAL HOLE INCLINED HOLE APPENDIX E DRILL HOLE PLAN CASINO (1973), Y.T. 218 APPENDIX F 125 400 FOOT SQUARE CELLS, CASINO DEPOSIT AREA, Y.T. o . 8 > o o UJ • 5 30001 000 E 8 00 S CM u CO < ffi j 1 : 2 3 1 . 5 6 M 200 s 7 C ; g 10 • HI • 12 .13 l'l 15 16 17 13 1600 S !9 Vi 21 22 23 ;24 25 26 27 28 29 30 31 32 !000 S 33 34 35 36 37 33 39 ,"io '11 '12 '13 4'! 45 46 2400 S '17 '18 lip 50 51 52 53 54 55 56 57 '58 59 2800 S 60 p l 62 63 .61 65 6G 67 68 ,69 70 71 72 3200 S 73 71 75 ' 76 77 73 79 ' 89 31 32 83 C'i 85 3600 S 86 87 38 80 90 91 92 93 94 95 96 4000 S 97 08 09 100 101 102 193 104 195 .196 197 4400 S 108 109 ; 119 1.1.1 ; 112 113 114 115 IIP 4800 S . 117 113 119 . 129 121 122 ,123 124 125 2000 W * o o o BASE LINE 3 0001 2000 E 3000 E '1200 3 2800.8 4400 S 4800 S 400 800 i2oo rr. I L E G E N D -400 FOOT SQUARE CELL AND CELL NUMBER APPENDIX Fi 125 400 FOOT SQUARE CELLS CASINO DEPOSIT AREA, Y.T. 220 APPENDIX G HYDROTHERMAL ENERGY IN MAGMAS IN REGARD TO THE FORMATION AND EMPLACEMENT OF BRECCIA. G.l ENERGY FROM VESCICULATION BY WATER FROM A GRANODIORITE MAGMA. In the f i r s t approach, the w r i t e r , considers the maximum energy that might be ava i lab le at the instant a magma c r y s t a l l i z e s and, as a consequence, v e s i c u l a t e s exsolving a l l i t s water. It th i s environment i t i s only by a volume expansion that work can be done rap id ly . An environment appropriate for a magma of granodiorite composition containing eight percent water (from Burnham, 1967, p. 62) i s considered in Figure G . l . When the magma reaches point g, ca l l ed Condition I, the pressure in the water equals the to ta l pressure, so water should bo i l o f f with any further decrease in pressure or increase in anhydrous phases. Bo i l i n g , however, might be retarded i f (1) there are few nucleation s i te s such as c r y s t a l s , (2) the v i s co s i t y i s high, or (3). water molecules do not c lu s te r to overcome the extremely high surface tension in a very t i ny bubble (Verhoogen, 1951). Thus, perhaps, the water can be retained metastably in the melt and the magma might r i s e to 2.9 k i l o -meters (Figure G . l , point h) where the magma i s at the point of s o l i d f y i ng . These conditions are tabulated in Table G . l . I f , in th i s environment ca l led Condition II, the water were exsolved in s tant l y and expanded ad iabat i ca l l y into ve s i c le s , the energy released can be calculated crudely from: 221 600 ' 700 300 900 1000 1100 1200 TEMPERATURE (°C.) . FI SURE. G.l: P-T PROJECTION.-SHOWING MELTING RELATIONSHIPS OF A GRANODIORITE MAGMA ASCENDING (FROM f TO g TO h) TO AN EPIZONAL ENVIRONMENT (MODIFIED FROM BURNHAM, 1967). 222 TABLE G.l DATA FOR POSTULATED CONDITIONS: I, II AND I l l Condition Depth 3 (km) Pressure (P: bars) Temp. (T: °C) Spec. c Vol.(V: cnrgirf 1 ) Enth-alpy (H: , cal.mole ) H2O in magma (Wt.%) I 8.2 2500 b 790 b 2.00 c - 8 b II 2.9 800 b 750 b 5.02 c 15,568 O d III 2.9 300 d 550 C 10.2 e . 14,105 _ a: 0.28 kb./km. b: Figure G.l c: Burnham et a l . (1969). d: Assumed. e: Ca l cu l a ted - ( f = 1.33, P 2 = 300 bars) Table G.4. 223 dW = -PdV Calculations in Table G.2 suggest that from one gram of water the work energy is 57.7 ca l o r i e s , and from one cubic centimeter of rock exsolving 8 percent water the work energy i s 11.5 ca lo r i e s . These are maximum figures for i t i s un l i ke l y that a l l the water i s retained metastably upon upward transport of the magma. Suppose that th i s work from ves i cu la t ion i s absorbed in crushing the rock and giving i t motion. Assume, furthermore, that the rock is considered incompressible so that no energy i s used in changing the volume of the rock. The energy required to comminute quartz under s t a t i c conditions so there are equal weights of larger and smaller pa r t i c l e s around one centimeter ( i . e . has a s i ze modulus of one centimeter) is 0.5 c a l . per cm.^ (cf. Muff ler et a l . , 3 1971). The energy ava i lab le for motion i s , thus, about 11 ca lor ies per cm. . From ca lcu lat ions in Table G.3, i f no other energy absorption occurred, th i s energy could l i f t one gram of rock 6,160 feet v e r t i c a l l y above i t s s ta r t ing point and impart to the rock an i n i t i a l v e l oc i t y of 0.303 km./sec. This ve loc i t y i s about one-sixteenth the ve l oc i t y of sound in rock (approximately 5 km.. sec . " ' ' ) . Therefore, i t i s highly un l i ke l y that ves icu lat ion w i l l produce a shock wave in the system. There seems l i t t l e doubt, however, that energy i s ava i lab le to fracture and move rock probably by explosive means i f one compares the maximum ava i lab le energy above (11.5 c a l . per cm. ) with the maximum value (4.0 c a l . per cm. ) calculated by Muff ler et a l . (1971) to have produced the craters at Yellowstone. 224 TABLE G.2 VESICULATION ENERGY Energy in water (conditions I and II in Table G . l ) : /w2 /-V2 From / dW = / -PdV y w i V V l where: W = work P = pressure V = volume or: AW = P(V 1 ~V 2 ) 3 3 AW = 800 bars ( 2 . 0 0 ~ - 5.02 x gm. gm. 3 = 800 bars x 1 cal. x (-3.02) cm. 41.8 bar cm? gm. = -57.7 cal./gm. of water Energy in rock with 8 wt.% water: Water in rock: 2.5 ^ x 0.08 = 0.2 ^ cm. cm. Energy in rock: -57.7 ^ x .2 ^ = -11.5 of rock • cm. cm. 225 TABLE G.3 HE IGHT AND V E L O C I T Y FROM A V A I L A B L E ENERGY Energy after comminution = |11.5 cal/cm3 - 0.5 caVcm3| =11.0 cal/cm3 Height calculation (ignoring factors such as air resistance, etc.): from: where: obtain: -3 mgh = 11.0 cal. cm. m = mass g = acceleration of gravity h = height -3 -1 -7 -1 h = 11.0 cal. cm. x 4.186 joules cal. x 10 ergpoule 2.5 gm.cm3 x 980 cm.sec."2 h = 1.88 x TO5 cm. h = 1.88 x 105 cm.x 1 in. x 1 ft. = 6,160 ft. 2.54 cm. 12 in. Velocity calcuation: from: where: or: thus: 1/2 my2 = 11.0 cal.cm73 m = mass v = velocity v2= 11-0 cal. cm73 x 4.186 joules cal."1 x 107 erg. 1 gm.cm. y2 = 9.20 x 108cm2sec"2 v = 3.03 x 104 cm. sec."1 joule" 1/ 2 v = .303 km.sec' 226 G.2 ENERGY FROM EXPANSION OF WATER INTO A CRACK PROPAGATED BY ADVANCING MAGMA One other configuration i s suggested in Figure G.2. If magma pressure propagates a crack ahead of a magma with water at i t s top at Condition II (Table G.l )apressure gradient can be formed. Suppose that the volume of the crack were large enough that each gram of water could be expanded ad iabat i -c a l l y to a f i n a l pressure (P 3 ) of 300 bars, Condition III (Table G.l) how much energy could be produced? Calculat ions f o r f ind ing V3 are shown in Table G.4 on the assumption of adiabat ic expansion and the r a t i o of s pec i f i c heats, t = 1.33 (Verhoogen, 1951; c f . Yarwood and Cast le, 1957, p. 31). Since P 3 and s p e c i f i c volume ( V 3 } are now known, the f i n a l temperature can be obtained from tables (Burnham et a l . , 1969).. In th i s i so lated system where there i s no transfer of heat, mass or work: or: therefore: or: where: dU - -PdV + TdS dU = dW+>$(adiabatic) 3 fl CdU =jCdW W = u 3 - u 2 W = work , U = internal energy , • Q = heat , P = pressure, T = temperature , S = entropy> €= i n s i g n i f i c a n t in s i z e , V = volume H = U + PV U = H - PV H = enthalpy Values for H, P and V are shown in Table G.l f o r Conditions II and II I. The calculat ions of Table G.5 show the energy released to be 58 cal/gm. of water. Now by d e f i n i t i o n : or : where 227 A MAGMA PRESSURE CRACK PROPAGATED BY MAGMA PRESSURE WATER IN CRACK AFTER ADIABATIC EXPANSION (CONDITION I I I ) WATER ON TOP OF MAGMA (CONDITION - I I ) FIGURE G.2: EXPANSION OF.WATER AT THE TOP OF A MAGMA COLUMN INTO A PROPAGATED CRACK. 228 TABLE G.4 VOLUME AFTER ADIABATIC EXPANSION  FROM CONDITION II TO CONDITION III (TABLE G.l) From: ^2^2 = P 3 V 3 ( for adiabatic expansion) where: P = pressure V = volume if= r a t i o of spec i f i c heat at constant pressure over s p e c i f i c heat at constant volume. 800'Vg = 300 V 3 V 3 = 2.66 V 2 assume: ^=1.33 (Verhoogen, 1951) obtain: log V? = log 2.66 + 1.33 log 5,02 1.33 log V 3 =1.01 or: V 3 = 10.2 cm3/gm 229 TABLE G.5 ENERGY IN EXPANSION FROM CONDITION II TO CONDITION III (TABLE G.l) From: U 2 = H 2 - P 2 V 2 where: U = internal energy H = enthalpy P = pressure V = volume obtain: U 2 = 15,568 ca l . x 1 mole - 800 bars x mol e 18 gm. 1_ c a l . x 5.02 cm? 41.8 bar cm? g m * or: U 2 = 769.8 caVgm. From: U 3 = H 3 " P 3 V 3 obtain: LU = 14,105 x 1 - 300 x 1 x 10.2 18 41.8 or: U 3 = 710 caVgm. Thus: A U = 769.8 - 710.4 = 58 cal./gm. 230 If th i s energy were transformed to k ine t i c energy of motion, one gram of water could be given a speed of 700 meters/second as shown by ca lcu lat ions of Table G.6. The ve loc i t y of sound in water vapour at 130°C. i s 424 meters per second (Hodgeman, 1952, p. 2150). Thus, at Condition III the speed of sound might be exceeded and a compressive shock wave could develop in the water vapour. If such were the case, th i s wave with a stress of ax in i t s wave front would transmit a stress (cr ) of 2ol to the surrounding rock. Stress at the interface i s governed by the equation (Rinehart, 1960): a 2D 2C 2 T = :  D2C2+ D ]C 1 where: D = density C = ve l oc i t y a = stress 1 = medium 1 = vapour 2 = medium 2 = rock i f : D 2 C 2 » P-iC, (that i s medium 2 i s much more r i g i d than medium 1) then: a x= 2 Since i s a shock wave the stress transmitted to the r e l a t i v e l y r i g i d rock surface i s extreme indeed and rupturing and transport of material l i k e l y takes place. In summary the process i s : magma migrates upward, water co l l ec t s on top of the magma, the magma pressure propagates a crack, the water explodes and extreme stresses occur on the wal l s of the crack causing rupturing and transport of mater ia l . The process may be repe t i t i ve and thus, represent an e f fec t i ve " d r i l l i n g " process for diatreme development. 231 TABLE G.6 VELOCITY FROM AVAILABLE ENERGY (TABLE G.5) 1/2 mv2 = 58 cal/gm. (Table G.5) m = mass v = ve loc i t y 7 7 v = 2 x 58 cal. x 4.186 joules x 10 ergs gm. cal. joule v 2 - 48.56 x TO8 cm2/sec.2 4 v = 7.0 x 10 cm/sec. v = 700 m/sec. From: where: thus: or: 232 APPENDIX H CELL VARIABLES (APPENDIX F) EXAMINED AT'CASINO, Y.T. V a r i a b l e T r a n s f o r m a t i o n 3 A. Geochemical 1. Soil tungsten average in cell 2. Soil silver average in cell 3. Soil gold average in cell 4. Rock copper average in cell 5. Rock molybdenum average in cell 6. Rock lead average in cell 7. Rock zinc average in cell B. Geophysical 1. Ground magnetic average in cell 2. Ground magnetic range in cell • 3. Distance from centre of main ground magnetic high, anomaly to cell centre 4. Aeromagnetic value at cell centre 5. Aeromagnetic range in cell 6. Distance from centre of amin aeromagnetic low ./anomaly to cell centre 7. Distance from centre of main aeromagnetic high anomaly to cell centre 8. Chargeability (I.P.) average in cell 9. Chargeability (I.P.) range in cell .10. Resistivity (I.P.) average in cell 11. Resistivity (I.P.) range in cell C. Lithological 1.. Percent area Klotassin granodiorite in cell 2. Percent inequigranular quartz monzonite in cell 3. Percent fine-grained quartz monzonite in cell 4. Percent Patton porphyry in cell 5. Percent tuff in cell 6. Percent breccia (breccia pipe) in cell 7. Percent tuff breccia in cell 8. Percent cobble breccia in cell 9. Length of rock contacts within cell D. Alteration Facies and Minerals 1. Percent argillic (3) alteration in cell 2. Percent phyllic (5) alteration in cell 3. Percent phyllic (6) alteration in cell 4. Percent potassic (7) alteration in cell 5. Length of alteration contacts within cell 6. Percent tourmaline occurrence within cell 7. Percent magnetite and/or hematite occurrence • within cell 8. Percent magnetite and/or hematite with tourmaline occurrence within cell l o g a r i t h m i c (TO) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) none l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) none l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) l o g a r i t h m i c (10) a r c s m e a r c s i n e a r c s i n e a r c s i n e a r c s i n e a r c s i n e a r c s i n e a r c s i n e none a r c s i n e a r c s i n e a r c s i n e a r c s i n e none a r c s i n e a r c s i n e a r c s i n e 233 D. Variable 9. Percent pyrite occurrence within cell 10. Percent molybdenite occurrence within cell 11. Percent molybdenite with pyrite occurrence within cell 12. Percent goethite within cell E. Drill Hole Data (data for only 20 to 35 holes) 1. Leached capping zone (a) thickness in feet (b) grade in percent copper (c) grade in percent molybdenite , (d) grade in percent copper equivalent" 2. Supergene oxide zone (a) thickness in feet (b) grade in percent copper (c) grade in percent molybdenite 3. Supergene sulphide zone (a) thickness in feet (b) grade in percent copper (c) grade in percent molybdenite 4. Enrichment zone (supergene oxide and •supergene sulphide.-zones) (a) thickness in feet ( b ) grade in percent copper (c) grade in percent molybdenite , (d) grade in percent copper equivalent (e) value0 in feet, percent copper equivalent0 5. Hypogene zone (a) grade in percent copper (b) grade in percent molybdenite (c) grade in percent copper equivalent0 Transformation arcsine arcsine arcsine arcsine none and logarithmic (TO) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) none and logarithmic (10) hone and logarithmic (10) none and logarithmic (10) none and logarithmic (10) a: As simple as possible a transformation was chosen to make the frequency-variable distribution approach a "norsaT" one. b: Copper equivalent equals percent copper plus two times percent molybdenite, c: Value equals copper equivalent times feet of enrichment. 234 . APPENDIX I HYPOGENE ALTERATION FACIES AVERAGED FROM DRILL HOLES OVER THE 200 FOOT BENCH INTERVALS CENTRED AT THE 4,000 AND 3,500 FOOT ELEVATIONS, CASINO DEPOSIT AREA, Y.T. 235 APPENDIX I HYPOGENE ALTERATION FACIES AVERAGED FROM DRILL HOLES OVER THE 2 0 0 FOOT BENCH INTERVALS CENTRED AT THE. 4 , 0 0 0 AMD 3 , 5 0 0 FOOT ELEVATIONS, CASINO- DEPOSIT A R E A , Y . T . -A l t e r a t i o n A l t e r a t i o n A l t e r a t i o n G r a d e a / H o l e L e n g t h i n B e n c h I n t e r v a l ' A l t e r a t i o n G r a d e a / H o l e L e n g t h i n B e n c h S e c t i o n H o l e 4 , 0 0 0 f t B e n c h ( 3 , 9 0 0 t o 4 , 1 0 0 f t ) 3 , 5 0 0 f t Bench ( 3 , 4 0 0 t o 3 , 6 0 0 f t ) S e c t i o n H o l e 4 , 0 0 0 f t B e n c h ( 3 , 9 0 0 t o 4 , 1 0 0 f t ) 3 , 5 0 0 f t B e n c h ( 3 , 4 0 0 t o 3 , 6 0 0 f t ) 0 + 0 0 R - 2 4 N . I . b N . I . 3 6 + OOS R - 2 2 N . I . N . I . N-S R - 2 3 N . I . N . I . P - l 9 2 . 5 / 1 7 5 N.r. P-21 N . I . 1 . 4 / 6 5 P - l 7. 5 . 5 / 2 0 0 5 . 7 / 1 7 0 P - 9 3 . 0 / 2 3 1 . 0 / 1 4 0 R-3A 5 . 6 / 2 0 0 N . I . P - 1 0 5 . 8 / 2 0 0 5 . 2 / 1 3 2 4 + OOS R - 2 0 5 . 0 / 1 1 2 5 . 0 / 2 8 P - 4 6 S 46A 5 . 6 / 1 0 5 N . I . P - 4 6 B 5 . 0 / 2 0 0 N . I . 6 + OOS P - l l 3 . 7 / 9 2 2 . 6 / 1 4 2 P - l 4 N . I . 6 . 2 / 2 0 0 P - 4 2 6 . 6 / 2 0 0 N . I . 8 + OOS P - 7 3 . 0 / 1 2 0 1 . 3 / 1 0 2 P - l 6 6 . 2 / 1 9 5 6 . 4 / 2 0 0 16 + OOS P - 3 6 4 . 5 / 3 0 2 . 4 / 2 0 0 R - l 3 4 . 4 / 2 0 0 5 . 0 / 1 5 0 P - 6 N . I . N . I . R - 4 6 . 0 / 2 0 0 7 . 0 / 1 8 5 P - 8 N . I . N . I . P - 5 3 . 4 / 2 1 0 1 . 0 / 3 0 P - 2 3 N . I . 4 . 5 / 2 0 0 R - 1 2 5 . 5 / 2 0 0 N . I . . R - l 1 6 . 5 / 1 9 5 N . I . 4 0 + 30S P - l 5 4 . 8 / 2 0 0 4 . 3 / 2 0 0 R - 9 5 . 0 / 1 5 0 N . I . R-32 5 . 0 / 5 7 N . I . R - 9 A 4 . 6 / 1 5 0 3 . 9 / 3 5 R-21 5 . 1 / 2 0 0 N . I . R - 1 0 : 4 . 8 / 1 3 5 4 . 1 / 4 5 P - 4 7 3 . 0 / 8 N . I . - • •20 •+ OOS R - 2 6 4 . 8 / 2 0 0 N . I . •R-14 3 . . 9 / 2 0 O P - 4 3 N . I . N . I . R - l - 9 5 . 0 / 2 0 0 5 . 0 / 1 5 P - l 4 5 . 1 / 2 0 0 N . I . P - l 2 - 4 . 0 / 5 8 2 . 6 / 1 9 8 P - 4 0 3 . 6 / 2 0 0 N . I . P - 2 6 1 . 0 / 5 2 1 . 0 / 2 0 0 R - 6 0 5 . 0 / 2 0 0 N . I . 24 + OOS R-8 5 . 0 / 2 0 0 5 . 0 / 2 0 0 R-17 5 . 0 / 2 0 0 N . I . P - 3 8 * 38A 4 . 8 / 2 0 0 N . I . R-15A 4 . 0 / 2 0 0 3 . 8 / 8 3 P - 3 5 N . I . 3 . 0 / 2 0 0 R - l 5 3 . 2 / 2 0 0 N . I . P-31 N . I . 1 . 5 / 2 0 0 P - 2 4 5 . 1 / 2 0 0 N . I . P - 4 8 N . I . 1 . 4 / 2 0 0 P - 4 4 . 4 / 2 6 0 N . I . . P - 3 6 . 2 / 2 6 0 N . I . 44 + OOS P - 2 0 4 . 1 / 2 0 0 6 . 9 / 4 7 P - 2 7 . 0 / 2 6 0 N . r . P - 1 8 6 . 0 / 1 0 5 5 . 7 / 2 0 0 R - 2 9 3 . 0 / 1 4 8 - 3 . 5 / 4 0 P - 3 2 N . I . 4 . 4 / 2 0 0 2 8 + OOS P - 2 2 N . I . 2 . 1 o r 7 . 0 / 2 0 0 ( ? ) R - 1 8 4 . 9 / 2 0 0 N . I . R-2 N . I . 7 . 0 / 2 0 0 R - l 6 6 . 7 / 2 0 0 N . I . • P - 3 7 N . I . 2 . 5 / 2 0 0 R - 3 0 7 . 0 / 2 0 0 N . I . P - 2 7 N . I . 1 . 0 / 2 0 0 R - l 6 . 6 / 2 0 0 7 . 0 / 2 0 0 P - l 5 . 0 / 1 5 2 N . I . 46 + OOS R-31 N . I . 4 . 3 / 2 0 0 R - 2 5 6 . 2 / 7 7 4 . 2 / 5 0 P - 2 5 N . I . 1 . 0 / 2 0 0 48 + OOS P - 2 9 N . I . 3 . 0 / 2 0 0 3 2 + OOS P - 3 9 N . I . 3 . 6 / 1 0 5 P - 4 4 6 . 7 / 2 0 0 4 . 6 / 1 1 3 R-38 • N . I . 4 . 3 / 1 6 0 P - 4 5 6 . 7 / 2 0 0 6 . 6 / 2 0 0 P - 3 0 N . I . 1 . 9 / 2 0 0 R - 5 5 . 7 / 2 0 0 N . I . P - l 3 6 . 3 / 2 0 0 1 . 2 / 2 0 0 52 + OOS P - 2 8 N . I . 2 . 8 / 2 0 0 P - 3 4 6 . 8 / 2 0 0 2 . 1 / 2 0 0 P-41 4 . 1 / 1 5 2 N . I . P - 4 1 A 3 . 2 / 8 5 N . I . R - 2 7 6 . 8 / 8 0 4 . 2 / 9 2 a : C a l c u l a t i o n o f . a l t e r a t i o n g r a d e . Each a l t e r a t i o n f a c i e s t y p e ( r e p r e s e n t e d b y a n u m b e r f r o m 0 t o 7) i s w e i g h t e d w i t h r e s p e c t t o l e n g t h o f i t s o c c u r r e n c e i n b e n c h i n t e r v a l ; f o r e x a m p l e , S e c t i o n 0 + 0 0 N - S , H o l e P - 2 1 : 2 5 f t x 2 a l t = 50 f t , a l t . , 4 0 f t x 1 a l t = 40 f t , a l t T o t a l s 6 5 f t 90 f t , a l t A l t e r a t i o n g r a d e = 90 f t , a l t * 65 f t = 1 . 4 a l t . b : N . I . = no i n f o r m a t i o n f o r b e n c h i n t e r v a l b u t h o l e on s e c t i o n . 236 APPENDIX J QUALITATIVE ANALYSIS OF ALTERATION MINERALS USING X-RAY DIFFRACTION J . l SAMPLE PREPARATION OF ORIENTED MOUNTS IN CLAY SIZE FRACTION (<2 MICRONS) Techniques below are modified from Car ro l l (1970, pp. 59 and 60). A few chips of sample to be tested were hand ground i n a porcelain mortar with water. The s lu r ry was allowed to s e t t l e for 40 seconds, then 2 ml. of suspension were transferred to a standard glass s l i d e . The suspension on the s l i de se t t led and was dried at room temperature, in a i r , f o r 4 to 6 hours before x-rayed. J.2 INSTRUMENT OPERATION The sample on the glass s l i de was X-rayed in the P h i l l i p s X-ray d i f f r a c t -ometer (model: PW 1050/65) at the Univers ity of B r i t i s h Columbia. Operating conditions were as fo l lows: 1. date of runs: March to Apr i l 1973 2. rad ia t ion : copper 3. f i l t e r : n icke l oxide 4. chart speed: 1,200 mm./hour 5. scanning speed: 2°29/minute 237 6. time constant: 7. k i l o v o l t s : 40 8. mill iamperes: 20 9. window: number 1 J.3 Mineral Interpretation in Mixtures Oriented s l ides were scanned from 2° to 37°29. Charts of water mounted oriented s l ides for the minerals l i s t e d i n Table J . l were prepared as standards. Charts of unknown mixtures were compared to the standards and minerals present were determined. Peaks that were unique f o r the mineral in question, or were dist inguishable with added thin sect ion data, were used for qua l i t a t i ve i n t e r -pretat ion. Table J . l l i s t s the main, cha rac te r i s t i c peaks for each mineral, the peak selected for quant itat ive in terpretat ion of each mineral and comments on possible confusion and resolut ion of re f l ec t i on s common to more than one mineral.- The simple mineralogy defined by th i s technique did not require addit ional treatment of the sample s l i des by g l y co l a t i ng , heating, etc. (cf: C a r r o l l , 1970, p. 67). 238 TABLE J . l X-RAY'INTERPRETATION OF MINERAL MIXTURES Mineral Quartz Orthoclase Plagioclase and/ or Orthoclase Plagioclase B io t i te Muscovite Kaol inite Montmorillonite Chlor i te Jaros i te Pyrophyl l i te 29 Peaks Examined to Determine Presence or Absence of Mineral -( l i s ted in order of peak in tens i t y ) 26.7; 20.85 27.4; 23.1; 22.5 ) 27.75; 13.5 j 28.2; 23.4; 21.9 ) 26.45; 8.75; 35.75; (17.6 peak ) i s weak compared to 17.8 ) muscovite peak) ) 8.8; 26.8; 17.8; (a fuzzy trace ) on the 7.0 s ide of 8.8 peak ) indicates hydromuscovite or ) i l l i t e ) ) 12.3; 24.9 fuzzy trace between 5.0 and 6.0 12.4; 25.2; 6.2; 18.8 28.8; 17.2; 8.75; 26.6; 28.5 9.6 29 Peak Examined for Qua l i ta t ive Inter-pretat ion, and Comments . 20.85 27.4 Thin sect ion and s ta in ing f o r potassium feldspar general ly required. 21.9 17.8. Thin section or specimen colour d i s t i n -guishes b i o t i t e from s e r i c i t e . 24.9. Can be present in minor amounts i f no peak at 24.9 but peak at 12.25 (provided there is no c h l o r i t e at 25.2). 5.7 25.2 17.2 9.6. Hot observed. 239 APPENDIX K X-RAY AND THIN SECTION DESCRIPTIONS OF ALTERATION FACIES. 240 " V . ' • TABLE K . I . - ;• • " ; ; ' - X - R A Y DATA AND T H I H S E C T I O N D E S C R I P T I O N S FOR S P E C I M E N S REPF.ESEHTATIVE O f THF ' : • P O T A S S I C A L T E R A T I O N F A C I E S ( 7 ) X - r a y D i f f r a c t i o n P e a k H e i g h t ! S p e c i m e n " Ho. a n d L o c a t i o n S u r f a c e S p e c 5 2 4 T 3 S - 2 2 G 0 E T 2 ) 2 8 0 3 S - 2 2 0 0 E ( F i g u r e 4 . 3 ) 3 >i 3 o . 3 2 O O S - l f ; 0 0 E { P l a t e 5 . 3 ) O H IT C o r e S p e c . „ t n o l e - . . F o o t a g e ) '?P1 ' - ^ 3 7 9 P 2 - 3 2 0 ( P l a t e 4 . 1 a n d 5 . 1 } F . Q Z M Z ' CAP 51 1 0 0 .. P . P P X X C A P T.BRXX C A P 9 6 1 0 0 T . B R X X CAP 6 7 - 1 0 0 (?) P . P P X X HYP 4 8 5 9 4 7 . N 5 6 5 3 N 6 2 N. P . P P X X HYP 6 6 H N H 1 0 0 4 8 N 6 8 N * ' ' A l t e r a t i o n D e s c r i p t i o n F r o m H a n d S p e c i m e n • a n d T h i h ' s e c t l o n P l a q i o c l a s e i s n e a r l y c o m p l e t e l y , a n d p o t a s s i u m f e l d s p a r s t r o n a l y a l t e r e d t o q u a r t z , s e r i c i t e and c l a y ( ? ) . B i o t i t e o c c u r s a s p r o b a M y p r i m a r y l a r g e p l a t e s a n d a s l i k e l y s e c o n d a r y c l u s t e r s o f f i n e l a t h s . The b i o t i t e i s a l t e r e d m o d e r a t e l y t o c h l o r i t e . M a g n e t i t e , l o c a l l y a l t e r e d t o h e m a t i t e , i s d i s s e m i n a t e d a n d a c c o m p a n i e s b i o t i t e c o n c e n -t r a t i o n s . H a n d s p e c i m e n i s m a l a c h i t e s t a i n e d . A l t e r a t i o n i s s t r o n a . Q u a r t z l o c a l l y h a s e m b a y e d m a r g i n s . P l a g i o c l a s e i s s t r o n a l y a l t e r e d t o q u a r t s , s e r i c i t e and d a y ( ? ) . - P o t a s s i u m f e l d s p a r c o n s t i t u t e s p a r t o f t h e g r o u n d m a s s . F e l t e d s e c o n d a r y b i o t i t e o c c u r s as p s e u d o -m o r p h s a f t e r h o r n b l e n d e , a s n a r r o w r i m s a r o u n d l a r g e r p r i m a r y b i o -t i t e p l a t e s t h a t a r e l o c a l l y k i n k b a n d e d , a n d a s c o n c e n t r a t i o n s • f o l l o w i n g g r a i n b o u n d a r i e s ( n o t a b l y r i m s o n e q u a r t z g r a i n ) . T h e S e c o n d a r y b i o t i t e h a s b e e n l a r g e l y a l t e r e d t o c h l o r i t e , a n d i s a s s o c -i a t e d w i t h d i s s e m i n a t i o n s o f m a g n e t i t e . A l t e r a t i o n i s e x t r e m e . P l a g i o c l a s e 1s c o m p l e t e l y a l t e r e d a n d p o t a s s i u m f e l d s p a r i s s t r o n g l y a l t e r e d t o q u a r t z , s e r i c i t e a n d c l a y ( ? ) . T h e s D e c i r e n i s s t r o n g l y i r a g n e t i c c o n t a i n i n g a b o u t $% d i s s e m i n a t e d m a n n e t i t e t h a t l o c a l l y i s a l t e r e d t o h e m a t i t e . A b u n d a n t c h l o r i t e i s p r o b a b l y a f t e r b i o t i t e b e c a u s e i t s f i n e f e l t e d t e x t u r e i n t h e g r o u n d m a s s i s s i m i l a r t o s e c o n d a r y b i o t i t e e l s e w h e r e . T r a c e t o u r m a l i n e o c c u r s . M i n o r g a e t h i t e f i l l s m i c r o v e i n l e t s a n d l i n e s c a v i t i e s . A l t e r a t i o n i s e x t r e n e . F c l d s p . i r s a r e a l m o s t c o m p l e t e l y a l t e r e d t o q u a r t z , s e r i c i t e a n d c l a y ( ? ) . P l a g i o c l a s e 1s a p p a r e n t l y c o m p l e t e l y - d e s t r o y e d b u t p o t a s s i u m f e l d s p a r I s l o c a l l y a p p a r e n t a n d may a l s o o c c u r i n t h e i r a t r i * . M i n o r ' c h l o r i t e , a f t e r s e c o n d a r y b i o t i t e , o c c u r s i n a s s o c i a t i o n w i t h d i s -s e m i n a t e d m a g n e t i t e . A 2 m m . - m a g n e t i t e v e i n l e t t h a t i s p a r t l y a l t -e r e d t o h e m a t i t e c u t s t h e h a n d s p e c i m e n . A l t e r a t i o n i s e x t r e r e . T h e s p e c i m e n c o n s i s t s m a i n l y o f s e c o n d a r y p o t a s s i u m f e l d s p a r s i 1 g h t -^ l y ^ a U e r o d * 1 : t o r c l a y : t ( ? ) ? a n d i f s e r . 1 c i t e . - ^ S e c o n d a . r y - . q u a r t z - i s - n o t a p p a r e n t 1n t h e a l t e r e d f e l d s p a r b u t m i c r o v e i n l e t s o f q u a r t z o c c u r . , B i o t i t e 1s m i n o r a n d p a r t l y a l t e r e d t o c h l o r i t e . The s p e c i m e n c o n t a i n s v e r y m i n o r m i c r o v e i n l e t s a n d d i s s e m i n a t i o n s o f s u l p h i d e a n d n a q n e t i t e t h a t i s p a r t l y a l t e r e d t o h e m a t i t e . A l t e r a t i o n i s e K t r m e . C l a y a n d c h l o r i t e i n d i c a t e s m i n o r s u p e r g e n e a l t e r a t i o n . P r i m a r y q u a r t z p h e n o c r y s t s a r e a b s e n t i n t h i n s e c t i o n b u t q u a r t z " ' " o c c u r s I n t h e m a t r i x , a s m i c r o v e i n l e t s , a n d i n t h e a l t e r a t i o n o f f e l d s p a r s . S t r o n g l y t w i n n e d p l a g i o c l a s e p h e n o c r y s t s a r e l o c a l l y . , a p p a r e n t b u t m o s t ' f e l d s p a r c r y s t a l s a r e d i f f i c u l t t o ' i d e n t i f y b e c a u s e o f a l t e r a t i o n t o q u a r t z , s e r i c i t e a n d c l . i v ( ? ) . B i o t i t e , ' l o c i l l y a U f v t - d t o c h l o r i t e o c c u r s a s l a m e p l a t e s a n d a s d i s t i n c t -l y s e c o n d a r y f e l t e d m a s s e s o f f i n e b i o t i t e l a t h s i n t h e m a t r i x . M a q n r t i t e i i n d c h . i l c o p y r i t e o c c u r a s d i s s e m i n a t i o n s . . P y r i t e . * | i i . w t r . m i c r o v e i n l e t s c u t t h e h a n d s p e c i m e n . A l t e r a t i o n i s s t r u i u i . C h l o r i t e a n d c l a y i n d i c a t e m i n o r s u p e r g e n e a l t e r a t i o n . The f e l d s p . t r s a r e . a l m o s t c o m p l e t e l y a l t e r e d t o q u a r t z , s e r i c i t e a n d c l a y ( ? ) ; p l a q i o c l a s e h a s b e e n c o m p l e t e l y d e s t r o y e d . B i o t i t e . l o c - . , » l l y i h l m - i t i/i ' t l . i s . i h i i m l . i n i ,is sivoml.irv f e l t e d c l u s t e r * , o f l . i t h s , M i c r i - v c i n l v t s o f p y r i t e a r e c u t by v e i n l e t s o f q u a r t z w i t h m i n o r p y r i t e . Tr.ires o f n . m n e t i t e a n d s u l p h i d e s a r e d i s s e m i n a t e d t t i r o u n h - . o u t t h e s p e c i m e n . A l t e r a t i o n I s e x t r e m e . C h l o r i t e a n d c l a y i n d i -c a t e m i n o r w e a k a l t e r a t i o n . I . Q Z M Z C A P 6 5 1 0 0 41 N 71 N H 91 N I.QZMZ HYP 8 3 1 0 0 N . N 1 0 0 N N 1 0 0 H C . B R X X HYP 7 4 1 0 0 4 2 N 3 9 81 F 6 76 N P 2 3 - 8 5 6 ( P l a t e 5 . 1 1 K.GRDR HYP 8 2 1 0 0 5 3 N 2 6 4 8 F 47 N F e l d s p a r s a r e m o d e r a t e l y a l t e r e d t o q u a r t z a n d s e r i c i t e . . C h l o r i - ' t i z e d f e l t e d p a t c h e s o f b i o t i t e l a t h s a r e c o n c e n t r a t e d a l o n g g r a i n b o u n d a r i e s a n d l o c a l l y r e p l a c e f e l d s p a r g r a i n s . C h a l c o p y r i t e a n d . p y r i t e a r e f i n e l y d i s s e m i n a t e d t h r o u g h o u t t h e s p e c i n e n s . A l t e r a -t i o n i s - m o d e r a t e . F e l d s p a r s a r e v e r y s t r o n g l y a l t e r e d t o q u a r t z a n d s e r i c i t e ; p l a g -i o c l a s e h a s b e e n c o m p l e t e l y d e s t r o y e d . C h l o r i t i 2 t d , f e l t e d c l u s -t e r s o f s e c o n d a r y b i o t i t e l a t h s o c c u r a r o u n d g r a i n b o u n d a r i e s a n d a r o u n d U n i t p l a t e s o f p r i i r a r y ( ? ) b i o t i t e . 5'/. o f t h e t h i n s e c - -t i o n c o n s i s t s o f d i s s e m i n a t e d p y r i t e a n d c h a l c o p / r i t e . T r a c e s o f m a g n e t i t e o c c u r . A l t e r a t i o n i s e / t r e m e . C h l o r i t e c o n t e n t i n d i c -a t e s m i n o r s u p e r q e n e a l t e r a t i o n . S r e c l m e n i s a K.GR0R c o b b l e f r o m t h e b r e c c i a . O u a r t z g r a i n s e x h i b i t u n d u l a t o r y a n d p a t c h y e x t i n c t i o n a n d a r e l o c a l l y r r . i c r o f r a c t u r e d . F e l d s p a r s a r » : w e a k l y a l t e r e d t o s e r i c i t e , q u a r t z a n d . d i / f ? ) . h a n d s p e c i m e n b i o t i t e p s c u d d r n o r p h i c a f t e r h o r n b l e n d e c h a f e s a r e a p p a r e n t . I n t h i n s e c t i o n , s l i g h t l y c h l o r i t i z e d c l u s t e r s o f s e c o n d -a r y b i o t i t e l a t h s o c c u r a l o n g q r a i n b o u n d a r i e s a n d a r o u n d l a r q e p l a t e s o f b i o t i t e . T r a c e s o f c a r b o n a t e o c c u r i n t h e t h i n s e c t i o n . C h a l c o p y r i t e a n d p y r i t e o c c u r m a i n l y a s f i n e d i s s e r r . i n a t i c n s b u t m i c r o v e i n l o t s a l s o o c c u r . A l t e r a t i o n i s e x t r e m e . C h l o r i t e , c l a y a n d c a r b o n a t e i n d i c a t e s m i n o r s u p e r g e n e a l t e r a t i o n . f e l d s p a r s a r e w e a k l y a l t e r e d t o q u a r t z , s e r i c i t e a n d c l a y ( ? ) . S e c o n d a r y b i o t i t e , p s e u d o m o r p h i c a f t e r h o r n b l e n d e , i s a p p a r e n t i n h a n d s p e c i m e n . I n t h i n s e c t i o n , a b u n d a n t f e l t e d c l u s t e r s c f s e c o n d -a r y b i o t i t e l a t h s a r e c o n c e n t r a t e d i r r e g u l a r l y a l o n n , g r a i n b o u n d -a r i e s . S u l p h i d e s a r e w e a k l y d i s s e m i n a t e d t h r o u g h o u t t h e r o c k , b u t t e n d t o b e c o n c e n t r a t e d w i t h t h e c l u s t e r s o f b i o t i t e . A t r a c e o f c a r b o n a t e o c c u r s . A l t e r a t i o n i s s t r o n g . C h l o r i t e , c l a y a n d c a r -b o n a t e i n d i c a t e s m i n o r s u p e r g e n e a l t e r a t i o n . a : A p p e n d i x o u t l i n e s X - r a y p r o c e d u r e s , b: H « a b s e n t , L • t r a c e , F - f a i r . c : C o o r d i n a t e s f o r s p e c i m e n l o c a t i o n a n d c o r r e s p o n d i n g c e l l n u m b e r a r e s h o w n I n A p p e n d i x E . 241 - • ' X-P.AV DATA AND THIN SECTION DESCRIPTIONS FOR ; • SPECIMENS REPRESENTATIVE OF THE Pt 'YLLIC ALTERATION FACIES (4^ t o f, n a i n l y . 5 ) . X - r a y D i f f r a c t i o n P e a k H e i g h t ?i-nP_rAL . •' .'•„•"":.""• • 6 § •' . • . Specimen tlo. 1$ g. S o £ « f= *» ce* r R r_ °* a . <u i- c. * J m a n d l o c a t i o n I S l | | c ] | j j ^ ' | J • J S u r f a c e S p e c . c L 6 0 0 S - T 8 0 Q £ / F . O Z H Z C A P 8 9 1 0 0 N 2 9 50.6 Nl> N 1 6 O 0 S - 2 2 0 0 E F.qzMZ C A P 7 9 1 0 0 N N 5 8 i > - ' ^ 10 c A l t e r a t i o n D e s c r i p t i o n F r o m H a n d S p e c i m e n a n d T h i n S e c t i o n 2 0 O O S - 2 0 O M P . P P X X C A P N It 71 1 0 0 ' 3 4 N 4 0 0 0 S - 1 4 0 0 E I.QZMZ C A P 4 8 1 0 0 H 47 1 0 0 • L N -4 T 0 0 S - 1 8 0 O E T . B R X X C A P 1 0 0 M N 85 inn N 11 4 4 0 0 S - 1 4 W , . Q Z M Z C A P , 0 0 . „ 3 7 1 0 0 N N D r i l l C o r e S p e c . " [ H o l e F o o t a g e ] -P 6 - 2 3 2 f . Q Z H Z SUS 69 1 0 0 „ „ 1 0 0 98 . H (pJiU S.6) M 2 M Z s u s 6 3 , 0 ° ** " 7 7 5 3 " ?pia"S5.5) C - B m H V P 5 5 " " « 1 0 0 fl M < P U t e s 4 9 C " P " ' ° ° " 6 " * 7 " 1 4 . 1 0 ) P 1 5 - 1 1 3 4 I . Q Z M Z HYP 9 5 5 0 fl n 1 0 0 .1. „ P o t a s s i u m f e l d s p a r is s t r o n g l y a l t e r e d a n d P l a q i o c l a s e i s c o m p l e t e l y - a l t e r e d t o sericite a n d q u a r t z . J a r o s i t e f i l l s m i c r o - v e i n s a n d f i l l s o r l i n e s b n x w n r k c a v i t i e s a f t e r d i s s e m i n a t e d s u l p h i t i e s t h . i t o r i n i n . i l l v o c c u p i e d 1 " o i t h e r o c k . H e m a t i t e d i s s e m i n a t i o n s o c c u r i n ' t r a c e a r c u n t i A l t e r a t i o n d e t e r m i n a t i o n i n f i e l d a n d f r o m x - r a y and t h i n s e c t i o n d a t a i n d i c a t e s n h y l l i c f a c i e s ( 5 ) o f h i q h i n t e n s i t y . - P o t a s s i u m f e l d ; . i i . i r i s w e a k l y , b u t p l a q i o c l a s e i s c o n p l e t e l v . a l t e r e d t o s e r i c i t e a n d q u a r t z . T r a c e s o f l i n o n i t e o c c u r o n m i c r o - f r . i c t u r c s . So^y* c l o u d y p a t c h e s o f s e r i c i t e a n d c l a y ( ? ) n a y r e p r e s e n t o r i n i n . i l biotite „ o r a i n s . P r e s e n c e ; o f p o t a s s i u m f e l d s p a r a n d c o m p l e t e a l t e r a t i o n o f p l a g i o c l a s e i n x - r a y a n d t h i n s e c t i o n d a t a i n d i c a t e s o o t a s s i u m f e l d s p a r -s t a b l e a l t e r a t i o n f a c i e s .(<•) o f e x t r e m e i n t e n s i t y . F i e l d f a c i e s d e t e r -m i n a t i o n w a s p h y l l i c ( 5 ) . The m a t r i x f s ' i n t e n s e l y a l t e r e d t o s e r i c i t e , q u a r t z a n d t r a c e s o f t o u r -- m a l l n e . P h e n o c r y s t s a r e a l s o c o m p l e t e l y a l t e r e d b u t . a s w e l l a s s e r i - • c i t e a n d q u a r t z , c o n t a i n p r o b a b l e c l a y t h a t c a u s e s t h e c r y s t a l s t o b e b r o w n i s h a n d s e m i - o n a q u e . T h e c l a y i s a l s o n o t e a b l e a s an a r n i l l a c e o u s o d o u r t o d a m p e n e d h a n d s p e c i m e n s . J a r o s i t e c o - ^ o n l v l i n e s , - f i l l s a n d f r i n o e s b o x w o r k c a v i t i e s t h a t o r i o i n a l l y w e r e d i s s e n i n a t e d s u l p h i d e s • o c c u p y i n g a b o u t 0 " o f t h e r o c k . C l a y i s l i k e l y s u o e r q e n e i n o r i g i n a n d , ' c o n s e q u e n t l y , f r o m x - r a y a n d t h i n s e c t i o n d a t a t h e a l t e r a t i o n f a c i e s i s p h y l l i c ( 5 ) o f h i q h i n t e n s i t y . P l a q i o c l a s e i s c o m p l e t e l y a n d p o t a s s i u m f e l d s p a r i s s t r o n n l y a l t e r e d t o q u a r t z , s e r i c i t e a n d m i n o r c l a y ( ? ) . B i o t i t e h a s b e e n a l t e r e d t o s e r i c i t e a n d i l l i t e ( ? ) . T h e h a n d s p e c i m e n h a s p o o r l y d e v e l o p e d f r a c t u r e c l e s v -~ a q e . D u a r t 2 g r a i n s , i n t h i n s e c t i o n , e x h i b i t u n d u l a t o r y and pa t e n v e x t i n c t i o n , a n d s u b p a r a l l e . m i c r o f r a c t u r e s a r e c o m m o n . A c r u s h e d z o q e w i t h d i s t i n c t i v e n o r t a r t e x t u r e , d e f o r m e d q u a r t z a n d k i n k - b a n d e d b i o t i t e ( n o w a l t e r e d ) , c r o s s e s t h e t h i n s e c t i o n . S i n c e t h e c l a y i s l i k e l y s i m c r -c f n e i n o r i q i n , x - r a y a n d t h i n s e c t i o n d a t a i n d i c a t e s t h a t a l t e r a t i o n f a c i e s i s p h y l l i c ( 5 l " o f a b o v e r e d l u m i n t e n s i t y . F i e l d . f a c i e s d e t e r m i n -, . a t i o n was a d v a n c e d a r o i 11 i c ( 6 " ) . . - F e I d ? p a r s . ; ; a r c i , c o n p l e t e l y ; a l t e r e d i t o s s e r i c l t e ' a n d ' q u a r t z i - a n d - c l j y ' ( ? ) . " " ' H i n o r ' t o u m a l i n e o c c u r s . J a r o s i t e f i l l s a n d 1 i n e s . b o x w o r k c a v i t i e s a f t e r d i s s p i ' i i n ; i t o r i s u l p h i d e s t h . i t o c c u p i e d about 2" o f t h e r o c k . A l t e r a t i o n . d e t e r m i n a t i o n s i n f i e l d a n d f r o m x - r a y a n d t h i n s e c t i o n d a t a b o t h i n d i -c a t e Dhyllic f a c i e s ( 5 ) o f e x t r e m e i n t e n s i t y . C l a y is l i k e l y o f s u o e r -c i e n e o r i q i n . F e l d s p a r s a n d m a f i c s a r e c o m p l e t e l y a l t e r e d t o q u a r t z , s e r i c i t e Aid c l a y ( ? } . L o c a l l y l a m e m u s c o v i t e c r y s t a l s ( a f t e r b i o t i t e ? ) o c c u r . J a r o s i t e r i m e d a n d f i l l e d b o x w o r k a n d m i c r o - v e i n s i n d i c a t e an o r i g i n a l V - s u l -p h i d e v o l u t i n * , f l . i y i i l i k e l y o f Mipenu'ne o r i n i n . cou^i-.iut - n t l y , t t u * I. i« :h p r o p o r t i o n s o f q u a r t z a n d s e r i c i t e i n d i c a t e d b y x - r a y a n d t h i n s e c t i o n d a t a I n d i c a t e ; a l t e r a t i o n i s p h y l l i c f a c i e s ( 5 1 o f e x t r e m e i n t e n s i t y . F i e l d f a c i e s d e t e r m i n a t i o n w a s a d v a n c e d a r n i l l i c ( 6 1 . " P I a n I o c 1 j s c i s c o m p l e t e l y a n d p o t a s s i u m f e l d s n j r I s w e a k l y a l t e r e d t o s e r i c i t e . q u a r t z a n d c l a y ( ? ) . O p a q u e s o c c u p y 1 " o f t h e r o c k , f l j y i s U k e l y o f s i i r c r n e n e o r i n i n , c o n s e q u e n t l y , t h e x - r a v a n d t h i n s e c t i o n d a t a I n d i c a t e s p o t a s s i u m f e l d s p a r s t a b l e f a c i e s {<•) o f e x t r e m e i n t e n -s i t y . F i e l d f a c i e s fleternination w a s p h y l l i c ( S ) . P l a q i o c l a t t ; i s s t r o n n l y - a n d p o t a s s i u m f e l d s p a r I s w e a k l y a l t t - r t d t o • s e r i c i t e , q i t a r t 2 a n d c l a y ( ? ) . T w i n n i n g i s s t i l l a p n a r e n t i n s o m e p l a q i o c l a s e q r a i n s . M i n o r t o u r m a l i n e o c c u r s . C l a y i s l i V e l y o f s u p e r q e n e o r i a i n . X - r a y a n d t h i n s e c t i o n d a t a c o n s e q u e n t l y , i n d i c a t e s p o t a s s i u m f e l d s p a r s t a b l e a l t e r a t i o n f a c i e s (-1) o f f a i r i n t e n s i t y . F i e l d f a c i e s d e t e m ' i n a t i o n w a s t h e s a m e . M a t r i x a n d f r a u - r c - n t s c o n s i s t o f o r i n t n a l q u a r t z a n d s e c o n d a r y s e r i -c i t e , q u a r t z , a n d s u l p h i d e s . S e r i c i t i z e d , k i n k - b a n d e d b i o t i t e o c c u r s a t t h e b o u n d a r y o f o n e p o r p h y r y f r a g m e n t . M i n o r t o u r m a l i n e o c c u r s . S u l p h i d e s o c c u p y a b o u t 1 5 " o f t h e r o c k . X - r a y a n d t h i n s e c t i o n d a t a I n d i c a t e s n h y l l i c ( S ) a l t e r a t i o n f a c i e s o f e x t r e m e i n t e n s i t y . F i e l d f a c i e s d e t e r n i n a t i o n w a s 1 p o t a s s i u n f e l d s p a r s t a b l e f a c i e s ( 4 ) . The ' d i s c r e p a n c y n a y b e a r e s u l t o f v a r i a t i o n w i t h i n t h e W c . r . i a . M a t r i x a n d f r a n r e n t s c o n s i s t o f o r i g i n a l q u a r t z a n d s e c o n d a r y s e r i c i t e , ' q u a r t / a n d s u l p h i d e s . S u l p h i d e s a c c o u n t f o r a b o u t 2 0 ' J o f t h ' ; t h i n s e c t i o n . * f i c r o - v i . ' i n s o f q u a r t / , i r i ? envi:rm. F i e l d d c . r . r a n d t h i n s e c t i o n d<itd I n d i c a t e p h y l l i c a l t e r a t i o n f a c i e ' . I n t e n s i t y . CJ) of extreme P l , i o f n f . l i i « ; r i * ; c n . - p l o t o l y , a n d p n t . i ' . ^ i u - n f f r l d ' . n a r i s a p p - i r ^ n t l y c o m p l e t e l y a l t e r e d t o s e r i c i t e , n u a r t z , a n d c l a y . T o u r m a l i n e i s a b u n d a n t a s d i s s f - r i n a t i o i i ' j . J t i r t i i i If; I im-', t>onmr\r c a v i t i e s thr>t v i « ; r G o r i ' i i n ^ l l y s u l p h i d e s o c c u p y i n f j a b o u t ? " o f t h e r o c k . F r a c t u r e c l e a v a o e i s w e l l d e v e l o p e d a n d a p p a r e n t i n h a n d s r > e c i r e n a n d t h i n s e c t i o n . O ' J^ r t ? • a n d t o u m d l i n e G r a i n s a n d b o / . w o r k c a v i t i e s a r e c u t b y t h e c l e a v a g e i n d i c a -t i n ' i t t i - i t t h e s i j i m r . i t i o n a c r o s s t h e f r a c t u r e i s p o s t m i m j f . i l i7 - ; t i r j n . H a n d s p e c i n e n , t t i i n s e c t i o n a n d x - r a y d a t a i n d i c a t e p h / l l i c s i ' . o r a t i o n f a c i e s ( M o f m o d e r a t e i n t e n s i t y w i t h s u p e r q e n e c l a y a l t e r a t i o n l i k e l y f r o m t h e p o t a s s i u m f e l d s p a r t h a t i s o n l y a p p a r e n t f r o m x - r a v d a t a . F e l d s p a r s i n t h e t h i n s e c t i o n a r e a p p a r e n t l y c o m p l e t e l y a l t e r e d t o s e r i c i t e a n d q u a r t z b u t p o t a s s i u m f e l d s p a r i s i n d i c a t e d i n t h e x - r a y p a t t e r n . 3 i o t i t e h a s bf?cn t o t a l l y a l t e r e d t o s e r i c i t e , o p a q u e m i n e r a l s a n d l e u c o x e n e . A p y r i t e v e i n l e t c r o s s e s t h e t h i n s e c t i o n . . F i e l d d e t e r m i n a t i o n , x - r a y a n d t h i n s e c t i o n d a t a i n d i c a t e p h y l H e a l t e r a t i o n f a c i e s ( 5 1 o f a b o v i * m e d i u m i n t e n s i t y . A p p e n d i x G o u t l i n e s x - r a y p r o c e d u r e s " ~" - • : " *1 " a b s e n t , L « t r a c e C o o r d i n a t e s f o r s p e c i m e n l o c a t i o n a n d c o r r e s p o n d i n g c e l l n u m b e r a r e s h o w n i n A p p e n d i x E. •. TABLE K.3 ' . X-RAY DATA AND THIN SECTION DESCRIPTIONS FOR SPECIMENS REPRESENTATIVE OF THE ARGILLIC ALTERATION FACIES (2 and 3, mainly 3). X-ray Diffraction Peak Height ^"fi™1. Specimen No. and Location Surface Spec. 2000S-600W •3 2L 3£> P.PPXX CAP 86 01 00 4-> c 01 o cu M %~ ^ tn 10 O 01 0) <u R9 0) • M *u •M 01 J- . +•> 4J N U o 4-» > c o JZ +i m O V) ••- O E t. U 01 U 00 "a> O CM «M O cn O CM <o c 10 • 4* • t- • O l/> o c QJ O 3 o u r*» i— i— •r- 3 .H o • f Ul C C M O CM a . CM CD z: 2^ CM U CM 43 100 48 D r i l l Core Spec. PI 2-190 F.QZMZ CAP 67 75 N 37 100 N P22-74 P22-742 C.BRXX SUS 94 100 N C.BRXX HYP 76 100 N 38 100 N N 25 100 L N A l t e r a t i o n D e s c r i p t i o n from Hand S p e c i m e n a n d T h i n S e c t i o n A l t e r a t i o n t o q u a r t z , s e r i c i t e a n d c l a y 1s p e r v a s i v e . N e a r l y o p a q u e c l a y m i n e r a l s ( w h i t e 1n r e f l e c t e d l i g h t ) a r e c o n c e n t r a t e d 1n c o m p l e t e l y r e p l a c e d f e l d s p a r p h e n o c r y s t s . B i o t i t e p h e n o c r y s t s a r e a l t e r e d t o m u s c o v i t e , c l a y a n d j a r o s i t e . J a r o s i t e i s I n d i g -e n o u s arid f i l l s a n d l i n e s b o x w o r k and v e i n l e t s a f t e r s u l p h i d e s . Opaque g r a i n s a c c o u n t f o r a b o u t 15 p e r c e n t o f t h e t h i n s e c t i o n . O r i g i n a l q u a r t z I s u n c h a n g e d . X - r a y and t h i n s e c t i o n d a t a I n d i c a t e s a r g i l l i c a l t e r a t i o n f a c i e s o f h i g h I n t e n s i t y w i t h o v e r l a p p i n g c h a r a c t e r i s t i c s o f p h y l l i c f a c i e s . F e l d s p a r g r a i n s a r e p e r v a s i v e l y a l t e r e d t o c l o u d y c l a y , q u a r t z and s e r i c i t e . C a r b o n a t e l o c a l l y o c c u r s a n d p r i m a r y b i o t i t e i s s l i g h t l y a l t e r e d t o c h l o r i t e . Opaque m i n e r a l s a s v e i n l e t s a n d d i s s e m i n a t i o n s o c c u p y a b o u t 5 p e r c e n t o f t h e t h i n s e c t i o n . An i r r e g u l a r m y l o n i t i z e d z o n e up t o 5 mm. w i d e c r o s s e s t h e t h i n s e c t i o n . X - r a y and t h i n s e c t i o n d a t a i n d i c a t e s a r g i l l i c a l t e r -a t i o n f a c i e s o f m o d e r a t e i n t e n s i t y w i t h o v e r l a p p i n g c h a r a c t e r -i s t i c s o f p r o p y l i t i c f a c i e s . F e l d s p a r s a r e c l o u d y and a l t e r e d t o c l e a r , v e r y w e a k l y b i r e -f r i n g e n t l a t h s t h a t l o c a l l y h a v e c e n t r a l z o n e s o f s e r i c i t e . T h e c l o u d i n e s s and l a t h s , i n c o n j u n c t i o n w i t h X - r a y d a t a , a b o v e i n d i c a t e k a o l i n i t e ( ? ) a n d i l l i t e ( 7 ) . 15 p e r c e n t o f t h e t h i n s e c t i o n i s s e c o n d a r y c a r b o n a t e . O r i g i n a l q u a r t z a n d b i o t i t e i s u n a l t e r e d . X - r a y a n d t h i n s e c t i o n d a t a I n d i c a t e s weak a r g i l l i c a l t e r a t i o n f a d e s w i t h o v e r l a p p i n g c h a r a c t e r -i s t i c s o f p r o p y l i t i c ( c a r b o n a t e ) f a c i e s . ro ro P24-228 P.DCIT SUS 53 79 N N 43 56 N N N 'Plates 3.7 » 3.9) P29-607 I.QZMZ HYP 85 N N N 32 100 N 55 N (Plates 3.8 a 3.9) F e l d s p a r g r a i n s a r e c o m p l e t e l y a l t e r e d t o c l a y , q u a r t z , s e r i c i t e , c a r b o n a t e a n d e p i d o t e . P r i m a r y b i o t i t e i s c h l o r i t i z e d a t b o r d e r s a n d a l o n g c l e a v a g e , and i s s t r o n g l y c a r b o n a t l z e d . X - r a y a n d t h i n s e c t i o n d a t a I n d i c a t e s a r g i l l i c a l t e r a t i o n f a c i e s o f m o d e r a t e i n t e n s i t y w i t h o v e r l a p p i n g c h a r a c t e r i s t i c s o f p r o p y l i t i c f a c i e s ( c a r b o n a t e , c h l o r i t e and e p i d o t e ) . TABLE K.4 X-RAY DATA AND THIN SECTION DESCRIPTIONS FOR SPECIMENS REPRESENTATIVE OF THE PROPYLITIC ALTERATION FACIES (1) X-ray Diffraction Peak Height f g 5 ^ -Specimen No. and Location U C L o.>> IM - e p i n o cu u co a c <a • oj o s o — i M O-CM 01 VI a u o - C +> • «- r-» O CM 0) CO •M •r-C o r— 41 O 01 <u +J OJ 4-> 1. +J •r - •*-> > c O T— (/> O CM •r- O i — en B «-O CM O </> o • c r » n» r«. "73 t— S i S e t o • E m . JC i n U CM 01 D r i l l Core Spec." (Hole-Footage) F.QZMZ SUS 64 62 46 33 53 N 100 N P9-458 P25-309 (Plates 3.10 & 3.12) P25-586(6) Plates 3.11 4.3.12) F.QZMZ HYP 54 62 49 N 36 65 B 94 N F.QZMZ HYP 69 100 45 N 41 53 F 100 N F.QZMZ HYP 62 100 57 N 33 8 8 L 100 N P26-356 HYP 46 73 45 40 51 55 N 60 ro CO Alteration Description From Hand Specimen and Thin Section Feldspars are very slightly altered to sericite and quartz. Twinning in plagioclase is distinct. Biot i te , however, is percent altered to chlorite with minor leucoxerie, clay(?) and carbonate. X-ray and thin section data Indicates propylitic alteration fades of medium Intensity. Feldspars are locally altered to s e r i c i t e , quartz and clay(?). Biotite Is 50 percent altered to chlorite with minor leucoxene and pyrite. A pyrite rich veinlet accompanied by epidote a l t e r - ; ation crosses the thin section. Traces of jarosite after sulphides occur. X-ray and thin section data indicates propylitic alter-ation facies of medium intensity. Feldspars are weakly altered to s e r i c i t e , quartz and clay(?). Twinning in plagioclase is distinct. Locally, carbonate occurs and biotite is altered to chlorite. X-ray and thin section data indicates propylytic alteration facies of weak intensity. The specimens is pervasively altered by minor amounts of quartz, sericite, carbonate and clay (?). Twinning in plagioclase 1s generally distinct but locally destroyed. Plagioclase grains with strongly altered cores are locally rimmed by a relatively clear, negative r e l i e f mineral that might be albite. Primary biotite is 10 percent chloritized.' The thin section is cut by a 3 mm. wide quartz-carbonate vein surrounded by 3 mm. wide envelopes altered with opaques, chlorite and carbonate. X-ray and thin section data indicates propylitic alteration facies of high intensity. Feldspars are pervasively, weakly altered with s e r i c i t e , quartz, -carbonate and clay (?). Twinning in feldspars Is not affected by alteration. Biotite 1s slightly chlorit ized. Traces of dissem-inated epidote occur. X-ray and thin section data indicates propylitic alteration f a d e s of f a i r intensity. 244 APPENDIX L PROPOSED OUTLINES OF OPEN PITS, 1970 CASINO DEPOSIT, Y.T. A P P E N D I X L = P R O P O S E D P I T O U T L I N E S , 1 9 7 0 . C A S I N O . Y . T . 43* 30' UJ O o o o o m U J o 0 0 U J o o m CM U J o O o f O D 4500 c" I . O Z M Z 3 1 3 ° 3 0 " LOOKING 4000^ SUO 3500 FT L E O E N D T O P O G R A P H Y B R E C C I A C O N T A C T S U P E R G E N E A L T E R A T I O N C O N T A C T DRILL HOLE CENTRE LINE o < < > UJ 3000 F T o in U J z U J £ o z >« M o ™ NI * Ld U J z CC 3 Q_ UJ o<-> o U- n >- cc , .1-UJ 0. 2 U J zz> < _ J (fl -ft t E < ° > CJ CD U J ZD O N E O O < U J or UJ o ce U J CC o 0. >UJ < a o_ 5*- o X a T. B R X X CAP S O S HYP s or CO t- CAP p o r> to OJ OJ sus CT) OJ N N O HYP ro PPXX N M O 4000 F T HYPOGENE 8 SUPERGENE CODES C A P » C A P P I N G Z O N E S U O = S U P E R G E N E O X I D E Z O N E S U S = S U P E R G E N E S U L P H I D E Z O N E H Y P > H Y P O G E N E Z O N E ROCK TYPE C. B R X X T U F F T B R X X P P X X F . Q Z M Z I Q Z M Z O o m CODES B R E C C I A B R E C C I A P I P E C O B B L E T U F F T U F F - B R E C C I A J P A T T O N P O R P H Y R Y F I N E G R A I N E D Q U A R T Z M O N Z O N I T E I N E Q U I G R A N U L A R Q U A R T Z M O N Z O N I T E C A S I N O C O M P L E X K L O T A S S I N B A T H O L I T H 3500 3000 FT UJ O o m U J O O o o o m U J O o o C M U J O O m CM U J O O o to 2500 2500PT F I G U R E 3.6: C R O S S S E C T I O N C - D (NEAR SECTION 3 6 * O O S ) C A S I N O D E P O S I T , Y . T . 100 >00 I VX • [ L G R D R I L E U C O C R A T I C G R A N O O I O R I T E F I N E - G R A I N E D Q U A R T Z D I O R I T E ULTRABASIC. SERPENTINI2ED , SCHIST. GNEISS. MARBLE. 1Y M E T A I QUARTZITE I •-8 & >• 1 Z ro in O) if < t— O _j z o x. 3 >-U •X CL cr O < a J uj o 2 u * obs.rvat.cf, s i t « ^ f o l i a t i o n • specimen site 91 ^  thin sect ion & / o r stained slab site (COG 91 ) 151# potassium-argon date site ( COG 151) *.•;' outcrop &./or auboutcrop S road ./"interpreted geologic contact FIG2.2: C A S I N O G E N E R A L G E O L O G Y 279* 40' 4500' 5 6 5 7 7 6 9 : S E C T I O N I - J 3500' 005° 30' 5 4500' 4000'. 3500' 313° 30' L 0 O K I N G 4 313° 30' 4 500' I 4000' 3500' 313° 30' II 3500' 5 6 5 7 76B 4 S E C T I O N E - F ( NEAR SECTION 28*00S ) 4500' : — i 4000' 3500' 4 5 65 65 S E C T I O N C - D (SEE DETAILED CROSS - SECTION FIGURE 3300' 4500' 4000' 4300' 4000' 3500' L E G E N D ^ TOPOGRAPHY •• BRECCIA CONTACT ALTERATION ZONE CONTACT (DEFINED, INFERRED ) 4,5,6.5.7 ALTERATION GRADE BRECCIA PIPE 5 65 65 5 4 S E C T I O N A - B ( NEAR SECTION 40 • 30 S ) F IGURE 3.7= V E R T I C A L S E C T I O N S SHOWING H Y P O G E N E A L T E R A T I O N Z O N I N G A N D B R E C C I A P I P E O U T L I N E IN C A S I N O D E P O S I T , Y . T . KX> 200 5 0 0 H VERTICAL AND HORIZONTAL SCALE 4500' 4000' 3500' 4500' 4000' 3500' L E G E N D ^ TOPOGRAPHY BRECCIA CONTACT ALTERATION ZONE CONTACT (DEF INEO, I N F E R R E D ) 4,5.65,7 ALTERATION GRADE BRECCIA PIPE ( NEAR SECTION 40* 30 S ) IGURE 3.7: V E R T I C A L S E C T I O N S SHOWING H Y P O G E N E A L T E R A T I O N ZONING AND B R E C C I A P IPE O U T L I N E IN C A S I N O D E P O S I T . Y .T . VERTICAL AND HORIZONTAL SCALE |AVE RAGE / FEET AVERAGED HYPOGENE ALTERATION ROCK TYPE HYPOGENE a SUPERGENE ZONES AVERAGE GRADE FOR ZONE COPPER EQUIVALENT = Cu%>2» MoSy. 5 0 0 W T| "TJ H -i O O c ~n CO O T| 33 X Ss. X II II H H o -< C o TJ TJ CD H CD f— rn I m o CD o 33 m o o m o CO x cn co -< c c -o CO o II II II 1 CO CO -< c e "0 ~o ~o o rn m O 3) 3J m CD CD 2 m m m z z CO CD H cr o -o m "o m o O 33 o O O — 3} m > > 61 m X m NE O o TJ X r > -< z r~ H rn H > m o 33 H > H O z o o z H )> o H J L o I z 5 0 0 E 1 0 0 0 E PL CAP .005 2.5/175 5 0 0 W N F. QZMZ 1. QZMZ SUS g CAP .323 8 .060 j \ \ \ \ \ \ \ \ \ 5.7/170 5.5/200 I.QZMZ PPXX 1. QZMZ | T . B R X X HYP SUS S U O CAP .314 .294 . 2 2 7 .044 1 B A S E L I N E 5 0 0 E 5.6/200 -< F.QZMZ T. BRXX . "TJ HYP SUS SUO .339 .691 .113 T. BRXX CAP .070 1 5 0 0 E 5.2/132 5.8/20C I.QZMZ F.QZMZ T. BRXX HYP SUS SUO CAP 0.336 .601 .370 .082 / / / 5.6/105 O 1 " T J \ T . B R X > \ T. BRXX % SUO CAP % .129 .115 / 6.2/200 C. BRXX / T . B R X X C . B R X X 1 HYP .500 SUS 5.0/200 TUFF T.BRXX / SUS SUO CAP J .408 .085 .095 | .373 / / / 2 0 0 0 E 2 5 0 0 E \ / 6.6/200 T. BRXX SUS 497 SUO 302 P P X X T B R X X J CAP 105 0 \ c / 5/ I 2.4/200 3 0 0 0 E I.QZMZ F . Q Z M Z C.BRXX F.C ZMZ HYP SUS CAP .308 .335 .049 ± 4.5/200 / i r 9 6 F.QZMZ I . Q Z M Z F. QZMZ HYP SUS CAP .287 .198 .055 BRXX F.QZMZ 1 0 0 0 E 1 5 0 0 E 2 0 0 0 E 2 5 0 0 E 3 0 0 0 E •a\ H Y B R I D G R A N O D I O R I T E L E U C O C R A T I C G R A N O D I O R I T E F I N E - - G R A I N E D Q U A R T Z D I O R I T E R p ] U L T R A B A S I C , S E R P E N T I N I Z E D S K A R N S C H I S T . G N E I S S . M A R B L E . Q U A R T Z I T E o X L U - J >-rn z in MP 6 < O u u OLI HIV MY z m cn oS m < r O _ j u 'X a. or O < LU 2 X iii _j 0 . 5 0 U foliation • observation site • specimen s i t e 91A thin sect ion &/or stained slab site (COG 91 ) 151 • potassium-argon date site ( COG 151) •' outcrop &/or suboutcrop ^ road / interpreted geologic contact FIG2.2: C A S I N O G E N E R A L G E O L O G Y 279*40' LOOKING 3500' 313* 30' 4000' 3500" 313" 30' LOOKINO 3300' S E C T I O N E - F (NEAR SECTION 28*OOS) 4500 4000' 3500' 4 5 63 65 S E C T I O N C - D (SEE DETAILED C ROSS - SE CTION FIGURE ) 4500' 4500' 4000' 3500 L E G E N D TOPOGRAPHY ••• BRECCIA CONTACT ALTERATION ZONE CONTACT (DEF INED, I N F E R R E D ) 4,5,65,7 ALTERATION GRADE I | BRECCIA PIPE 5 6.5 65 5 4 S E C T I O N A - B ( NEAR SECTION 40 *30S ) FIGURE 3.7= V E R T I C A L S E C T I O N S SHOWING H Y P O G E N E A L T E R A T I O N ZONING AND B R E C C I A PIPE O U T L I N E IN C A S I N O D E P O S I T , Y .T . 100 700 JOO M V E R T I C A L A N D H O R I Z O N T A L S C A L E 223° 30' UJ 43° 30' 4500PT B R X X CL LO < o 1 O o I.QZMZ 313° 30 ' L O O K I N G 400CK1-suo 200 B R X X 3 5 0 0 FT L E O E N D T O P O G R A P H Y B R E C C I A C O N T A C T S U P E R G E N E A L T E R A T I O N C O N T A C T DRILL HOLE C E N T R E L I N E z m o UJ to o r- z U J 2 < o Z x CC OJ M M * Q t- Ld UJ 3° UJ _ J z CC 3 o < CL UJ O O < o u_ M cr UJ >- CC . , 1 -UJ z > Ul p E ^ Z 9UJ < O <_1 Od CO cr< °> AH CJ CD UJ O UJ z UJ o O CL AVERAG 3PER EQ VERAGE FEET RO AVERAG 3PER EQ > o X o xx c B R X X i.ozrv sus H Y P H Y P O G E N E a S U P E R G E N E C O D E S C A P = C A P P I N G Z O N E S U O = S U P E R G E N E O X I D E Z O N E S U S • S U P E R G E N E S U L P H I D E Z O N E H Y P = H Y P O G E N E Z O N E R O C K T Y P E C O D E S B R E C C I A B R E C C I A P I P E C . B R X X = C O B B L E T U F F = T U F F T. B R X X = T U F F - B R E C C I A P P X X = P A T T O N P O R P H Y R Y F . Q Z M Z = F I N E G R A I N E D Q U A R T Z M O N Z O N I T E I. Q Z M Z = I N E Q U I G R A N U L A R Q U A R T Z M O N Z O N I T E C A S I N O C O M P L E X K L O T A S S I N B A T H O L I T H LO QL U_ CD < O O o r -3 CM 00 CM • CO CD CO CM " M N O CL >- — X PO X Q_ N rsl O UJ 2 5 0 0 " 2 5 0 0 ^ F I G U R E 3.6' C R O S S S E C T I O N C - D ( N E A R S E C T I O N 3 6 * O O S ) C A S I N O D E P O S I T , Y.T. 00 VJ M 00 »O0 FT I ro cn O O I A V E R A G E / F E E T A V E R A G E D H Y P O G E N E A L T E R A T I O N ROCK T Y P E H Y P O G E N E 6 S U P E R G E N E Z O N E S A V E R A G E G R A D E F O R Z O N E C O P P E R E Q U I V A L E N T ' C U % » 2 K MoS°/cj 5 0 0 W — -n TJ o o 5 N N C 2 2 M M P o co O X ^ X CO CO -< cz cz T W O z _ m z o m E o CD 33 il -n TJ > > o c o > H M 2 O 2 2 O ^ z o M Z _ m o z T J o 3 ) T J -< 20 II II II H H O c e o "n n CD "n -n co CD m o o H -< T) m o o D m CO m M O z m CD T J rn o o T J T J m CO CO cz c TJ TJ m m 33 33 CT) CD m m z z m m CO o C X r~ --o o X M O M m o z N M o z m X o -< T l O CD m T J O J> T J T J CD N O z m CO CO H C 3 ) O 3 3 m TJ m o o 33 O O CD > r-H o x H o > r- Co H — x z J L o o o > 2 co m x 5 0 0 E 1 0 0 0 E 1 5 0 0 E m CO <z " 0 m C D m m o o o m CO o m 33 > T3 X -< H > m 2 33 ~ i > O o m Q m o o CD > TJ N § 5" o CAP .005 2 . 5 / 1 7 5 F. Q Z M Z I . Q Z M Z SUS CAP . 3 2 3 .060 y \ \ • x -< TJ \ \ \ \ c CO \ \ \ \ 5 . 7 / 1 7 0 5 . 5 / 2 0 0 \ \ M \ \ \ \ \ \ \ \ 5 0 0 W O > TJ > cd • 33 • X • X I . Q Z M Z PPXX I . Q Z M Z [ T . B R X X HYP SUS suo CAP .314 .294 . 2 2 7 .044 5 . 6 / 2 0 0 X -< F.QZMZ T. BRXX TJ HYP SUS SUO . 3 3 9 .691 .113 C D > " 0 B A S E L I N E 5 0 0 E T. BRXX CAP . 0 7 0 5.2/132 5 . 8 / 2 0 C I .QZMZ F.QZMZ T. BRXX HYP SUS SUO CAP 0 .336 .601 .370 . 0 8 2 / / / 5.6/105 o ! y> TJ \ T . B R X X \ T. BRXX X SUO CAP % .129 .115 / 6 . 2 / 2 0 0 / C.BRXX T . B R X X C . B R X X HYP . 5 0 0 SUS 5 . 0 / 2 0 0 T U F F T .BRXX / SUS SUO CAP 1 . 4 0 8 .085 .095 ( .373 / / / 2 0 0 0 E 2 5 0 0 E / ^lorT 6 . 6 / 2 0 0 T. BRXX P P X X | T B R X X SUS SUO CAP . 4 9 7 .302 .105 j _ 6 2 £>9S \ \ \ I . Q Z M Z F . Q Z M Z C.BRXX F.G ZMZ HYP SUS CAP . 3 0 8 .335 .049 / 3 0 0 0 E L 4 . 5 / 2 0 0 / i F.QZMZ 1 Q Z M Z F. QZMZ HYP SUS CAP .287 .198 .055 ro cn O O OJ O o o Oi O O BRXX F.QZMZ 1 0 0 0 E 1 5 0 0 E 2 0 0 0 E 2 5 0 0 E 3 0 0 0 E LOOKING 4500' 5 6 5 7 7 6 5 S E C T I O N I - J 313° 30' 4500'* 4000'. 3500' 313' 30' 4 500" 4000' 3300' 313° 30' T 3500' 005° 30' 5 3300' 5 6.5 7 76 S E C T I O N E - F (NEAR SECTION 2 8 * 0 0 3 ) 6 5 V 6.5 5 4 N 1 ' D \ I / 1 1 / , 4500' 4000' 3500' 4 5 65 65 S E C T I O N C - D (SEE DETAILED C ROSS - SE CTION FIGURE 5 4 3300' 4500' 4000' 4300 4000' 3300' V1 3500' L E G E N D ^ TOPOGRAPHY ••• BRECCIA CONTACT ALTERATION ZONE CONTACT (DEFINED, INFERRED ) 4.5.6.5.7 ALTERATION GRADE I | BRECCIA PIPE 5 65 65 5 4 S E C T I O N A - B ( NEAR SECTION 40* 30S ) IGURE 3.7: V E R T I C A L S E C T I O N S S H O W I N G H Y P O G E N E A L T E R A T I O N Z O N I N G A N D B R E C C I A P I P E O U T L I N E IN C A S I N O D E P O S I T , Y . T . " 0 0 100 V E R T I C A L A N D H O R I Z O N T A L S C A L E 

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