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Petrology and structure of the Tuzo Creek Molybdenite Prospect near Penticton, British Columbia. Leary, George Merlin 1970

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PETROLOGY AND STRUCTURE OP THE TUZO CREEK MOLYBDENITE PROSPECT NEAR PENTICTON, BRITISH COLUMBIA by. George Merlin Leary Sc. University of B r i t i s h Columbia, 1967 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of GEOLOGY We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 197Q In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study . I f u r t h e r agree tha permiss ion f o r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed without my w r i t t e n p e r m i s s i o n . Department of GEOLOGY  The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada i ABSTRACT The Tuzo Creek Molybdenite Prospect i s i n southern B r i t i s h Columbia approximately twenty air-miles east-southeast of Penticton within the Nelson-Valhalla b a t h o l i t h i c complex. A stock of po r p h y r i t i c quartz monzonite, approximately \}% miles i n diameter, and younger sub-volcanic s i l l s , dykes and masses of quartz-albite-sanidine porphyry were eraplaced into a basement of Nelson granodiorite of probable Jurassic Age. Mid (?) T e r t i a r y alkaline basic dykes are the youngest intrusions present. Porphyries were emplaced successively at three d i f f e r -ent times along structures developed eit h e r by subsidence of the stock or by regional deformation. D i f f e r e n t i a t i o n , l e v e l of c r y s t a l l i z a t i o n of phenocrysts, l e v e l of emplacement and regional c o r r e l a t i o n of acid intrusions are discussed. Two phases of hydrothermal a c t i v i t y are recognized, separated i n time by intrusions of porphyry. In both cases, a l t e r -ation was controlled by fractures and l o c a l shear and breccia zones. The f i r s t phase resulted i n widespread wallrock a l t e r a t i o n , quartz veining and mineralization throughout most of the stock and bodies of pre-mineral porphyry. Zoning of a r g i l l i z a t i o n , potash f e l d s p a t h i z a t i o n and s i l i c i f i c a t i o n and of oxide or sulphide f i e l d s of mineralization occurs on a large scale throughout the a l t e r a t i o n halo. A large zone of low grade molybdenite m i n e r a l i -zation occurs i n a zone of more intense wallrock a l t e r a t i o n containing stockworks of quartz veins and p y r i t e . The chemical and physical aspects of wallrock a l t e r a t i o n and mineralization are considered i n l i g h t of experimental studies done by others. The second phase of hydrothermal a c t i v i t y only occurred l o c a l l y and involved development of secondary s e r i c i t e and quartz with associated Zn, Pb, Cu, Pe and Mo sulphides and c a l c i t e and f l u o r i t e . A l l structures can be explained either by periods of subsidence of the stock or by genetic r e l a t i o n s h i p to forces developed by periodic movements along a nearby regional f a u l t zone following the West Kettle River v a l l e y . Source rocks of hydrothermal f l u i d s , paragenesis, zoning and exploration p o t e n t i a l f o r molybdenite are discussed. i i i TABLE OP CONTENTS CHAPTER I INTRODUCTION Page GENERAL REMARKS 1 l o c a t i o n and Access. 1 Physiography I4. History of Detailed Exploration ij. Acknowledgements 5 REGIONAL GEOLOGY 6 Rock Types 6 Structure 9 Economic Geology 10 PRELUDE TO PETROLOGY AND STRUCTURE OP THE PROSPECT 10 Geological Summary Statement 10 Presentation and Data 12 CHAPTER II INTRUSIVE ROCKS HORNBLENDE GRANODIORITE 15 Petrography and Mineralogy 16 Deuteric (?) A l t e r a t i o n 17 PORPHYRITIC BIOTITE QUARTZ MONZONITE 18 Structure 18 Phenocrysts 19 Groundmass 21 L i t h o l o g i c Variations 22 Deuteric (?) A l t e r a t i o n 22 QUARTZ-ALBITE-SANIDINE PORPHYRIES 23 Introduction 23 General Description 2l± Phenocrysts 25 Groundmass 28 Regional Correlation 29 Pre-Mineral R o o f - s i l l and Dykes 30 Distinguishing Features 30 D i s t r i b u t i o n 31 Contact Relationships 32 i v Intra-Mineral S i l l s and Dykes 3 3 Structure 3 ^ 1 Deuteric A l t e r a t i o n and Mineralization 3 5 Post-Mineral Dykes and Masses 3 5 Structure 3 6 L i t h o l o g i c Variations 3 7 Deuteric A l t e r a t i o n and Min e r a l i z a t i o n 3 8 LATE DYKES . k.0. Structure J 4 . I Alkaline Quartz Gabbro Lj.1 Composite Alkaline Basalt - Augite Trachyte I J 2 Altered Lati t e ljij. Discussion l j.6 DIFFERENTIATION OF ACID INTRUSIVE ROCKS lj.6 LEVEL OF EMPLACEMENT OF THE STOCK AND PORPHYRIES lj.7 CRYSTALLIZATION OF PHENOCRYSTS I 4 . 8 CONCLUSION 5 0 CHAPTER III STRUCTURE INTRODUCTION 5 1 REGIONALLY SHEARED GRANODIORITE 5 2 Discussion 5 3 FAULTS 5 3 FOLIATION Sk Discussion 5 7 SHEAR AND BRECCIA ZONES 5 7 FRACTURING 6 0 Introduction 6 1 Period - I : Fracturing and Quartz Veining 6 l Discussion 68 Period - I I : Fracturing 69 DISCUSSION OF STRUCTURES CONTROLLING EMPLACEMENT OF INTRUSIVE ROCKS 7 0 STRUCTURAL INTERPRETATION 7 2 CHAPTER IV HYDROTHERMAL ALTERATION AND MINERALIZATION DEFINITIONS AND FIGURES 7 6 INTRODUCTORY SUMMARY 7 8 REGIONALLY ALTERED GRANODIORITE 8 l Discussion 8 2 V PHASE - I : MAIN PHASE OP ALTERATION AND MINERALIZATION 8k Relationship between Structure, Wallrock A l t e r a t i o n and Mineralization 8 I 4 . Surface Oxidized Zone 8 5 Wallrock A l t e r a t i o n 86 Peripheral S h e l l 8 6 Fracture F i l l i n g s 8 9 Central Zone 9 0 Upper Quartz-Hydromica Sub-Zone 91 Overlap of Sub-Zones 9 3 Fracture F i l l i n g s Lower Quartz-Potash Feldspar Sub-Zone 91+ Fracture F i l l i n g s 98 Quartz Veining 1 0 0 Conclusions 1 0 3 Mineralization I O I 4 . Oxide F i e l d (Hematite-Magnetite-Pyrite) 1 0 5 Sulphide F i e l d (Pyrite) 1 0 6 Molybdenite Zone 1 0 8 Paragenesis and Zoning 1 1 3 Geochemical Character of Wallrock A l t e r a t i o n 1 1 6 Interpretation of the Hydromica-Potash Feldspar Boundary 1 1 8 Geochemical Character of Mineralization 1 2 0 Exploration Potential of the Molybdenite Zone 1 2 1 PHASE - I I : INTRA-MINERAL PORPHYRY ASSOCIATION 1 2 3 General Statement 1 2 3 Timing 12\± Pervasive Wallrock A l t e r a t i o n and Mineralization 1 2 5 Intensely Altered Zones and Related Features 1 2 7 Discussion 129 GROSS PARAGENESIS 1 3 0 SOURCE ROCKS OF HYDROTHERMAL FLUIDS 1 3 1 CHAPTER V SUMMARY AND CONCLUSIONS SUMMARY 1 3 3 CONCLUSIONS I 3 8 BIBLIOGRAPHY 1 ^ 1 v i LIST OF TABLES TABLE I - Geological Sequence of Events 1 1 II - C l a s s i f i c a t i o n of Thin and Polished Sections Studied 1 3 III - Estimated Mode of Granodiorite 1 6 IV - Estimated Mode of Quartz Monzonite 1 8 V - Average Estimated M 0d e of Quartz-Albite-Sanidine Porphyries-- 2 5 VI - Composition of Albite i n Porphyries 2 7 VII - Estimated Mode of Late Dykes \\S VIII - Periods of D e f o r m a t i o n — 5 2 IX - Period-I Mineralized-Fracture and Quartz Vein. Frequency i n "Intensely Fractured Zones 1 - 8 " and i n the "Central Quartz Vein Stockwork Zone" <• 6 3 X - D e f i n i t i o n of Degrees of Wallrock A l t e r a t i o n 7 7 XI - C l a s s i f i c a t i o n of Quartz Veins 1 0 2 - 1 0 3 XII - Modes of Occurrence of Molybdenite 1 0 9 XIII - Average Percent Molybdenite i n Host Rocks i n DDH's 1 - l j . within the "Molybdenite Zone" 1 1 1 XIV - Average Percent Molybdenite i n H 0st Rocks i n PSH's 1 - 1 3 — 1 1 2 XV - Phaae-I and -II Gross Paragenesis 1 3 0 VI1 LIST OP FIGURES Page Figure 1 - General Location Map 2 2 - Location Map 3 3 - Preliminary Geological Map of the Kettle River Area 7 l± - Control Survey Map In Pocket 5 & 6 - Geology (Plan and Sections) In Pocket 7 & 8 - Structure, Hydrothermal A l t e r a t i o n & Mineralization (Plan & Sections) In Pocket 9 - Period-I F o l i a t i o n and the "Foliated Shear Zone" $6 1 0 , 1 1 & 1 2 (A,B,C) Azimuth and Dip Frequency Diagrams of Period-I Fractures and Quartz V e i n s ^ j ^ ^ £ , 6 1 3 - Combined Stress and S t r a i n E l l i p s o i d Diagram f o r Structures of Regional Orig i n 7k lk - Interpretive Representation of Zonal Arrangement of Phase-I Wallrock A l t e r a t i o n and Mineralization 1 1 5 v i i i LIST OF PLATES (pp. l l j . 2 - 1 5 9 ) Plate 1 : View looking west towards map-area from the access road near the junction of Tuzo Creek and West Kettle River. ("X" marks a common spot on Plates 1 to k)> Plate 2 : View looking southwest from a helicopter; note the straight, moderately in c i s e d draw (follows a young f a u l t ) . Plate 3 : View looking north over the campsite from a helicopter; note the l e v e l of the i n c i s e d I n t e r i o r Plateau upland i n the background. Plate I4.: View looking north of the West K e t t l e River Valley; the town of Beaverdell l i e s at the i n t e r s e c t i o n of major valleys i n the background; note the Inter i o r Plateau upland surface. Plate 5 : Fresh hornblende granodiorite; note the hypidio-morphic texture, weak f o l i a t i o n and large i n t e r -s t i t i a l grains of quartz (pale grey). Plate 6: Fresh por p h y r i t i c b i o t i t e quartz monzonite; note the large euhedral sanidine phenocrysts ( l i g h t ?rey) and medium grained phenocrysts of oligoclase white), rounded quartz (glassy grey) and b i o t i t e (black) and the fine grained groundmass. Plate 7' Pre-mineral Porphyry (altered); note the large euhedral sanidine phenocrysts and deformed quartz ( l i g h t grey) phenocrysts. Plate 8: Intra-mineral Porphyry (weakly altered); note phenocrysts consisting of rounded grains of quartz (glassy grey), large euhedral sanidine (white), i n d i s t i n c t a l b i t e (grey) and altered b i o t i t e (dark); also note the aphanitic groundmass. Plate 9 s Post-Mineral Porphyry ( r e l a t i v e l y f r e s h ) ; note the si m i l a r texture of pre-, i n t r a - and post-mineral porphyry, L e f t : Fine-grained pink phase showing a granular texture. Center : Grey to pink predominant phase. Right: Dark pink phase. i x Plate 1 0 : Sanidine phenocrysts from post-mineral porphyry; l e f t and center c r y s t a l s are oriented with a-axis v e r t i c a l and c-axis downwards to the l e f t , c r y s t a l s show 0 1 0 , 0 0 1 , 1 1 0 and 2 0 1 faces. Plate 1 1 : Alkaline Quartz Gabbro (late dyke); note the medium grained phenocrysts consisting of labra-dorite laths ( l i g h t grey) and augite (dark) i n a fine-grained, granophyric-like groundmass. Plate 1 2 : Composite Alkaline Basalt - Augite Trachyte (late dykes); Left : Right Alkaline basalt showing phenocrysts of labradorite laths ( l i g h t grey) and augite (dark) i n a fine-grained ground-mass, Augite a l k a l i augite Trachyte showing phenocrysts of feldspar laths to rhombs (white), (dark grey) and b i o t i t e (black) i n a fine-grained granular groundmass. (Note rims around feldspar phenocrysts i n both rock types). Plate 1 3 : Altered L a t i t e (late dyke); note small phenocrysts of a ltered feldspar (white) i n a f i n e grained groundmas s. Plate 11}.: A r g i l l i z e d Granodiorite from the "quartz-hydromica-sub-zone"; note the a l t e r a t i o n selvage consisting of hydromica and quartz along a pyrite-molybdenite bearing fra c t u r e . Plate 1 5 : Sample from the overlap zone between the upper "quartz-hydromica sub-zone" and the lower "quartz-potash feldspar subr-zone"; sample i l l u s t r a t e s pervasively K-feldspathized pre-mineral porphyry showing l a t e r pyrite-molybdenite bearing fractures with selvages of quartz and hydromica. Plate 1 6 : Samples i l l u s t r a t i n g quartz veins i n K-feldspathized rocks from the "central quartz vein stockwork zone" (see Table XI). Plate 1 7 : Discontinuous, i r r e g u l a r quartz veins and s i l i c i -f i e d zones i n a r g i l l i z e d granodiorite from the "quartz-hydromica sub-zone"; Type 2 veins (Table * I ) . X Plate 18: Abundant molybdenite (black) occurring along fractures and coating breccia fragments i n brecciated and K-feldspthized quartz monzonite from the "quartz-potash feldspar sub-zone". Plate 195 Molybdenite (dark metallic) and magnetite (black) occurring exclusive of one another along fractures without showing crosscutting relationships i n K-feldspathized quartz monzonite. Plate 20: Heavy molybdenite (black)mineralization occurring i n v e i n l e t s and along fractures i n K-feldspathized quartz monzonite from the high grade zone i n t e r -sected along DDH 1. Plate 21: Molybdenite (black) bearing fracture with a selvage of hydromica and quartz i n a r g i l l i z e d pre-mineral porphyry from the "quartz-hydromica sub-zone". Plate 22: Serrate fracture coated with molybdenite (black). Plate 2 3 : Banded quartz-hydromica-molybdenite vei n l e t s (Type 3 b veins: see Table XI) Plate 2l\\ Banded quartz-magnetite veins and magnetite bearing fractures i n K-feldspthized rocks (Type 1 veins; see Table XI); L e f t : from the "oxide f i e l d " at depth Center and r i g h t : from "fracture zone-8" within the "oxide f i e l d " . Plate 2 5 : Banded quartz-magnetite veins i n a r g i l l i z e d and K-feldspathized granodiorite; sample taken from f l o a t below "fracture zone-8". Plate 26: Heavy hematite (specularite) and magnetite mi n e r a l i -zation i n intensely fractured and granulated, a r g i l -ized and s i l i c i f i e d pre-mineral porphyry from "fracture z o n e - 5 " . Plate 2 7 J Hematite and magnetite along fractures i n a r g i l l i z e d and s i l i c i f i e d pre-mineral porphyry from "fracture z o n e - 5 " • Plate 28: Brecciated and intensely s i l i c i f i e d and a r g i l l i z e d quartz monzonite from "fracture z o n e - 5 " ; abundant hematite and magnetite healing breccia fragments. x i Plate 29: Massive sulphide v e i n l e t s (Phase-II minerali-zation) ; L e f t : Banded pyrite-molybdenite-calcite vein Center: Sphalerite-galena-pyrite-chalcopyrite vein cutting pre-mineral porphyry Right: Galena-chalcopyrite vein. Plate 3 0 : Breccia zone (Period-II) i n quartz monzonite containing a large fragment of molybdenite mineralized rock (on l e f t ) ; note c a l c i t e f i l l i n g (white) CHAPTER I INTRODUCTION GENERAL REMARKS This study deals with the petrology of in t r u s i v e rocks, wallrock a l t e r a t i o n and mineralization and with the structure of a region containing an altered and mineralized g r a n i t i c stock near Beaverdell i n southern B r i t i s h Columbia. Material presented i s based on detailed geological map-ping of a four square-mile area, logging and sampling of 1 + , 8 6 5 feet of B.Q. Wireline and 9 7 6 feet of Packsack diamond d r i l l core, and on a petrographic and mineralographic study involving 1 5 2 t h i n sections and 2 3 polished sections. Location and Access The prospect i s located i n south central B r i t i s h Columbia within the southern part of the In t e r i o r Plateau approx-imately f i v e air-miles southwest of Beaverdell (Figure 1 and 2 ) . The eastern edge of the map-area that covers the prospect i s one-h a l f mile west of the junction of the West Kettle River and Tuzo Creek. GENERAL LOCATION MAP TUZO CREEK MOLYBDENITE PROSPECT . Figure / K E _ 0 W N A ( 5 4 M i l e s ) \ R O C K C R E E K Wi M i l e s ) F I G U R E 2 LOCATION MAP TUZO C R E E K M O L Y B D E N I T E P R O S P E C T B R I T I S H C O L U M B I A S C A L E I I N C H 2 M I L E S The map-area i s accessible from Beaverdell by gravel road. Good access within the map-area i s provided by approxi-mately seven and one-half miles of four-wheel drive roads that traverse the east side and top of a ridge. Physiography The map-area covers a short, rounded north-south trend-ing ridge and much of i t s surrounding slopes (Figure I4.). Maximum r e l i e f i s 2 5 0 0 feet from the Tuzo creek v a l l e y to the top of the ridge at an alti t u d e of 5 1 0 0 feet. From the top of the ridge to approximately the 4 7 0 0 foot contour, slopes are gently dipping and r o l l i n g , whereas below this l e v e l slopes are r e l a t i v e l y steep and moderately i n c i s e d by numerous draws that intermittently have seepages and flowing water. Small l o c a l swamps and one perman-ent lake are present on the upper part of the ridge (see Plates 1 to The area i s covered by a parkland type of evergreen fo r e s t growth that i s r e l a t i v e l y open on the upper part of the ridge but on steeper slopes, and p a r t i c u l a r l y along draws, i s mixed with a f a i r l y dense growth of underbrush. History of Detailed Exploration The altered and mineralized area was explored f o r base metal deposits by Kennco Explorations (Western) Ltd. i n 1 9 6 1 and 5 1 9 6 2 , and by AMAX Exploration, Inc. from 1 9 6 I 4 . to 1 9 6 6 . AMAX presently holds 1 8 f u l l - 3 i z e d claims and one f r a c t i o n a l claim (Figure Ij.). Main access roads were constructed by Kennco. The res u l t s of an induced p o l a r i z a t i o n survey, conducted by McPhar Geophysics f o r Kennco, are available! through the d i s t r i c t min-ing recorder. The writer, as an employee, was d i r e c t l y involved i n a l l stages of exploration by AMAX. Work included g r i d construc-tio n , geochemistry, geological mapping, diamond d r i l l i n g , core logging, road b u i l d i n g , trenching, sampling, surveying and a ground magnetometer survey. Acknowledgements Special acknowledgement i s given to J. M. Patterson f o r h is help during preliminary mapping, and es p e c i a l l y f o r his suggestions during detailed exploration of the prospect. Ack-nowledgement i s due to AMAX Exploration, Inc. f o r bearing the cost of thin and polished sections, map reproductions and photo-graphs, and f o r permission to publish this t h e s i s . My special thanks are given to Drs. K. C. McTaggart and A. J. S i n c l a i r f o r t h e i r h e l p f u l suggestions and c r i t i c i s m s during the preparation of t h i s thesis. 6 REGIONAL GEOLOGY Included i s a Preliminary Geological Map of the Kettle River Area (Figure 3) that has been reproduced, though s i m p l i -f i e d , from maps published by L i t t l e (8). The area i s underlain by Precambrian (?) to Jurassic metamorphosed and deformed sedimentary and volcanic rocks that were intruded, during the Mesozoic, by a few u l t r a b a s i c plutons and numerous g r a n i t i c stocks and batholiths. These rocks are p a r t l y o v e r l a i n by T e r t i a r y sedimentary and volcanic rocks, and are intruded by small bodies of acid porphyry and s y e n i t i c dykes, stocks and batholiths. Rock Types For d e t a i l s of l i t h o l o g y , etc. of rock types r e f e r to L i t t l e (8). Rocks older than Mesozoic g r a n i t i c intrusions are not discussed below. The center of the area i s underlain by a large i r r e g u l a r but roughly c i r c u l a r Mesozoic " g r a n i t i c " b a t h o l i t h . It comprises a large portion of the quartz monzonitic V a l h a l l a Intrusions that occupy a central p o s i t i o n i n the Nelson-Valhalla b a t h o l i t h i c complex of southern B r i t i s h Columbia. • The b a t h o l i t h intrudes l a r g e l y g r a n o d i o r i t i c Nelson Intrusions. However, i n the f a r eastern portion of the area, contacts between the two phases are l o c a l l y gradational, and i n the Nelson area to the east, con-tacts are commonly gradational (8, 11). 120° 00' 50* 0 0' -(- 118° 00' 50° 00' OkanagaH Kji-JiAOA'.N' K E T T L E 16 : 1 5 a.-3S AS* i l l ' S t e f f i 4 , - - o o ^ i a & i s ^ 120° 00' '••is •" >5 ( \H . B. MINE ' ( A g ^ P b . Z n J PRELIMINARY GEOLOGICAL MAP OF KETTLE RIVER AREA Reproduced From Original Preliminary Geological Mcps By H.W. L i t t le - , Maps 6 - 1 9 5 7 And Map 15 - 1961 ( EAST AND W E S T H A L V E S ) BRITISH COLUMBIA SCALE 8 M I L E S Figure 3 N D Basalt } PLATEAU BASALT Coryell Intrusions (Mainly Syenite) 19, 10 - Midway Volcanic Group 17, 9 - Kettle River Formation CONTINENTAL SEDIMENTARY and VOL CA NIC S TRA TA Quartz Feldspar Porphyry Intrusions Valhalla Intrusions (Mainly Porphyritic Quartz Monzonite, and Granite J Nelson Intrusions ( Mainly Granodiorite and Quartz Diorite ) Ultrabasic Intrusions 4 Ross/and Group 13 Limestone 12 Nicola Group II Old Tom Formation 10 Shoemaker Formation 9 Independence Formation 8 Barslow Formation 2 Mounts Roberts Formation 7,3 Anarchist Group 6 Blind Creek Formation 5 Cache Creek - Group 4 Kobau Group M ETAMOPHOSE D EUGEOSYN CLINAL SEDIMENTARY AND VOLCANIC STRATA 2 Chapperon Group I Monashee and Grand Forks Groups HIGHLY METAMORPHOSED . MIOG EOS YNCL IN A L SEDIMENTARY STRATA Producing Mine Highland - Bell 8 C e n t e r e d a b o u t B e a v e r d e l l , w i t h i n t h e V a l h a l l a b a t h o -l i t h , i s a n i r r e g u l a r mass o f N e l s o n I n t r u s i o n s a n d o l d e r m e t a -m o r p h o s e d r o c k s . S t o c k s o f v a l h a l l a i n t r u d e t h e m a s s ; o n e o f w h i c h i s l o c a t e d w i t h i n t h e s o u t h e r n p o r t i o n o f t h e mass a n d w i t h i n t h e m a p - a r e a o f t h e " T u z o C r e e k M o l y b d e n i t e P r o s p e c t " . I n t h e K e t t l e R i v e r a r e a , N e l s o n I n t r u s i o n s a r e p r e -d o m i n a n t l y n o n - p o r p h y r i t i c , h y p i d i o m o r p h i c a n d c o n t a i n h o r n -b l e n d e w h e r e a s V a l h a l l a I n t r u s i o n s a r e g e n e r a l l y p o r p h y r i t i c w i t h l a r g e p h e n o c r y s t s o f m i c r o p e r t h i t e a n d c o n t a i n b i o t i t e a n d r a r e l y h o r n b l e n d e . T o w a r d s t h e e a s t , V a l h a l l a I n t r u s i o n s b e c o m e , p r e -d o m i n a n t l y n o n - p o r p h y r i t i c a n d a l l o t r i o m o r p h i c i n t e x t u r e . T h e b a t h o l i t h i c c o m p l e x i s t e n t a t i v e l y a s s i g n e d t o t h e J u r a s s i c a n d C r e t a c e o u s ( ? ) . T h i s i s b a s e d o n s t r a t i g r a p h i c e v i d e n c e a n d a g e d a t i n g (10). S t o c k s , d y k e s , a n d s i l l s o f q u a r t z f e l d s p a r p o r p h y r y l o c a l l y i n t r u d e V a l h a l l a a n d o l d e r r o c k s . P o r p h y r y i n t r u s i o n s i n c l u d e t h e S h i n g l e C r e e k P o r p h y r y n e a r P o n t i c t o n , t h e T u z o C r e e k P o r p h y r y , d i s c u s s e d h e r e i n , a n d t h e O u e l l e t t e c r e e k P o r p h y r y a d j a c e n t t o t h e E a s t K e t t l e R i v e r v a l l e y . P o r p h y r i e s a r e p r o b a b l y o f e a r l y T e r t i a r y age b e c a u s e t h e S h i n g l e C r e e k a n d O u e l l e t t e C r e e k i n t r u s i o n s h a v e r e l a t e d c o n t e m p o r a n e o u s p y r o -c l a s t i c s t h a t p r o b a b l y a r e i n t e r c a l a t e d w i t h s t r a t a o f t h e E a r l y T e r t i a r y K e t t l e R i v e r F o r m a t i o n . A l l p o r p h y r i e s o c c u r a d j a c e n t t o r o u g h l y n o r t h - s o u t h t r e n d i n g r e g i o n a l f a u l t z o n e s t h a t l i e a l o n g m a j o r v a l l e y s . E a r l y T e r t i a r y s e d i m e n t a r y a n d v o l c a n i c s t r a t a u n c o n -f o r m a b l y o v e r l i e o l d e r r o c k s . I n p a r t i c u l a r , t h e y l i e a l o n g 9 parts of the Okanagan Valley and Kettle and Granby River v a l l e y s . C o r y e l l Intrusions consist predominantly of medium grained, reddish syenite that grades l o c a l l y into basic or acid phases. Dykes and stocks occur widespread whereas batholiths, having north-south elongation, only occur i n the eastern part of the region along Granby River and Lower Arrow Lake. They are known to be of T e r t i a r y Age and are l i k e l y , i n part at l e a s t , contemporaneous with the Midway Volcanic Group. Late T e r t i a r y plateau basalts o v e r l i e parts of the north-central portion of the area. These lavas are probably c o r r e l a t i v e with those of the Columbia River and I n t e r i o r Plateau regions. Structure A l l formations, except Late T e r t i a r y basalts, have been folded and faulted with most intense deformation i n oldest rocks. The s t r u c t u r a l h i s t o r y of the region has not been worked out i n any d e t a i l . The most prominent tectonic features are strong f a u l t and shear zones that l i e along major north-south trending v a l l e y s . Subsequent movements along these zones have affected a l l rocks except Late T e r t i a r y basalts. Fault and shear zones have controlled l o c a l i z a t i o n of T e r t i a r y basins of sedimen-tation, centers of volcanism, and C o r y e l l batholiths, and probably have controlled l o c a l i z a t i o n of porphyry in t r u s i o n s . Economic Geology 10 Copper, gold and s i l v e r occurring i n replacement and vein deposits have had a long h i s t o r y of in t e r e s t i n the area. Copper i s presently being produced from the Phoenix Mine and s i l -ver and gold are being produced from the Horn S i l v e r Mine. The Highland-Bell Mine, located near the Tuzo creek Molybdenite Prospect (Figure 2), produces Ag, Pb and Zn. Only recently has molybdenum been of in t e r e s t i n the area. Numerous molybdenite occurrences are known but none have had any production. PRELUDE TO PETROLOGY AND STRUCTURE  OF THE PROSPECT Geological Summary Statement The map-area of the Tuzo Creek Molybdenite Prospect l i e s over the southern-most portion of a mass of Nelson i n t r u -sive rocks that are positioned c e n t r a l l y within a younger batho-l i t h of V a l h a l l a i n t r u s i v e rocks. Within the map-area i s a small stock of Val h a l l a quartz monzonite that i s fringed and p a r t i a l l y capped by older Nelson granodiorite. S i l l s , dykes and masses of quartz feldspar porphyry successivley intruded the above rocks at three d i f f e r -ent times. Two phases of hydrothermal a c t i v i t y are recognized. Intermediate to basic dykes cut a l l the above rocks and are themselves o f f s e t by late f a u l t s . Table I i l l u s t r a t e s the geological sequence of events i n d e t a i l . T A B L E I - G E O L O G I C A L SEQUENCE OF EVENTS ( N o t e : A r r o w s a r e p o i n t e d t o w a r d s t h o s e f e a t u r e s t h a t v ; e r e c o n t r o l l e d b y v a r i o u s s t r u c t u r e s ) I N T R U S I O N S S T R U C T U R E IIYDROTHEEKAL OR D E U T E R I C A L T E R A T I O N AND A S S O C I A T E D M I N E R A L I S A T I O N u '"o to • H . -H is -P r - i EH , Q -O iti a, 0 -p L a t e D y k e s E r o s i o n t o p r e s e n t l e v e l P E R I O D - I I I ; F a u l t i n g C o n j u g a t e T c - n s i o n a l F i s s u r e s D e u t e r x c A l t e r a t i o n P o s t - M i n e r a1 P o r p h y r y D y k e s a n d M a s s e s B e u t e r i c A l t e r a t i o n a n d M i n e r a l i s a t i o n . C o n j u g a t e T e n s i o n a ] F i s s u r e £ 3 PH&SE-II? I n t r a - M i n e r a l P o r p h y r y A s s o c i -a t i o n . ( A r g i l l i z a t i o n a n d s i l . L c i f i c a f c i o n ; s p h a l e r i t e , g a l e n a , c h a l c o p y r i t e , p y r i t e - , m o l y b d e n i t e ) P S R I O D - I I ; L o c a l s h e a r i n g , b r e c c i a t i o n a n d fx a c t u r i n g I n t r a - M i n e r a l P o r p h y j S i l l s a n d D y k e s D e u t e r i c A l t e r a t i o n a n d M i n e r a 1 i s a t i o n ( i n c l u d e d w i t h P h a s e - I I ) P r e - M i n e r a l P o r p h y r y , R o o f - s i l l a n d D y k e s »S tr u c t v . r e s e a v i s e d b y s u b s i d e n c e o f t h e s t o c k P E R I O D - I ? I n t e n s e s h e a r i n g , w i d e s p r e a d f r a c t u r i n g and. l o c a l b r e c c i a t i o n P H A S E - I ; M a i n P h a s e o f w a l l r o c k A l t e r c a t i o n a n d M i n e r a l i s a t i o n . ( W i d e s p r e a d a r g i l l i z a -t i o n , a i l i c i f i c a t i o n , K - f e1d s p a111 i s a t i o n ; q u a r t z v e i n i n g ; p y r i t e , h e m a t i t e , m a g n e -t i t e , m o l y b d e n i t e ) S t r u c t u r e s c a u s e d b y s u b s i d e n c e o f t h e s t o c k P o r p h y r i t i c B i o t i t e Q u a r t s M o n s o n i t e S t o c k Dal i t e r i c A11 e r a t i o n ( ? ) P r o . b a b l e r e g i o n a 1 f a u l t i n c r a n d s h e a r i n o B a t h o i i t h i c H o r n b l e n d e G r a n o d i o r i t e D e u t e r i c A l t e r a t i o n ( ? ) 12 Presentation and Data The main body of this report i s divided into three chapters dealing with a) Intrusive Rocks, b) Structure and c) Hydrothermal A l t e r a t i o n and M i n e r a l i z a t i o n . Included are two sets of figures, each comprising of a plan and two sections. One set (Figures 5 and 6) show rock types and f a u l t s while the other (Figures 7 and 8) i l l u s t r a t e s hydrothermal a l t e r a t i o n , mineralization and important s t r u c t u r a l features along with s i m p l i f i e d rock types. Also included i s a control map (Figure ii) showing topography, roads, control points and g r i d l i n e s f o r map-ping diamond d r i l l holes, claims and the outline of the area of molybdenite mineralization. A l l above figures were drawn at a scale of 1 inch equals i+OO feet whereas o r i g i n a l surface mapping was done at a scale of 1 inch equals 200 f e e t . The text i s also i l l u s t r a t e d with appropriate Tables and Plates. A l l known outcrops within the gridded area (Figure li) were mapped. Elsewhere, outcrops were mapped mainly along roads and p a r t i c u l a r l i n e s and traverses. Outcrops are abundant, except i n more heavily vegetated regions, but are commonly small and, i n places, l a r g e l y are made up of rubble. They com-monly r i s e to only a few feet above the s o i l cover; making i t d i f f i c u l t and often impossible to determine contact attitudes. Core from four BQ, Wireline diamond d r i l l holes* Abbreviated to DDH i n remainder of text TABLE II - C l a s s i f i c a t i o n of Thin and Polished Sections Studied Thin sections studied from fresh and altered rock types -ROCK TYPES AND NUMBER OP THIN SECTIONS STUDIED Zone of Hydrothermal A l t e r a t i o n Granodiorite Quartz Monzonite Pre-Min. Porphyry Intra-Min. Porphyry Post-Min. Late Dykes Porphyry  Otc DDH Otc DDH Otc DDH Otc DDH Fresh + Peripheral S h e l l x Central Zone x Totals 3 h 9 5 5 3 5 7 l 9 13 16 2 k k 1 12 Otc DDH Otc DDH 10 lk 10 19 21 21. 21 2k 10 +Some fresh samples taken from unaltered remnants within peripheral s h e l l xDefined i n section "Hydrothermal Alte r a t i o n and Mineralization" -^Samples from regionally altered granodiorite Otc Samples taken from outcrop DDH Samples taken from B.Q. Wireline diamond d r i l l holes Thin and Polished Sections Studied from Mineralized Fractures and Veins Type of Mineralization Number of Thin Sections Number of Polished Sections Hematite and Magnetite 1 8 Hematite-Magnetite-Pyrite-Molybdenite 1 3 Pyrite-Molybdenite 1 l i Molybdenite 7 ij. Gale na-Sphalerite-Chalc opyrite-P y r i t e-Molybde n i te JL Totals 12 23 Ik t o t a l l i n g i i , 8 6 5 feet and from 1 3 Packsack diamond d r i l l holes+ t o t a l l i n g 9 7 6 feet was logged and sampled i n d e t a i l . Wireline d r i l l holes are shown on sections (Figures 6 and 8 ) . Only molybdenite assays equal to or greater than ,0k% are shown along d r i l l holes (Figure 8 ) . Average molybdenite assays from a l l holes are given i n the text. Core diameter and average percent core recovery, respectively are 1 - 5 / 8 " at 97% f o r DDH's and 7 / 8 " at 7 7 $ f o r PSH's. A t o t a l of 1 5 2 t h i n sections were studied from f r e s h rock types and t h e i r altered equivalents and from vein and f r a c -ture f i l l i n g s . Also studied were 2 3 polished sections containing sulphide and/or oxide minerals. Sample locations f o r thin and polished sections are shown on accompaning figures and a c l a s s i -f i c a t i o n of sections i s given i n Table I I . Percentages of minerals present i n rocks have been estimated v i s u a l l y . + Abbreviated to PSH i n remainder of text 15 CHAPTER II INTRUSIVE ROCKS This section deal3 with d i s t r i b u t i o n , f i e l d r e l a t i o n s , primary petrography and mineralogy, structure and genesis of intr u s i v e rocks (Figures 5 and 6). HORNBLENDE GRANODIORITE Fresh and altered equivalents of granodiorite almost completely fringe a younger i n t r u s i v e complex of quartz monzon-i t e and porphyries. Granodiorite also occurs as a central, east-west trending, Irregular mass that caps much of the southern flank of a younger stock of quartz monzonite. This mass i s r e l a -t i v e l y f r e s h along most of i t s southern edge. Granodiorite i s a leucocratic, medium grained, hypidio-morphic rock consisting of pale-grey plagioclase, pale-pink i n t e r s t i t i a l to large p o i k i l i t i c orthoclase, glassy i n t e r s t i t i a l quartz and dark-green hornblende prisms (Plate 5)« Accessory minerals consist of brown sphene, magnetite, apatite and zi r c o n i n order of decreasing abundance. Commonly, the rock i s weakly f o l i a t e d and lineated due to oriented laths of plagioclase and prisms of hornblende. Granodiorite i s s i m i l a r to much of the Nelson Intrusions. Hence, the two are considered equivalent. 16 C o m p o s i t i o n o f th© g r a n o d i o r i t e i s s h o w n i n T a b l e I I I . P l a g i o c l a s e ( A n ^ t o A n 2 - j ) 5 0 - 5 5 $ O r t h o c l a s e 15$ Q u a r t z 2 0 - 2 5 $ H o r n b l e n d e 7-10$ A c c e s s o r i e s ( s p h e n e , m a g n e t i t e , a p a t i t e , z i r c o n ) 1-2 $ T A B L E I I I : E s t i m a t e d Mode o f G r a n o d i o r i t e P e t r o g r a p h y a n d M i n e r a l o g y P l a g i o c l a s e c o m m o n l y f o r m s e u h e d r a l l a t h s 2 - 5 mm l o n g . I t i s t w i n n e d a c c o r d i n g t o a l b i t e , p e r i c l i n e a n d C a r l s b a d t w i n l a w s a n d s h o w s n o m a l o s c i l l a t o r y z o n i n g f r o m A n ^ t o A n £ ^ . Z o n i n g i n c r y s t a l s i s m o r e p r o n o u n c e d i n t h e o u t e r m o s t c o m p o s i -t i o n z o n e s w h i c h c o m m o n l y f o r m a c l e a r , t h i n e n v e l o p e a r o u n d m o r e c a l c i c p l a g i o c l a s e . R i m s o f c r y s t a l s c o m m o n l y a r e r e p l a c e d l o c a l l y b y m e r m y k e t i c q u a r t z a n d p a r t l y i n t e r g r o w n w i t h f i n e g r a i n e d q u a r t z . O r t h o c l a s e h a s a n o p t i c a n g l e o f a p p r o x i m a t e l y 70° . I t f o r m s c l e a r , t w i n n e d c r y s t a l s g r o w n i n t e r s t i t i a l l y t o s l i g h t l y p o i k i l i t i c a l l y w i t h r e s p e c t t o p l a g i o c l a s e a n d h o r n -b l e n d e a n d i n p l a c e s w i t h r e s p e c t t o m e d i u m g r a i n e d q u a r t z . L o c a l l y , o r t h o c l a s e o c c u r s a s l a r g e p o i k i l i t i c s u b h e d r a u p t o 3 cm l o n g . O r t h o c l a s e c o m m o n l y c o n t a i n s f i n e - g r a i n e d , a n h e d r a l t o e u h e d r a l g r a i n s o f q u a r t z , p a r t i c u l a r l y t o w a r d s e d g e s o f c r y s t a l s , a n d a l s o c o m m o n l y c o n t a i n s m i n o r d i s c o n t i n u o u s f i l m s o f q u a r t z a l o n g 001 c l e a v a g e s . A l s o , o r t h o c l a s e o c c a s i o n a l l y c o n t a i n s m i n o r a m o u n t s o f 0 1 0 - o r i e n t e d , e x s o l v e d a l b i t e . C l e a r m e d i u m - t o f i n e - g r a i n e d , a n h e d r a l q u a r t z o c c u r s i n t e r s t i t i a l t o 1 7 hornblende and plagioclase and l o c a l l y to orthoclase. Commonly, coarser-grained quartz and some orthoclase show undulatory extinc-t i o n . Hornblende occurs as subhedral to euhedral prisms generally 3 to 6 mm long though occasionally up to 1 cm. long. It i s l i g h t -to dark-green pleochroic and sometimes twinned on 1 0 0 . Pine-grained, anhedral to euhedral accessory minerals occur disseminated; often as small composite aggregates. They occur p a r t i c u l a r l y within and adjacent to hornblende prisms. Sphene i s occasionally medium grained and brown i n hand specimens. Deuteric (?) A l t e r a t i o n "Fresh" granodiorite has been affected by s l i g h t deu-t e r i c and/or hydrothermal a l t e r a t i o n . Hornblende i s most attacked. It i s p a r t i a l l y to completely altered to pseudomor-phous, green pleochroic c h l o r i t e along cleavages with associated disseminated epidote and minor quartz and c a l c i t e . Some associa-ted magnetite i s l i k e l y secondary. Plagioclase has been altered s l i g h t l y ; p a r t i c u l a r l y along cleavages, within cores and c e r t a i n of the more:calcic zones, to hydromica (?), c a l c i t e and epidote and l o c a l l y to c h l o r i t e i n c r y s t a l s adjacent to altered horn-blende. Orthoclase i s replaced l o c a l l y by euhedral, fine grained epidote with associated quartz adjacent to altered hornblende. Elsewhere i t i s unaltered or cut by t h i n c a l c i t e v e i n l e t s . Sphene shows s l i g h t a l t e r a t i o n along fractures and c r y s t a l edges to leucoxene. "Fresh" granodiorite commonly i s cut by sparse epidote veinlets up to 1 / 8 inch wide. 1 8 PORPHYRITIC BIOTITE QUARTZ MONZONITE Unaltered quartz monzonite i s a d i s t i n c t l y p o r p h y r i t i c , l i g h t - c o l o r e d massive rock containing large phenocrysts of dark-pink sanidine i n a fine-and medium-grained matrix. The matrix consists of crowded phenocrysts of li g h t - c o l o r e d plagioclase, quartz and b i o t i t e set i n a f i n e grained groundmass of dark-pink sanidine, quartz, b i o t i t e and accessory minerals (Plate 6). Quartz monzonite i s t e x t u r a l l y and mineralogically s i m i l a r to and, therefore, correlated with V a l h a l l a Intrusions (See "Regional Geology"). Sanidine Phenocrysts 10-1$% Groundmass 20% Plagioclase (An, 0 to An-^) l\.0% Quartz Phenocrysts 1 0 $ Groundmass 1 5 $ B i o t i t e 3 $ Accessories (Magnetite, apatite, zircon and sphene) ^ TABLE IV: Estimated Mode of Quartz Monzonite Structure Quartz monzonite occurs as a rounded, p a r t i a l l y un-roofed stock-like body with a triangular plan (sides approxi-mately lh miles long). The top of the body i s c l o s e l y c o i n c i -dent with the top of the ridge as described under "Physiography". 1 9 C o n t a c t s b e t w e e n g r a n o d i o r i t e a n d q u a r t z m o n z o n i t e w e r e n o t o b s e r v e d ; l a r g e l y d u e t o t h e p r e s e n c e o f a y o u n g e r i n t r u s i v e p o r p h y r y s i l l t h a t i n m o s t p l a c e s s e p a r a t e s t h e two p h a s e s o n t h e e a s t e r n f l a n k s o f t h e q u a r t z m o n z o n i t e b o d y , a n d p a r t l y d u e t o s h o r t a g e o f o u t c r o p a n d / o r p r e v a l e n c e o f s h e a r i n g w h e r e p o r p h y r y was n o t e m p l a c e d . T h e p o r p h y r y s i l l a l s o s e p a r a t e s a r e a s o f e x p o s e d q u a r t z m o n z o n i t e a t t h e p r e s e n t l e v e l o f e r o -s i o n . T h e q u a r t z m o n z o n i t e b o d y i s b e l i e v e d a n i n t r u s i v e s t o c k f o r t h e f o l l o w i n g r e a s o n s : 1 ) T h e q u a r t z m o n z o n i t e b o d y h a s a a t o c k - l i k e 3hape. 2) T h e r e i s a d i s t i n c t d i f f e r e n c e i n l i t h o l o g y b e t w e e n g r a n o d i o r i t e a n d q u a r t z m o n z o n i t e a n d a n a b s e n c e o f l a t e r a l t e x t u r a l o r raineralogical c h a n g e s i n e i t h e r r o c k t y p e t o w a r d s m u t u a l c o n t a c t s . 3) V a l h a l l a I n t r u s i o n s , s i m i l a r t o q u a r t z m o n z o n i t e , i n t r u d e o r a r e o t h e r w i s e g r a d a t i o n a l i n t o N e l s o n I n t r u s i o n s , s i m i l a r t o g r a n o d i o r i t e ( s e e " R e g i o n a l G e o l o g y " ) . P h e n o c r y s t s S a n i d i n e p h e n o c r y s t s v a r y i n s i z e f r o m a f r a c t i o n o f a n i n c h t o t h r e e i n c h e s l o n g b u t a r e g e n e r a l l y 1 t o l h i n c h e s i n l e n g t h . T h e y a r e c o m m o n l y e u h e d r a l , i n p l a c e s t w i n n e d a c c o r d -i n g t o C a r l s b a d t w i n l a w a n d c o m m o n l y c o n t a i n m i n o r i n c l u s i o n s o f p l a g i o c l a s e , q u a r t z a n d b i o t i t e p a r t i c u l a r l y i n t h e o u t e r p o r t i o n s o f c r y s t a l s . I n t h i n s e c t i o n , i n t e r i o r s o f l a r g e s a n i -d i n e c r y s t a l s a r e r e l a t i v e l y c l e a r w h e r e a s o u t e r f r i n g e s c o m m o n l y a r e " c l o u d e d " t o a " d i r t y " d a r k g r e y . O u t e r m o s t p o r t i o n s o f s a n i d i n e p h e n o c r y s t s o f t e n show a s i n g l e i n t e r g r o w n seam o f 20 fine-grained, anhedral quartz grains. Edges of phenocrysts commonly are intergrown s l i g h t l y with fine-grained quartz of the groundmass. Fringes of cry s t a l s do not vary o p t i c a l l y from t h e i r i n t e r i o r s except that f a i n t o s c i l l a t o r y zoning i s appar-ent. Sanidine commonly contains up to 15 percent evenly d i s t r i -buted m i c r o c r y s t a l l i n e , exsolved lamellae of a l b i t e p a r a l l e l to 0 1 0 . In sanidine, the optic a x i a l plane i s oriented p a r a l l e l to 010 and the optic angle varies from 35 ° to 5 5 ° • Plagioclase phenocrysts occur as evenly d i s t r i b u t e d , subhedral to euhedral, medium-grained (range 0 . 5 - 8 ram; average 3 mm long) laths and f a i r l y often as small intergrown clusters of l a t h s . Phenocrysts are normally zoned, with s l i g h t o s c i l l a -tions, from An^Q to A n ^ . Often i n d i v i d u a l laths do not show the complete range of composition. Twinning according to the a l b i t e , p e r i c l i n e and Carlsbad twin laws i s common. In thi n section, plagioclase phenocrysts are colored i r r e g u l a r l y , completely or only i n outermost portions to a " d i r t y " yellowish-brown; probably due to oxidation of contained i r o n . Edges of cr y s t a l s are often somewhat i r r e g u l a r since they are intergrown with, and appear b i t t e n - i n t o , by fine-grained quartz. Medium-to coarse-grained alpha quartz (range 1 mm -1 cm; average ij. ram) occurs as evenly d i s t r i b u t e d , rounded to somewhat i r r e g u l a r phenocrysts of short, prismatic hexagonal habit. Occasionally present are aggregates of intergrown c y r s t -als and aggregate chains of o p t i c a l l y continuous euhedral c r y s t a l s . Quartz phenocrysts commonly are embayed by fingers of f i n e -grained sanidine with minor quartz, and have rounded to sutured 2 1 borders. Quartz with sutured borders i s intergrown with f i n e -grained sanidine of the groundmass. Quartz phenocrysts generally show f a i n t polysynthetic twinning. They commonly show weak to intense undulatory e x t i n c t i o n and some phenocrysts are shattered but undistorted. Pine-to medium-grained (range . 0 5 - 3 mm; average 1 -lh mm) plates of greenish black b i o t i t e occur evenly d i s t r i b u t e d i n quartz monzonite. B i o t i t e i s pale-tan to greenish-brown pleochroic and commonly has ragged ends. Groundmass Occurring i n t e r s t i t i a l l y to and, i n part, intergrown with edges of phenocrystsof sanidine, plagioclase, and quartz i s a f i n e grained (range . 0 3 to 2 . 5 mm) groundmass consisting of highly "clouded" sanidine, quartz and minor b i o t i t e , plagio-clase and accessory minerals. The average grain size of the groundmass i s v a r i a b l e . In general, i t averages 0 . 7 7 mm i n outcrops and i n d r i l l holes to a depth of a few hundred feet. At greater depths, average grain size i s approximately 0 . 1 2 mm. The finer-grained groundmass i s a granophyric intergrowth of quartz and sanidine. The coarser-grained groundmass i s more granular with quartz and sanidine showing mutual grain r e l a -tionships. Sanidine i n groundmasses i s o p t i c a l l y i d e n t i c a l to sanidine phenocrysts though i s more highly "clouded". Fine-grained accessory minerals are euhedral to an-hedral. They include apatite, magnetite, sphene and zircon i n decreasing order of abundance. 22 Li t h o l o g i c Variations Apart from s l i g h t v a r i a t i o n i n average grain size of groundmass with depth, the only other l i t h o l o g i c v a r i a -t i o n observed occurs near the center of the eastern-most exposure where phenocrysts are widely dispersed and plagio-clase occurs more abundantly i n the fine-grained groundmass and i s highly intergrown around edges with quartz. One exposure, within the western part of the central granodiorite mass, shows a dyke with s i m i l a r texture cutting granodiorite. Deuteric (?) A l t e r a t i o n Plagioclase and b i o t i t e i n "fresh" quartz monzonite have been very s l i g h t l y altered d e u t e r i c a l l y (?). Plagioclase contains minor disseminated fine-grained hydromica and clear to " d i r t y " epidote. B i o t i t e has been altered to varying degrees, though i s generally only peripherally altered to green pleochroic c h l o r i t e with associated opaque leucoxene (?) along cleavages and l o c a l l y with associated magnetite and f l u o r i t e . Accessory sphene has been altered to an opaque, white r e f l e c t i v e mineral (probably leucoxene). 2 3 QUARTZ-ALBITE-SANIDINE PORPHYRIES Introduction Dykes, s i l l s and dyke-like masses of l i g h t - c o l o r e d quartz-albite-sanidine porphyry have successively intruded granodiorite and the quartz monzonite stock. Intermittent to in t r u s i o n of porphyry were periods of shearing and f r a c t u r i n g , hydrothermal a l t e r a t i o n and mineralization. The primary texture and mineralogy of a l l porphyries i s p r a c t i c a l l y i d e n t i c a l although three main in t r u s i v e phases can be distinguished i n the f i e l d and show some differences i n thin section. These porphyry phases include pre -, i n t r a -and post-mineral porphyry. F i e l d c r i t e r i a f o r separation into phases i s l i s t e d below: 1 ) Presence or absence of fr a c t u r i n g , hydrothermal a l t e r a t i o n and mineralization within the a l t e r -ation halo (Figure 7 and 8 ) ; 2 ) Intrusive relationships among the three porphyry phases; 3 ) Pre-mineral porphyry has inherent s t r u c t u r a l c h a r a c t e r i s t i c s ; LL) Presence or absence of well defined c h i l l e d con-tacts; 5 ) Degree of hydrothermal a l t e r a t i o n . Use of above c r i t e r i a ; i s believed to have resulted i n a high degree of certainty regarding the v a l i d i t y of the three 2k separate phases shown on accompanying maps. D i s t i n c t i o n between pre- and intra-mineral porphyry i s d i f f i c u l t on the surface towards the center of the a l t e r a t i o n halo, where a l t e r -ation has been most intense, and some porphyry may be mapped i n c o r r e c t l y i n t h i s region. Also, near the outer edge and outside the a l t e r a t i o n halo, i n t r a - and post-mineral porphyries are d i f f i c u l t to d i s t i n g u i s h . However, because post-mineral dykes widen outwards from within the a l t e r a t i o n halo into large dyke-like masses, i t i s believed that most porphyry bodies outside the a l t e r a t i o n halo are post-mineral. Since a l l porphyry phases have primary petrographic and mineralographic s i m i l a r i t i e s they are described together i n the following section. D i s t r i b u t i o n , mode of emplacement and p a r t i c u l a r c h a r a c t e r i s t i c s of each of the porphyry phases i s discussed i n other following sections. General Description Colors of phenocrysts and groundmasses mentioned below, r e f e r to a l l post-mineral porphyry but only to fresher equivalents of altered pre- and intra-mineral porphyry. Some of the petrographic variations of phenocrysts and groundmasses i n d i f f e r e n t porphyry phases are described i n t h i s section. Porphyries consist of phenocrysts of large pink sanidine, varicolored a l b i t e , clear to smoky quartz and chlor-i t i z e d b i o t i t e set i n an aphanitic to fine-grained, pale 25 greenish-grey groundmass (Plates 7 to 1 0 ) . The average mode of porphyries i s shown i n Table V. Phenocrysts Large Sanidine ( > 1 cm) 10-15$ Small Sanidine ( < 1 cm) 5-10$ Albite 2 0 - 2 5 $ Quartz 10$ C h l o r i t i z e d b i o t i t e , 2-3 $ Accessories (apatite, magnetite, p y r i t e , sphene, zircon) 1 $ Groundmass i i 0 - 5 0 $ TABLE V: Average Estimated Mode of Quartz-Albite-Sanidine Porphyries Phenocrysts Sanidine phenocrysts are commonly euhedral and range i n length from . 0 5 mm to three inches. Large phenocrysts, greater than 1 cm long, average about 1 to lh inches i n length. They are commonly l i g h t - t o medium-pink, occasionally with white to cream colored i n t e r i o r s (Plate 1 0 ) . Small phenocrysts, less than 1 cm i n length, are commonly li g h t - p i n k to cream colored and often blend i n with the groundmass or are i n d i s t i n -guishable from a l b i t e phenocrysts. Sanidine most commonly occurs as simple cr y s t a l s elongated along the a-axis with 010 and 001 faces terminated by 110 and 201 faces. Some c r y s t a l s show twinning according to the Carlsbad twin law and are elon-gated along the c-axis. Large aanidines commonly contain minor inclusions of a l b i t e , quartz and altered to fresh b i o t i t e . Inclusions are more abundant towards edges of crys-t a l s where a l b i t e laths are oriented p a r a l l e l to growth zones of sanidine c r y s t a l s . In t h i n section, a l l sanidines are 26 r e l a t i v e l y c l e a r t h o u g h t h e y c o n t a i n d i s s e m i n a t e d s p e c k s o f o p a q u e m a t e r i a l w h i c h i s m o r e a b u n d a n t i n f i n e - g r a i n e d s a n i -d i n e a n d i n t h e f r i n g e o f l a r g e c r y s t a l s . T h i s o p a q u e m a t e r i a l a p p e a r s t h e same a s t h a t c l o u d i n g s a n i d i n e i n q u a r t z m o n z o n i t e a n d p r o b a b l y c o n s i s t s o f i r o n o x i d e s . P i n e g r a i n e d s a n i d i n e c o m m o n l y show p a r t i a l t o l o c a l l y c o m p l e t e o v e r g r o w t h s o n a l b i t e p h e n o c r y s t s . P a r t i a l o v e r g r o w t h s o c c u r o n s i d e s , e n d s a n d / o r c o r n e r s o f a l b i t e l a t h s . T h e o p t i c p l a n e i n s a n i d i n e i s o r i e n t e d p a r a l l e l t o 010 a n d t h e o p t i c a n g l e v a r i e s f r o m 30° t o 60 . L a r g e p h e n o c r y s t s g e n e r a l l y show m i n o r e x s o l v e d m i c r o -c r y s t a l l i n e a l b i t e l a m e l l a e o r i e n t e d a l o n g 010 a n d h a v e c o n c e n -t r i c o s c i l l a t o r y z o n i n g . I n d i v i d u a l g r o w t h z o n e s a l w a y s show r o u n d e d c o r n e r s a n d l o c a l l y show seams o f e x s o l v e d a l b i t e a n d d i s c o n t i n u o u s t r a n s v e r s e f r a c t u r e s . A l b i t e p h e n o c r y s t s a r e s u b h e d r a l t o e u h e d r a l a n d v a r y i n s i z e f r o m . 0 5 t o 8 mm ( a v e r a g e 1-Lj. mm). T h e y a r e v a r -i o u s l y c o l o r e d f r o m p a l e g r e e n , l i g h t g r e y , c r e a m a n d l o c a l l y w h i t e t o l i g h t t o m e d i u m r e d d i s h - p i n k . I n t h i n s e c t i o n , a l b i t e i s n e a r l y a l w a y s " c l o u d e d " l i g h t t o d a r k y e l l o w i s h - b r o w n , p r o b a b l y d u e t o o x i d a t i o n o f c o n t a i n e d i r o n . I t i s u n z o n e d a n d shows c o m p l e x a l b i t e , p e r i c l i n e a n d c a r l s b a d t w i n s . C o m p o s i -t i o n o f a l b i t e i s a l w a y s i n t h e r a n g e A n D t o A n l Q b u t i s p r e d o m i n a n t l y l e s s t h a n A n ^ . C o m p o s i t i o n o f a l b i t e i n v a r i o u s p o r p h y r y p h a s e s i s s h o w n i n T a b l e V I . 27 Pre-mineral Porphyry- An 2 - Ang (Average of An^) Intra-mineral Porphyry An - Anu Post-mineral Porphyry An Q - An£ TABLE VI: Composition of Albit e i n Porphyries A l l porphyries contain some a l b i t e showing stress twinning and bending but i n pre-mineral porphyry, deformed a l b i t e i s much more common. Quartz phenocrysts are glassy to smoky and are com-monly euhedral, though they are generally rounded and embayed. They vary i n size from .05 mm to 1% cm (average 2-5 mm) and have a short, hexagonal dipyramidal habit t y p i c a l of primary beta-quartz though they are now alpha-quartz. In t h i n section, quartz i s cle a r , shows f i n g e r - l i k e embayments of the ground-mass and often shows f a i n t polysynthetic twinning. Inclusions of a l b i t e and altered b i o t i t e are ra r e l y found i n quartz. Quartz i s undeformed or shows weak undulatory e x t i n c t i o n i n i n t r a - and post-mineral porphyry. In pre-mineral porphyry, quartz i s commonly more intensely deformed and includes quartz showing moderate to intense undulatory extinc t i o n to cry s t a l s that are broken and undeformed or strung-out and often recrys-t a l l i z e d to f i n e aggregates. Strung out aggregate c r y s t a l s of quartz are commonly recognized i n hand specimens of pre-mineral porphyry. Green c h l o r i t i z e d b i o t i t e occurs as phenocrysts varying i n size from .05 to 3 mm (average .5 - 1 .5 mm). Remnants of l i g h t - t o dark-greenish brown pleochroic b i o t i t e are rare. A l t e r a t i o n of b i o t i t e i s discussed In l a t e r sections. Accessory minerals are fine-grained, euhedral to subhedral and consist of apatite, magnetite, p y r i t e , sphene and zircon i n decreasing order of abundance. Subhedral to euhedral, medium-to coarse-grained, cream colored phenocrysts consisting of an unknown feldspar with intergrown graphic quartz are present l o c a l l y . The feldspar shows a l b i t e - and p e r i c l i n e - l i k e twins i n parts of c r y s t a l s that fade out into untwinned parts having apparent lower birefringence. The intergrowth probably represents a binary eutectic of an unmixed anorthoclase and quartz. Also present l o c a l l y are small phenocrysts of a feldspar (possibly anorthoclase) with s p i n d l e - l i k e p a r a l l e l twins. Groundmass The groundmass i n a l l porphyries i s commonly aphan-i t i c and colored a pale greenish-grey. In t h i n section, i t i s commonly s l i g h t l y " d i r t y " a n d microcrystalline-granular with an average grain size of . 0 1 to . 0 2 ram. Dark c h i l l e d contacts occur only i n i n t r a - and post-mineral porphyry. They range from %, foot to 1 5 feet i n width. Narrow dykes and s i l l s are often e n t i r e l y c h i l l e d . Widest c h i l l e d contacts occur i n post-mineral porphyry. Such contacts contain fewer phenocrysts i n a dark green, aphanitic ground-mass that grades into normal appearing porphyry. Close to contacts phenocrysts are often s l i g h t l y broken and i n t h i n sections, porphyries show a"dirty"brown, microcrystalline 29 g r o u n d m a s s w i t h o r w i t h o u t f l o w l i n e s a r o u n d b r o k e n p h e n o -c r y s t s . T o w a r d s t h e c e n t e r o f w i d e r i n t r a - a n d p o s t - m i n e r a l d y k e s a n d s i l l s t h e g r o u n d m a s s c o m m o n l y b e c o m e s s l i g h t l y c o a r s e r - g r a i n e d a n d p h e n o c r y s t s b e c o m e m o r e a b u n d a n t . C o a r s e r g r o u n d m a s s e s a r e u n e v e n g r a i n e d b u t g r a i n s a v e r a g e a p p r o x i -m a t e l y .03 t o .07 mm i n s i z e . T h e y show e u t e c t i c - l i k e i n t e r -g r o w t h s b e t w e e n c l e a r g r a p h i c t o s k e l e t a l a n d s p h e r u l i t i c c r y s t a l s o f q u a r t z u p t o .5 mm i n s i z e a n d f i n e r - g r a i n e d , " d i r t y " a l k a l i f e l d s p a r . P a r t i a l s p h e r u l i t e s o f q u a r t z h a v e c o m m o n l y g r o w n a r o u n d e d g e s o f f e l d s p a r p h e n o c r y s t s . A l s o , q u a r t z c o m m o n l y s h o w s w i d e d a r k h a l o s o f o p t i c a l l y c o n t i n u o u s q u a r t z a n d i n t e r g r o w n " d i r t y " a l k a l i f e l d s p a r . L o c a l l y , i n p r e - m i n e r a l p o r p h y r y t h e g r o u n d m a s s i s s l i g h t l y c o a r s e r - g r a i n e d w i t h g r a i n s a v e r a g i n g .03 t o .05 mm i n s i z e . S u c h g r o u n d m a s s e s h a v e a g r a n u l a r t e x t u r e a n d c o n s i s t o f c l e a r q u a r t z a n d " d i r t y " a l k a l i f e l d s p a r . R e g i o n a l C o r r e l a t i o n T h e a b o v e p o r p h y r i e s a r e v e r y s i m i l a r t o t h e S h i n g l e C r e e k P o r p h y r y ( B o s t o c k ) n e a r P e n t i c t o n . S i m i l a r i t i e s o f d e t a i l e d t e x t u r e s a n d o p t i c a l p r o p e r t i e s o f s a n i d i n e p h e n o -c r y s t s a r e s t r i k i n g . T h e s e p o r p h y r y i n t r u s i o n s a r e u n d o u b t -e d l y c o r r e l a t i v e . I t i s s u g g e s t e d t h a t p o r p h y r y o c c u r r i n g a t t h e T u z o C r e e k M o l y b d e n i t e P r o s p e c t b e r e f e r r e d t o a s t h e T u z o C r e e k P o r p h y r y . 3 0 Pre-Mineral R o o f - S i l l and Dykes Prom d i s t r i b u t i o n , contact relations and inherent s t r u c t u r a l features, the pre-mineral porphyry i s thought to be a gently easterly dipping, inverted saucer-shaped mass up to 3 5 0 feet thick that was conformably and f o r c e f u l l y i n t r u -ded between granodiorite and the top and eastern flanks of the quartz monzonite stock. Pre-mineral porphyry can be referred to as a r o o f - s i l l . Dykes of pre-mineral porphyry, cut t i n g quartz monzonite i n DDH 1 , are l i k e l y feeder-dykes to the roof-s i l l from a buried porphyry stock. Distinguishing Features Pre-mineral porphyry was recognized early during mapping because i t i s fractured, altered and mineralized i n degrees comparable to that i n coarser c r y s t a l l i n e rocks and predominatly occurred as i r r e g u l a r masses. Pre-mineral porphyry i s commonly more intensely altered than intra-mineral porphyry. However, other features, l i s t e d below, d i s t i n g u i s h i t from intra-mineral porphyry within the a l t e r a t i o n halo and from other porphyries outside the a l t e r a t i o n halo. 1 ) Commonly deformed and strung-out phenocrysts of quartz (Plate 7 ) j 2) Some large sanidine phenocrysts are broken and somewhat strung out; 3 ) L o c a l l y f o l i a t e d altered b i o t i t e phenocrysts 3 1 best shown where porphyry i s freshest; l o c a l l y more intensely altered porphyry shows a crude f o l i a t i o n due to p a r a l l e l strung-out phenocrysts and/or some i n d i c a t i o n of f o l i a t i o n i n the groundmass; i i ) Generally, the groundmass appears fine-grained due to an abundance of fine grained phenocrysts. Pre-mineral porphyry also shows differences i n t h i n sections from other porphyries. These include the common presence of stress twinning and bending of a l b i t e phenocrysts, a s l i g h t l y more c a l c i c composition of a l b i t e (Table VI) and l o c a l l y para-l l e l o r i e n t a t i o n of a l b i t e l a t h s . D i s t r i b u t i o n Pre-mineral porphyry underlies areas, along the top and on the northeastern slope of the ridge (see "Physiography"). Outer parts of the porphyry mass occur as elongate lobes con-cordant with and separating the quartz monzonite stock and southeastern capping and northeastern fringe of granodiorite. The west-central portion of the porphyry mass separates areas of exposed quartz monzonite. In DDH's 2 , 3 and l\. pre-mineral porphyry was found i n thicknesses of 7 5 to 3 ^ 0 feet separat-ing the granodiorite capping from underlying quartz monzonite. Packsack holes c o l l a r e d i n quartz monzonite near pre-mineral porphyry ( i e : PSH's 9 , 1 0 and 1 1 ) did not in t e r s e c t porphry i n holes bottoming at 3 7 to 1 5 6 f e e t . An i n c l i n e d d r i l l hole ( i e : PSH 1 2 ) , located at the top of the ridge and c o l l a r e d i n granodiorite, intersected pre-mineral porphyry and showed that the adjacent lobe of porphyry dipped beneath granodiorite at an angle of approximately ILO and has an approximate true thickness of 150 feet. In DDH 1 , feeder-dykes of porphyry from 25 to 110 feet wide were found cutting the quartz monzonite stock. These dykes are probably apophyses from a mass or stock of porphyry at depth. Also, a few small dyke-like bodies of probable pre-mineral porphyry occur within the granodiorite capping and i n one place, on the lower road east of Pault-A, a dyke-like apophysis of the large porphyry mass, described above, has intruded quartz monzonite. Contact Relationships Contacts with coarser c r y s t a l l i n e rocks are not defined c l e a r l y because of diffuse textures due to hydro-thermal a l t e r a t i o n . Also, lack of outcrop and shearing i n contact regions has obscured contacts. However, where contacts are f a i r l y well defined, e s p e c i a l l y i n d r i l l holes, they com-monly show f a i r l y sharp breaks i n l i t h o l o g y between porphyry and granodiorite or quartz monzonite. Near the top of DDH 3, porphyry shows a sharp, narrow c h i l l e d contact against granodiorite and, at a depth of 381^ feet i n DDH 2, porphyry has a sharp i n t r u s i v e contact with quartz monzonite and i s c h i l l e d f o r 10 feet from the contact. In DDH 3 at a depth of feet, a sharp contact between porphyry and quartz monzon-i t e , examined In t h i n section, showed porphyry to consist of an i n t r u s i v e breccia adjacent to a sharp contact with quartz monzonite. Another t h i n section of porphyry from the sur-face, near DDH [L, showed small inclusions of quartz monzonite. Porphyry commonly contains some inclusions that generally can be i d e n t i f i e d near contacts with granodiorite and quartz monzonite. Some contacts between porphyry and quartz monzonite appear gradational. They occur along the top of the ridge, i n DDH Lj. and l o c a l l y i n DDH 1. They show increasing amounts of plagioclase phenocrysts i n porphyry towards contacts with the groundmass remaining l i g h t - c o l o r e d microcrystalline-granU' l a r . Sharp contacts with quartz monzonite generally are not found i n these cases but porphyry i s probably i n t r u s i v e since l o c a l l y i t also contains inclusions of quartz monzonite. Intra-Mineral S i l l s and Dykes Intra-mineral porphyry occurs as fractured, altered and mineralized s i l l s and dykes intruding a l l of the above rock types. They p a r t i c u l a r l y intrude the granodiorite cap-ping and underlying pre-mineral porphyry r o o f - s i l l and quartz monzonite stock. They commonly intrude more intensely, and often d i f f e r e n t l y , altered rocks and cut o f f some mineralized fr a c t u r e s . Where intra-mineral porphyry does not intrude pre-mineral porphyry i t can be distinguished by the following features: 1) Lack of inherent s t r u c t u r a l features ( i e : deformed quartz and f o l i a t i o n ) c h a r a c t e r i s t i c of pre-mineral porphyry; 3k 2) Presence of c h i l l e d contacts up to 5 feet wide (only r a r e l y present i n pre-mineral porphyry); 3) Presence of lesser degrees of a l t e r a t i o n than i n pre-mineral porphyry; II) Crosscutting relationships with some mineralized fractures and veins; 5) Crosscutting relationships with, and presence of inclusions o f , d i f f e r e n t l y altered and mineralized rocks. Locally observed, both on surface and i n d r i l l holes, are c h i l l e d contacts between si m i l a r intra-mineral porphyry intrusions. The e a r l i e r i n t r u s i o n generally shows s l i g h t l y more intense a l t e r a t i o n . Structure Intrusions of pre-mineral porphyry to the southwest of c o l l a r s of DDH's 2 , 3 and i|. occur as four i r r e g u l a r masses that contain large included blocks of granodiorite. The northwestern-and southwestern-most bodies are gently dip-ping as determined, respectively, from diamond d r i l l hole intersections and outcrop, and appear to be composite s i l l -l i k e sheets intruded near to and along the contact between the pre-mineral porphyry r o o f - s i l l and granodiorite. These s i l l s range from ILO to 100 feet thick. Two larger exposed masses, occurring between the above s i l l s , are elongated northeasterly and commonly have off-shooting dykes, p a r t i c u -l a r l y at t h e i r ends. Attitudes of off-shooting dykes are variable and i n a general manner radiate from the central masses. These central masses are probably s i l l - l i k e i n nature. Also, at the top of the ridge i s a small i n t r u s i o n occurring approximately concordant with the southeasterly-dipping contact between pre-mineral porphyry and granodiorite. Apart from the thick intra-mineral porphyry s i l l s intersected near the tops of DDH 2 and 3 , two other zones, consisting of several narrow dykes, were intersected below depths of 650 feet within the quartz monzonite stock i n each of DDH's 3 &nd LL. A few other narrow dykes intrude quartz monzonite and pre-mineral porphyry i n the upper portion of DDH LL. Dykes commonly range from a few feet to 30 feet i n width. Core attitudes of a l l c h i l l e d intra-mineral porphyry contacts ( i e ; 28 measurements) i n v e r t i c a l d r i l l holes most frequently range from L|.50to 90° to the core axis. Most porphyries are, therefore, moderately to gently dipping and for this reason the two dyke zones, mentioned above, are probably connected between DDH's 3 and L|.. Deuteric A l t e r a t i o n and Mineralization Intra-mineral porphyry bodies are strongly altered and sparsely mineralized d e u t e r i c a l l y . These features are discussed under "Phase-II: Intra-mineral Porphyry Association" Post-Mineral Dykes and Masses Post-mineral porphyry occurs as abundant dykes and dyke-like masses throughout the central-southwestern to north-eastern portions of the region. It i s int r u s i v e i n t o a l l 36 above rock types. C o n t a c t s are sharp and show up to ten feet of c h i l l i n g i n the porphyry groundmass. Post-mineral porphyry always appears nearly fresh or s l i g h t l y altered d e u t e r i c a l l y . Outcrops are elongated p a r a l l e l to the s t r i k e of dykes, show jo i n t planes, weather to a grey color and show d i f f e r e n t i a l erosion with respect to adjacent outcrops of rusted and broken older i n t r u s i v e rocks. Structure A series of post-mineral porphyry dykes and small dyke-like masses l i e i n a northeasterly trending zone that approximately commences at, and widens to the northeast from, the top of the ridge. In th i s zone, porphyry commonly occurs as a series of connected en.echelon pinching dykes. The most prominent series of dykes trend north-northeasterly to north-easterly and dip moderately to steeply to the northwest. A leas prominent series of dykes trend northerly to north-northwesterly and dip moderately to steeply to the west. In the southern, f a r eastern and f a r northern por-tions of the map-area are large massive bodies of porphyry from which dykes project inwards towards the center of the area. The main massive body of porphyry to the south occurs as an east-west elongated, lense-like body that i s s l i g h t l y concave to the north. Attitudes of dykes emanating from these large masses conform to those f o r dykes within the central portion of the region. 37 A l l dykes and masses are coarsely jointed and weakly fractured. Dykes show transverse and conformable, longitud-i n a l j o i n t sets. In DDH's, dykes are sheared l o c a l l y i n zones up to one foot wide, e s p e c i a l l y near or at contacts. L i t h o l o g i c Variations The predominant phase of grey to pink post-mineral porphyry i s named on the basis of color of a l b i t e phenocrysts. Various colors of phenocrysts can be found i n the same dyke. Gradations across dykes and masses of porphyry from predomin-antly pink to grey and pale-green a l b i t e are common. Prom t h i n sections, pink a l b i t e s are, as a rule, less altered d e u t e r i c a l l y than are l i g h t e r - c o l o r e d a l b i t e s . Two minor variations of post-mineral porphyry are recognized (Figure 6). They consist of an early fine-grained pink phase and a l a t e (?), dark-pink phase (Plate 9). The early phase occurs as dykes towards the bottom of DDH's 2 and 3 and has been intruded by dykes of grey to pink porphyry. It shows more dispersed phenocrysts of feldspar and quartz i n a pinkish-red, fine-grained granular goundmass. The dark-pink phase i s very s i m i l a r to the predominant phase of porphyry, but i t s a l b i t e phenocrysts are a very dark pinkish-red and are very fresh i n t h i n section. Occurring l o c a l l y , within the eastern portion of the large body of porphyry to the south, are small areas showing broken c r y s t a l s of feldspars and quartz i n a l i g h t green, aphanitic groundmass. Similar rocks near to granodiorite 38 contain abundant inclusions of granodiorite. Thin sections showed broken phenocryststo be the same as phenocrysts i n porphyry. The groundmass i s brown colored and microcrystal-l i n e , s imilar to that i n c h i l l e d contacts of porphyry dykes. These areas are l i k e l y s i t e s of explosive sub-volcanic vents developed during emplacement of porphyry. They are referred to as "Intrusive Cry s t a l Breccia" on Figure %. Deuteric A l t e r a t i o n and Mineralization A l l post-mineral porphyry intrusions have been more or less uniformly d e u t e r i c a l l y altered and mineralized. Joint planes and fractures are commonly sparsely coated with c h l o r i t e and minor amounts of f l u o r i t e . V einlets, up to \ inch wide, consisting of c a l c i t e , f l u o r i t e , quartz, hydromica and minor epidote are present l o c a l l y . In places, p y r i t e , magnetite, sphalerite, galena and molybdenite, i n order of decreasing abundance, occur along joi n t s and fractures, and i n v e i n l e t s ; commonly with associated gangue minerals (types as noted above). Assays show that post-mineral porphyry dykes contain between .01 and .02 percent molybdenite. Shear zones, commonly have minor associated c h l o r i t e , f l u o r i t e and sparse sulphide minerals. A l t e r a t i o n of post-mineral porphyry has affected feldspar phenocrysts and the groundmass to a minor degree. Al b i t e generally i s altered s l i g h t l y to plates of hydromica (?) with associated disseminated c a l c i t e and less commonly 3 9 f l u o r i t e o r e p i d o t e . A l t e r a t i o n i s o f t e n s l i g h t l y m o r e i n t e n s e i n t h e c e n t e r s o f a l b i t e c r y s t a l s . P i n k a l b i t e o f t e n shows l e s s a l t e r a t i o n t h a n g r e y o r p a l e - g r e e n a l b i t e . P i n k e n v e l o p e s a r e o b s e r v e d i n p l a c e s a r o u n d m o r e a l t e r e d , l i g h t e r - c o l o r e d c o r e s . S a n i d i n e p h e n o c r y s t s a r e f r e s h , o r a r e a l t e r e d t o m i n o r d i s s e m i n a t e d c a l c i t e a n d v e r y m i n o r a m o u n t s o f h y d r o m i c a a l o n g c l e a v a g e s . F l u o r i t e , c h l o r i t e a n d / o r e p i d o t e a r e p r e s e n t l o c a l l y i n s a n i d i n e . B i o t i t e h a s b e e n a l t e r e d c o m p l e t e l y t o p s e u d o m o r p h s o f c h l o r i t e p l a t e s c o m m o n l y w i t h r i m s a n d some i n t e r l e a v i n g o f h y d r o m i c a a n d w i t h c a l c i t e a n d m i n o r f l u o r i t e a l o n g c l e a v a g e s . P s e u d o -m o r p h s c o n t a i n a d i s s e m i n a t e d o p a q u e m i n e r a l w h i c h i s p r o b a b l y l e u c o x e n e . A c c e s s o r y s p h e n e i s c o m m o n l y a l t e r e d t o l e u c o x e n e some o f w h i c h h a s c o r e s o f m a g n e t i t e . E m b a y m e n t s i n q u a r t z p h e n o c r y s t s a r e c o m m o n l y i n t e n s e l y a l t e r e d . A l l s e c o n d a r y m i n e r a l s c a n b e f o u n d i n e m b a y m e n t s . D i s s e m i n a t e d i n t h e g r o u n d m a s s a r e m i n o r v e r y f i n e - g r a i n e d a l t e r a t i o n p r o d u c t s . Commonly i n t h e g r o u n d m a s s a r e l o c a l , i r r e g u l a r p a t c h e s o f s e c o n d a r y m i n e r a l s c o n s i s t i n g o f c a l c i t e , h y d r o m i c a , f l u o r i t e , c h l o r i t e , e p i d o t e a n d / o r q u a r t z o f t e n w i t h a s s o c i a t e d m i n o r a m o u n t s o f p y r i t e , m a g n e t i t e , h e m a -t i t e , s p h a l e r i t e a n d / o r m o l y b d e n i t e . P y r i t e o f t e n h a s a n a s s o c i a t e d e x t r e m e l y h i g h r e f l e c t i v e , h e x a g o n a l , p l a t y , o p a q u e m i n e r a l t h a t i s p o s s i b l y a t e l l u r i d e . C h l o r i t e i n p a t c h e s o c c u r s a s c o n c e n t r i c a l l y z o n e d , s p h e r u l i t e s a n d i s p r o b a b l y p r o c h l o r i t e . P a t c h e s o f s e c o n d a r y m i n e r a l s a r e m o s t a b u n d a n t ko where the groundmass i s s l i g h t l y coarser grained and, i n these cases, patches often occur along a mid-line between phenocrysts with e u t e c t i c - l i k e overgrowths. Features i n d i c a t i n g that a l t e r a t i o n and minerali-zation of post-mineral porphyry was deuteric i n o r i g i n are l i s t e d below: 1) F a i r l y uniform a l t e r a t i o n of porphyry i n con-junction with widespread joints and fractures, indicate that a l t e r a t i o n i s not rela t e d to f l u i d movement along j o i n t s , etc; 2) Complex assemblage of secondary s i l i c a t e , oxide and sulphide minerals, occuring along fractures and disseminated,indicate lack of chemical or other gradients such as i s often the case with hydrothermal environments; 3) Intense a l t e r a t i o n and deposition of secondary minerals i n embayments of quartz phenocrysts, indicate that embayments acted as traps to gener-ated late f l u i d s ; II) Patches of secondary minerals occurring along the mid-line between phenocrysts with e u t e c t i c - l i k e overgrowths, indicate a late c r y s t a l l i z a t i o n of secondary minerals i n remaining open spaces. LATE DYKES Porphyritic, basic to intermediate fine-grained dykes of alkaline nature intrude a l l above rock types. Most common are composite basalt-trachyte dykes showing gradations, along and across s t r i k e , from more basic to more alkaline phases. Estimated modes of dykes are given i n Table VII. Structure Dykes are widespread, but are p a r t i c u l a r l y concen-trated i n a northeasterly-trending zone across the center of the map-area. The zone i s coincident with the post-mineral porphyry dyke zone (described above). Dykes commonly trend north-northeasterly to northeasterly and dip k5°to 70° to the northwest. Not uncommon are dykes trending approximately north-e r l y or transverse dykes trending northwesterly to west-northwesterly. They commonly curve and pinch-out along s t r i k e and l o c a l l y occur as a series of en echelon dykes. Structures c o n t r o l l i n g i n t r u s i o n of late dykes are s i m i l a r to those that controlled i n t r u s i o n of post-mineral porphyry dykes. Alkaline Quartz Gabbro Gabbro dyke3 occur i n the south and far-northern portions of the map-area. They are not present i n the dyke-zone described above. They are medium greyish-green and porphyritic and consist of f i n e to medium grained subhedral to euhedral phenocrysts of l a b r a d i o r i t e (An^o) a n a augite i n a fine grained ( .1 - .5 mm), granophyric-like groundmass of a l k a l i feldspar, b i o t i t e , c h l o r i t i z e d augite, quartz and magnetite (Plate 11) . Locally, augite and labradorite pheno-crysts occur intergrown. Augite commonly contains a few grains of fine-grained, euhedral apatite grains near edges of crystals. Labradorite phenocrysts commonly are aligned crudely. They show oscillatory zoning but no significant change i n composition towards edges of crystals. They locally show replacement quartz and a l k a l i feldspar in cores and com-monly contain various amounts of evenly disseminated speck3 of alk a l i feldspar, except for outermost portions of crystals which are clear. Augite i n the groundmass and some augite phenocrysts are deuterically altered in varying degrees to chlorite and minor amounts of biotite. Biotite also shows local alteration to chlorite. Gabbro dykes have chilled contacts. A thin section from one contact was texturally and mineralogically similar to alkaline basalt dykes (described below). Composite Alkaline Basalt - Augite Trachyte Composite dykes are most common and contain fine to medium grained, subhedral to euhedral phenocrysts of slightly aligned feldspar lathes and augite in a fine grained, black or dark-green to buff-orange colored groundmass (Plate 12) . Gradations from dark to orange colored groundmasses are common and occur over a few feet, both along and across dykes. Darker phases are alkaline basalt and contain pale green phenocrysts of labradorite laths and augite in a fine grained ( .01 - .08 mm) groundmass, consisting of sub-parallel m i c r o l i t e s of a more sodic plagioclase (greater than A I ^ Q ) , b i o t i t e plates, augite, i n t e r s t i t i a l " d i r t y " a l k a l i f e l d s -par and quartz and disseminated magnetite. Intermediate to buff-orange colored phases are augite trachyte. They contain phenocrysts of white to cream colored laths or elongated rhombs (up to 1 cm long) probably an a l k a l i feldspar, i n addi-t i o n to augite and minor b i o t i t e . The groundmass i s f i n e -grained (.05 - .2 mm) and granular and consists of laths and i n t e r s t i t i a l ' u i r t y " a l k a l i feldspar with b i o t i t e plates and disseminated magnetite. One t h i n section showed a minor i n t e r -s t i t i a l feldspathoid mineral, probably s o d a l i t e . Another t h i n section showed phenocrysts of labradorite i n a groundmass typ-i c a l of augite trachyte. It probably represents a type of gradational phase. Texture of labradorite i n basalt, and of augite i n both phases i s the same as that described f o r quartz gabbro. However, labradorite l o c a l l y shows rims i n hand specimens of basalt. In t h i n section, these rims consist of laminated, o s c i l l a t o r y zoned labradorite around cores showing replacement to a l k a l i feldspar. In trachyte, feldspar pheno-crysts show zoned rims, with negative r e l i e f and a negative optic angle of approximately 50°to 60°j probably high a l b i t e . Gores of these phenocrysts are poly s y n t h e t i c a l l y twinned and have weak, posit i v e r e l i e f and a very high, negative optic angle. Cores are probably a high temperature mixed Na-K-Ca feldspar. Both basalt and trachyte phases are d e u t e r i c a l l y a l t e r e d . Labradorite shows i n c i p i e n t carbonate and a r g i l l i c a l t e r a t i o n . Some cores of a l k a l i feldspar phenocrysts are kk weakly to moderately altered to hydromica (?) and minor c a l c i t e and are grey i n hand specimen whereas rims remain f r e s h and pale colored. Augite i n both phases, i s altered i n vary-ing degrees to c a l c i t e , c h l o r i t e and b i o t i t e . Some b i o t i t e i n groundmasses i s altered to c h l o r i t e . Some c a l c i t e and clay minerals are common i n the groundmass of trachyte. Altered L a t i t e Dykes of l a t i t e mainly occur l o c a l l y i n the central dyke-zone and cut composite dykes. They t y p i c a l l y show s l a t y cleavage p a r a l l e l to attitudes and are uniformly textured. They consist of f i n e grained (.5 - 1*5 mm) phenocrysts of white, altered feldspar laths and minor b i o t i t e i n a greenish-grey, f i n e grained (.5 - .2 mm) groundmass consisting of b i o t i t e plates, altered a l k a l i feldspars, i n t e r s t i t i a l quartz and disseminated magnetite and minor p y r i t e (Plate 13) ' In t h i n section, feldspar phenocrysts have a form t y p i c a l of plag-ioclase but are e n t i r e l y altered to pseudomorphs of c a l c i t e and minor amounts of k a o l i n i t e . A l k a l i feldspars i n the ground-mass are"di r t y " and show no twinning. They commonly are altered p a r t l y to k a o l i n i t e and c a l c i t e . Minerals Alkaline Alkaline Augite Altered Quartz Gabbro(l) Basalt (3)* Trachyte (ii) L a t i t e ( l ) --Phenocrysts--Labradorite (approximately An 6 o) 50$ 10-15$ A l k a l i ( ? ) Feldspar 10-20$ Altered -Plagio-clase (?) 20$ Augite 15$ 5-10$ 5-10$ B i o t i t e 0-2$ 1-2$ --Groundmass— Sodic Plagioclase >(An 2 Q) I L O -A l k a l i Feldspar 25$ 5-15$ 60-70$ 60$ B i o t i t e 5$ 5-10$ 5-10$ 10$ Augite and altered Augite 3$ 1-3$ 1-2$ Quartz 5$ 1-5$ 5$ Feldspathoid (Sodalite ?) 0-3$ - - A c c e s s o r i e s — Magnetite 2$ 2-5 $ 2-5 $ 1-2$ Pyrite h $ Apatite 1$ 1-2 $ 1-2 $ (1) - Number of t h i n sections studied (#) - Includes c h i l l e d border of quartz gabbro dyke. TABLE VII: Estimated Modes of Late Dykes. 1 * 6 Discussion The complex mineralogy and replacement textures of composite dykes, as well as the presence of sudden t r a n s i -tions from one phase to another, indicate conditions of mag-matic disequilibrium; probably due to ass i m i l a t i o n of g r a n i t i c c r u s t a l material by primary b a s a l t i c magma. Dykes are cor-re l a t e d with C o r y e l l Intrusions on the basis of petrographic s i m i l a r i t i e s . DIFFERENTIATION OF ACID INTRUSIVE ROCKS The quartz monzonite stock and younger quartz - a l b i t e -sanidine porphyries a l l have si m i l a r mineralogy, modal compo-s i t i o n and textures. The composition of plagioclase i s more sodic i n porphyries than i n the stock. These features c l e a r l y show that these intrusions are d i f f e r e n t i a t e s of a common parent magma. Also, these features suggest a close r e l a t i o n -ship i n time and environment of emplacement of the stock and porphyries. Granodiorite i s l i k e l y a related early d i f f e r -entiate as features l i s t e d below serve to in d i c a t e : 1. Nelson and V a l h a l l a Intrusions commonly grade into one another i n some regions (see "Regional Geology"); 2. Large p o i k i l i t i c grains of orthoclase i n granodiorite are reminiscent of the presence of large sanidine phenocrysts i n the stock and porphyries ; 3. The composition of plagioclase i n granodiorite i s more c a l c i c than i n younger intrusions; i i . Lesser amount of potash feldspar i n granodiorite than i n younger Intrusions; 5. The c r y s t a l l i z a t i o n h i s t o r y of granodiorite includes early growth of andesine-oligoclase succeeded by probable ternary eutectic c r y s t a l -l i z a t i o n of potash feldspar-oligoclase-quartz as indicated by textural relationships between mineral phases. As discussed below under " C r y s t a l l i z a t i o n of Phenocrysts", both quartz monzonite and porphyries undoubtedly c r y s t a l -l i z e d phenocrysts under ternary eutectic conditions involving two feldspars and quartz. Therefore, the hi s t o r y of c r y s t a l l i z a t i o n of oldest to youngest in t r u s i v e s indicates a genetic r e l a t i o n s h i p , through d i f f e r e n t i a t i o n , between granodiorite and younger i n t r u s i v e s ; 6. Presence of the same accessory minerals i n a l l in t r u s i o n s . LEVEL OF EMPLACEMENT OF THE STOCK AND PORPHYRIES Crustal l e v e l of emplacement of the stock and porphyries must have been within a few thousand feet of the old erosion surface and, therefore, sub-volcanic. Porphyritic textures, fine-grained to aphanitic groundmasses and presence of sanidine phenocrysts i n both the stock and porphyries and c h i l l e d porphyry contacts are features t y p i c a l of acid i n t r u s i v e rocks that cooled r a p i d l y i n a sub-volcanic environment. Porphyries c o r r e l a t i v e to above ( i . e . Shingle Creek and Ouellette Creek Porphyries; see "Regional Geology") have related contemporaneous p y r o c l a s t i c rocks and, therefore, reached or came within a few thousand feet of the old erosion surface. Pyroclastic rocks are not known to be associated with the Tuzo Creek Porphyries but l o c a l explosive breccias occur within some bodies of post-mineral porphyry. CRYSTALLIZATION OF PHENOCRYSTS Phenocrysts of quartz, a l b i t e and sanidine i n porphyries are believed to have c r y s t a l l i z e d contemporaneously under ternary eutectic conditions. Inclusions of a l b i t e and quartz i n the outer portions of large sanidine phenocrysts and overgrowths of sanidine on a l b i t e phenocrysts indicate simultaneous c r y s t a l l i z a t i o n of the two feldspars and quartz. Also, mode of porphyries i s very si m i l a r to that of the Shingle Creek Porphyry ( I I ) whose normative composition l i e s close to the experimentally determined ( 1 3 ) eutectic point i n the calcium-free "granite system". Since only very minor amounts of calcium i s present i n plagioclase ( i . e . An^), c r y s t a l l i z a t i o n of phenocrysts can be considered to have ocr cured i n the NaAlSi^0g-KA13i^0Q-Si0 2 ;-H20 system. In order f o r two feldspars to c r y s t a l l i z e together with quartz i n t h i s system, water vapour pressures of 3 * 5 0 0 Kg/crtr^ or more, or k9 c r u s t a l depths of approximately 11 km's or more are required as determined experimentally by Tuttle and Bowen (1958)• Conditions of c r y s t a l l i z a t i o n must explain o s c i l l a t o r y zoning i n large sanidine phenocrysts and rounded and embayed forms of quartz. Similar textures of phenocrysts, mode, composition of a l b i t e and o p t i c a l properties of sanidine i n the Shingle Creek Porphyry lead Bostock to the same conclusion with regards to c r y s t a l l i z a t i o n of phenocrysts. Quartz, oligoclase and sanidine phenocrysts i n quartz monzonite are s i m i l a r petrographically to phenocrysts i n porphyry. Since plagioclase i s more c a l c i c (ie. An^ Q to An-j^) i n quartz monzonite, ternary eutectic c r y s t a l l i z a t i o n of phenocrysts can occur at any reasonable depth because of the c a l c i c nature of i t s source magma (13). However, because of the close s i m i l a r i t y between phenocrysts i n porphyry and quartz monzonite, depth of c r y s t a l l i z a t i o n of phenocrysts i n both rock types must have been e s s e n t i a l l y the same. Ternary eutectic c r y s t a l l i z a t i o n i n quartz monzonite continued i n the h i g h - l e v e l c r u s t a l environment because sanidine and oligoclase phenocrysts show continued growth (ie. intergrown with fine-grained quartz i n outer portions of phenocrysts) and the groundmass shows a e u t e c t i c - l i k e intergrowth between fine-grained quartz and sanidine. 50 CONCLUSION Prom the foregoing,the writer concludes that granodiorite, quartz monzonite and porphyries are a l l related to the same parent magma and belong to a continuous d i f f e r -e n t i a t i o n s e r i e s . Also, quartz monzonite and porphyries are relat e d late d i f f e r e n t i a t e s derived from p a r t i a l l y c r y s t a l -l i z e d d i f f e r e n t i a t e d magma at depths of 11 Km's or more, and were emplaced i n a sub-volcanic environment. It i s suggested that quartz monzonite and porphyry were derived from a deep pocket of p a r t l y c r y s t a l l i z e d magma related to the Nelson-Valhalla b a t h o l i t h i c complex. Batho-l i t h i c rocks are believed to be the e a r l i e r d i f f e r e n t i a t e s of the parent magma. 51 CHAPTER III STRUCTURE INTRODUCTION The region has had a complex s t r u c t u r a l h i s t o r y involving shearing, f r a c t u r i n g , f a u l t i n g , b r e c c i a t i o n and f i s s u r i n g . Successive s t r u c t u r a l deformation i s recognized. Structures developed are defined according to t h e i r type and time of occurrence on Table I. Temporal aspects are based on crosscutting relationships between s t r u c t u r a l elements and intru s i v e rocks and between d i f f e r e n t l y mineral-ized crosscutting structures. Structures that controlled hydrothermal a l t e r a t i o n and mineralization or are post-mineral and post-intrusive i n age are grouped into three periods of deformation. These periods of deformation occurred after i n t r u s i o n of the pre-mineral porphyry r o o f - s i l l . They are l i s t e d and defined below i n Table VIII. S t r u c t u r a l elements developed during Periods I to III deformation are discussed i n subsequent sections. 52 Period-I: Intense shearing, widespread f r a c t u r i n g and l o c a l b r e c c i a t i o n ; p r i o r to i n t r u -sion of intra-mineral porphyry. Structural elements developed include f o l i a t i o n , shear and breccia zones and fractures. Period-II: Local shearing, b r e c c i a t i o n and f r a c t u r -ing; between time of i n t r u s i o n of i n t r a -and post-mineral porphyry. S t r u c t u r a l elements developed include shear and breccia zones and fractures. P e r i o d - I l l : Faulting; a f t e r i n t r u s i o n of late dykes. Str u c t u r a l elements developed include shear and breccia zones. TABLE VIII: Periods of Deformation Apart from structures developed during Periods I to III deformation, other structures recognized include the following: 1) Regional shearing p r i o r to i n t r u s i o n of the quartz monzonite stock (discussed under "Regionally Sheared Granodiorite"); 2) Successive development of subsidence f i s s u r e s and conjugate tensional f i s s u r e s (see "Discussion of Structures C o n t r o l l i n g Emplacement of Intrusive Rocks"). REGIONALLY SHEARED GRANODIORITE Granodiorite shows widespread intergranular shearing and brecciation, f r a c t u r i n g and hydrothermal a l t e r a t i o n along the western and southern portions of the map-area (Figures 5 and 6). Inter-granular deformation i s developed uniformly but has been r e l a t i v e l y weak. The o r i g i n a l hypidiomorphic texture of grano-d i o r i t e i s generally d i s c e r n i b l e . Deformation and a l t e r a t i o n of granodiorite preceded emplacement cf the quartz monzonite stock. This i s based on observations i n the mutual v i c i n i t y of exposures 53 of deformed and altered granodiorite and quartz monzonite since int r u s i v e contacts were not found. That i s , i n the mutual v i c i n i t y of the two rock types quartz monzonite does not show intergranular shearing and i s either f r e s h or contains a d i f f e r e n t a l t e r a t i o n mineral assemblage. Discussion The contact between V a l h a l l a and Nelson Intrusions, as mapped by L i t t l e (Figure 3 ) , occurs outside but near the western and southern edges of the map-area. This was substan-t i a t e d by cursory examination of exposures and stream f l o a t around the periphery of the map-area. Therefore, i t i s suggested that the presence of the sheared and altered region of granodiorite within the map-area was the r e s u l t of i n t r u s i v e e f f e c t s of b a t h o l i t h i c V a l h a l l a Intrusions occurring outside of the map-area. The sheared and altered region of granodiorite i s further discussed i n a l a t e r section e n t i t l e d "Regionally Altered Granodiorite". FAULTS Numerous northeasterly-trending f a u l t s ( P e r i o d - I l l ) displace a l l rock types and occur i n the central to north-eastern portions of the region. They terminate towards th southwest and merge into only a few f a u l t s towards the northeast. Draws traversing the northeastern slope of the ridge follow f a u l t s . Prominent f a u l t s , l a b e l l e d Fault-A,-B, -Q, and -D, dip approximately 55° to 80° to the northwest. Dip of f a u l t s was determined from attitudes of adjacent shears and intersections i n d r i l l holes. Only Faults-B and -C and l o c a l small f a u l t s show good displacement of dykes. These f a u l t s are reverse, with d i p - s l i p movement ranging from approximately SO feet to 200 -300 f e e t . Probably a l l or at least most f a u l t s have had rev-erse movement. Since a l l f a u l t s terminate towards the south-west, movement must have been r o t a t i o n a l and, therefore, some s t r i k e - s l i p movement has occured. Fault-C shows increasing displacement towards the northwest which i s i n agreement with r o t a t i o n a l movement. Faults are discussed further i n a following section, e n t i t l e d "Shear and Breccia Zones", as a portion of Period-I l l zones of shearing and br e c c i a t i o n that are present. FOLIATION Weak to intense secondary f o l i a t i o n grouped with Period-I deformation, occurs i n zones i n pre-mineral porphyry, quartz monzonite and l o c a l l y i n granodiorite. F o l i a t i o n large-l y occurs i n a zone between and conformable with younger Faults -B and -G (Figure 9 ) . Within this zone ( i e ; " F o l i a t e d Shear Zone " ) , f o l i a t i o n occurs only l o c a l l y at the surface towards 55 the southwest but i s well developed at depth i n DDH's 1 and II and on surface, at lower a l t i t u d e s , towards the northeast. F o l i a t i o n i s characterized by varying degrees of breaking and stretching-out of quartz and potash-feldspar phenocrysts and by shearing and granulation of groundmasses. It i s commonly only intense i n zones approximately 10 to 30 feet wide and i s best developed i n quartz monzonite. Intensely f o l i a t e d zones show quartz phenocrysts strung-out into long (up to 1 or 2 inches), t h i n lenses and sanidine phenocrysts rotated, broken and strung-out to a few inches. F o l i a t e d rocks are laminated l o c a l l y with augen of potash feldspar. Degree of f o l i a t i o n i s more intense i n DDH 1 than i n DDH LL and, i n general, tends to increase towards the northeast. F o l i a t i o n commonly str i k e s northeasterly and dips 65 ° to 9 0 ° northwest, p a r a l l e l with younger f a u l t s . Also present i s a less common, cross f o l i a t i o n , trending north-westerly and generally dipping 8 0 0 to 9 0 ° northeast. Locally, rocks show complex f o l i a t i o n with two or more attitudes i n the same outcrop. In DDH LL, f o l i a t i o n has angles to the core-axis ranging most frequently from 6 0 ° to 35°. In DDH 1, f o l i a t i o n i s p a r a l l e l i n both porphyry and quartz monzonite and has angles to the core-axis ranging most frequently from \\$0 to 9 0 ° . Resolving core angles into dip angles with respect to each DDH, suggests that f o l i a t i o n at depth roughly i s p a r a l l e l to younger .faultsj though also, cross trends probably are present. f F o l i a t i o n T r e n d ( D e f i n e d a n d I n f e r r e d ) N o t e : F o r a d d i t i o n a l s y m b o l s s e e F i g u r e 7 a n d 8 S c a l e : 1 I n c h = 8 0 0 F e e t F I G U R E 9 : P E R I O D - I F O L I A T I O N A N D T H E " F O L I A T E D S H E A R Z O N E " 57 Discussion Forces causing Period - I f o l i a t i o n must have been corapressional and, therefore, movement within the " f o l i a t e d shear zone" was of reverse character. The indicated increase i n degree of f o l i a t i o n towards the northeast is i n harmony with r o t a t i o n a l movement. Therefore, i t i s suggested that the " f o l i a t e d shear zone" i s due to confined, reverse shearing movement of a r o t a t i o n a l character, s i m i l a r to that of late f a u l t s , and can be expected to pinch-out or disipate towards the southwest. Compressional forces that caused development of f o l i a t i o n probably are related to regional tectonics. The conjugate system of f o l i a t i o n , though northwesterly-trending f o l i a t i o n only occurs l o c a l l y , indicates either roughly north-south or east-west directed compressional forces. The same tectonics that caused Period - I f o l i a t i o n were l i k e l y regener-ated to produce Period - III f a u l t s . SHEAR AND BRECCIA ZONES Shear and breccia zones, commonly up to ten feet wide, occur l o c a l l y throughout the faulted region. They com-monly st r i k e northeasterly and dip 55° to 90° to the northwest. Some st r i k e northerly or r a r e l y west-northwesterly to north-westerly and generally dip steeply to the west or north, 58 r e s p e c t i v e l y . Shear and breccia zones commonly show intergranular shearing and/or angular to rounded rock f r a g -ments up to a few inches accross. These zones are altered and mineralized to varying degrees. Three periods of shearing and b r e c c i a t i o n are recognized. These periods are l i s t e d and defined above under "Introduction". Period-I shear and breccia zones occur widespread throughout the fau l t e d region i n pre-mineral porphyry and older intr u s i v e rocks. In DDH's, zones are f a i r l y evenly d i s t r i b u t e d , commonly range from 6 inches to 5 feet wide and have cumulative widths of up to approximately 60 feet i n each d r i l l hole. In addition, i n DDH's 2 and 3 , two zones 118 and 105 feet wide respectively are present (shown on Figure 8 ) . These were also s i t e s of very intense f r a c t u r i n g . Some zones intersected along d r i l l holes within the " f o l i a t e d shear zone" contain rotated fragments of f o l i a t e d quartz monzonite or consist of highly granulated or comminuted rock. Also, there are l o c a l small breccias i n DDH LL, ranging from hn to 33§" wide and i n "intensely fractured zones 1 to 8" (Figure 7» discussed l a t e r ) ranging from V to 1 foot wide. These small breccias consist of angular rock fragments within a f a i r l y sharp walled zone and are l a r g e l y healed by secondary gangue minerals and hematite and magnetite. Period-II shear and breccia zones occur mainly i n DDH's 3 and LL where younger f a u l t s are intersected, generally below depths of 900 feet, ^hese zones cut intra-mineral 59 porphyry dykes and previously altered and mineralized rock. They commonly range from a few inches to 5 feet i n width. One zone, near the bottom of DDH LL i s 20 feet wide. Cumula-tive widths of Period-II shear and breccia zones are approxi-mately 50 feet i n DDH LL and 20 feet i n DDH 3 . In addition, l o c a l small breccias up to 1 inch wide commonly cut i n t r a -mineral porphyry. They contain angular porphyry fragments healed with gouge and gangue and sulphide minerals. Core angles of Period-II zones show that they predominantly dip steeply. Probably, zones are lar g e l y p a r a l l e l to northeasterly-trending and steeply northwest-dipping e a r l i e r Period-I f o l i a t i o n and shear and breccia zones and l a t e r P e r i o d - I l l f a u l t s . See Plate 30. P e r i o d - I l l shear and breccia zones cut a l l rock types. They define P e r i o d - I l l f a u l t s but also occur widespread as minor zones of deformation. They consist of l a r g e l y unalt-ered and unmineralized sheared and brecciated rock, gouge and dark mylonite. These zones commonly are up to 2 feet wide, and r a r e l y are up to 20 feet wide. 0 6 0 FRACTURING  Introduction Period-I f r a c t u r i n g occurs i n pre-mineral porphyry and older i n t r u s i v e rocks and i s present i n varying i n t e n s i t y throughout the hydrothermal a l t e r a t i o n halo (Figures 7 and 8). These fractures are the most important s t r u c t u r a l element pres-ent for they lar g e l y have controlled the main phase of hydro-thermal a l t e r a t i o n , quartz veining and mineralization>(Phase-I: discussed l a t e r ) . Period-II f r a c t u r i n g probably occurred widespread but generally i s not very intense. It i s only important i n the region along the western ends of Faults-A and -B where Period-II fractures p a r t l y controlled Phase-II hydrothermal a l t e r a t i o n and mineralization (discussed l a t e r ) i n i n t r a -mineral porphyry and older in t r u s i v e rocks. Quartz veining, related to Phase-I hydrothermal a c t i v i t y , i s termed Period-I quartz veins In t h i s section f o r purposes of s i m p l i c i t y because quartz veins occur along Period-I f r a c t u r e s . Azimuth and dip frequency diagrams and frequencies of Period-I fractures and quartz veins are shown on Figures 1 0 , 1 1 and 12 and are given i n Table IX, respectively. Attitudes of Period-II fractures, along with those of Period-I fractures, were only obtained from the region along and past the western end of Fault-B. Figures 10 and 11 include both 6 1 Period-I and -II fractures from t h i s region. Period-I Fracturing and Quartz Veining Weak fr a c t u r i n g , present i n unaltered peripheral rocks, r a p i d l y increases i n i n t e n s i t y where rocks begin to show hydrothermal a l t e r a t i o n and mineralization. Fracturing continues to increase i n i n t e n s i t y towards "intensely f r a c -tured zones"; shown on accompanying maps (Figures 7 and 8 ) . These zones include, "peripheral zones" occurring i n the nor-thern and western portions of the a l t e r a t i o n halo and a "central quartz vein stockwork zone". The "stockwork zone" located near the centre of the a l t e r a t i o n halo, trends northeasterly and i s conformable with the central to western portions of a larger "central zone" of most intense wallrock a l t e r a t i o n and with a region of molybdenite mineralization. The "stockwork zone" i s s p a t i a l l y centered above, within and adjacent to the upper portion of the northeasterly-trending " f o l i a t e d shear zone" (discussed previously). The l i m i t s of the "stockwork zone" have only been shown at and near surface on maps, whereas at depth, i t s l i m i t s are roughly conformable to the outline shown for the "central zone" of wallrock a l t e r a t i o n . The "central quartz vein stockwork zone" i s chara-cte r i z e d by widespread intense f r a c t u r i n g , as are "peripheral zones", and by widespread quartz vein stockworks i n i t s upper 6 2 part, p a r t i c u l a r l y i n the granodiorite capping, and by l o c a l , confined zones of quartz vein stockworks with sparse i n t e r -vening quartz veins at depth (Table IX). Within the "stock-work zone", f o l i a t e d rocks are as intensely fractured as others; however, opening along fractures, as evidenced from the d i s t r i -bution of quartz veins, has been more prevalent i n the upper part of the zone ( i e , i n the part p a r t i c u l a r l y l y i n g above the " f o l i a t e d shear zone " ) . "Intensely fractured zones" are s t r u c t u r a l l y charact-erized by opening and/or shearing along some of the fractures. Fracture f i l l i n g s , consisting of gangue, sulphide and/or oxide minerals, predominantly are less than 1 / 1 6 " wide throughout the whole of the a l t e r a t i o n halo.. However, within "peripheral zones", openings up to V occur along many of the fractures and i n the "central quartz vein stockwork zone", openings commonly 1 / 8 " to 1 / 2 " wide have controlled quartz veining. Also, some of the fracture openings i n fracture zone-8 have controlled quartz veins. Quartz veining only l o c a l l y occurs outside of "intensely fractured zones". Shearing along fractures, con-s i s t i n g of minor granulation, shearing and/or brecciation, i s more prevalent i n "intensely fractures zones" but commonly only occurs along a small percentage of the fractures. (See Plates 1 6 and 21L to 28). The average range of frequency of fractures plus quartz veins i n "intensely fractured zones" i s from I 4 . to 1 1 per foot. Refer to Table IX f o r de t a i l s of frequencies of CENTRAL QUARTZ VEIN STOCKWORK ZONE INTENSELY FRACTURED ZONES 1-8 FRACTURE FREQUENCY L a r g e l y W i t h i n t h e G r a n o d i o r ite- C a p p i n g Range: 2 - 9 / f t Average: 3-4 / f t >' At Depth (DDH's 1-4) No s y s t e m a t i c c o u n t i n g o f a l l f r a c -t u r e s ; however f r a c t u r i n g i n t e n s i t y i s comparable t o t h a t o f I n t e n s e l y Zoneo 3.-7 Zone 8 7. L.i . :vi3.ts a r e -1 i s Zone : i o f a l t e r a t i o n k-:c a c r u r e a • so n e s r o u g h l y t h e same as t h e " C e n t r a l Commonly 5-10 prom-i n e n t f i r ' s / f t . X-Iumer ou s ha i r -1 i ne f r 1 s (up t o 10/inch) Corranonly 6 - 1 2 / f t QUARTZ VEIN FREQUENCY F a i r l y e v e n l y d i s t r i b u t e d v e i n s Range: l-15/.t't Aver a ge: 3 - 5/f t. V e i n s o c c u r . i n l o c a l w e l l defined. sor.es p r e s e n t t o depths o f 65Q-?70' (DDH 2 bottomed i n a v e i n e d zone) . Only 3. o c a 1 qu a r t : v e i n s Z o n e B x a n ge £r; >J..L £.~X 19b ! wide C oiumo n 1 y 1 - 'l/£ l o c a l l y up t o 2 0 / f t a c r o s s 1 f t <•  7 - . 9 (commonly 20-50 ' v/ide) . V e i n s occur s p a r s e l y b Range: 1-1 Average: 1 Cfcv/Ofi 3 / r t n zones. ) W i t h i n t ) y.ones WIDTH OF VEINS Range: l / l 6 Average: !/<' : - I 1' Vx - 1/2" Aver aqe: / I S - 3/C" l / o - 1/4" AVERAGE FRACTURE AND QUARTZ VEIN FREQUENCY 7 - s / f t E s t i m a t e d a t depth.. 4-8/:! Some t t h r o u g h o u t zone h a i r l i n e f r a c t u r e s 5-3.0 prominent f r s / f t ; numerous h a i r -l i n e f r a c t u r e s n - n / f t SOURCE 0? DATA C o u n t i n g and e s t i i a a t i o n o f number o f v e i n s i n o u t c r o p s . PSH's 1-3,8, 12 and. 13 >K's 1-4 Counting' o f f r a c -t u r e s i n some . o u t c r o p s . FSH 11 Co u nt i n g o f f r a c -t u x e s i n some o u t c r o p s . PSK 0 JK0TE: Background f r a c t u r e f r e q u e n c y i s a p p r o x i m a t e l y 2 - 5 / f t TABLE IX: • P e r i o d - I M i n e r a l i s e d * - F r a c t u r e and Q u a r t z V e i n Frequency i n I n t e n s e l y F r a c t u r e s Zones I t o 3 and i n t h e C e n t r a l Q u a r t z V e i n S t o c k w o r k Zone I n c l u d e s a l l f r a c t u r e s c o n t a i n i n g secondary gangue, 'sulphide, and/or o x i d e m i n e r a l s due t o Phase - I b ydr o t h e r ma 1 a l t e r a t i o n and miners'! i s a t i o n I S 1 0 5 0 9 1 0 1 5 F R E Q U E N C Y A Z I M U T H F R E Q U E N C Y D I A G R A M ( A l l f r a c t u r e s a n d q u a r t z v e i n s ; 2 0 8 o b s e r v a t i o n s ) " F R E Q U E N C Y O F F R A C T U R E S A N D Q U A R T Z V E I N S D I P P I N G > 8 2 ^ ° I N V A R I O U S Q U A D R A N T S 9 0 ° 8 0 » 7 0 ° 6 0 ° 6 0 ° D I P A N G L E 4 0 ° 3 0 ° 2 0 ° ' H I S T O G R A M O F D I P F R E Q U E N C Y ( A l l , f r a c t u r e s a n d q u a r t z v e i n s ; 2 0 8 o b s e r v a t i o n s ) F I G U R E 1 0 : P E R I O D - I F R A C T U R E A N D Q U A R T Z V E I N A Z I M U T H A N D D I P F R E Q U E N C Y D I A G R A M S P r e d o m i n a n t P e r i o d -S h a o r i n g A z i m u t h 2 8 0 R a n g * o f P r e d o m i n a n t T r e n d * I n . Z o n e * 1 - 8 a n d n e a r F a u l t — B Rang* of C r o i * and Conjugal* T r * n d « in Zon** 5 , 7 and 8 , and near F a u l t - B FIGURE 11: PERIOD -I AZIMUTH FREQUENCY DIAGRAM FOR ALL FRACTURES AND QUARTZ VEINS PERIPHERAL TO THE CENTRAL QUARTZ VEIN STOCKWORK ZONE (Showing range of azimuths i n Intensely Fractured Zones : 1 to 8 and in region of Fault - B.) 1 0 0 F R E Q U E N C Y 5 1 0 12 - A : I N C L U D E S B O T H E A S T A N D W E S T Z O N E S 2 8 0 io y 5 R a n g * o f P r e d o m i n a n t T r a n d t P r e d o m i n a n t P e r i o d ~ i S h e a r i n g A z i m u t h F R E Q U E N C Y 12~B: E A S T Z O N E 2 8 0 P r a d o m l n a n t P a r l o d — 1 S h e a r i n g A z i m u t h F R E Q U E N C Y R a n g * o f P r e d o m i n a n t T r e n d * 12 - C : W E S T Z O N E F I G U R E 12 ( A , B A N D C ) : P E R I O D - I Q U A R T Z V E I N A N D F R A C T U R E A Z I M U T H F R E Q U E N C Y D I A G R A M S F O R T H E C E N T R A L Q U A R T Z V E I N S T O C K W O R K Z O N E 67 fractures and quartz veins, and f o r width of quartz veins. Background fracture frequency within the a l t e r a t i o n halo i s estimated to average 2-5 fractures per foot. However, f r a c -ture frequency at the bottoms of DDH's below the "stockwork zone" i s often s i m i l a r to that of "intensely fractured zones" but fractures commonly lack opening. Figures 10, 11 and 12 show azimuth frequencies of fractures and quartz veins. Figure 10 also i l l u s t r a t e s that fractures and veins predominantly have dips greater than 70° and, therefore, azimuth frequency diagrams are very u s e f u l . From figure 10, which shows azimuth frequencies f o r a l l f r a c -tures and quartz veins, no regular trend pattern i s obvious, except that a great range of predominant trends i s present. However, trend r e g u l a r i t i e s become apparent when each of "intensely fractured zones" i s considered independently. That i s , fracture zones -1 and -3 to -6 (Figure 11) each show a single range of predominant fracture trends that together, roughly radiate about the western end of the "central quartz vein stockwork zone". Also, fracture zone -5 shows a less predominant trend p a r a l l e l to the predominant shearing azimuth. Fracture zones -7 and -8 and the region along the western end of Fault-B, a l l show predominant fracture and quartz vein trends from north-northeast to northeast, approximately p a r a l l e l to the shearing azimuth. They also show either cross trends, as i n zone-8, or conjugate trends about the shearing azimuth, as i n zone-7 and near the end of Fault-B. S i m i l a r l y , 68 i n the "central quartz vein stockwork zone" both east and west zones (Figures 7 and 12) show simple conjugate trends of fractures and quartz veins with respect to the shearing azimuth. The west zone also shows a northeasterly-trending fracture and quartz vein set p a r a l l e l to the shearing azimuth. Discussion A genetic rel a t i o n s h i p between Period-I shearing, that produced the wide " f o l i a t e d shear zone" and narrow shear and breccia zones, and Period-I f r a c t u r i n g i s strongly i n d i -cated because of the following features: 1) Close s p a t i a l r e l a t i o n s h i p between the region characterized by complex f r a c t u r i n g , including longitudinal (fracture and quartz vien trends that are roughly p a r a l l e l to the shearing azimuth), conjugate and cross trends, and the " f o l i a t e d shear zone" ; 2) Relationship between orientations of l o g i t u d -i n a l , conjugate and cross fractures and quartz veins and the predominant shearing azimuth; 3) Presence of r a d i a l fractures to the southwest, west and northwest of the western end of the "central quartz vein stockwork zone"; i i ) Shearing nature of some fractures; 5) Most extensive opening occurs along fractures above and to the north of the " f o l i a t e d shear zone". Radial fractures are believed to represent a h o r s e t a i l i n g feature caused by d i s i p a t i o n or pinching-out of the " f o l i a t e d shear zone". These fractures probably were i n part the r e s u l t of development of s t r a i n i n the rocks due to reverse r o t a t i o n a l movement within the " f o l i a t e d shear zone". Complex 6 9 f r a c t u r i n g , s p a t i a l l y associated with the " f o l i a t e d shear zone", probably was the r e s u l t of wrenching e f f e c t s due to shear movements. Shearing and f r a c t u r i n g must be related to regional tectonics since these s t r u c t u r a l features do not indicate any genetic r e l a t i o n s h i p with doming, subsidence or cooling of the stock and/or r o o f - s i l l apart from close s p a t i a l r e l a t i o n s h i p with the quartz monzonite stock. This s p a t i a l r e l a t i o n s h i p probably i s inherent. That i s , emplacement of the stock probably was controlled i n part by a northeasterly-trending shear zone located i n the same region affected by Periods -I to -III deformation. Period-II Fracturing As stated above under "Introduction", attitudes of Period-II fractures were only obtained from the region along and past the western end of Fault-B. They were obtained from intra-mineral porphyry and adjacent granodiorite. Orienta-tions of both Periods-I and -II fractures are similar and were discussed together i n the preceeding section. Period-II f r a c t u r i n g i s developed best along the western ends of Faults-B and -C, and i s most intense i n regions affected by Period-II shear and breccia zones i n DDH's 3 and i i . The frequency of fractures i n these regions, attributed to Period-II f r a c t u r i n g , i s estimated at 2 - I L per foot. Minor 70 Period-II f r a c t u r i n g also occurs widespread since l o c a l fractures and ve i n l e t s carrying abundant c a l c i t e and f l u o r i t e ( p a r t i c u l a r l y associated with Phase-II a l t e r a t i o n and mineral-iza t i o n ) occur i n most DDH's, and fractures o f f - s e t t i n g Period -I fractures and quartz veins are common along a l l d r i l l holes. Quartz veins only l o c a l l y occur along Period-II fractures. DISCUSSION OP STRUCTURES CONTROLLING EMPLACEMENT OF INTRUSIVE ROCKS Structures c o n t r o l l i n g emplacement of various sequential intrusive rocks are believed to have been related, at d i f f e r e n t times, to either regional or l o c a l tectonics. Structures c o n t r o l l i n g emplacement of the quartz monzonite stock are not known. It was suggested under "Discussion" of "Period-I Fracturing and Quartz Veining" that emplacement of the stock was controlled i n part by a north-easterly-trending shear zone. A l l V a l h a l l a stocks, intruding Nelson granodiorite and older rocks i n the Beaverdell area (Figure 3), occur along or close to the West Ke t t l e River f a u l t zone. It appears then,that the emplacement of stocks was controlled by this f a u l t zone and/or by subsidiary f a u l t s . This tends to substantiate the above suggestion. Control f o r emplacement of the pre-mineral porphyry r o o f - s i l l along the top and eastern flanks of the quartz monzonite stock undoubtedly was due to subsidence of part of the stock. Simultaneous subsidence of the stock and i n t r u s i o n 71 of the r o o f - s i l l explain primary s t r u c t u r a l features of pre-mineral porphyry i n d i c a t i n g f o r c e f u l i n t r u s i o n and absence of evidence f o r collapse of the granodiorite roof with subsidence of the stock. Gently to moderately dipping dykes and s i l l s of intra-mineral porphyry must have been l o c a l i z e d along tensional f i s s u r e s due to further subsidence of the stock and r o o f - s i l l . Structures c o n t r o l l i n g emplacement of post-mineral porphyry and late dykes were of a d i f f e r e n t nature than those c o n t r o l l i n g pre- and Intra-mineral porphyry. Intrusions of post-mineral porphyry and late dykes have s i m i l a r trends and both consist of single dykes and series of connected en echelon dykes. Predominant dyke trends are northeasterly. Less predominant dyke trends are northerly-to west-northwesterly. The;. presence of en echelon dykes and conjugate dyke-trends strongly indicate that c o n t r o l l i n g structures were ge n e t i c a l l y related to regional tensional forces. Similar structures were developed at two d i f f e r e n t times because intrusions of post-mineral porphyry preceded that of late dykes. Post-mineral porphyry dykes are most abundant and have conjugate dyke orientations with a least angle of difference of approximately 55°« The bisector of this angle trends roughly N 1 5 ° E . Therefore regional tensional forces producing conjugate ten-sional f i s s u r e s must have been roughly directed W 1 5 N and E 1 5 ° S . 72 STRUCTURAL INTERPRETATION It has already been shown that f r a c t u r i n g was g e n e t i c a l l y r e l a t e d to shearing. Also i t has been concluded that emplacement of pre- and intra-mineral porphyry was con-t r o l l e d by gently to moderately dipping tensional f i s s u r e s produced by two successive periods of subsidence of the stock. A simple regional i n t e r p r e t a t i o n of other struc-tures, including f o l i a t i o n , shear and breccia zones and f a u l t s developed during Periods-I to -III deformation and tensional f i s s u r e s that controlled emplacement of post-mineral porphyry and late dykes, i s possible through a p p l i c a t i o n of a combined stress and s t r a i n e l l i p s o i d diagram (Figure 13) because of the following s t r u c t u r a l features: 1) Development of Periods - 1 to III deformation and tensional f i s s u r e s have involved regeneration i n type and o r i e n t a t i o n of structures; 2) Conjugate structures developed for a l l types of deformation, though both sets of these structures were not equally developed; 3) Compressional forces that caused shearing and f a u l t i n g were probably directed at right angles to tensional forces that produced f i s s u r e s . The t h i r d s t r u c t u r a l feature, l i s t e d above, should be c l a r i f i e d . It i s known that approximately Wl5°N and E 15°S directed tensional forces produced conjugate f i s s u r e s because the bisector of the l e a s t conjugate angle should be at right angles to the directions of tensional forces. The o r i e n t a t i o n 7 3 of compressional forces that caused shearing and f a u l t i n g i s not known. However, the estimated average l e a s t angle of difference between conjugate shear structures i s 70° f o r which the bisector, and therefore the d i r e c t i o n of compressional forces, roughly trends at r i g h t angles to the d i r e c t i o n of ten-sional forces. Figure 1 3 shows the directions of maximum compres-sional and tensional forces plus the trends and conjugate angles of structures i n r e l a t i o n to a combined stress and s t r a i n e l l i p s o i d . Compressional and tensional forces, related i n the above described manner and as shown on Figure 1 3 , can be resolved from l e f t or r i g h t l a t e r a l r o t a t i o n a l forces, respectively directed roughly northeast-southwest or north-west -southeast. They are believed to have been resolved from r i g h t l a t e r a l r o t a t i o n a l forces because of the following l i s t e d features: 1 ) N 3 0°W and S30°E directed r i g h t l a t e r a l r o t a t i o n a l forces are approximately p a r a l l e l to the trend of the West Kettle River f a u l t zone which undoubt-edly was active p r i o r to and a f t e r emplacement of the quartz monzonite stock; 2) A genetic r e l a t i o n s h i p between structures and the West Kettle River f a u l t zone i s strongly indicated because a l l structures terminate or become less well developed towards the southwest away from the f a u l t zone. Therefore, i t i s suggested that both compressional and tension-a l structures are g e n e t i c a l l y related to periodic r i g h t l a t e r a l r o t a t i o n a l deformation produced by right l a t e r a l s t r i k e - s l i p movements along the West Kettle River f a u l t zone. Periods of Approximate trend of the West Kettle River f a u l t zone \\\ Assumed di r e c t i o n of r e l a t i v e \ movement Probable d i r e c t i o n of maximum' compression producing Periods \ -I to III shearing and ^ f a u l t i n g Direction of r o t a t i o j/ forces \ V Direction of maximum tension producing fissures c o n t r o l l i n g post-mineral porphyry and late dyke s \ NOTE: \ Predominant and less predominant^ trends of shearing and fault i n g , and of fissures for post-mineral porphyry are shown. / FIGURE 13: COMBINED STRESS AND STRAIN ELLIPSOID DIAGRAM FOR STRUCTURES OF REGIONAL ORIGIN r o t a t i o n a l deformation must have been resolved, at d i f f e r e n t times, into compressional or tensional forces. 76 CHAPTER IV HYDROTHERMAL ALTERATION AND MINERALIZATION DEFINITIONS AND FIGURES The terms s l i g h t , weak, moderate, intense and very intense are used i n subsequent sections i n order to quantify degrees of wallrock a l t e r a t i o n . These terms are defined i n Table X as ranges of percent replacement of one or more host minerals by a p a r t i c u l a r type of wallrock a l t e r a t i o n product or products.. Most of the s i g n i f i c a n t types of wallrock a l t e r a -t i o n including a r g i l l i z a t i o n , K-feldspathization, a l b i t i z a t i o n , and p r o p y l i t i z a t i o n , are quantified by thi s method. In some cases, above terms are used to quantify degree of replacement of host minerals by two or more types of wallrock a l t e r a t i o n . Degrees of s i l i c i f i c a t i o n are c l a s s i f i e d d i f f e r e n t l y . That i s , weak and intense degrees of s i l i c i f i c a t i o n are c l a s s i f i e d ^ respectively, as approximately up to 10$ increase i n t o t a l quartz content i n rocks and from $0% to 90% t o t a l quartz content i n rocks. Degrees of wallrock a l t e r a t i o n were mapped i n the f i e l d but precise ranges reported were determined from th i n sections. 77 Degree of Wallrock A l t e r a t i o n Ve ry Sl i g h t Weak Moderate Intense Intense Approximate Range of percent Replace-ment of Host Mineral 10$ 10-25$ 26-50$ 51-90$ 90$ or Minerals TABLE X: D e f i n i t i o n of Degrees of Wallrock A l t e r a t i o n Periods-I and -II structures each controlled a phase ( i e . Phase-I and -II, respectively) of wallrock a l t e r a t i o n and mineralization. Rocks affected by Phase-I wallrock a l t e r -ation and mineralization occur widespread and include granodior-i t e , the quartz monzonite stock and pre-mineral porphyry r o o f - s i l l and related dykes. Phase-II wallrock a l t e r a t i o n and mineralization l o c a l l y affected above rocks and i n t r a -mineral porphyry. Phase-I altered and mineralized rocks occur much more widespread than Phase-II, and also are much! more important because of associated molybdenite. Features of Phase-I, i n c l u d -ing "periperal s h e l l " and "central zone" of wallrock a l t e r a t i o n , f i e l d s of hematite-magnetite-pyrite, pyrite and molybdenite mineralization and zones of quartz vein stockworks, are shown on Figures 7 and 8 . Also shown on these figures are s i m p l i f i e d geology, peripheral Intensely fractured zones and young f a u l t s . Shown along DDH's on sections (Figure 8) are zones of intense s i l i c i f i c a t i o n and zones of moderate to intense K-feldspathization. 78 Also shown along DDH's are zones assaying . 0 1 $ or more M0S2 and zones heavily mineralized with hematite and magnetite. Features of both Phase-I and -II a l t e r a t i o n and mineralization are grouped together on Figures 7 and 8 because features of Phase-II do not a l t e r , i n any s i g n i f i c a n t way, the features of Phase-I. Regions characterized by Phase-II a l t e r -ation and mineralization are l a b e l l e d on figures ( i e : near bottoms of DDH's 3 and 1L). Intra-mineral porphyry i s not shown on Figures 7 and 8 , even though i t was affected by Phase-I I , because i t i s desirable to show only the geological setting during Phase-I. Both on surface and along DDH's, features of wal l -rock a l t e r a t i o n and mineralization appear very discontinuous. However, features are act u a l l y quite continuous within host rocks since they are not projected across dykes and/or s i l l s younger than phases of a l t e r a t i o n and mineralization. INTRODUCTORY SUMMARY A region of sheared, a r g i l l i z e d and feldspathized granodiorite fringes the map-area on the west and south (Figures 5 and 6). The age of deformation and a l t e r a t i o n of granodiorite within t h i s region i s believed to be pre-quartz monzonite. Two younger phases ( i e : Phase-I and Phase-II) of hydrothermal a l t e r a t i o n and mineralization have occurred intermittent to emplacement of porphyries. These phases are 79 discussed below. Pa r t l y overlapping the altered and sheared region i n granodiorite i s a large zoned wallrock a l t e r a t i o n and mineralization halo centered within the quartz monzonite stock (Phase-I hydrothermal.; a l t e r a t i o n and mineralization; see Figures 7 and 8). A l t e r a t i o n and mineralization has affected the porphyry r o o f - s i l l and older rocks, and was controlled by Period-I structures. The a l t e r a t i o n halo has an indicated e l l i p s o i d a l shape that i s elongated i n a northeast -southwest d i r e c t i o n . It i s up to 9,i|00 feet long and up to 6,900 feet wide. Wallrock a l t e r a t i o n t y p i c a l l y i s pervasive, though commonly i s more intense along fractures and within l o c a l shear and breccia zones. A l t e r a t i o n consists mainly of a r g i l l i z a t i o n , K-feldspathization, s i l i c i f i c a t i o n , a l b i t i z a t i o n and p r o p y l i t i z a t i o n . The a l t e r a t i o n halo i s sub-divided into a "peripheral s h e l l " of weak to moderate degrees of wallrock a l t e r a t i o n , and a "central zone" of intense to very intense degrees of wallrock a l t e r a t i o n . The "central zone" i s located c e n t r a l l y within the a l t e r a t i o n halo. It trends northeasterly and i s shaped l i k e an elongate e l l i p s o i d with i t s shorter axis v e r t i c a l or t i l t e d s l i g h t l y to the southeast. At the surface, the zone i s 5 A 0 0 feet long and up to 1,700 feet wide. It widens at depth to an indicated maximum width of up to 2,300 feet, and has a v e r t i c a l range of up to 1 ,050 feet from the present l e v e l of erosion. On surface within the "peripheral s h e l l " , the degree of a r g i l l i z a t i o n increases towards the 80 "central zone". The "central zone" i s divided into an upper and lower part; based on d i s t r i b u t i o n of secondary hydromica, potash feldspar and quartz. These parts are named respect-i v e l y , "quartz-hydromica sub-zone" and "quartz-potash feldspar sub-zone". Quartz veining occurs widespread i n the upper sub-zone but occurs only i n l o c a l zones i n the lower sub-zone. The "quartz-potash feldspar sub-zone" grades downwards into u n s i l i -c i f i e d rocks of the "peripheral s h e l l " . Sulphide and/or oxide minerals (Phase-I) occur throughout, and la r g e l y confined to, the a l t e r a t i o n halo. They mainly include specular hematite, magnetite, p y r i t e , molybdenite and minor Zn, Pb, Cu sulphides i n decreasing order of abundance. These minerals occur predominantly along fractures. Lesser amounts occur i n quartz veins, along shear and breccia zones and disseminated. D i s t r i b u t i o n of sulphide (pyrite) and oxide (hematite-magnetite-pyrite) mineral assemblages i s zonally arranged and s p a t i a l l y related to wallrock a l t e r a t i o n zones. That i s , pyrite occurs i n a region having the form of a sou t h e a s t e r l y - t i l t e d mushroom with i t s stem occurring through-out much of the "central zone" and cap spreading l a t e r a l l y from below the upper part of the "central zone". At the present l e v e l of erosion, the p y r i t e cap l a r g e l y i s l i m i t e d to the southern portion of the "peripheral s h e l l " and adjoin-ing "central zone". The py r i t e region i s referred to as the "sulphide f i e l d " . Associated hematite, magnetite and pyr i t e occur l a t e r a l l y about the pyrite stem, below the p y r i t e 81 cap. This region i s referred to as the "oxide f i e l d " . Molybdenite occurs mainly within that portion of the "central zone" l y i n g within the "sulphide f i e l d " . This region i s r e f e r -red to as the "molybdenite zone". Phase-II a l t e r a t i o n and mineralization includes 1) pervasive a l t e r a t i o n and r e l a t i v e l y sparse mineralization that i s confined l a r g e l y to intra-mineral porphyry s i l l s and dykes and 2) zones of intense a r g i l l i z a t i o n and s i l i c i f i c a t i o n c ontrolled by Period-II structures, p a r t i c u l a r l y at depth near bottoms of DDH's 3 and l i . Wallrock a l t e r a t i o n products consist mainly of s e r i c i t e , quartz and c a l c i t e . Open space f i l l i n g s of Pe, Zn, Pb, Cu and Mo sulphides, i n decreasing order of abundance, and c a l c i t e , f l u o r i t e , s e r i c i t e and quartz are associated with Phase-II wallrock a l t e r a t i o n . REGIONALLY ALTERED GRANODIORITE The sheared and altered region of granodiorite, along the western and southern portions of the map-area, has been b r i e f l y discussed under "Regionally Sheared Granodiorite" (Figures 5 and 6). Within this region, wallrock a l t e r a t i o n i s l a t e r a l l y zoned inwards and rocks show corresponding gradual megascopic changes. Altered and intergranular-sheared g r a n i t i c rock generally retains a poor megascopic medium-grained hypidio-raorphic texture. In outermost regions,rocks consist of dark-pink feldspar and lesser amounts of grey-to pale-green feldspar 82 and quartz. Inwardly, with respect to the edge of the map-area, rocks contain increasing amounts of altered pale-green feldspar. Innermost regions commonly do not contain any dark-pink K-feldspar. A completely altered mafic mineral i s present throughout the region and commonly appears to have had a p r i s -matic habit t y p i c a l of hornblende. Three a l t e r a t i o n zones are recognized. They consist of an outer pink zone, a wide mixed zone and a narrow, inner green zone. One t h i n section was studied from each character-i s t i c a l t e r a t i o n zone. A l l showed a remnant medium-grained hypidiomorphic texture, s i m i l a r to granodiorite, with pronounced intergranular shearing and b r e c c i a t i o n . Grey feldspar consists of stress twinned and bent laths of secondary a l b i t e (approx. An^) completely replacing primary plagioclase laths i n a l l zones. However, mixed and green zones show some remnants of primary, zoned, more c a l c i c plagioclase. Pink feldspar i s secondary K-feldspar with a negative optic angle of approxi-mately 6 0 °and birefringence of . 0 0 5 or l e s s . It occurs abundantly i n the pink zone as pseudomorphs after primary i n t e r -s t i t i a l and p o i k i l i t i c grains of orthoclase. K-feldspar undoubtedly has replaced some plagioclase because of i t s abund-ance i n the pink zone. It i s not as abundant i n the mixed zone; and i n the green zone, K-feldspar i s e n t i r e l y primary l i g h t colored orthoclase. Hydromica and c a l c i t e replace a l l feldspars i n increasing degrees towards the inner edge of the region. The prismatic mafic mineral i s altered completely to 8 3 c h l o r i t e and epidote with Increasing amounts of associated hydromica inwardly. Minor disseminated accessory magnetite and apatite occur throughout the region. Epidote, mauve and green f l u o r i t e , c a l c i t e , c h l o r i t e and l o c a l l y c a s s i t e r i t e (recognized i n one thi n section) com-monly occur along fractures and shears. Granodiorite showing s i m i l a r a l t e r a t i o n as described above, though commonly less intense, also occurs l o c a l l y i n the f a r northeastern portion of the map-area. These altered areas of granodiorite l i e outside the younger Phase-I a l t e r a t i o n halo. Discussion It was suggested previously (see "Regionally Sheared Granodiorite) that the sheared and altered region of granodior-i t e was due to int r u s i v e e f f e c t s of b a t h o l i t h i c V alhalla Intrusions occurring outside the map-area to the west and south. The zonal d i s t r i b u t i o n of a l t e r a t i o n products within the sheared and altered region suggests that either the move-ment of hydrothermal f l u i d s was directed l a t e r a l l y inwards from the west and south because more highly feldspathized rocks should l i e closer to the source magma; or inwardly decreasing temperature gradients from the west and south were present because fe l d s p a t h i z a t i o n normally requires higher temperatures than a r g i l l i z a t i o n (6,7>9). Either s i t u a t i o n i s consistent with the above suggestion. 814-It can only be concluded that both the shearing and hydrothermal a l t e r a t i o n of granodiorite along the west and south periphery of the map-area are related g e n e t i c a l l y to a batho-l i t h i c mass of V a l h a l l a Intrusions that occurs outside the west-ern and southern l i m i t s of the map-area. PHASE-I; MAIN PHASE OF ALTERATION AND MINERALIZATION Relationship Between Structure, Wallrock A l t e r a t i o n and Mineralization Period-I fractures and l o c a l shear and breccia zones have controlled Phase-I a l t e r a t i o n and mineralization. Fract-ures have been the main avenues of f l u i d movement throughout the a l t e r a t i o n halo for the following reasons: 1) Absence of f i s s u r e s and only l o c a l shear and breccia zones; 2) Fractures controlled quartz veining; 3) Fractures l a r g e l y controlled deposition of sulphide and oxide minerals and associated gangue minerals; li) Selvages of more intense wallrock a l t e r a t i o n commonly occur along fractures; 5) The outer edge of the a l t e r a t i o n halo cl o s e l y corresponds to the outward l i m i t s of s i g n i f i c a n t f r a c t u r i n g ; Hydrothermal f l u i d s must have ascended i n the region of the "central zone" of wallrock a l t e r a t i o n for the following reasons: 1) The "central zone" i s by f a r the largest region present of intense wallrock a l t e r a t i o n ; 85 2) Intensity of f r a c t u r i n g within a large portion of the "central zone" of wallrock a l t e r a t i o n i s simi l a r to that i n peripheral "intensely fractured zones" though these commonly are regions of only weak to moderate wallrock a l t e r a t i o n s ; 3) The " f o l i a t e d shear zone" (Figure 9) l a r g e l y i s s p a t i a l l y coincident with the "central zone of a l t e r a t i o n . It i s concluded that the " f o l i a t e d shear zone" directed hydro-thermal f l u i d s upwards. Fluids must have spread upwards and outwards, predominantly along fractures, from the upper part of the " f o l i a t e d shear zone". Surface Oxidized Zone Altered and mineralized rocks exposed within the a l t e r -ation halo are gossaned. Varying degrees of oxidation and hydration of p y r i t e , hematite and magnetite to yellow to reddish-brown limonite i s present to depths of 15 to 25 feet. Pyrite has been most attacked by surface weathering. Assays f o r MoS£ and t o t a l Mo from PSH's 1 to 3 indicate p a r t i a l oxidation and removal of molybdenite also to depths of 15 to 25 feet. Molybdenite occurs sparsely i n outcrops. Surface samples nearly always assay .01 or .02$ MoS2. In PSH's, molybdenite becomes more abundant within a few feet of the surface and MoS£ assays commonly average .03 to .06$ (Table XIV). Therefore, s i g n i f i c a n t s o l u t i o n and removal of molybdenite must have occurred to depths of a few feet. F e r r i molybdite r a r e l y was recognized. Some th i n sections show a yellow mineral that may 86 be j a r o s i t e and l o c a l l y a yellow, hexagonal, platy mineral that may be wulfenite. Black manganese s t a i n (Probably pyrolusite) commonly occurs i n minor amounts coating fractures i n a l l acid rock types and coating quartz phenocrysts i n porphyry throughout the "peripheral s h e l l " of wallrock a l t e r a t i o n . Locally i t occurs abundantly coating outcrops of granodiorite near PSH5. Manganese staining i s lacking within the "central zone" except for i t s presence i n post-mineral porphyry. Wallrock A l t e r a t i o n Apart from wallrock a l t e r a t i o n , fracture f i l l i n g s (except f o r quartz veins) also are discussed i n subsequent sections. Peripheral S h e l l The "peripheral s h e l l " i s a thick s h e l l characterized by weak to moderate degrees of wallrock a l t e r a t i o n . I t compl-et e l y surrounds a northeasterly-trending "central zone" of more intense wallrock a l t e r a t i o n . The l a t e r a l outer l i m i t s of the s h e l l show close correspondence to the d i s t r i b u t i o n of pre-mineral porphyry. Within the s h e l l , wallrock a l t e r a t i o n i n exposed rocks l a r g e l y i s of a d i f f e r e n t type from that at depth towards the bottoms of DDH's. The "peripheral s h e l l " at depth i s discussed under the section "Central Zone". 87 Altered rocks include granodiorite, quartz monzonite and pre-mineral porphyry. A r g i l l i z a t i o m a n d p r o p y l i t i z a t i o n are the predominant types of wallrock a l t e r a t i o n . Exposed rocks t y p i c a l l y are pervasively bleached white. They commonly show primary textures. The white bleaching i s due to weak to moderate a r g i l l i z a t i o n of plagioclase i n a l l rock types and of the groundmass i n the porphyry r o o f - s i l l . Primary pink potash feldspars commonly are fresh or s l i g h t l y to weakly a r g i l l i z e d i n a l l rocks. Mafic minerals commonly are completely a r g i l l i z e d and/or c h l o r i t i z e d . They generally have a pale green color. In the outer portions of the "peripheral s h e l l " (up to approximately 500 feet from the edge of the a l t e r a t i o n halo), a l l rocks commonly are pale-greenish colored and grade outwards into fresh rocks and inwards into white, a r g i l l i z e d rocks. The pale green coloration i s due to the color of the a r g i l l i c mineral replacing plagioclases along with more predominant c h l o r i t e a l t e r a t i o n of b i o t i t e i n porphyry and quartz monzonite, and c h l o r i t e and epidote a l t e r a t i o n of hornblende i n granodio-r i t e . Degree, of a r g i l l i z a t i o n of both feldspars and mafics increases towards the "central zone" and towards small l o c a l zones within the "peripheral s h e l l " characterized by moderate to l o c a l l y intense a r g i l l i z a t i o n of feldspars and mafics. The largest of these zones roughly i s centered about "intensely fractured zone-7"• 88 Many of the fractures within the "peripheral s h e l l " have l i g h t colored a l t e r a t i o n selvages. Some selvages are not recognized e a s i l y i n hand specimen. Selvages are more common nearer to the "central zone", p a r t i c u l a r l y i n the southern por-t i o n of "intensely fractured zone -5 " where they commonly are pale-green. Selvages commonly have i r r e g u l a r outer edges and range up to a t o t a l width of inch. They show rapidl y Increas-ing degrees of a r g i l l i z a t i o n of feldspars towards fr a c t u r e s . Local shear and breccia zones, to the north of the"central zone", are intensely a r g i l l i z e d and s i l i c i f i e d across widths ranging from a few feet to 10 fe e t . Also, smaller sheared and granulated zones, up to a few inches wide, show si m i l a r a l t e r a t i o n . They occur more widespread, associated with f r a c t u r i n g , and l i k e l y grade into fractures. In t h i n section, remnant plagioclase i n porphyry and quartz monzonite nearly always i s clouded a " d i r t y " yellowish-brown; probably due to oxidation of contained i r o n . In a l l rocks, plagioclase i s altered to f a i r l y evenly dispersed very f i n e hydromica that occurs as plates and mattes. Plates of hydromica commonly occur along cleavages. The more c a l c i c plagioclase i n granodiorite occasionally shows more a l t e r a t i o n i n cores or certa i n composition zones. Weakly a r g i l l i z e d K-feldspars i n a l l rocktypes are altered p a r t i c u l a r l y along cleavages and discontinuous fractures to hydromica. B i o t i t e i n porphyry and quartz monzonite shows secondary plates of green pleochroic c h l o r i t e that i s replaced i n increasing degrees to plates of hydromica towards the "central zone". Hornblende i n granodiorite i s altered completely to plates of c h l o r i t e with disseminated epidote i n the outer portion of the s h e l l , and shows increasing degrees of replacement to hydromica, without epidote, towards the "central zone". Pyrite occurs disseminated i n granodiorite p a r t i c u l a r l y associated with secondary minerals that replace hornblende within the "sulphid f i e l d " . Hematite, magnetite and pyrite s i m i l a r l y occur i n granodiorite within the "oxide f i e l d " . The groundmass i n porphyry commonly contains minor disseminated, very small, microscopic patches of associated magnetite, p y r i t e , c h l o r i t e , hydromica, quartz and/or c a l c i t e . Also, the porphyry ground-mass shows evenly disseminated hydromica p a r t i a l l y replacing a l k a l i feldspar. Disseminated secondary magnetite i n porphyry commonly occurs as complete to p a r t i a l replacement of some of the accessory and/or secondary pyrite within the "oxide f i e l d " A l l hydromica has si m i l a r o p t i c a l properties, even i n more intensely a r g i l l i z e d fracture selvages. It shows colorless to very pale-green pleochroism, good cleavage, low po s i t i v e r e l i e f and moderate birefringence, and has a very low optic angle (less than 5°)« Fracture F i l l i n g s Fractures commonly contain variable amounts of hema-t i t e , magnetite and/or pyrite with associated quartz and hydro mica. Also, epidote and c h l o r i t e occur along fractures p a r t i -c u l a r l y i n outer portions of the "peripheral s h e l l " . Minor f l u o r i t e and c a l c i t e occur l o c a l l y along fract u r e s . Fracture f i l l i n g s commonly are up to 1/16" wide, though many of the f i l l i n g s are up to \ " wide i n "intensely fractured zones-1 to -8". Central Zone The "central zone" i s characterized by Intense to very intense degrees of wallrock a l t e r a t i o n . Types of a l t e r a -t i o n mainly include a r g i l l i z a t i o n , potash-feldspathization, a l b i t i z a t i o n and s i l i c i f i c a t i o n . The "central zone" can be c l a s s i f i e d as a " s i l i c e o u s " region. Its upper part i s weakly s i l i c i f i e d pervasively and contains widespread stockwork quartz veining and numerous zones of intense s i l i c i f i c a t i o n whereas i t s lower part only contains zones of weak or intense s i l i c i f i c a t i o n and zones of stockwork quartz veining. Within the "central zone", regions of pervasive a r g i l l i z a t i o n or potash-feldspathization of primary feldspars respectively, l a r g e l y occur conformable with the upper and lower parts of the " s i l i c e o u s " region. Therefore, the "central zone" i s sub-divided into an upper "quartz-hydromica sub-zone" and a lower "quartz-potashfeldspar sub-zone". The upper sub-zone l a r g e l y i s l imited to the granodiorite capping and underlying porphyry r o o f - s i l l . It occurs throughout the exposed portion of the "central zone" to depths of up to ij.00 feet and overlaps the lower "quartz-potash feldspar sub-zone" by as much as 150 f e e t . The "quartz-potash feldspar sub-zone" only occurs at depth. It was intersected i n a l l DDH's and occurs to depths of up to 91 1050 f e e t . It mainly occurs within the quartz monzonite stock but i s also present i n pre-mineral porphyry dykes i n DDH 1 and s i l l s i n DDH 2. Upper Quartz-Hydromica Sub-Zone Within the "quartz-hydromica sub-zone" both granodio-r i t e and porphyry commonly show remnant primary textures. However, because a l t e r a t i o n i s often so intense, remnants of less altered rock must be found i n the f i e l d i n order to ident-i f y the rock type with assurance. Granodiorite commonly has a mottled medium-grained texture and shows white to pale-green intense a r g i l l i c a l t e r a -t i o n of feldspars and hornblende (Plate l i x ) . Intensely s i l i c i -f i e d granodiorite i s grey i n color and commonly has a s l i g h t l y mottled texture due to remnants of a r g i l l i z e d feldspars and hornblende. Locally, either the clay mineral replacing plagioclase or remnant plagioclase i s a bright pinkish color due to "clouding" by i r o n oxides. This "clouding" i s probably due to weathering since i t does not occur i n d r i l l holes, except l o c a l l y within the near surface oxidized zone. Porphyry t y p i c a l l y shows white a r g i l l i z e d feldspars i n a grey s i l i c e o u s groundmass. Intensely s i l i c i f i e d zones contain less amounts of white a r g i l l i z e d f e l d s p a r . Remnant primary pink orthoclase i s present l o c a l l y i n granodiorite and large pink to white, a r g i l l i z e d sanidine phenocrysts commonly are recognizable i n porphyry. A l l feldspars are completely altered i n more intensely a r g i l l i z e d 92 and/or s i l i c i f i e d rock. Mafic minerals generally are i n d i s t i n c t . The "quartz-hydromica sub-zone" i s characterized by pervasive, intense to very intense replacement of plagioclases and mafics and moderate to intense replacement of potash feldspars by mattes, plates and cleavage controlled seams of hydromica. The o p t i c a l properties of hydromica and replacement textures are the same as i n the "peripheral s h e l l " ; though hydromica commonly i s s l i g h t l y more coarse grained i n the "central zone". Some secondary quartz (up to 10%) commonly i s associated with hydromica that replaces feldspars. Remnant unaltered a l b i t e i n porphyry i s always "clouded" i n t h i n section to a yellowish-brown; i d e n t i c a l l y to that i n the "peripheral s h e l l " . Altered b i o t i t e i n porphyry often has minor associated c a l c i t e , p y r ite and specks of leucoxene (?). Altered hornblende i n granodiorite commonly has minor associa-ted p y r i t e , quartz and leucoxene (?). Many fractures have a l t e r a t i o n selvages up to a t o t a l width of 1 inch (plate II4.). Selvages consist of more intensely a r g i l l i z e d feldspars with variable amounts of associated secondary quartz. Some of the quartz veins, d i s -cussed l a t e r i n d e t a i l , l a t e r a l l y grade into intensely altered wallrocks. Zones of intense s i l i c i f i c a t i o n are common. They contain $0 to 90$ fin e grained, granular quartz with associated remnants of a r g i l l i z e d feldspars and mafics. They range greatly i n widths from narrow fracture controlled zones to 11x5 feet 93 wide. Zones are commonly 10 to 60 feet wide (zones 5 feet wide, or more, are shown on ^igure 8 ) . Pyrite and minor f l u o r i t e occur disseminated through-out the "quartz-hydromica sub-zone". Also, minor molybdenite, sphalerite and galena occur disseminated but appear largely l i m i t e d to the "sulphide f i e l d " of mineralization. Overlap of Sub-Zones Core from DDH's 3 and l\. showed that the "quartz-hydromica sub-zone" overlaps the "quartz-potash feldspar sub-zone" by approximately 150 f e e t . Rocks i n the overlap include porphyry and quartz monzonite. They show secondary pinkish-red potash feldspar occurring as f i l l i n g s or selvages along some fractures, as pervasive p a r t i a l replacement of the plagioclases and as i r r e g u l a r , pervasive a p l i t i c patches with associated quartz replacing groundmasses and some feldspar phenocrysts. K-feldspathized rocks show l a t e r crosscutting fractures with hydromica and quartz selvages and show some pervasive a r g i l l i z a t i o n and s i l i c i f i c a t i o n of primary feldspars and secondary potash-feldspars (Plate 15) . Also, minor c a l -c i t e a l t e r a t i o n of sanidines commonly occurs i n the overlap region. Hydromica a l t e r a t i o n shows rapid t r a n s i t i o n into pre-dominantly potash-feldspar a l t e r a t i o n at the base of the "quartz-hydromica sub-zone". Overlap of sub-zones also i s present on surface near the eastern end of the "central zone". Here, K-feldspathization, a r g i l l i z a t i o n and s i l i c i f i c a t i o n are a l l present i n the quartz monzonite stock. Secondary K-feldspar 9 ^ only occurs l o c a l l y elsewhere i n the "quartz-hydromica sub-zone" and always shows varying degrees of replacement to quartz and hydromica. Secondary a l b i t e , c h a r a c t e r i s t i c of the "quartz-potash feldspar sub-zone", was recognized i n only one t h i n section of granodiorite from the "quartz hydromica sub-zone". Fracture F i l l i n g s Fracture f i l l i n g s within the "quartz-hydromica sub-zone" are up to 1/16" wide. They commonly consist of associated hydromica-quartz-pyrite i n decreasing order of abundance, gener-a l l y with minor amounts of associated c a l c i t e and/or f l u o r i t e . (mauve and green). Minor molybdenite, sphalerite and galena also occur along fractures with these gangue minerals but are l a r g e l y confined to the "sulphide f i e l d " of mineralization. Hematite and magnetite occur along fractures with the same gangue minerals i n the eastern portion and along part of the northwestern fringe of the "quartz-hydromica sub-zone" within the "oxide f i e l d " of mineralization. Lower Quartz-Potash Feldspar Sub-Zone Within the "quartz-potash feldspar sub-zone", quartz monzonite generally i s recognizable since i t commonly shows primary te x t u r a l features including feldspar and quartz pheno-crysts, green plates of altered b i o t i t e and a fine-grained, commonly pinkish-red granular groundmass; or shows f o l i a t i o n i n varying degrees. Occasionally, pre-mineral porphyry i s d i f -f i c u l t to d i s t i n g u i s h from quartz monzonite, e s p e c i a l l y where both rock types are f o l i a t e d . However, porphyry can generally 95 be distinguished since i t s groundmass i s t y p i c a l l y aphanitic, l i g h t colored and siliceous-appearing. Wallrock a l t e r a t i o n of quartz monzonite i s character-ized by weak to commonly moderate to intense degrees of replacement of plagioclase phenocrysts by pinkish-red potash feldspar. Degree of K-feldspathization tends to decrease with depth. Remaining plagioclase nearly always consists of micro-s c o p i c a l l y " d i r t y " , clouded yellowish-brown pseudomorphs of secondary a l b i t e with variable but commonly minor amounts of associated plates and mattes of hydromica ( o p t i c a l properties same as i n "quartz-hydromica sub-zone"). In hand specimen, a l b i t i z e d and a r g i l l i z e d plagioclase i s white to pale-green colored and often subhedral. It amounts to 10 to 35$ of the rock depending upon the degree of K-feldspathization. In t h i n section, secondary K-feldspar occurs as clear to very " d i r t y " or black-clouded, f i n e - t o medium-grained, i r r e g u l a r grains and aggregates replacing plagioclase phenocrysts inwards from edges of c r y s t a l s . Secondary K-feldspar i s s i m i l a r o p t i c a l l y to primary sanidine. That i s , i t has a negative optic angle of approximately 30°to 50°and a birefringence lower than that c h a r a c t e r i s t i c of orthoclase. H a i r l i n e fractures are com-monly f i l l e d with segmented quartz and potash feldspar with minor associated p y r i t e . Potash feldspar i s p r e f e r e n t i a l l y deposited where fractures cross plagioclase phenocrysts. Also, these fractures commonly have microscopic, discontinuous selvages of secondary K-feldspar that are confined to 96 phenocrysts of plagioclase. Other fractures, recognizable i n hand specimen and l o c a l l y common i n zones of lesser degrees of K-feldspthization, consist of zones up to 1 / V wide of very fine-grained secondary K-feldspar that replace plagioclase phenocrysts and the groundmass. In more intensely K-feldspthi-zed zones, secondary K-feldspar also l o c a l l y occurs pervasively i n the groundmass i n varying degrees probably due to r e c r y s t a l -l i z a t i o n of primary sanidine and replacement of quartz. Locally, a p l i t i c patches and i r r e g u l a r v e i n l e t s consisting of secondary K-feldspar and quartz occur i n the groundmass. Primary phenocrysts of sanidine commonly appear fresh and pinkish-red colored. In t h i n section, these show l o c a l re-c r y s t a l l i z a t i o n to fine-grained secondary potash feldspar. Locally, sanidine phenocrysts are p a r t l y to completely cream colored due to a r g i l l i z a t i o n . In t h i n section, primary and secondary potash feldspar (including K-feldspar i n the ground-mass) commonly are s l i g h t l y altered to hydromica and c a l c i t e . B i o t i t e commonly i s completely altered to pseudomorphous c h l o r i t e with associated hydromica and minor amounts of associated c a l -c i t e , specks of leucoxene (?) and f l u o r i t e . In the " f o l i a t e d shear zone", deformed quartz phenocrysts are r e c r y s t a l l i z e d , i n varying degrees, to fine-grained aggregates. A l t e r a t i o n of pre-mineral porphyry does not d i f f e r from that of quartz monzonite except that remnant a l b i t e i s either primary or simply r e c r y s t a l l i z e d . In hand specimen, secondary K-feldspar i s commonly cream to pale-pink colored 97 and generally was not recognized as secondary K-feldspar i n the f i e l d . Moderate to intense zones of K-feldspathization, shown on sections, were defined by the degree of pinkish-red colo r a t i o n i n diamond d r i l l core. However, the degree of K-feldspathization i n pre-mineral porphyry i s comparable to that i n quartz monzonite, and K-feldspathized zones should be considered to extend across porphyry within the "quartz-potash feldspar sub-zone". S i l i c i f i c a t i o n within the "quartz-potash feldspar sub-zone" occurs widespread. It i s only l o c a l l y intense i n zones commonly a few inches to ten feet wide (zones 5 feet wide, or more, are shown on sections) that mainly occur along shear and breccia zones. Also, wide shear and breccia zones i n DDH's 2 and 3 are intensely s i l i c i f i e d and contain abundant disseminated magnetite and lesser amounts of hematite and p y r i t e . Intense zones of s i l i c i f i c a t i o n contain 50 to 90$ f i n e grained granular quartz. These zones commonly contain i r r e g u l a r remnants of a r g i l l i z e d feldspar with lesser amounts of associated secondary K-feldspar. S i l i c i f i c a t i o n and quartz veining appear related since 1) highly broken l e s s - s i l i c i f i e d rock remnants within intensely s i l i c i f i e d zones are often r i d d l e d with quartz ve i n l e t s and 2) quartz veined zones often occur adjacent to intensely s i l i c i f i e d zones. Some quartz veins have associated seams of K-feldspar within and/or along edges of veins and l o c a l l y as a l t e r a t i o n selvages. Thinner quartz veins l o c a l l y grade into fractures mainly f i l l e d with K-feldspar. 98 Weak s i l i c i f i c a t i o n i s f a i r l y common but also tends to occur i n narrow zones or as i r r e g u l a r patches mixed with K-feldspa-thized rocks. S econdary quartz i n these zones or patches occurs as variable amounts of fine-grained granular grains i n the groundmass of porphyry and quartz monzonite i n amounts greater than that present i n primary groundmasses (probably amounts up to 10$ increase i n t o t a l quartz content of rocks). Altered rocks contain disseminated pyrite and very minor magnetite or molybdenite within the "sulphide f i e l d " of mineralization. Magnetite occurs more abundantly disseminated i n the "oxide f i e l d " of mineralization. Below the "quartz-potash feldspar sub-zone", within the"peripheral s h e l l " , degree of K-feldspathization i s only l o c a l l y moderate and i s commonly s l i g h t to weak. Here, second-ary K-feldspar occurs mainly along fractures and i n narrow zones. Plagioclase i n quartz monzonite nearly always i s com-p l e t e l y a l b i t i z e d with minor associated hydromica and c a l c i t e ; i d e n t i c a l to remnant plagioclase within the "quartz-potash feldspar sub-zone". A l t e r a t i o n of b i o t i t e , and clay and carbon-ate a l t e r a t i o n of primary and secondary K-feldspar are of s i m i l a r degrees and types as within the "quartz-potash feldspar sub-zone", though chlorite appears to be replacing b i o t i t e i n higher degrees at greater depths. Fracture F i l l i n g s Apart from quartz veins along some fractures and K-feldspar along microscopic h a i r l i n e to l o c a l megascopic f r a c -tures, the remainder of fractures have f i l l i n g s up to 1/16" 9 9 wide. F i l l i n g s consist of quartz, hydromica, c h l o r i t e , c a l c i t e and f l u o r i t e (mauve and green) i n decreasing order of abundance. Also present are traces of apatite and l o c a l k a o l i n i t e or K-feldspar. Commonly, fractures do not have recognizable s e l -vages i n hand specimen apart from pervasively K-feldspathized and/or s i l i c i f i e d wallrocks. Some fractures show secondary K-feldspar selvages i n t h i n section s i m i l a r to those along h a i r -l i n e fractures. P y r i t e , molybdenite and very minor amounts of sphalerite and galena occur mainly along above described f r a c -tures. Except f o r p y r i t e , the other sulphides l a r g e l y are lim i t e d to the "sulphide f i e l d " of mineralization. Hematite and magnetite also occur along these fractures, mainly within the "oxide f i e l d " of mineralization. Chlorite generally i s r e l a t i v e l y more abundant along fractures within the "peripheral s h e l l " below the "quartz-potash feldspar sub-zone". Above described mineralized fractures r a r e l y show crosscutting relationships with quartz veins or with fractures having f i l l i n g s or selvages of secondary K-feldspar. Therefore, wallrock a l t e r a t i o n , quartz veining and mineralization are i n d i -cated to have occurred contemporaneously. Local paragenetic i r r e g u l a r i t i e s are present within the "quartz-potash feldspar sub-zone". They are l i s t e d below. 1) K-feldspar r a r e l y was observed along fractures cutting intensely s i l i c i f i e d zones. 2 ) Zones of quartz veins cut intensely s i l i c i f i e d and hematite and magnetite mineralized rocks along DDH's 2 and 3 within the "oxide f i e l d " . 100 2) Continued -Both the s i l i c i f i e d and mineralized rocks and l a t e r quartz veins were associated with K-f e l d s p a t h i z a t i o n of wallrocks (see Type-IA veins i n section on "Quartz Veining"). 3) Molybdenite bearing fractures only r a r e l y cut quartz veins. The above paragenetic variations are not s i g n i f i c a n t . They undoubtedly are due to l o c a l r e - f r a c t u r i n g of rocks during Phase-I hydrothermal a c t i v i t y since younger fracture f i l l i n g s tend to show a regeneration of the same hydrothermal condi-tions at any given s i t e . These features are further discus-sed i n the subsequent section. Quartz Veining The d i s t r i b u t i o n and frequency of quartz veins was discussed i n the section "Period-I Fracturing and Quartz Veining". Apart from true quartz veins, two types of pseudo quartz v e i n l e t s are present that are not included with quartz vein frequencies or quartz veined zones shown on Figures 7 and 8. One type i s r e l a t i v e l y common and consists of lensoid to discontinuous ptygmatic seams, up to approximately 2 inches long and generally less than l / l i " wide, consisting of f i n e granular quartz. They only occur i n pre-mineral porphyry and quartz monzonite and are due to deformation and r e c r y s t a l l i z a -t i o n of o r i g i n a l quartz phenocrysts caused by the shear move-ments that produced Period-I f o l i a t i o n . The other type of 101 pseudo quartz vei n l e t s consists of i r r e g u l a r and discontinuous fine-grained quartz vei n l e t s r i d d l i n g l e s s - s i l i c i f i e d rock remnants within and adjacent to intensely s i l i c i f i e d zones (esp e c i a l l y associated with s i l i c i f i e d ^eriod-I shear and breccia zones shown alond DDH's 2 and 3)» True quartz veining i s r e l a t i v e l y unimportant since most molybdenite occurs along fract u r e s . However, some import-ant genetic conclusions can be drawn from t h e i r study. Quartz veins commonly range i n width from 1/8" to 1/2" and consist predominantly of fine-grained granular quartz. Three d i f f e r e n t types of veins occur within the "central quartz vein stock-work zone". One type of vein i s s i m i l a r to those occurring i n "fracture zone - 8 " . D i s t r i b u t i o n of types of veins i s re-lated s p a t i a l l y to the "oxide" or "sulphide" f i e l d s of minerali-zation, and to sub-zones of wallrock a l t e r a t i o n within the "central zone". Types of veins are l i s t e d and discussed i n Table X l . (See plates 16, 17 and 23 to 25) . 102 1) Banded Straight-Walled Veins Within the "Oxide F i e l d s " a) Sharp walled; some containing seams of potash feldspar and discontinuous seams of magnetite and/or disseminated p y r i t e ; probably f a i r l y continuous; located i n DDH's 2 and 3> see Plate 16 and 2l\. ( r i g h t ) . These veins have l o c a l very t h i n selvages of secondary potash feldspar and cut s i l i c i f i e d zones with associated r i d d l i n g of quartz v e i n l e t s , abundant disseminated magnetite and K-feldspathization and a r g i l l i z a t i o n of rock remnants. They also commonly cut magnetite and hematite mineralized zones where oxides occur mainly along fractures. b) Sharp walled veins i n "Fracture Zone - 8 " ; West Portion: veins contain abundant magnetite that occurs along borders and disseminated; commonly associated K-feldspar v e i n l e t s and selvages along quartz veins; associated fractures f i l -led with abundant magnetite and lesser amounts of quartz and K-feldspar also with l o c a l K-feldspar selvages; minor associated p y r i t e ; see Plate 2\\. and 25. Bast Portion: veins contain hematite and magnetite and have selvages of hydromica, probably with some secondary quartz; numerous fractures with hematite and magnetite, also with some selvages of hydromica; minor associated p y r i t e . 2) Continuous to Discontinuous Massive Veins within the "Sulphide F i e l d "  Variable from sharp to gradational walls and from continuous (up to 10 feet on surface) to discontinuous (6 inches to a few feet on surface); most common type of veins within the "sulphide f i e l d " ; some are pale-pinkish colored; commonly branching; r a r e l y show crosscutting relationships with other quartz veins or mineralized f r a c -tures commonly contain minor amounts of disseminated c a l c i t e , f l u o r i t e (colorless to green), hydromica, p y r i t e and traces of molybdenite; veins contain hematite and magnetite within those parts of the western fringe of the "central quartz vein stockwork zone" that l i e within the "oxide f i e l d " ; see Plate 17. 3) Banded Discontinuous Veins within the "sulphide f i e l d " a) Vuggy and often somewhat i r r e g u l a r ; r e l a t i v e l y common and occur only within the "quartz-hydromica sub-zone" ( p a r t i -c u l a r l y within the granodiorite capping); contain seams of quartz of d i f f e r e n t grain size with inwardly projecting 103 euhedral medium-grained quartz c r y s t a l s along portions of the center of veins; contain seams of hydromica and minor molybdenite; contain minor disseminated p y r i t e . b) Irregular; Contain good seams of molybdenite and abundant seams of hydromica with lesser amounts of associated c a l c i t e , f l u o r i t e (colorless to green) and p y r i t e ; l o c a l l y occur mixed with Type -2 veins; p a r t i c u l a r l y occur i n zones of s i g n i f i c a n t molybdenite mineralization ( i e : greater than .03% MoSg) that are s p a t i a l l y associated with quartz veined zones; veins of this type and Type -2 only occur l o c a l l y within the "oxide f i e l d " ; See Plate 23. Phase-I wallrock a l t e r a t i o n and mineralization can be drawn from the above c l a s s i f i c a t i o n of quartz veins and data given i n the section "Wallrock A l t e r a t i o n " . These conclusions are l i s t e d below: 1) Near surface environment during hydrothermal a c t i v i t y (indicated by the presence of vuggy veins which are li m i t e d to the "upper quartz-hydremica sub-zone") 2) Wallrock a l t e r a t i o n , quartz veining and mineral-i z a t i o n were contemporaneous. This i s indicated by the follow-ing features: TABLE XI - C l a s s i f i c a t i o n of Quartz Veins. Conclusions Three important genetic conclusions with respect to a) Veins respectively contain oxide and/or sulphide minerals depending on the f i e l d of mineralization i n which they occur; b) Some veins grade into altered wall-rocks and others have a l t e r a t i o n selvages of the same type as pervasive wallrock a l t e r a t i o n ; c) S p a t i a l association of more widespread quartz vein stockworks with the r e l a t i v e l y more intensely s i l i c i f i e d "quartz-hydromica sub-zone", and of zones of quartz vein stockworks with intensely s i l i c i f i e d zones within the "quartz-potash feldspar sub-zone"; 10k d) Mineralized fractures and quartz veins only r a r e l y show crosscutting r e l a t i o n s h i p s ; e) Mineralogy of fracture f i l l i n g s and quartz veins are s i m i l a r . 3 ) Local r e - f r a c t u r i n g of rocks during hydrothermal a c t i v i t y with regeneration of e a r l i e r type of hydrothermal con-d i t i o n s . (Indicated by paragenetic i r r e g u l a r i t i e s as given above under Type - I A and - 2 quartz veins and as l i s t e d under "Fracture F i l l i n g s " i n the section "Lower Quartz-Potash Feldspar Sub-Zone"). Mineralization Secondary sulphide and/or oxide minerals occur throughout, and lar g e l y confined to, the a l t e r a t i o n halo. These minerals include hematite (predominantly sp e c u l a r i t e ) , magnetite, p y r i t e , molybdenite, brown to black sphalerite, galena, chalco-p y r i t e , a platy t e l l u r i d e (?) and c a s s i t e r i t e i n decreasing order of abundance. They are predominantly fine-grained and occur mainly along fract u r e s . Lesser amounts occur disseminated or coating rock fragments i n shear and breccia zones, as part-i a l healing of narrow breccias, i n quartz veins and disseminated i n altered wallrocks. Associated gangue minerals along fractures and i n quartz veins were discussed, respectively, i n sections e n t i t l e d "Fracture F i l l i n g s " ( i n sections dealing with the "Peripheral S h e l l " and "Central Zone") and "Quartz Veining". A l t e r a t i o n selvages along fractures were discussed i n the sec-t i o n e n t i t l e d "Wallrock A l t e r a t i o n " . See Plates I i i , 1 5 and 1 8 to 2 8 . io5 "Oxide" and "Sulphide" f i e l d s of mineralization are defined on the basis of d i s t r i b u t i o n of hematite, magnetite and p y r i t e , and are characterized respectively, by the assemblage hematite-magnetite-pyrite and by p y r i t e . Boundaries between f i e l d s are shown on Figures 7 and 8 . The shape of f i e l d s and t h e i r r e l a t i o n s h i p to wallrock a l t e r a t i o n was discussed under "Introductory Summary" Rela t i v e l y sharp boundaries occur bet-ween f i e l d s . Only l o c a l l y does minor amounts of magnetite (less than 1/2$ across a few 10 's of feet) occur within the "sulphide f i e l d " . F i e l d s of mineralization are discussed i n d e t a i l i n following sections. Oxide F i e l d (Hematite-magnetite-pyrite) "Intensely fractured zones -1 to - 8 " and zones along DDH's 2 and 3 (including sheared and brecciated zones and highly fractured zones) are heavily mineralized with hematite and magnetite. These zones contain between 3 to 5$ oxide minerals ( l o c a l l y contain up to 10$ oxide minerals across widths up to 30 feet or more) and up to 1$ p y r i t e . Oxide minerals and minor pyrite are f a i r l y evenly d i s t r i b u t e d throughout the remainder of the "oxide f i e l d " and commonly amount to approxi-mately 1$ of rocks. Relative d i s t r i b u t i o n of hematite and magnetite i s i r r e g u l a r . Often eit h e r hematite or magnetite predominate i n highly fractured zones. Overall, both appear to be present i n roughly equal proportions. Minor chalcopyrite, malachite and azurite l o c a l l y 106 occur along fractures and disseminated, associated with oxide minerals and minor p y r i t e , to the northwest of Pault-C i n the contact region of quartz monzonite and pre-mineral porphyry with granodiorite. Locally, the estimated highest grade of copper mineralization present i s .$% across a few f e e t . Also, i n that part of the "oxide f i e l d " that l i e s within the "central zone" of wallrock a l t e r a t i o n , minor molyb-denite occurs with oxide minerals and pyrite along fractures adjacent to the "sulphide f i e l d " . Sulphide F i e l d (Pyrite) As described previously under "Introductory Summary", the "sulphide f i e l d " has the form: of a t i l t e d , mushroom. Its stem trends northeasterly at depth and occurs within and below the central to western portions of the "quartz-potash feldspar sub-zone". Its cap spreads l a t e r a l l y , l a r g e l y from below the upper "quartz-hydromica sub-zone", to the south, east and probably i n a l l other directions ( i e : i t i s inf e r r e d to have been eroded). The l i m i t of the stem i s not known at depth and i s open at the bottoms of DDH's 1 and i x . Pyrite (probably minor associated marcasite; included with estimates of % pyrite) occurs throughout the "sulphide f i e l d " . I t i s most abundant along the southern portion of the "quartz-hydromica sub-zone" and, up to at least 500 feet to the south from i t s edge, within the adjoining "peripheral s h e l l " . This region commonly contains 2 to 3>% pyrite to depths up to 107 at l east 210 feet ( i e . high pyrite content was found i n rocks to depths of 90 feet and 210 feet, respectively, i n DDH's 3 and 2 and to bottoms of PSH's li to 8 at depths of up to 106 f e e t ) . In t h i s region, p y r i t e occurs disseminated with lesser amounts along fractures and i n massive v e i n l e t s . Commonly 1/2 to 1$ p y r i t e i s present throughout the remainder of the "sulphide f i e l d " . Here i t occurs along fractures, disseminated and as minor amounts i n quartz veins. Apart from p y r i t e and gangue minerals, fractures within that part of the "sulphide f i e l d " that l i e s within the "central zone" commonly carry variable amounts of molybdenite, minor sphalerite and galena and traces of chalcopyrite, a microscopic platy, hexagonal t e l l u r i d e (?) and microscopic grains of c a s s i t e r i t e . These minerals also occur sparsely d i s -seminated. Surface chip samples, taken across widths of up to 75 feet, assayed as follows: Pb .05 to .10$ Zn °.15 to .20$ Cu trace to .20$ MoS2 .01 to .03$ These assays only show the approximate order of magni-tude of metal content because of processes of surface leaching, oxidation and hydration, and enrichment (see "Surface Oxidized Zone"). Sphalerite and galena occur widespread but are more abundant within the "quartz-hydromica sub-zone". They occur disseminated and along fractures i n roughly equal proportions. A l l sulphides, except for p y r i t e , appear subordinate i n abund-ance with respect to molybdenite i n d r i l l holes. 108 Molybdenite Zone On surface, d i s t r i b u t i o n of molybdenite i s confined to the western to east-central portion of the "central zone" that l i e s within the "sulphide f i e l d " , except for a s l i g h t overlap into the "oxide f i e l d " i n the eastern portion of the "central zone" (zone of molybdenite mineralization i s up to 14-300 feet long on surface). At depth, molybdenite occurs to the bottom of a l l DDH's beyond the l i m i t s of the "central zone" and "sulphide f i e l d " . However, d i s t r i b u t i o n of zones contain-ing s i g n i f i c a n t grades of molybdenite mineralizaion ( i e : .0lr$ M0S2 or more) la r g e l y are related s p a t i a l l y to that part of the "central zone" occurring within the "sulphide f i e l d " . This region defines the "molybdenite zone" and includes most of the western to central portions of the "central zone". Therefore, the "molybdenite zone" has a length of up to irOOO feet, i n a northeasterly d i r e c t i o n , and a width commonly ranging between 800 to 1000 feet on surface. It widens at depth to an indicated maximum width of up to 1800 feet and has a v e r t i c a l range of up to 1050 f e e t . Modes of occurrence of molybdenite are l i s t e d i n Table XII, i n decreasing order of importance. 109 1) Coatings along planar ( l o c a l l y serrate) fractures (associated with quartz, hydromica, p y r i t e , c a l -c i t e and f l u o r i t e i n decreasing order of abundance; associated c h l o r i t e i s also r e l a t i v e l y abundant along fractures within the "quartz-potash f e l d -spar sub-zone"); see Plates 111, 15 and 18 to 22; 2) Seams and disseminated i n banded discontinuous quartz veins (Type-3; Table XI) ;see Plate 23; 3) Disseminated i n continuous to discontinuous massive quartz veins (Type-2; Table XI); Ix) Coating angular to rounded rock fragments i n shear and breccia zones; see Plate 18; 5) Disseminated i n wallrocks. TABLE XII: Modes of Occurrence of Molybdenite Molybdenite i s always fine-grained and occurs as single plates and massive scales i n a l l modes of occurrence. A l l modes of occurrence often occur together or show close s p a t i a l associa-tions without crosscutting r e l a t i o n s h i p s . Within mineralized zones containing .0ii$ MoS2 or more, approximately 80$ of the molybdenite occurs along fractures (determined from counting of mineralized fractures and seams of molybdenite i n quartz veins, and estimation of the e f f e c t Cf disseminated molybdenite i n quartz veins and wallrocks). S i g n i f i c a n t molybdenite mineralization occurs i n f a i r l y evenly d i s t r i b u t e d zones. These zones commonly range from 10 to 60 feet wide and contain .Oli to .ll±$ MoS2 (10 foot assay i n t e r v a l s ) . One 10 foot zone assayed .27$ MoS2. Also one high grade zone, intersected for 50 feet i n DDH 1, contains an average of .ii7$ MoS2 and i s bordered by zones 100 and 70 feet wide, respectively containing .Oil and .05$ MoS2 (Plate 20). 110 However, the reported grade i n the high grade zone i s mis-leading since r e l a t i v e l y continuous veins up to 3 / 8 " wide were heavily mineralized with molybdenite and c l o s e l y p a r a l -l e l e d the d r i l l core axis. Also present, however, are s i m i l a r heavily mineralized transverse veins and numerous associated mineralized f r a c t u r e s . Veins are dark-colored and consist of quartz with abundant seams and disseminations of molybdenite with lesser amounts of associated hydromica, chlor-i t e , f l u o r i t e , c a l c i t e and apatite. Veins consist of the same minerals that coat f r a c t u r e s . Mineralized zones mentioned above, are not character-ized by more intense f r a c t u r i n g but by more abundant molyb-denite along f r a c t u r e s . Most of the best molybdenite mineralized zones show a close s p a t i a l r e l a t i o n s h i p with pre-mineral porphyry i n t r u -sive contacts. Both the width and grade of s i g n i f i c a n t MoSg mi n e r a l i -zation i n zones tend to decrease with depth within the "molyb-denite zone." Mineralized or unmineralized fractures and quartz veins at depth probably are oriented mainly i n conjugate pairs as are fractures and quartz veins on surface within the eastern portion of the "central quartz vein stockwork zone". Orienta-tions of heavily mineralized fractures or veins that were transverse and roughly p a r a l l e l to the core axis i n the high grade zone i n DDH 1 probably conform to conjugate trends (Figure 12B) I l l of fractures and quartz veins f o r the eastern portion of the "central quartz vein stockwork zone". quartz monzonite and pre-raineral porphyry) within the "molybdenite zone" i n DDH's, from east to west, i s given below i n Table X j . n . S i m i l a r l y , average percent MoS2 i n a l l PSH's i s given i n Table XIV, from both within and outside the "molybdenite zone". DDH Avg.$MoS2 i n Length of Host Length of DDH to Base of Host Rocks Only Rocks (feet) "Molybdenite Zone" (feet) 2 .02 31L2 550 (base of "sulphide Average percent MoS2 i n host rocks ( i e . granodiorite, 3 1 .03 .08 f i e l d " ) 530 750 (base of "quartz-potash feldspar sub-zone") k .0k 713 1028 Note: Average core recovery i s 97$; Diameter of core i s 1-5/8" TABLE XIII - Average Percent MoS? i n Host Rocks i n DDH's 1-lx within the "Molybdenite Zone II 112 Within the "Sulphide F i e l d " "Molybdenite Zone" PSH Average % MoS2 Length of Host Total Length of Hole i n Host Rock3 Only Rock (feet) (feet)  1 .06 li3 60 2 .01+ 63 63 3 .06 65 65 6 .01 37 37 7 .07 Sk 72 8 .03 73 106 12 .02 96 123 13 .05 56 56 Outside the "Molybdenite Zone" k .02 103 103 5 .01 • 1+0 50 Within the "Oxide F i e l d " 9 .02 lOli 156 10 .02 37 37 11 .005 ii-8 I18 Note: Average core recovery.is 77$; Diameter of core i s 7/8" TABLE XIV: Average Percent MoS2 i n Host Rocks i n PSH's 1 -13. Minor molybdenite l o c a l l y occurs along fractures i n association with hematite, magnetite and pyr i t e i n DDH's 2 and 3 and on surface, to the east, within the "oxide f i e l d " adjacent to the "molybdenite zone". Also, a few fractures and i r r e g u l a r patches and vei n l e t s of associated hematite, magnetite, p y r i t e , and molybdenite occur i n DDH 2 within the "sulphide f i e l d " . However, i n most instances where minor magnetite occurs within the "sulphide f i e l d " (hematite r a r e l y occurs within the "sulphide f i e l d " ) , fractures either contain magnetite, with or without p y r i t e , or pyrite and/or molybdenite and do not 113 crosscut one another, even on a microscopic scale (Plate 19) . These features strongly indicate that hematite, magnetite, p y r i t e , and molybdenite were a l l deposited contemporaneously. Paragenesis and Zoning Phase-I wallrock a l t e r a t i o n , quartz veining and mineralization were developed simultaneously due to a contin-uous phase of hydrothermal a c t i v i t y . This i s strongly indicated by the following l i s t e d features: 1) Selvages along mineralized (presence of sulphide and/or oxide minerals) fractures and quartz veins consisting of the same secondary minerals (hydro-mica or K-feldspar) that occur as pervasive w a l l -rock a l t e r a t i o n products i n any given part of the a l t e r a t i o n halo. 2) Quartz-hydromica or quartz-potash feldspar associa-t i o n i n d i f f e r e n t parts of the "central zone". 3) S i l i c i f i c a t i o n and quartz veining are related s p a t i a l l y and temporaly. i i) Near absence of crosscutting relationships between mineralized structures. 5) Very s i m i l a r mineralogy of fracture f i l l i n g s and quartz veins. 6) Zonal arrangement of "sulphide" and"oxide" f i e l d s of mineralization and s p a t i a l r e l a t i o n s h i p with zones of wallrock a l t e r a t i o n . Local intimate association between sulphide and oxide mineral assemblages. 7) Gradual increase i n degree of a r g i l l i z a t i o n within the "peripheral s h e l l " towards the "quartz-hydromica sub-zone". 8) Gradual decrease i n degree of K-feldspathization within the "quartz-potash feldspar sub-zone" into the "peripheral s h e l l " at depth. Ilk 9 ) Sudden t r a n s i t i o n from the "quartz-hydromica sub-zone" into the "quartz-potash feldspar sub-zone" with only a narrow zone of overlap that i s conformable with the boundary between sub-zones. 10) Minor stages of re - f r a c t u r i n g during hydrothermal a c t i v i t y commonly show a regeneration df the e a r l i e r type of hydrothermal conditions i n any given part of the a l t e r a t i o n halo. Zoning of wallrock a l t e r a t i o n products and oxide and sulphide mineral assemblages occurs on a large scale. It i s i l l u s t r a t e d i n an i n t e r p r e t i v e , transverse cross-section of the a l t e r a t i o n halo on Figure llj.. Wallrock a l t e r a t i o n i s strongly indicated to have occurred throughout an ellipsoidal-shaped region. A l t e r a t i o n e s s e n t i a l l y consists of a hydromica region or cap l y i n g above a K-feldspar region that has the form of a f l a t - l y i n g double convex lense. Degree of wallrock a l t e r a t i o n , to either hydromica or K-feldspar, increases inwards towards an ellipsoidal-shaped core ("central zone") characterized by intense to very intense degrees of wallrock a l t e r a t i o n . The "central zone" occurs within both the hydromica and K-feldspar regions. S i l i c i f i c a t i o n and quartz veining conformably occur throughout the "central zone" and are zoned v e r t i c a l l y since they are best developed i n the "quartz-hydromica sub-zone". A sharp bound-ary exists between the "upper quartz-hydromica" and "lower quartz-potash feldspar" sub-zones. The upper sub-zone overlaps the lower sub-zone up to 150 f e e t . The"sulphide f i e l d " and "oxide f i e l d " of mineralization have a symmetrical d i s t r i b u t i o n with respect to parts of the a l t e r a t i o n halo. That i s , the T R A N S V E R S E VERT ICAL SECTION (Coincident with Sect ion 2A-2A') MOLYBDENITE MINERALIZATION Outline of tht "CENTRAL ZONE" REGIO/vy / "OX JOE Tie**'1* 0 _ F E L D S P A R S ^ sis ^ OIRECTION OF MOVEMENT OF HYDROTHERMAL FLUIDS Outline of fh « * ^ "PERIPHERAL SHELL" _k£¥fj-\ • \ v BOUNDARY BETWEEN THE * ' -HYDROMICA REGION AND POTASH FELDSPAR REGION S c a l e : 1 I n c h = 8 0 0 F e e t F I G U R E 1 4 : I N T E R P R E T I V E R E P R E S E N T A T I O N O F Z O N A L A R R A N G E M E N T OF P H A S E - I W A L L R O C K A L T E R A T I O N A N D M I N E R A L I Z A T I O N 116 "sulphide f i e l d " has the form of a t i l t e d mushroom with i t s cap occurring throughout most of the hydromica region and stem passing downwards into the potash feldspar region through the "quartz-potash feldspar sub-zone". Molybdenite mineraliza-t i o n mainly occurs within that part of the "central zone" that l i e s within the "sulphide f i e l d " . It i s zoned v e r t i c a l l y as evidenced by decreasing width and grade of s i g n i f i c a n t l y min-e r a l i z e d zones with depth. Geochemical Character of Wallrock A l t e r a t i o n As previously concluded under "Relationship between Structure, Wallrock A l t e r a t i o n and Mineralization", the " f o l i a -ted shear zone" directed hydrothermal f l u i d s upwards and that f l u i d s must have spread upwards and outwards, predominantly along fractures, from i t s upper part (Figure 9 and 111). Move-ment of f l u i d s along fractures and migration into wallrocks resulted i n chemical reactions between wallrocks and hydrother-mal f l u i d s that produced secondary wallrock minerals. S i g n i f i -cant secondary wallrock minerals, that indicate important transfer of elements between wallrocks and hydrothermal f l u i d s , are discussed. Element transfers given*rare substantiated from studies of hydrothermal systems by others (6, 7» 9). Within the potash feldspar region (Figures 8 and llj.), secondary K-feldspar occurs replacing plagioclase of d i f f e r e n t compositions i n d i f f e r e n t rock types ( i e : quartz monzonite and porphyry). Associated a l b i t i z a t i o n with minor hydromica and 117 c a l c i t e a l t e r a t i o n of remnant plagioclases do not indicate any net addition or removal of elements except f o r a s l i g h t addi-t i o n of H+ ions and GOg. E s s e n t i a l l y , chemical reactions within the K-feldspathized region are characterized by base ion exchan-ges. That i s , K+ ions are introduced and exchanged fo r Na+ and Ga++ ions that are leached out of rocks. Within the hydromica region, secondary hydromica occurs replacing a l l primary minerals i n a l l rock types, though the important reaction has been with plagioclases. Therefore, the hydromica region i s characterized by K+ and H+ ion i n t r o -duction and leaching of Na+ and Ca++ ions with generation of excess SiO£. Excess s i l i c a mainly was deposited along with replacement hydromica since the two minerals occur intimately mixed i n the "quartz-hydromica sub-zone". S i l i c a was introduced within the "central zone". Here, introduced quartz i s present as a pervasive wallrock a l t e r -ation mineral mainly occurring i n zones containing up to 90$ quartz. Generation of excess s i l i c a from wallrocks within the "quartz-hydromica sub-zone" along with introduction of s i l i c a : throughout the "central zone" accounts for more abundant s i l i c i -f i c a t i o n and quartz veining within the "quartz-hydromica sub-zone" than i n the "quartz-potash feldspar sub-zone". In essence, the geochemical character of wallrock a l t e r a t i o n involved increasing degrees of leaching of Na+ and Ga++ ions and introduction of K+ ions towards the center of the "central zone" with s i m i l a r l y associated increasing degrees of 118 H+ ion introduction within the hydromica region. Also, s i l i c a was introduced within the "central zone" and generated excess s i l i c a was deposited i n s i t u within the "quartz hydromica sub-zone". Hydrothermal f l u i d s supplied K+ and H+ ions and SiOg." Leached Ga++ ions probably reappear l a r g e l y i n c a l c i t e and f l u o r i t e that are associated with quartz veins and fracture f i l -l i n g s . Na+ ions may have been removed upwards or may have migrated downwards i n hydrothermal f l u i d s , due to chemical gradients. Downward migration i s more l i k e l y since secondary a l b i t e becomes more abundant i n deeper l e v e l s of the "peripheral s h e l l " . Also, hydrothermal f l u i d s must have supplied S, PI, Pe, Mo, Pb and Z n. Intrepretation of the Hydromica-Potash Feldspar Boundary The lower boundary of the "quartz-hydromica sub-zone" i s r e l a t i v e l y sharp but overlaps and shows crosscutting r e l a -tionships with the underlying "quartz-potash feldspar sub-zone" f o r distances of up to 150 feet. The p o s i t i o n and character of the boundary can be explained i n either purely chemical or physical terms, based on experimental studies i n hydrothermal systems by others (6 ,7 , 9 ) . In chemical terms, the K+/H+ a c t i v i t y r a t i o i n hydro-thermal f l u i d s would decrease upwards due to K+ ion introduction within the "quartz-potash feldspar sub-zone" u n t i l the r a t i o i s such that both K+ and H+ ion introduction occur with the 119 development of the "quartz-hydromica sub-zone". With isothermal conditions, the e f f e c t of temperature of wallrocks also would tend to control the l e v e l at which the boundary occurred. In physical terms, a r g i l l i z a t i o n occurs p r e f e r e n t i a l l y to K-feldspathization at lower temperatures. Therefore the boundary can be explained as a r e s u l t of a steep temperature gradient with higher temperatures at depth. Also, the overlap can be explained by changing chemi-c a l or physical parameters with time. Probably both chemical gradients i n hydrothermal f l u i d s and steep temperature gradients controlled the p o s i t i o n and character of the boundary. However, steep temperature gradients are believed to have been more important because of the following features: 1) The lower boundary of the "quartz-hydromica sub-zone" i s r e l a t i v e l y sharp and i s conformable with the shape of the top of the stock and porphyry r o o f - s i l l . 2) I f the boundary was due e n t i r e l y to chemical gradients, secondary K-feldspar l i k e l y would have been developed widespread i n the "quartz-hydromica sub-zone" as an early wallrock a l t e r a t i o n mineral. 3) The overlap of sub-zones can be explained e a s i l y i n terras of decreasing temperature with time. 1+) The environment i s one i n which a steep tempera-ture gradient, with depth, i s to be expected because of the a) subvolcanic l e v e l of emplace-ment of the stock and porphyries, b) vuggy chara-cter of quartz veins i n the granodiorite capping that indicate a sub-volcanic environment during hydrothermal a c t i v i t y and because c) hydrothermal a c t i v i t y undoubtedly was related g e n e t i c a l l y to porphyry and did not occur at some late date a f t e r subsidence of temperature gradients. (see following section, on "Source Rocks of Hydrother-mal F l u i d s " ) . 120 5) The upward dis c o n t i n u i t y of the " f o l i a t e d shear zone", which i s roughly coincident with the lower boundary of "quartz-hydromica sub-zone ", also can be explained as a r e s u l t of a steep tempera-ture gradient. That i s , i n the shear zone f o l i a t i o n occurred i n deeper higher-temperature regions while contemporaneous extensive f r a c t u r -ing occurred i n higher lower-temperature regions. Geochemical Character of Mineralization The presence of well defined "sulphide" and "oxide" fields of mineralization were the r e s u l t , respectively, of sulphidizing and o x i d i z i n g conditions i n the hydrothermal f l u i d during mineral deposition (3). These conditions were developed at the same time but i n d i f f e r e n t parts of the a l t e r a -t i o n halo. The presence of more abundant t o t a l i r o n i n the "oxide f i e l d " ( i e . contains an estimated average content of 2% hematite + magnetite + pyrite) than i n the "sulphide f i e l d " ( i e . contains an estimated average content of 1% pyrite) indicates that iro n , during transport i n the hydrothermal f l u i d , was p r e f e r e n t i a l l y associated with oxygen-rich complex ions. Also, the f a c t that the "molybdenite zone" occurs within the "sulphide f i e l d " indicates that molybdenum, during transport i n the hydrothermal f l u i d , was either p r e f e r e n t i a l l y associated with sulphur-rich complex ions or was simply p r e f e r e n t i a l l y associated with hydrothermal f l u i d s of lower 0/S fugacity r a t i o . Deposition of molybdenite was p r e f e r e n t i a l l y associated with the region of most intense degrees of K+ ion or K+ and H+ ion metasomatism ( i e . "central zone"). 121 The r e l a t i v e l y sharp boundary between the "sulphide f i e l d " and "oxide f i e l d " i s to be expected. That i s , experi-mental studies i n the Pe-S-0 system have shown that well defined f i e l d s of i r o n oxide and i r o n sulphide deposition occur i n hydrothermal environments. Deposition of oxide or sulphide minerals depends upon the r e l a t i v e f u g a c i t i e s of oxygen and sulphur ( i e . 0/S fugacity r a t i o ) . The r e l a t i v e p o s i t i o n and shape of the "oxide f i e l d " with respect to that of the "sulphide f i e l d " (Figure ll|) indicates that development of the "oxide f i e l d " must have been the r e s u l t of an increasing 0/S fugacity r a t i o i n the hydrothermal f l u i d i n a l a t e r a l d i r e c t i o n about the stem of the "sulphide f i e l d " . Such an increasing 0/S fugacity r a t i o could have been caused by mixing of hydro-thermal f l u i d s with oxygenated meteoric waters or by some chemical gradient brought about by reactions between hydro-thermal f l u i d s and wallrocks. Exploration Potential of the Molybdenite Zone The "molybdenite zone" i s a favourable exploration target f o r economic deposits of molybdenum ore. It occurs i n a geological environment similar to that of many major producers of molybdenum ore. S i m i l a r i t i e s are l i s t e d below: 1) The presence of a small composite g r a n i t i c i n t r u -sive complex emplaced i n a high l e v e l c r u s t a l environment j 122 2) Intrusions are quartz monzonite to granite i n composition; 3 ) Intrusions have a porphyritic texture. Ix) Development of favourable structures that control-led mineralization; 5) Presence of quartz veining and K-feldspathization, a r g i l l i z a t i o n and s i l i c i f i c a t i o n of wallrocks. Exploration programs f o r molybdenum ore should be directed towards further t e s t i n g of the "central zone" of intense wallrock a l t e r a t i o n , and i n p a r t i c u l a r , where the "central zone" l i e s within the "sulphide f i e l d " of mineraliza-t i o n ( i e . the "molybdenite zone" as defined). Also within the molybdenite zone, exploration should be directed towards (a) regions of pre-mineral porphyry intrusive contacts and (b) regions of more intense f r a c t u r i n g . The eastern part of the "molybdenite zone" has been eliminated by four deep DDH's as a pot e n t i a l bearerof any large tonnage, low grade ore bodies. However, the high grade zone ( i e . 50 feet of .It 7% MoS2) intersected i n DDH 1 has poten-t i a l as a low tonnage, high grade zone or pod and could be further tested by a transverse, i n c l i n e d d r i l l hole. The western part of the "molybdenite zone" has not been tested at depth. It i s up to 2000 feet long and between 500 and 1000 feet wide on surface and probably extends to depths of up to 1100 feet or more. This region i s an a t t r a c -tive exploration target f o r the following reasons: 123 1) Predominant fracture trends i n "intensely f r a c -tured zone -5" are directed towards, and could in t e r s e c t , the "molybdenite zone" at depth. 2) Prom the s t r u c t u r a l i n t e r p r e t a t i o n of fr a c t u r i n g i t i s expected that (a) i n t e n s i t y of f r a c t u r i n g would remain high at depth and that (b) degree of opening along fractures may increase with depth. PHASE II - INTRA-MINERAL PORPHYRY ASSOCIATION General Statement Phase-II wallrock a l t e r a t i o n and mineralization includes 1) s l i g h t to moderate degrees of pervasive a l t e r a t i o n and associated mineralization of a l l intra-mineral porphyry s i l l s and dykes and 2) l o c a l intense wallrock a l t e r a t i o n , with abundant associated sulphide minerals, occurring along Period-II shear and breccia zones and fractures i n intra-mineral porphyry and older in t r u s i o n s . The second type above, p a r t i c u l a r l y occurs i n zones near the bottom of DDH's 3 and i i (outlined and la b e l l e d on Figure 8) s p a t i a l l y associated with the lower i n t r a -mineral porphyry dyke-zone (Figure 6 ) . Phase-II wallrock a l t e r a t i o n products consist mainly of s e r i c i t e , quartz and c a l c i t e . Sulphide minerals include p y r i t e , sphalerite, galena, chalcopyrite and molybdenite i n decreasing order of abundance. Veinlets of c a l c i t e and f l u o r i t e (colorless to green), with or-without associated sulphides, occur l o c a l l y along DDH's 3 and I I . 12i i Timing Phase-II a l t e r a t i o n and mineralization occurred i n t e r -mittent to time of emplacement of i n t r a - and post-mineral porphyry. Intrusion of intra-mineral porphyry followed cessa-t i o n of Phase-I hydrothermal a c t i v i t y . This i s evidenced by the following l i s t e d features: 1) Intra-mineral porphyry shows crosscutting r e l a -tionships with a l l features of Phase-I including (a) a l l types of wallrock a l t e r a t i o n and (b) sulphide and/or oxide bearing fractures and quartz veins; 2) Intra-mineral porphyry l o c a l l y contains angular inclusions of rocks showing features of Phase-I as l i s t e d i n 1 (a) and 1 (b) above; 3) K-feldspathization and hematite and magnetite mineralization i n d i c a t i v e of Phase-I hydrother-mal a c t i v i t y , do not occur i n intra-mineral porphyry. Phase-II a l t e r a t i o n and mineralization followed i n t r u -s i on of intra-mineral porphyry and preceeded i n t r u s i o n of post-mineral porphyry. Phase-II shows a close time rela t i o n s h i p with the l a t e s t period of c r y s t a l l i z a t i o n of intra-mineral porphyry i n t r u s i o n s . That i s , pervasive a l t e r a t i o n and mineralization i s c l e a r l y of deuteric nature. Furthermore, zones of intense wallrock a l t e r a t i o n and associated sulphides show a genetic r e l a t i o n s h i p with intra-mineral porphyry since zones commonly occur within and adjacent to intra-mineral porphyry intrusions. These features are discussed i n d e t a i l i n subsequent sections. 125 A l l features of Phase-II wallrock a l t e r a t i o n and mineralization show crosscutting relationships with a l l features of Phase-I wallrock a l t e r a t i o n and mineralization. Post-mineral porphyry shows crosscutting relationships with a l l altered and mineral-i z e d rocks. Pervasive Wallrock A l t e r a t i o n and Mineralization Intra-mineral porphyry t y p i c a l l y i s altered pervasively and mineralized uniformly. Albi t e phenocrysts are varicolored, though commonly are bleached to a light-grey or pale-green to pale-pink. Sanidine phenocrysts commonly are pale-pink and occasionally white to pale-green. Groundmasses are pale-green to bleached-white. In t h i n sections, feldspar phenocrysts show s l i g h t to moderate degrees of replacement to s e r i c i t e (mattes and plates) and c a l c i t e . B i o t i t e always i s altered completely to. plates of s e r i c i t e , often with minor amounts of associated c a l c i t e , c h l o r i t e , leucoxene (?) and occasionally f l u o r i t e . Groundmasses contain disseminated s e r i c i t e , c a l c i t e , minor py r i t e and l o c a l l y f l u o r i t e , galena, sphalerite and molybdenite. Phenocrysts and groundmasses l o c a l l y contain minor secondary granular quartz. Embayments i n quartz phenocrysts commonly consist of s e r i c i t e , c a l c i t e , quartz, f l u o r i t e and p y r i t e . In exposed intra-mineral porphyry and i n some of the upper dykes and s i l l s i n DDH's, porphyry commonly contains l o c a l dissemina-ted rounded spots i n the groundmass, up to 1/2" across, consist-ing of aggregates of p y r i t e and s e r i c i t e with rims of s e r i c i t e . 126 Fractures i n intra-mineral porphyry commonly are. coated with s e r i c i t e , c a l c i t e , quartz and/or f l u o r i t e (color-less to green) and mineralized sparsely with p y r i t e , sphaler-i t e , galena, chalcopyrite and/or molybdenite. Fractures occas-i o n a l l y have a l t e r a t i o n selvages, up to a t o t a l width of 1/i i " , consisting of more intense s e r i c i t e a l t e r a t i o n of feldspars with minor associated quartz. Many of these coated fractures probably are due to Period-II f r a c t u r i n g . However, the bulk of them probably were developed by shrinkage of porphyry upon c r y s t a l l i z a t i o n . This i s evidenced by the f a c t that some mineralized fractures were observed to be discontinuous i n intra-mineral porphyry at intr u s i v e contacts. S e r i c i t e , i n a l l modes of occurrence, commonly shows a good platy form. It has p o s i t i v e r e l i e f and a negative optic angle of approximately 30 • Minor k a o l i n i t e (very low b i r e -fringence; p o s i t i v e r e l i e f ) i s associated with s e r i c i t e and occurs as very fine-grained scales, specks and/or mattes. Near the western end of F a u l t - B on surface, s e r i c i t i -zation ( l o c a l associated s i l i c i f i c a t i o n ) uniformly i s more intense throughout i r r e g u l a r regions i n both intra-mineral porphyry and granodiorite. Some of these regions are included within the outline of the "central zone" ( i e . Phase-I) and account for some of the i r r e g u l a r i t i e s i n i t s o u t l i n e . They also include separate outlined regions i n the same area. Elsewhere, Phase-II pervasive a l t e r a t i o n l a r g e l y i s limited to intra-mineral porphyry bodies. 127 Commonly less than 1$ p y r i t e , occurring along f r a c -tures and disseminated, ,,is present i n intra-mineral porphyry. Molybdenite content commonly i s .01 to .02$. Intensely Altered Zones and Related Features Zones of intense a r g i l l i z a t i o n and s i l i c i f i c a t i o n , outlined near the bottoms of DDH's 3 and ii (Figure 8 ) , are characterized by intense a l t e r a t i o n of intra-mineral porphyry and quartz monzonite adjacent to fractures and within several shear and breccia zones (commonly up to f i v e feet wide). Also, l o c a l l y present are altered breccias up to one inch wide. Altered rocks consist of variable amounts of s e r i c i t e and quartz, replacing feldspar phenocrysts and groundmasses, with minor amounts of associated c a l c i t e , f l u o r i t e and p y r i t e . Pyrite, sphalerite: (yellow to black), galena, chalcopyrite, minor molybdenite and traces of a platy t e l l u r i d e (?) occur with variable amounts of s e r i c i t e , quartz, c a l c i t e , and f l u o r i t e as (1) fracture f i l l i n g s up to 1/8" wide, (2) i r r e g u l a r fracture f i l l i n g s , v e i n l e t s and patches i n shear and breccia zones and as (3) the matrix i n breccias up to one inch wide. Sulphides are fine to medium grained except f o r molybdenite which always i s f i n e grained. Shear and breccia zones commonly contain 1 - 2 $ .pyrite and 1-3$ combined Zn, Pb and Cu sulphides. Sulphides are more abundant i n the outlined zone shown along DDH i i than along that i n DDH 3 . The best mineralized zone i s a 20 foot wide shear and breccia zone that occurs i n DDH 1+ at depths 128 between 1350 and 1370 f e e t . It i s estimated to contain 5$ combined sphalerite and galena and 1% chalcopyrite. The lower ten feet of this zone assayed .05$ M0S2. Other zones of molybdenite mineralization, shown on sections within the intensely altered zones outlined,are also ^hase-II features and occur i n shear and breccia zones. Veinlets of c a l c i t e with minor amounts of associated f l u o r i t e and py r i t e and l o c a l v e i n l e t s of p y r i t e , up to h inch wide, occur widespread through-out outlined zones near the bottoms of DDH's 3 and Jx. Elsewhere i n DDH's 3 and Ix, Phase-II mineralized fractures and shear and breccia zones (up to 3 feet wide) only occur l o c a l l y i n intra-mineral porphyry and older i n t r u s -ions. They become more abundant towards intensely altered zones near the bottoms of DDH's 3 and ix. Also present are l o c a l v e i n l e t s of massive sulphides, up to ig" wide, segmented with the gangue mineral assemblages c a l c i t e - f l u o r i t e and/or qu a r t z - s e r i c i t e (Plate 29). Mixed c a l c i t e and f l u o r i t e vein-l e t s , up to V wide, containing minor amounts of pyr i t e occur more widespread but are only abundant (up to 1 per foot) across a few feet, '^hey also occur l o c a l l y i n DDH 1 . Six banded c a l c i t e - f l u o r i t e - s u l p h i d e veins, up to 2" wide, occur scattered i n DDH ix (Plate 29) . Quartz veins, up to h inch wide, only occur rarely i n intra-mineral porphyry and generally are barren. Shear and breccia zones and veinlets commonly occur i n rocks adjacent to intra-mineral porphyry intrusions. 129 Discussion R e s t r i c t i o n of the pervasive type of Phase-II a l t e r a -t i o n to bodies of intra-mineral porphyry indicates deuteric processes. Also, the presence i n intra-mineral porphyry of disseminated spots of s e r i c i t e - p y r i t e , more intense a l t e r a t i o n of embayments i n quartz phenocrysts and evenly d i s t r i b u t e d sulphides indicate deuteric processes. Intense a l t e r a t i o n and associated abundant sulphide minerals that occur along Period-II structures cutting i n t r a -mineral porphyry and older rocks are features of hyrdrothermal o r i g i n . The close s p a t i a l r e l a t i o n s h i p of zones of intense a l t e r a t i o n with the lower dyke-zone, intersected near the bottoms of DDH'sr^and Ii, and the close s p a t i a l relationship of L other l o c a l zones of intense a l t e r a t i o n and v e i n l e t s with intra-mineral porphyry intrusions strongly indicate a genetic r e l a t i o n s h i p between Phase-II hydrothermal a c t i v i t y and i n t r a -mineral porphyry. It i s concluded that a l t e r a t i o n and mineralization of intra-mineral porphyry i s l a r g e l y of deuteric o r i g i n ; except at depth, where crosscutting Period-II structures have controlled movement of hydrothermal f l u i d s generated from intra-mineral porphyry intrusions. Prom the width and estimated contents of sulphide minerals i n Phase-II mineralized zones, i t i s probable that 130 these zones are not of economic significance f o r any of the base metals. However, d r i l l core was only assayed f o r moly-bdenite content. assemblages associated with each phase ( i e . Phase-I and -II) of hydrothermal a c t i v i t y show a gross paragenesis that i s ch a r a c t e r i s t i c of c l a s s i c a l sequences of mineral deposition i n hydrothermal environments. Mineral assemblages are given below i n Table XV. HYDROTHERMAL PREDOMINANT MINERALS DEPOSITED ALONG FRACTURES GROSS PARAGENESIS Predominant sulphide, oxide and gangue mineral PHASE Met a l l i c Minerals Gangue Minerals Phase-I (main phase) Hematite, magnetite,pyrite Quartz hydro-mica and molybdenite and K-feldspar Phase-II Pyrite, sphalerite, galena, Se r i c i t e , q u a r t z , chalcopyrite and molybdenite c a l c i t e and f l u o r i t e TABLE XV: Phase-I and -II Gross Paragenesis 131 SOURCE ROCKS OF HYDROTHERMAL FLUIDS Phase-I and -II hydrothermal a c t i v i t y , respectively, are believed related g e n e t i c a l l y to pre- and intra-mineral porphyry. A genetic r e l a t i o n s h i p between Phase-II hydrother-mal a c t i v i t y and intra-mineral porphyry i s c l e a r l y demonstrated as discussed i n e a r l i e r sections. Features that suggest a genetic r e l a t i o n s h i p between Phase-I hydrothermal a c t i v i t y and pre-mineral porphyry are l i s t e d below: 1) Intra- and post-mineral porphyry intrusions were r i c h i n v o l a t i l e and acqueous fr a c t i o n s because both were altered and mineralized d e u t e r i c a l l y . Furthermore, Intral-mineral porphyry generated hydrothermal f l u i d s as a re s u l t of st r u c t u r a l deformation ( i e . Period-II structures). I n t u i t i v e l y then, pre-mineral porphyry was prob-ably also r i c h i n v o l a t i l e s and acqueous f r a c -tions ; 2) Close s p a t i a l r e l a t i o n s h i p between best zones of molybdenite mineralization and pre-mineral porphyry i n t r u s i v e contacts; 3) Extent of the Phase-I a l t e r a t i o n halo shows a close correspondence to the d i s t r i b u t i o n of pre-mineral porphyry; li) Pre-mineral porphyry dykes, intersected i n DDH 1 within the center of the a l t e r a t i o n halo, probably lead into a mass or stock or pre-mineral porphyry at depth from which the bulk of hydrothermal f l u i d s could have been generated; 5) From the geochemistry of Phase-I a l t e r a t i o n and mineralization along with the c o n t r o l l i n g struc-t u r a l framework, i t i s c e r t a i n that hydrothermal f l u i d s ascended upwards along the " f o l i a t e d shear zone" near the center of the a l t e r a t i o n halo i n the region of pre-mineral porphyry dykes, i n t e r -sected i n DDH 1 , that are probably apophyses from an underlying stock of pre-mineral porphyry; 132 6) The gross paragenesis of Phase-I and -II sulphide, oxide and gangue mineral assemblages indicate a genetic a f f i l i a t i o n between phases of hydro-thermal a c t i v i t y and, therefore, indicate that pre-mineral porphyry was a source rock to phase-I hydrothermal f l u i d s just as intra-mineral porphyry was a source rock to Phase-II hydrothermal f l u i d s . Above l i s t e d features are believed to s u f f i c i e n t l y demonstrate that Phase-I hydrothermal a c t i v i t y was related g e n e t i c a l l y to pre-mineral porphyry intrusions. Hydrothermal f l u i d s were generated from the pre-mineral porphyry r o o f - s i l l and feeder-dykes, though the bulk of the f l u i d s must have been generated from a buried mass or stock of pre-mineral porphyry. Period-I deformation produced avenues f o r release of v o l a t i l e and acque-ous fracti o n s from pre-mineral porphyry. Also, t h i s was c l e a r l y the case for Period-II deformation and intra-mineral porphyry. Post-mineral porphyry was altered only d e u t e r i c a l l y probably since no deformation clo s e l y followed i t s emplacement. 133 CHAPTER V SUMMARY AND CONCLUSIONS SUMMARY The region of the Tuzo Creek Molybdenite Prospect has had a complex h i s t o r y of igneous intrusion, s t r u c t u r a l deforma-t i o n and hydrothermal a c t i v i t y . Intruding a basement of Nelson granodiorite i s a triangular-shaped (sides approximately lh miles long), rounded, p a r t i a l l y capped stock of Va l h a l l a porphyritic quartz monzonite. Subsidence of the stock was accompanied by emplacement, along i t s top and eastern flanks, of a quartz-albite-sanidine porphyry s i l l (pre-mineral) up to 350 feet thick. Peeder-dykes lead upwards into the s i l l , probably from a porphyry stock at depth. Strong regional deformation (Period-I) produced a northeasterly-trending and steeply north-dipping upwardly and probably southwesterly-discontinuous " f o l i a t e d shear zone" i n the south-central portion of the stock. Contemporaneously, there was l o c a l development of northwesterly-trending f o l i a t i o n and shear and breccia zones. Movement i n the " f o l i a t e d shear zone" probably was of a reverse r o t a t i o n a l character and hinged to the southwest i n the west-central portion of the region. Widespread f r a c t u r i n g was produced by shear movements. 131+ Fracture trends show a r a d i a l pattern or h o r s e t a i l i n g e f f e c t at the southwestern end of the " f o l i a t e d shear zone". Within and adjacent the " f o l i a t e d shear zone", throughout the central to northeastern portions of the region, fracture and quartz vein trends show conjugate, longitudinal and/or cross trends with respect to the predominant northeasterly-trending shearing azimuth. Most intense f r a c t u r i n g occurs within and peripheral to the " f o l i a t e d shear zone". Most extensive opening along fractures, commonly up to V or V occurs p e r i -pheral to the " f o l i a t e d shear zone". Hydrothermal a c t i v i t y (Phase-I) was controlled by Period-I structures, and centered about the " f o l i a t e d shear zone". Fractures and l o c a l shear and breccia zones controlled wallrock a l t e r a t i o n , quartz veining and mineralization. Wall-rock a l t e r a t i o n has affected most of the stock and porphyry s i l l and occurs throughout a northeasterly-trending e l l i p s o i d a l -shaped halo. The a l t e r a t i o n halo i s zoned and consists of 1) a "peripheral s h e l l " characterized by lesser degrees of a l t e r a t i o n mainly consisting of a r g i l l i z a t i o n (hydromica) at higher l e v e l s and felds p a t h i z a t i o n (potash feldspar and a l b i t e ) at lower levels and (2) a large, northeasterly-trending "central zone" (completely surrounded by the peripheral s h e l l ) character-ized by more intense a l t e r a t i o n consisting of a r g i l l i z a t i o n (hydromica),feldspathization (K-feldspar and a l b i t e ) and s i l i c i -f i c a t i o n . The central zone i s sub-divided into an upper "quartz-hydromica sub-zone" and a lower "quartz-potash feldspar sub-zone". A sharp boundary occurs between the upper hydromica 135 and lower potash feldspar regions. The boundary Is indicated to extend throughout the a l t e r a t i o n halo as a gently outward-dipping surface. Quartz veining and s i l i c i f i c a t i o n occur throughout the "central zone" but are most abundant i n the "quartz-hydromica sub-zone". Chemically, wallrock a l t e r a t i o n i s e s s e n t i a l l y characterized by increasing degrees of leaching of Na+ and Ca++ ions and introduction of K+ ions towards the "central zone" with associated increasing degrees of H+ ion introduction within the upper hydromica region. Also, some s i l i c a was introduced into wallrocks and deposited along open fractures within the "central zone". Mineralization i s present throughout the a l t e r a t i o n halo, predominantly occurring along fractures and to a lesser degree i n quartz veins. D i s t r i b u t i o n of sulphide and oxide mineral assemblages define a mushroom-shaped "sulphide f i e l d " , with i t s stem roughly centered along the "central zone", and an "oxide f i e l d " , surrounding the stem and below the cap of the "sulphide f i e l d " . The "sulphide f i e l d " i s characterized by widespread p y r i t e whereas the "oxide f i e l d " i s characterized by the assemblage hematite-magnetite -pyrite . A "molybdenite zone" occurs i n that part of the "central zone" that l i e s within the "sulphide f i e l d " . The "molybdenite zone" measures up to liOOO feet i n a north-easterly d i r e c t i o n . It has an indicated maximum width of up to 1800 feet and has a v e r t i c a l range of up to 1050 f e e t . S i g n i f i c a n t grades of molybdenite occur i n separate zones, commonly up to 10 's of feet wide, containing .Oil to .1x7$ MoS£. 1 3 6 Economic p o t e n t i a l f o r large ore-bodies of low grade molybdenite mineralization i s l i m i t e d to the western portion of the "molyb-denite zone" which has not been tested by diamond d r i l l i n g . Also, one $0 foot i n t e r s e c t i o n , i n DDH 1 , containing .1+7$ MoS2 could be tested further by a cross hole. Cessation of Pha3e-I hydrothermal a c t i v i t y was f o l -lowed by further sibsidence of the stock producing a series of gently dipping tensional f i s s u r e s that controlled further empl-acement of porphyry (intra-mineral). This porphyry was strongly altered d e u t e r i c a l l y (mainly s e r i c i t e ) with associated minor amounts of p y r i t e , sphalerite, galena, chalcopyrite and molyb-denite occurring disseminated and along fract u r e s . Also, deformation (Period-II) of a character similar to Period-I, but lacking f o l i a t i o n , l o c a l l y affected intra-mineral porphyry and adjacent rocks at depth. Period-II structures controlled intense a r g i l l i z a t i o n ( s e r i c i t e ) and s i l i c i f i c a t i o n of wallrocks (Phase-II) and more abundant sulphide deposition, p a r t i c u l a r l y within and adjacent to bodies of intra-mineral porphyry, of a mineralogy i d e n t i c a l to that related to deuteric mineralization. Phase-II mineralization was not extensive enough to be economi-c a l l y important f o r any of the base metals. Further emplacement of porphyry (post-mineral) con-s i s t s of en echelon series of a moderately-to steeply-dipping conjugate dyke system and of l o c a l large dyke-like masses that were controlled by tensional f i s s u r e s . Post-mineral porphyry i s weakly altered d e u t e r i c a l l y and sparsely mineralized. 137 Late basic to intermediate dykes of alkaline nature lar g e l y occur within a northeasterly-trending zone across the center of the region. They were emplaced along northeasterly-trending and l o c a l northwesterly-trending ten-si o n a l f i s s u r e s . Northeasterly-trending and northwesterly-dipping reverse r o t a t i o n a l f a u l t s ( P e r i o d - I l l ) o f f s e t a l l rock types. They were hinged to the southwest i n the central portion of the region. Transverse shears also occur l o c a l l y . 138 CONCLUSIONS Conclusions, l a r g e l y of genetic nature, concerning the petrology and structure of the Tuzo Creek Molybdenite Prospect are l i s t e d below: 1) Granodiorite, quartz monzonite and porphries are a l l part of a single d i f f e r e n t i a t i o n s e r i e s . 2) Phenocrysts i n porphyries and probably those i n quartz monzonite have c r y s t a l l i z e d at depths of approximately 11 km1s or more. 3) The quartz monzonite stock and porphyries were successively emplaced from great depths ( i e . at least 11 km's) into a sub-volcanic environment. Ix) Both l o c a l and regional structures were regenerated successively i n type and o r i e n t a t i o n . Local structures include (a) two periods of development of gently-dipping f i s s u r e s due to subsidence of the stock and (b) two periods (I and II) of f r a c t u r i n g , g e n e t i c a l l y related to wrenching shear movements due to termination or pinching-out of regional reverse r o t a t i o n a l shearing. Regional structures include (a) two periods (I and II) of shearing and a late period (III) of f a u l t i n g and (b) two periods of development of tensional f i s s u r e s . 5) Regional structures can be interpreted through app l i c a t i o n of a combined stress and s t r a i n e l l i p s o i d diagram. 139 They were caused by successive and intermittent periods of compression and tension whose respective forces must have been resolved from successive periods of development of r o t a t i o n a l forces generated by r i g h t l a t e r a l s t r i k e - s l i p movements along the West Kettle River f a u l t zone. 6) Phase-I and -II hydrothermal a c t i v i t y were con-t r o l l e d , respectively by Periods-I and -II structures and followed emplacement of pre- and intra-mineral porphyry, respectively. Gross paragenesis of deposited gangue, sulphide and oxide minerals i s i n l i n e with other hydrothermal environments. 7) Phase-I hydrothermal a c t i v i t y was the most important since i t developed a large, zoned a l t e r a t i o n halo and had associated s i g n i f i c a n t molybdenite mineralization. Wallrock a l t e r a t i o n , quartz veining and mineralization are related paragenetically to a single, probably prolonged phase of hydrothermal a c t i v i t y . Hydrothermal f l u i d s must have ascended upwards along the " f o l i a t e d shear zone" and spread outwards and upwards from i t s upper part mainly along fractu r e s . Control of wallrock a l t e r a t i o n mineral assemblages was undoubtedly both chemical and physical, though physical control i s believed to have been the most important since steep temperature gradients best explain the sharp boundary between the potash feldspar and hydromica regions i n view of experimental studies i n hydro-thermal systems by Hemley, and others. "Oxide" and"sulphide" f i e l d s of mineralization, due to differences i n 0/S fugacity r a t i o i n the hydrothermal f l u i d were brought about by an increasing 0/S fugacity r a t i o l a t e r a l l y about the stem of the "sulphide f i e l d " . Molybdenum i n transport i n the hydrothermal f l u i d was associated p r e f e r e n t i a l l y either with S-rich complex ions or simply with f l u i d s of lower 0/S fugacity r a t i o . Deposition of molybdenite was associated preferen-t i a l l y with regions of most intense K.+ ion or K+ and H+ ion metasomatism. 8) Source rocks of Phase-I and -II hydrothermal f l u i d s were undoubtedly pre- and intra-mineral porphyry, respectively. Fluids were released from porphyries as a r e s u l t of Period-I and -II deformation. Phase-I f l u i d s must have been released l a r g e l y from a buried stock of pre-mineral porphyry. 9 ) Geological c h a r a c t e r i s t i c s of the prospect are r e f l e c t i v e of major producers of molybdenum ore. Consider-able economic potential f o r molybdenum ore s t i l l remains within the "molybdenite zone". l i i l BIBLIOGRAPHY BADGLEY, P.O. ( 1 9 6 5 ) ; Jointing and Fracture Analysis; in Structural and Tectonic P r i n c i p l e s , Ed. by Harper and Row: Chap. Ix. BARTON, Jr . , P.B., and B.J. SKINNER ( 1 9 6 7 ) ; Sulphide Mineral S t a b i l i t i e s ; i n Geochemistry of Hydrothermal Ore Deposits, Ed. H.L. Barnes, pp. 2 3 6 - 3 3 3 BARNES, H.L. and G.K. CZAMANSKE, ( 1 9 6 7 ) ; S o l u b i l i t i e s and Transport of Ore Minerals;in Geochemistry of Hydro-thermal Ore Deposits. Ed. H.L. Barnes, pp. 3 3 4 - 3 8 5 BOSTOCK, H.H. ( 1 9 6 6 ) ' Feldspar and Quartz Phenocrysts i n t h e Shingle Creek Porphyry, B.C.; G.S.C. B u l l . 1 2 6 . DRUMMOND, A.D. and E.T. KIMURA, ( 1 9 6 8 ) ; Hydrothermal A l t e r a t i o n at Endako Mines - A Comparison to Experi-mental Studies; Paper presented at Annual Meeting of C.I.M.M., Vancouver, B.C. HEMLEY, J . J . (1959); Some Mineralogical E q u i l i b r i a i n the System K 20-Al 20^-Si0 2-H 20; Am.J.Sc. 2 5 7 , p p . 2 1 x 1 - 2 7 0 . HEMLEY, J.J. And W.R. JONES, ( 1 9 6 4 ) ; Chemical A 3 p e c t s of Hydrothermal A l t e r a t i o n with Emphasis on Hydrogen Metasomatism; Econ. Geology, Vol. 5 9 , p p . 5 3 8 - 5 6 9 LITTLE, H.W. (1957); Geology of the Kettle River Area (East-Half), B.C.; G.S.C. Preliminary Map 6 - 1 9 5 7 ( 1 9 6 1 ) ; Geology of the Kettle River Area (West-Half), B.C.; G.S.C. Preliminary Map 1 5 - 1 9 6 1 MEYER, C. and J.J. Hemley, ( 1 9 6 7 ) Wallrock A l t e r a t i o n : i n Geochemistry of Hydrothermal Ore Deposits, Ed. H.L. Barnes, pp 1 6 6 - 2 3 5 . NGUYEN, K.K., A.J. SINCLAIR, and W.G. LIBBY ( 1 9 6 8 ) ; Age of the Northern Part of the Nelson Batholith; Can. Jour, of Earth Sciences, Vol. $, p . 9 5 5 « REINECKE, L. ( 1 9 1 5 ) ; Ore Deposits of the Beaverdell Map-Area, B.C.; G.S.C. Mem.79. SALES, R.H. and C. MEYER, ( 1 9 4 8 ) ; Wallrock A l t e r a t i o n at Butte, Montana; Am. Inst, of Min. and Met.Eng., Trans., Vol. 1 7 8 , pp. 9 - 3 5 . TUTTLE, O.F. and N.L. BOWEN, ( 1 9 5 8 ) ; O r i g i n of Granite i n Light of Experimental Studies i n the System NaAlSioOn-K A l S i 3 0 Q -Si0 2-H 20; G.S.A. Mem. 7 4 . 11+2 Plate 1: View looking west towards map-area from the access road near the junction of Tuzo Creek and West Kettle River. ("X" marks a common spot on Plates 1 to i+). Plate 2: View looking southwest from a helicopter; note the straight, moderately incised draw (follows a young f a u l t ) . 114, Plate l i : View looking north of the 'West Kettle River Valley; the town of Beaverdell l i e s at the in t e r s e c t i o n of major v a l l e y i n the background; note the Interior Plateau upland surface. 145 Plate 5: Freah hornblende granodiorite; note the hypidio-morphic texture, weak f o l i a t i o n and large i n t e r -s t i t i a l grains of quartz (pale grey). Plate 6: Fresh porphyritic B i o t i t e Quartz Monzonite; note the large euhedral sanidine phenocrysts ( l i g h t ?rey) and medium grained phenocrysts of oligoclase white), rounded quartz (glassy grey) and b i o t i t e (black) and the fine grained groundmass. 11+6 Plate 7: Pre-mineral Porphyry (altered); note the large euhedral sanidine phenocrysts and deformed quartz ( l i g h t grey) phenocrysts. Plate 8: Intra-Mineral Porphyry (weakly altered); note phenocrysts consisting of rounded grains of quartz (glassy grey), large euhedral sanidine (white), i n d i s t i n c t a l b i t e (grey) and altered b i o t i t e (dark), also note the aphanitic groundmass. 147 Plate 9: Post-Mineral -Porphyry ( r e l a t i v e l y fresh); note the similar texture of pre-, i n t r a - and post-mineral porphyry, L e f t : Pine-grained pink phase showing a granular texture. Center: Grey to pink predominant phase. Right: Dark pink phase l i i . 8 Plate 10: Sanidine phenocrysts from post-mineral porphyry; l e f t and center crystals are oriented with a-axis v e r t i c a l and c-axis downwards to the l e f t , c r y s t a l s show 010, 001, 110 and 201 faces. STAEDTLER Nr . R 30 8 3/12" Plate 11: Alkaline Quartz G abbro (late dyke); note the medium grained phenocrysts consisting of labra-dorite laths ( l i g h t grey) and augite (dark) i n a fine-grained, granophyric-like groundmass. 11+9 Plate 12: Composite Alkaline Basalt - Augite Trachyte (late dykes); L e f t : Alkaline basalt showing phenocrysts of labradorite laths ( l i g h t grey) and augite (dark) i n a fine-grained ground-mass, Right: Augite Trachyte showing phenocrysts of a l k a l i feldspar laths to rhombs (white), augite (dark grey) and b i o t i t e (black) i n a fine-grained granular groundmass. (note rims around feldspar phenocrysts i n both rock types) 150 Plate 13: Altered L a t i t e (late dyke): note small phenocrysts of altered feldspar (white) i n a fine grained groundmass. Plate Hi: A r g i l l i z e d Granodiorite from the "quartz-hydromica-sub-zone"; note the a l t e r a t i o n selvage consisting of hydromica and quartz along a pyrite-molybdenite bearing fr a c t u r e . 151 Plate 15: Sample from the overlap zone between the upper "quartz-hydromica sub-zone" and the lower "quartz-potash feldspar sub-zone"; sample i l l u s t r a t e s pervasively K-feldspathized pre-mineral porphyry showing l a t e r pyrite-molybdenite bearing fractures with selvages of quartz and hydromica. Plate 16: Samples i l l u s t r a t i n g quartz veins i n K-feldspathized rocks from the "central quartz vein stockwork zone" (see Table XI). 152 Plate 17: Discontinuous, i r r e g u l a r quartz veins and s i l i c i -f i e d zones i n a r g i l l i z e d granodiorite from the "quartz-hydromica sub-zone"; Type 2 veins (Table XI). Plate 18: Abundant molybdenite (black) occurring along fractures and coating breccia fragments i n breccia-ted and K-feldspathized quartz monzonite from the "quartz-potash feldspar" sub-zone". 153 Plate 1 9 : Molybdenite (dark metallic) and magnetite (black) occurring exclusive of one another along fractures without showing crosscutting relationships i n K-feldspathized quartz monzonite. Plate 20: Heavy molybdenite (black) mineralization occurring i n veinlets and along fractures i n K-feldspathized quartz monzonite from the high grade zone intersected along DDH 1. 71 91 81. OZ ZZ 7Z 3Z BZ OE ZZ \ z 6\, i s e i , r e ! , m , !9."l • i ^ i , P*I. I?! Plate 21: Molybdenite (black) bearing fracture with a selvage of hydromica and quartz i n a r g i l l i z e d pre-mineral porphyry from the "quartz-hydromica sub-zone". Plate 22: Serrate fracture coated with molybdenite (black) 155 Plate 2li: Banded quartz-magnetite veins and magnetite bearing fractures i n K-feldspathized rocks (Type 1 veins; see Table X l ) ; Le f t : from the "oxide f i e l d " at depth Center and r i g h t : from "fracture zone -8" within the "oxide f i e l d " . 156 Plate 25: Banded quartz-magnetite veins i n a r g i l l i z e d and K-feldspathized granodioritej sample taken from f l o a t below "fracture zone - 8 " . Plate 26: Heavy hematite (specularite) and magnetite minerali-zation i n intensely fractured and granulated, a r g i l -l i z e d and s i l i c i f i e d pre-mineral porphyry from "fracture zone - 5 " . 157 « I ; M M | i | i | i | M i | i | i | i | i | i | i | i | i | H I | H I | H l ! H i | l | l | l | l | H ' | H i | i | ' | M ' | ' l ' | M ' | ' M | ' M | i M Plate 27: Hematite and magnetite along fractures i n a r g i l l i z e d and s i l i c i f i e d pre-mineral porphyry from "fracture zone - 5 " . Plate 28: Brecciated and intensely s i l i c i f i e d and a r g i l l i z e d quartz monzonite from "fracture zone - 5 " ; abundant hematite and magnetite healing breccia fragments. 158 Plate 29: Massive sulphide v e i n l e t s (Phase-II m i n e r a l i -zation) ; L e f t : Banded pyrite-molybdenite-calcite vein Center: Sphalerite-galena-pyrite-chalcopyrite vein cutting pre-mineral porphyry Right: Golena-chalcopyrite vein. 159 Plate 30: Breccia zone (Period-II) i n quartz monzonite containing a large fragment of molybdenite mineralized rock (on l e f t ) ; note c a l c i t e f i l l i n g (white). Y M B P. 0 h 4 D. D . H . I i499' i' 01 - 9 0 ° 1006' at- o P S . H I P S H 2 o 6 0 ' ot-90° 63'o: - 4 5 « L 20 4 - 00 S MOE 2807 A • - 140,000 N D D H 4 OUTLINE OF AREA OF MOLYBDENITE MINERALIZATION BO. WIRELINE DIAMOND DRILL HOLE Vertical, Inclined; Showino Number, Inclination and Length Located by Transit Survey PACKSA CK DIAMOND DRILL HOLE Vertical, lnclinec: Showing Number, Inclination and Length Loco ted with respect to Grid CUT GRID PICKET - L INE ( Line 2000 feet South) - Marked at 100' Intervals CUT CLAIM LINE ( Claim Post ) - Marked at 100' Intervals MAIN CONTROL STATION Name, Number; Located by Te .'/urometer Survey GEODETIC GRID POINTS As Defined by MCLAREN AND ASSOCIATES TOPOGRAPHIC CONi'OUR 100' Intervals-, Plotted by LOCKWOOD SURVEY CORP LTD From Airborne Photographic and Ground Survey Data DENOTES POINT TIED IN BY TRANSIT SURVEY B Q. Wireune Diamond Drill Hole Claim Pos' Grid Point DENOTES POINT TIED IN PY AIRBORNE SURVEY Claim Post Grid Point CLAIM POST Approximately Located by Chain and Compass CLAIM BOUNDARY Plotted From Surveyed Positions of Cloim Posts CLAIM BOUNDARY Approximately Located N0TE : Claims Shown are Presently Held by AMAX EXPLORATION INC. >e- Mo 2, 4-10, 15-21, 32, 34 and 36; Chip 5 Fraction ) ROCK OUTCROP SWAMP STREAM, INTERMITTENT STREAM NOTE-ROAD ( Four Wheel Drive Road ) B.O. Wireline Diamond Drilling by CANADIAN LONG/EAR LTD. (1966 ) Pocksock Diamond Drilling by Local Contract (1965, 1966) Topography by LOCKWOOD SUhVEY CORPORATION LTD. (1967) Control Stations and Field Survey by MCLAREN AND ASSOCIATES (1967) Nickel-Line Grid by Local Contract (1964, 1965) Drawn by G M Leory (1968) , Completed by N. Grant Brown FIGURE 4 CONTROL SURVEY MAP TUZO C R E E K MOLYBDENITE PROSPECT BRITISH COLUMBIA S C A L E I INCH -- 4 0 0 F E E T To Accompany Thesis PETROLOGY AND STRUCTURE OF THE TUZO CREEK MOLYBDENITE PROSPECT by G. M. Leory ( 1969) I L N D L A T E CORYELL DYKES >-or CD L d o or o_ 9 < or >-or < or LU h or < e o CO CO < or ~3 5 CO < 0_ L CO o Q_ z z A L T E R E D L A T I T E C O M P O S I T E A L K A L I N E B A S A L T -A L K A L I N E Q U A R T Z G A B B R O AUGITE T R A C H Y T E QUARTZ, ALBITE, SANIDINE PORPHYRIES (Dark Pink Phase, One Dyke at Depth ) A >> or UJ D Y K E S and ( Grey to Pink Predominant Phase, Intrusive Crystal Breccia) M A S S E S ( Fine - Grained Pink Phase, Few Dykes al Depth) S I L L S and D Y K E S ( Light - Colored ) R O O F - S I L L and D Y K E S ( L ight - Colored, Slightly Deformed or Foliated ) _I < or L U i LU or Q. VALHALLA STOCK P O R P H Y R I T I C B I O T I T E Q U A R T Z M O N Z O N I T E NELSON BATHOLITHIC ROCK H O R N B L E N D E GRANODIORITE ; Regionally Sheared and Altered vv S Y M B O L S / A F A U L T ( P e r i o d - M l ) . Defined (Dip Direction and Upthrown Side), Inferred S H E A R and B R E C C I A Z O N E ( M a i n l y Period - iTl ). Vertical, Inclined F O L I A T I O N ( P e r i o d - T ) Vertical, Inclined INTRUSIVE C O N T A C T ; Defined and Approximate, Projected and Inferred D.D . H. 2 D.D.M.I o o \ 6 NOTE : ATT ITUDE of INTRUSIVE C O N T A C T ; Vertical, Inclined B . Q W I R E L I N E D I A M O N D D R I L L H O L E (Number), Vertical, Inclined P A C K S A C K D IAMOND D R I L L H O L E ( Number)-, Vertical, Inclined R O C K O U T C R O P S W A M P S T R E A M I N T E R M I T T E N T S T R E A M 4 W H E E L D R I V E R O A D S A M P L E L O C A T I O N of T H I N and P O L I S H E D S E C T I O N S Contour Interval is 100 Feet Geology by GM. Leary (1964 - 1966) Drawn Dy GM Leary (1968); Completed by N Grant Brown F I G U R E 5 GEOLOGY TUZO C R E E K MOLYBDENITE PROSPECT BRITISH COLUMBIA SCALE I INCH = 400 FEET To Accompany Thesis PETROLOGY AND STRUCTURE OF THE TUZO CREEK MOLYBDENITE PROSPECT by G M. Leary ( 1969 ) LOOKING WEST I3°30' SOUTH IA* 2500' _25Q0_ IB LOOKING NORTH 17° 30* EAST LOOKING NORTH 19° 30 WEST IB SECTIONS To ACCOMPANY FIGURE 5 M B 0 L S FIGURE 6 D . D . H . 2 u 861 N O T E • F A U L T ( P e r i o d H i ) ; Defined (Relative Direction of Movement ) , Inferred B. Q . W I R E L I N E D I A M O N D D R I L L H O L E (Number, Length of Hole) Geology by G.M Leary (1964 - 1966) Drawn by G M. Leary (1968), Completed by N Grant Brown VERTICAL SECTIONS IA-IA1 AND IB-IB 1 GEOLOGY TUZO C R E E K MOLYBDENITE PROSPECT BRITISH COLUMBIA HORIZONTAL AND VERTICAL SCALE INCH = 400 FEET To Accompany Thesis PETROLOGY AND STRUCTURE OF THE TUZO CREEK MOLYBDENITE PROSPECT by GM Leary (1969) L E G E N D ( S i m p l i f i e d ) < UJ z UJ or CL P O R P H / R Y R O O F - S I L L A N D D Y K E S Q U A R T Z M O N Z O N I T E S T O C K H O R N B L E N D E G R A N O D I O R I T E N O T E Intrusive Contacts Are Projected Across Intra - And Post - Mineral Intrusives Y M B 0 L S / P E R I O D - IH F A U L T S ; Defined (Dip Direction And Upthrown Side), Inferred P E R I O D - 1 I N T E N S E L Y F R A C T U R E D Z O N E S A I I Peripheral Zones - I To - 7 Peripheral Zone - 8} With Quartz Veining (Phase- T) He a vi ly Min e r alized With Herniate And Magnetite ( Phase - T) Central Quartz Vein Stockwork Zone (Quartz Veins Are Phase-T) Associated Pyrite And Molybdenite ( Phase - T) P H A S E - \_ W A L L R O C K A L T E R A T I O N Outline Of The Alteration Halo f ^.Outline Of Moderately Argillized Regions Within The Peripheral Shell / 0 • * — - r Outline Of Region Of Intense To Very Intense Alteration., Argillization And S'Ucification In Upper Part ( Exposed) Potash Feldspathization And Silicification In Lower Part (At Depth) M a i n l y Region Of Weak To Moderate Alteration-Projected Defined And Approximate Argillization In Upper Part (Exposed) M a m l y *\ Potash Feldspathization In Lower Part (At Depth) P H A S E - I 9 \ FT£0 PH'°E M I N E R A L I Z A T I O N Boundary Between Hematite - Magnetite Of Mineralization (Defined, Projected) Area Of Molybdenite Mineralization - Pyrite And Pyrite Fields N O T E 5 Geology by GM. Leory (1964- 1966) Drawn by G.M Leary (1968)-, Completed by N Grant Brown F I G U R E 7 STRUCTURE, HYDROTHERMAL ALTERATION AND MINERALIZATION TUZO CREEK MOLYBDENITE PROSPECT BRITISH COLUMBIA S C A L E I INCH = 4 0 0 F E E T To Accompany Thesis ' PETROLOGY AND STRUCTURE OF THE TUZO CREEK MOLYBDENITE PROSPECT by G.M Leary (1969) LOOKING NORTH 17° 30' EAST LOOKING NORTH 19° 30' WEST QUARTZ-HYDROMICA S U B - Z O N E QUARTZ—K FELDSPAR SUB-ZONE SECTIONS TO ACCOMPANY FIGURE 7 2 B ' E f » SOOO* 4000' 3500' S Y M B O L S Period - HI Faults; Defined (Relative Direction Of Movement), Inferred a Wide Shear And Breccia Zone ( Period -1 ) CD Peripheral Fracture Zones - 5 And - 7 ( Period ~±) Projected Surface Area Of The Central Quartz Vein Stockwork Zone FIGURE 8 Projected Surface Area Of Molybdenite Mineralization D I A M O N D D R I L L H O L E I L L I S T R A T I O N S P H A S E -T F E A T U R E S Length 30' - .07 I / % MoS2 (>04 %) Moderate To Intense Potash Feldspathization Intensely Silicified Zones Quartz Vein Stockwork Zones (Average 1—3 1/2 Veins Per Foot) Zones Heavily Mineralized With Hematite And Magnetite V E R T I C A L S E C T I O N S 2 A - 2 A ' A N D 2 B - 2 B ' STRUCTURE, HYDROTHERMAL ALTERATION AND MINERALIZATION TUZO CREEK MOLYBDENITE PROSPECT BRITISH COLUMBIA P H A S E - U F E A T U R E S H O R I Z O N T A L A N D V E R T I C A L S C A L E I I N C H = 4 0 0 F E E T 1 0 - 0 5 A (See Above) Outline Of Zone Of Intense Argi/lization And Silicif ication 1 P H A S E II ^Intensely Silicified Zones N O T E •  Geology by G.M. Leary (1964 - 1966) Drawn by G.M. Leary (1968) Completed by N. Grant Brown To Accompany rhesis " PETROLOGY AND STRUCTURE OF THE TUZO CREEK MOLYBDENITE PROSPECT by G.M Leary (1969) 

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