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The spuzzum pluton Northwest of Hope, B.C. Vining, Mark Richard 1977

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THE SPUZZUM PLUTON NORTHWEST OF HOPE, B . C. by MARK RICHARD VINING B.Sc, University of Washington, 1974 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i in THE FACULTY OF GRADUATE STUDIES (Department of Geological Sciences) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA April, 1977 © Mark Richard Vining, 1977 In p resent ing 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 fo 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 fo r reference and study. I f u r t h e r agree t h a t permiss ion for e x t e n s i v e copying of 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 . It i s understood that copying or p u b l i c a t i o n of 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 The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date 13 An/ WI i ABSTRACT The Spuzzum Ba t h o l i t h underlies an area northwest of Hope, B.C. It i s nearly 60 km. long i n a northerly d i r e c t i o n and 10 to 20 km. across. The southern part of the body i s zoned from pyroxene d i o r i t e i n i t s core, through hornblende d i o r i t e , to biotite-hornblende t o n a l i t e . Tonalite forms about two thirds of the pluton's area, forming a nearly continuous rim. The pluton intrudes upper Paleozic Chilliwack Group, the Cretaceous (?) Giant Mascot Ultramafic Body, and S e t t l e r Schist of unknown age. K-Ar ages for t o n a l i t e and d i o r i t e range from 76 to 103 m.y. D i o r i t e consists of subhedral orthopyroxene and plagioclase ( A n ^ to A n ^ ) , with v a r i a b l e amounts of hornblende and clinopyroxene. Tonalite i s l a r g e l y composed of anhedral quartz and b i o t i t e , and subhedral hornblende and plagioclase (An,_Q to An.^) • Tonalite and some d i o r i t e s are f o l i a t e d . These rocks are l o c a l l y hornblendized, resembling hornblende gabbro. Pods of d i r e c t i o n l e s s hornblendite are common i n hornblendized rocks. F o l i a t i o n s and mineralogical zonation o u t l i n e a crude tongue-like structure, modified by l a t e r deformation. Spuzzum d i o r i t e appears to have intruded the main part of the Giant Mascot Ultramafic Body but some hornblendites are younger than d i o r i t e . The Giant Mascot Ultramafic Body, 2 by 3 km., i s zoned from dunite or p e r i d o t i t e , through pyroxenite, to a rim of hornblendite up to 100 m. across. Hornblendite occurs also as dykes. i i Orthopyroxenes of Spuzzum d i o r i t e are weakly aluminous hypersthene; those of the contact with Giant Mascot pyroxenite are bronzite. Clinopyroxenes of the same rocks are somewhat more aluminous s a l i t e s and diopsides. Hornblendites from Spuzzum d i o r i t e and the Giant Mascot U l t r a -mafic Body resemble a l k a l i basalt i n composition. Hornblende analyses f a l l into three categories: edenite, pargasite-common hornblende, and t h i r d l y , more i r o n - r i c h common hornblende. It i s concluded that Spuzzum d i o r i t e and t o n a l i t e o r iginated by c r y s t a l s e t t l i n g from quartz d i o r i t e magma at depth, followed by d i a p i r i c r i s e of a zoned pluton composed of r e s i d u a l t o n a l i t e l i q u i d cored by drawn-up d i o r i t i c cumulate. A mathematical test shows the compositions of d i o r i t e and t o n a l i t e to be consistent with t h i s hypothesis. The r i s i n g pluton subsequently engulfed the Giant Mascot Ultramafic Body. Hornblendites may have formed by metasomatism of these rocks and adjacent d i o r i t e or t o n a l i t e as a consequence of the second b o i l i n g of t o n a l i t e and the coursing of r e s u l t a n t hydrothermal f l u i d through the nearly s o l i d pluton. i i i CONTENTS I. INTRODUCTION A. General Statement 1 B. Location and Access 1 C. Previous Work 1 D. Present Investigation 3 E. Acknowledgement s 4 II. GENERAL GEOLOGY A. Introduction 5 B. Settler Schist 7 C. Giant Mascot Ultramafic Body 8 D. Spuzzum Pluton 9 E. Regional Structure 12 III. SPUZZUM PLUTON A. Introduction Ik B. Petrography 15 1. Zoned Diorite arid Tonalite 15 2. Hornblendized Rocks 21 3. Ultramafic Bodies 23 C. Structure 39 1. Internal Structure 39 2. Contact Relationships 42 iv IV. MINOR INTRUSIONS A. Mafic Dykes and Pipes 50 B. Pegmatite Dykelets and Veins t 50 C. Tonalite Aplite Dykelets 51 V. HORNBLENDITE ASSOCIATKD WITH THE GIANT MASCOT ULTRAMAFIC BODY 52 VI. CHEMISTRY A. Introduction 54 B. Plagioclase 54 C. Pyroxene 54 D. Hornblende 67 VII. ORIGIN A. Introduction 79 B. Differentiation of Spuzzum Magma 8 l 1. Discussion 8 l 2. Test of the Hypothesis 85 3. Results 90 C. Origin of the Pluton 93 D. Water in the Spuzzum Pluton 97 E. Rise and Emplacement of the Pluton 100 F. Origin of Hornblendite 1 0g' V BIBLIOGRAPHY 113 APPENDICES Appendix I - Modes and Mineralogical Data 117 Appendix II - Pyroxenes from Literature 124 Appendix III - Hornblendes from Literature 127 Appendix IV - Computer Program for the Differentiation Test 129 Appendix V - Catalogue of Field Data 135 vi LIST OF TABLES Number Description Page I Compilation of K-Ar Age Determinations for the Spuzzum Batholith 11 Ila Average Modes of the Spuzzum Pluton l 6 lib Average Optically Determined Plagioclase Compositions l 6 III Key to Spuzzum and Giant Mascot Mineral Analyses 55 IV Plagioclase Compositions from Spuzzum Analyses 56 Va Spuzzum Orthopyroxene Analyses and Formulas 59 Vb Spuzzum Clinopyroxene Analyses and Formulas 60 VI Calculated Equilibration Temperatures of Spuzzum Pyroxene Pairs 63 VII Calculated Equilibration Temperatures of Giant Mascot Pyroxene Pairs 65 VIII Key to Spuzzum and Giant Mascot Hornblende Analyses 68 IX Spuzzum and Giant Mascot Hornblende Analyses and Formulas 69 X Key to Whole-Rock Analyses from Literature 72 XI Whole-Rock Analyses and Adjusted C.I.P.W. Norms for Comparison with Spuzzum Hornblendite 73 XII Calculation of Diorite and Tonalite Densities 8h XIII Pyroxene Compositions Used in the Differentiation Test 91 XTVa Results of the Differentiation Test: Input Parameters and RMS Residua 91 XTVb Results of the Differentiation Test: Compositions of Phases 92 XV Calculation of Water Content of the Spuzzum Pluton 99 v i i LIST OF FIGURES Number Description Page 1 General Location Map of the Greater Hope Area, B. C. 2 2 General Geology Map of the Greater Hope Area, B. C. 6 3 Modal Variation Diagram for the Spuzzum Pluton 17 4 Crystallization Sequences for Rocks of the Spuzzum Pluton 18 5a Multiple Parallel Hornblendite Dykes in Hornblendized Diorite 36 5b Fragmented Schist Xenolith i n Hornblendized Diorite, Cut by Hornblendite Dykelets 36 5c Domelike Protrusion of Hornblendite into Hornblendized Diorite 37 5d Irregular Contact of Hornblendite Against Hornblendized Diorite 37 5e Injection of Diorite and Invasion of Hornblendite into a Schist xenolith 38 6 Foliation Patterns in the Spuzzum Pluton 41 7 Local Geology Map of the Giant Mascot Mine hk 8 C-F-M Diagram for Spuzzum and Giant Mascot Pyroxenes and Hornblendes 6 l +3 9 Fe Atoms per Formula Unit in Spuzzum and Giant Mascot Pyroxenes 62 10 Histograms of Equilibration Temperatures for Pyroxene Pairs 66 11 Fe +3 Atoms per Formula Unit i n Spuzzum and Giant Mascot Hornblendes 71 12 Variation Diagram of C.I.P.W. Norms of Whole-Rock Analyses for Comparison with Spuzzum Hornblendite 74 13 Mg/(Mg + Fe) and Al versus Si per Formula Unit in Spuzzum and Giant Mascot Hornblendes 77 14 Chemical Relationships in Spuzzum Differentiation 82 15 Calculation of Plagioclase Melting Curves 88 v i i i LIST OF FIGURES Number Description Page 16 Calculated Plagioclase Melting Curves for Various Conditions 89 17 Schematic Diagram of the Origin, Rise, and Emplacement of the Spuzzum Pluton 96 18 Evolution of the Spuzzum Pluton Projected in Pressure-Temperature Space 102 19 Schematic Diagram of Crystallization versus Temperature for Rocks of the Spuzzum Pluton 103 20 Character of Metasomatism Between the Spuzzum Pluton and Giant Mascot Ultramafic Rocks 109 ix LIST OF PLATES Number Description Page 1 Irregular Hornblendite Pods 25 2 Hornblendite Body in Diorite 25 3 Hornblendite Pod in Diorite 26 4 Dykelets and Stringers of Hornblendite 27 5 Dykelets and Stringers of Hornblendite 28 6 Xenoliths of Diorite in Hornblendite Body 29 7 Hornblendite Veins and Pods in Diorite 30 8 Hornblendite Replacing Pegmatite 31 9 Hornblendite Replacing Pegmatite 32 10 Hornblendite Dykelet 33 11 Xenoliths of Diorite in Hornblendite Body 33 12 Hornblende Produced by Locallized Metasomatism 34 13 Hornblende Produced by Locallized Metasomatism 35 14 Hornblendite Dykelet Cutting Diorite and Pyroxenite 48 15 Mafic Dykes in Diorite 48 ACCOMPANYING MAPS (in pocket) Geology Between the Fraser River and Emory Creek, Northwest of Hope, B. C. Mineralogical Zonation in the Spuzzum Pluton (on same sheet) 1 I. INTRODUCTION A. General Statement The object of this thesis was to examine and describe that part of the Spuzzum Pluton that lies between American Creek and Emory Creek near Hope, B. C, and also to determine the contact relationships between the Giant Mascot Ultramafic Body and the surrounding Spuzzum Pluton. B. . Location and Access The thesis area, about 11 by 12 kilometres, is approximately centred on the Giant Mascot Copper-Nickel Mine 10 kilometres northwest of Hope. Mapping was carried on mainly within the American Creek and Emory Creek watersheds, and, to a lesser extent, in the north part of the Garnet Creek watershed (fig. l ) . Much of the area, except the upper part of Stulkawhits Creek, has been extensively logged within the last several years. Networks of logging roads cover the countryside except at high elevation. Although most of these roads are in very poor repair, making even poor foot trails, they were very useful during mapping. Elevations range from near sea level at the Fraser River to just over 1500 metres; valley bottoms in the thesis area l i e from 600 to 1070 metres. Areas not logged are heavily forested except for occasional open areas on ridgetops. Outcrop is generally scarce and difficult to place on the map except in logged areas or on ridgetops. C. Previous Work The Spuzzum Intrusions, hornblende tonalite and minor diorite, were first studied by Morris (1955), and later by McTaggart and Thompson (1967), 2 Fig. 1 GENERAL LOCATION MAP OF THE GREATER HOPE AREA, B. C. (thesis area outlined in dashed line) 3 the type area being near Spuzzum, north of Yale, B, C. At that time the plutonic rocks in the area of this thesis were included in the Chilliwack Batholith (Cairnes, 1944). McTaggart and Thompson (1967) also distinguished the Yale Intrusions, s i l l s and stocks of granodiorite to tonalite, and considered them to be younger than type Spuzzum tonalite. Roddick and Hutchinson (1970) described the Scuzzy Pluton of leucocratic granodiorite northwest of Yale. The most comprehensive effort to sort out plutonic rocks near Hope was by T. A. Richards (Richards and White, 1970; and Richards, 1971). He assigned to the Spuzzum Intrusions the rocks that are the subject of this study, and distinguished several other stocks and plutons south of Hope which had previously been assigned to the Chilliwack Batholith. His work has been recently revised and condensed (Richards and McTaggart, 1976). The Giant Mascot Ultramafic Body was studied in detail by Aho (1956), but l i t t l e was done to relate his findings to regional geology. McLeod (1975) studied ore genesis in a drift of the Giant Mascot Mine. Lowes (1971) studied in detail the structure and metamorphism of rocks between the Fraser River and Harrison Lake. In more recent exploratory efforts by Giant Mascot Mines Ltd. and the B. C. Department of Mines and Petroleum Resources, the ultramafic rocks between the Fraser River and Harrison Lake have been remapped (Eastwood, 1971; and unpublished material by Giant Mascot Mines, Ltd.). Detailed studies of schists in contact with Spuzzum tonalite include Read ( i 9 6 0 ) , Richards (1971), Lowes (1971), and Pigage (1973). D. Present Investigation Field work for this thesis was carried on mostly during the summer months of 1975, and laboratory work during the winter and spring of 1976. k Mapping was done on 20 chain airphotos made by the government of British Columbia and enlarged sections on 1:50,000 National Topographic Series maps. For the vicinity of the Giant Mascot property a 1:3600 map was made available by Giant Mascot Mines, Ltd. E. Acknowledgements This thesis was prepared under the supervision of K. C. McTaggart, to whom I am thankful for guidance, encouragement, and field assistance. Thanks are given to Mr. F. W. Holland of Giant Mascot Mines, Ltd., for lodging at the mine; to Dr. P. A. Christopher of the B. C. Department of Mines and Petroleum Resources for initiating the project, financial support, and field assistance; to Mr. C. L. Hronek of Vancouver, B. C, for assistance on some traverses; and to Mr. Allen Doherty of the University of New Brunswick for invaluable field assistance through August 1975. The B. C. Department of Mines and Petroleum Resources provided field equipment and a special research grant. 5 II. GENERAL GEOLOGY A. Introduction The mid-Cretaceous Spuzzum Pluton lies on the southeastern margin of the Coast Plutonic Complex in the axial belt of the Northern Cascades structural system (Monger, 1970). It intrudes Settler Schist primarily (fig. 2), but also the Chilliwack Group in the southwest, and in the north-west, gneiss which may be the migmatized equivalent of Settler Schist (McTaggart and Thompson, 1967). Non-plutonic rocks in this region include: (l) Custer (Skagit) Gneiss east of the Hope Fault, a high grade migmatitic complex of layered gneiss and schist; (2.) Upper Paleozoic Hozameen Group east of the Yale Fault, composed of ribbon chert, pelite, basic volcanics, and minor limestone; (3) Upper Paleozoic Chilliwack Group to the west, composed of pelite, sandstone with minor conglomerate, pyroclastics, basic volcanics, limestone, and minor chert; (4) Jurassic Ladner Group northeast of the Hozameen Fault, composed of pelite, volcanic sandstone, and minor conglomerate and volcanics; and (5) Eocene conglomerate and minor sandstone adjacent to the Hope Fault on the east, forming a narrow belt that pinches out north of the thesis area (McTaggart and Thompson, 1967; Monger, 1970; McTaggart, 1970). Ultramafic rocks occur in a crudely northwest-trending belt with its southern end at the Giant Mascot Mine. These rocks consist of gabbro to partly serpentinized peridotite and, except for the Giant Mascot Ultramafic Body, have been considered alpine type (McLeod, 1975). The Coquihalla Serpentinite Belt stretches along the Hozameen Fault east of the Fraser River. 6 Fig. 2 GENERAL GEOLOGY MAP OF THE GREATER HOPE AREA, B. C. SCALE 1:320,000 i i i i i i i i 6 km. LEGEND (units not labelled) rivers, lakes alluvium f 0 0 0 0 o O 0 Eoc. conglom. w w w * * w \1 undivided J-K sediments .1 - / \ undivided plutonic rock H schists gneisses ultrabasic rock faults Geology after: Monger (1970) Richards (1971) this study 7 Intrusive rocks neighboring the Spuzzum Pluton include: ( l ) Scuzzy Pluton of uncertain age to the northwest, composed of coarse l e u c o c r a t i c granodiorite with minor t o n a l i t e ; (2) Eocene and Paleocene Yale Intrusions forming a north-trending b e l t east of the Fraser Canyon, a heterogeneous assemblage ranging from granite to gabbro, granodiorite being most abundant; (3) Early Oligocene S i l v e r Creek Stock south of Hope, composed of homogeneous mesocratic t o n a l i t e ; (1+) Early Oligocene H e l l ' s Gate Stock at He l l ' s Gate, composed of fine-grained granodiorite or trondhjemite; and (6) Middle Miocene Mount Barr B a t h o l i t h to the south, a four phase complex ranging from t o n a l i t e to quartz monzonite (Roddick and Hutchinson, 1970; and Richards, 1971). The Hicks Lake Stock west of Ruby Creek, composed of mafic t o n a l i t e , i s c o r r e l a t e d with phase 1 of the Mount Barr B a t h o l i t h (Richards, 1971). B. S e t t l e r Schist North of Emory Creek, S e t t l e r Schist consists of layered p e l i t i c s c h i s t , g r a p h i t i c p e l i t i c s c h i s t , quartzofeldspathic s c h i s t , micaceous q u a r t z i t e , and minor c a l c - s i l i c a t e layers and t a l c - a n t h o p h y l l i t e pods. P e l i t i c assemblages are t y p i c a l of s t a u r o l i t e through s i l l i m a n i t e zones of the Barrovian f a c i e s s e r i e s . P e l i t i c and c a l c - s i l i c a t e assemblages indicate pressures and temperatures of 5.5 to 8 k i l o b a r s and 550 to 700° during r e g i o n a l metamorphism (Pigage, 1973). 8 Richards (1971) described upgrading near the contact with Spuzzum tonalite thus: "A later contact metamorphic aureole some 1000 yards wide was superimposed on the regionally metamorphosed schists. In the schists close to the contact with the tonalite, fibrolite and sillimanite occur with muscovite and biotite while further away coarse porphyroblasts of muscovite and chlorite pseudomorph staurolite. Thus, i t appears that the tonalite has truncated the earlier-formed regional metamor-phic isograds and superimposed a younger thermal metamor-phism upon the older regional metamorphism." (p. 30) Richards concluded that contact metamorphism took place at a pressure of about U.5 kilobars, which corresponds with a depth of about 13 kilometres. C. Giant Mascot Ultramafic Body An irregular shaped body, zoned crudely from hornblendite to peridotite, is situated at the Giant Mascot Copper-Nickel Mine. The 2 by 3 kilometre body consists of pipes of olivine pyroxenite or dunite surrounded by pyroxenite which is the most common rock type. This is in turn surrounded by a remarkable marginal zone of coarse pegmatitic hornblendite up to 100 metres across. The southwest half of the body is a highly varied horn-blendic assemblage that contains many bodies of feldspathic rocks, horn-blendite dykes, and various other rocks. Copper and nickel orebodies are in this part of the ultramafic body (Aho, 1956). The different varieties of ultramafic rocks are closely related; most of their mutual contacts are gradational, but some are sharp locally. The body as a whole is in line with, and may be related to, a string of gabbro or hornblendite to pyroxenite or dunite bodies in schist to. the northwest (Lowes, 1971). The associated feldspathic rocks, mainly hypersthene-augite-hornblende diorites but also gabbroic rocks and 9 norite, appear to have conflicting age relationships, cutting and "being cut by one another and the ultramafic rocks. A large degree of contemporaneity between them and the ultramafic rocks is suggested (Aho, 1956). Potassium-argon ages of ultramafic rocks of orebodies range from 104 to 119 million years. Hornblendite dykes have an age of 95 million years and are the youngest ultramafic rocks (McLeod, 1975). Aho (1956) interpreted the mineralogical zonation in orebodies, that is pyroxenite to dunite, as resulting from conversions between orthopyroxene and olivine by hydrothermal addition or subtraction of Si02. Many of the mutually crosscutting relationships in these rocks support this hypothesis. McLeod (1975) preferred to explain the overall zonation pattern and inter-s t i t i a l sulphides by diapiric intrusion of an ultramafic crystal - sulphide melt mush that may have preceded the Spuzzum Pluton. Similarities in mineral compositions between ultramafic rocks and surrounding feldspathic rocks, as well as the intimate field relationships among them, support this view (Aho, 1956; McTaggart, 1971; and McLeod, 1975). D. Spuzzum Pluton Diorite and tonalite of the Spuzzum Intrusions (McTaggart and Thompson, 1967), or the Spuzzum Batholith (Richards and McTaggart, 1976), extend for many kilometres along the west side of the Fraser River north of Hope, forming one of the large plutons of the Coast Plutonic Complex (fig. 2). In the north i t consists mainly of biotite-hornblende tonalite, and fairly common hornblende diorite with occasional hornblendite bodies (McTaggart and Thompson, 1967). In the south tonalite remains the same, but diorite has a distinct mineralogical zonation. This zonation is concentric and 10 characterized by pyroxene diorite in the middle grading continuously to pyroxene-hornblende diorite at the contact with tonalite, but these types are nearly the same chemically (Richards, 1971). Tonalite in the south forms an outer sheath to the intrusion, containing the zoned diorite core. Tonalite is gneissoid in a l l parts of the batholith; diorite in the south, however, may be directionless or weakly foliated. The southern part of the batholith appears to have a tongue-shaped structure, and may have been intruded as a pluton separate from the northern part but contemporaneous with i t . In the north tonalite shows a gradational and conformable contact with metamorphic rocks correlated by McTaggart and Thompson (1967') with the Hozameen Group. In the south the Spuzzum Batholith intrudes Settler Schist and Giant Mascot ultramafic rocks (Richards, 1971; and McLeod, 1975). Small to large xenoliths of gneiss and schist are included in tonalite in a l l parts. In some places schist and marble xenoliths occur in diorite in the south. Potassium-argon ages from a l l parts of the batholith are listed in table I, and their localities are shown in fig. 2. Ages range from 76 to 103 million years, some determinations being concordant between hornblende and biotite. There is not a clear separation between ages of tonalite and diorite, but tonalite ages are generally younger. Considering that this area has undergone considerable metamorphism, plutonism, and deformation, resetting is easily possible and these ages should be considered minimum (Monger, 1970). Tonalite was "considered to be -younger than diorite (Richards, -1971), : intruding i t along its contact with country rock. In this study the hypothesis that diorite and tonalite were intruded as a single zoned pluton is favoured. Both Richards and this author have considered only the 11 TABLE I COMPILATION OF K-AR AGE DETERMINATIONS FOR THE SPUZZUM BATHOLITH Symbol in fig. 2 • < 0 • < < • < A. • Reference Age ( m.y. ) Mineral Rocktype McTaggart and 76 + k Bio tonalite Thompson (1967) 76 + 3 Hbd tonalite Richards and 103 + 5 Bio tonalite White (1970) 103 + 5 Bio tonalite it 79 + k Hbd tonalite it 81 + k Bio tonalite it 83 + k Bio tonalite McLeod (1975) 8 5 . 1 + 2 . 8 Hbd tonalite it 7 9 . 4 + 2 . 5 Bio tonalite it 89.6 + 3 .1 Hbd + Px diorite it 8 9 . 5 + 2 . 8 Hbd diorite 12 southern part of the larger Spuzzum Batholith, this author hereafter referring to that part only as the Spuzzum Pluton. E. Regional Structure " The structure of the Cascade Mountains, as detailed by Misch (1966), in northern Washington State and South-ern British Columbia, is that of a central north-northwesterly trending gneiss complex, comprising rocks of the Skagit Metamorphic Suite, flanked by thrust plates that overlie autochthonous Mesozoic rocks." (Lowes, 1971, p. 6) The Skagit Metamorphic Suite (Custer Gneiss) disappears in the Fraser Canyon; in Washington i t is bounded on the west by the Straight Creek Fault and on the east by the Ross Lake Fault (Misch, 1966). A narrow graben, formed by the Hope and Yale Faults, extends from the international border northward through Hope, and onward for about 250 kilometres. This graben may be part of a major tectonic boundary extending into Yukon Territory (Price and Douglas, 1972). The steeply dipping Hozameen Fault bounds the Hozameen Group on the east in southern British Columbia. In the North Cascades of Washington the fault is called the Ross Lake Fault Zone (Misch 1966) and is a west-dipping thrust fault. The Hozameen Fault appears to cross the Fraser Canyon Fault Zone (Hope and Yale Faults) and east of the Fraser Canyon is marked by a conspicuous belt of serpentinite. McTaggart and Thompson (1967) regarded the fault as being older than the Fraser Canyon Fault Zone, extending northwestward from i t at a low angle near Keefers, B. C. West of the metamorphic core the Church Mountain Thrust Plate, mainly Chilliwack Group, overlies Mesozoic rocks. This is in turn overlain by the Shuksan Thrust Plate of phyllite and greenschist of uncertain age in Washington (Misch, 1966). The Church Mountain Thrust extends northward 13 and passes beneath Harrison Lake, where Chilliwack Group rocks are in faulted contact with Mesozoic rocks to their west. Faultbound and sheared mafic and ultramafic rocks in Settler Schist west of the Spuzzum Pluton may mark the northward extension of the root zone of the Shuksan Thrust (Lowes, 1971). Folding and faulting in this region are the result of several episodes of deformation, some involving metamorphism and plutonism. McTaggart and . Thompson (1967) summarized the deformational periods in south central British Columbia thus: " l . Northwest-trending folding and faulting during the development of the Custer Gneiss, affecting both Custer and Hozameen rocks (late Paleozoic or early Mesozoic?). 2. Northeasterly folding and thrusting (mid-Cretaceous?). 3. Deformation associated with the Hozameen Fault (mid Cretaceous?). h. Folding and metamorphism of the Hozameen Group north-west of Hope [Settler Schist] and northwest of Stout, with accompanying emplacement of the Spuzzum Intrusions (late Late Cretaceous). 5. North-south folding and faulting along Fraser River (Eocene and earlier?). 6. Deformation (slight) accompanying emplacement of the Chilliwack batholithic rocks (Miocene and earlier?)." (p. 1222) 14 III. SPUZZUM PLUTON A. Introduction Richards (1971) divided the Spuzzum Pluton south of American Creek, into two major units, biotite-hornblende tonalite and diorite. He further subdivided diorite into three types separated by gradational contacts: (l) hypersthene-augite diorite, (2) augite-hypersthene-hornblende diorite, and (3) biotite-hypersthene-hornblende diorite. North of American Creek rapid variation in amounts of biotite and pyroxenes makes Richards' types difficult to map and, in addition, the area is complicated by the occurrence of another distinctive type. Therefore Spuzzum diorite "proper" is subdivided in this study on the criterion of relative abundance of hydrous versus anhydrous mafic minerals. Two major categories are defined: pyroxene diorite and hornblende diorite depending on whether or not pyroxene > hornblende + biotite (+ chlorite). Tonalite is characterized by lack of pyroxene and abundance of quartz. These rocks occur in a concentric-ally zoned pattern with pyroxene diorite in the core surrounded by hornblende diorite, in turn surrounded by tonalite (map in pocket). Rocks believed to have formed by the hornblendization of diorite or tonalite, characterized by abundance of hornblende, with plagioclase and perhaps quartz and biotite, but no pyroxene, f a l l into a fourth category. This type grades to normal diorite or tonalite. Small ultramafic bodies, widespread and locally very abundant, are closely associated with hornblendized rocks. Small bodies of tonalitic and rarer dioritic pegmatite occur throughout the Spuzzum Pluton. 15 B. Petrography 1. Zoned Diorite; a na Tonalite Since d i o r i t e and t o n a l i t e are considered to he c l o s e l y r e l a t e d g e n e t i c a l l y and to form a sing l e i n t r u s i v e body, they are treated as a single u n i t . In general these rocks are weakly-seriate p o r p h y r i t i c , medium-grained, and leuco- to mesocratic. Average modes and o p t i c a l l y determined p l a g i o c l a s e compositions f o r pyroxene d i o r i t e , hornblende d i o r i t e , and t o n a l i t e are l i s t e d i n tables I l a and b and shown i n f i g . 3. Modes and mineralogical data f o r i n d i v i d u a l specimens are l i s t e d i n appendix I. The interpreted c r y s t a l l i z a t i o n sequences f o r these rocks are shown i n f i g . k. Plagioclase becomes l e s s c a l c i c and decreases i n amount from pyroxene d i o r i t e to t o n a l i t e . Small grains are anhedral and la r g e r ones are dominantly subhedral. Small grains are generally unzoned but l a r g e r grains c o n s i s t e n t l y have sub- to euhedral weakly o s c i l l a t o r y normal zoning, with superimposed weak to strong patchy zoning. Carlsbad twins, many showing syneusis, are abundant i n l a r g e r grains. Deformational a l b i t e and r a r e r p e r i c l i n e polysynthetic twins are abundant i n a l l grains, except i n t o n a l i t e i n which f i n e grains have l i t t l e or no twinning. Plagioclase of most pyroxene d i o r i t e i s unaltered and minute inc l u s i o n s (hematite?) commonly give i t a pink colour. Some large grains are bent or polygonized. In hornblende d i o r i t e the pink colour i s r a r e , and large grains are commonly bent, oc c a s i o n a l l y broken, and enclosed i n f i n e r subgranoblastic matrix. Plagioclase of t o n a l i t e i s white and some contains muscovite and epidote. Grains are commonly bent, broken, or polygonized, and r e c r y s t a l l i z e d mortar i s abundant. TABLE Ha AVERAGE MODES OF THE SPUZZUM PLUTON Hornblendized Pyroxene Hornblende neral Rocks Transition Diorite Diorite Tonalite Qz .6 1.7 1.4 7.2 15.7 Plag 53.1 56.7 64.5 60.4 51.3 Opx 0 10.5 16.9 7.4 0 Cpx 0 tr 10.3 2.6 0 Hbd 44.7 30.5 5.4 14.6 22.1 Bio 1.0 .3 .5 6.6 9.5 Chi 0 0 0 0 .8 Ep 0 0 0 0 .2 Ap .1 tr .1 tr tr Opaque .7 .3 .9 1.2 .5 Total 100.2 100.0 100.0 100.0 100.1 Colour index 46.3 41.6 34.1 32.4 33.0 No. in average 12 3 16 5 .12 TABLE lib AVERAGE OPTICALLY DETERMINED PLAGI0CLASE COMPOSITIONS Hornblendized Pyroxene Hornblende Rocks Transition Diorite Diorite Tonalite high 65.8 69-7 62.1 53.8 50.0 low 43.5 46.3 43.7 41.2 32.5 average 54.7 58.0 52.9 47-5 41.3 No. in average 8* 3 14 5- 10 * two of the twelve analyses have no plagioclase determinations Note: Values are compiled from appendix I; abbreviations are the same. "Transition" refers to a type transitional between fully hornblendized and normal diorites. Where more than five plagioclase determinations are available, high and low values are discarded. 17 Fig. 3 MODAL VARIATION DIAGRAM FOR THE SPUZZUM PLUTON 18 Fig. k CRYSTALLIZATION SEQUENCES FOR ROCKS OF THE SPUZZUM PLUTON PYROXENE DIORITE HORNBLENDE DIORITE 100 TONALITE /OO Per Cent Crystals 19 Quartz is fine- to medium-grained, anhedral, and interstitial. Large rounded grains occur in tonalite, but in pyroxene diorite i t is confined to clusters of pyroxenes. Strain shadows and polygonization are increasingly abundant from pyroxene diorite to tonalite. Annealing has occurred in some specimens. Pyroxenes are present in diorite, but not in tonalite. Augite is more severely corroded than hypersthene, in many cases appearing "moth eaten." Both varieties are fine- to medium- or coarse-grained, dominantly subhedral and elongate, with large grains tending to cluster together. Many specimens are coarsely glomeroporphyritic, some specimens having finer-than-average plagioclase. Fine lamellar exsolution is abundant'in both pyroxenes on ( 1 0 0 ) , commonly with exsolved blebs in cores of larger grains. Platelets of hematite (?) oriented on (100) and possibly other planes are almost ubiquitous. Augite has abundant simple twinning on ( 100) . As the amount of hornblende increases, augite becomes mottled with tiny structurally continuous blebs of the amphibole. This replacement follows simple zoning in some augite crystals. Hornblende fine- to coarse-grained, anhedral and generally interstitial. The amphibole is pleochroic: fi - "tf> <*, oc = pale yellow, (3 = brownish olive, Y = olive green In tonalite and some hornblende diorite, rims or whole crystals may have ft = green and Y = bluish green. In diorite i t rims, embays, and encloses pyroxenes. It appears to pseudomorph pyroxene glomerocrysts in some hornblende diorites and one tonalite specimen (24/7/75/1). Irregular clouds of oriented opaque inclusions suggest replacement of pyroxene with hematite platelets. Clouds of worm-like quartz inclusions, common in 20 t o n a l i t e and seen i n some hornblende d i o r i t e s , also suggest replacement of pyroxene. Colourless amphibole ( T - V ^ O 0 , £ ~ . 0 2 8 , Y A C ^ • \") 0 ) , occurs as skin against hypersthene i n c l u s i o n s i n hornblende i n d i o r i t e , or as i r r e g u l a r patches i n hornblende of hornblende d i o r i t e or t o n a l i t e . B i o t i t e i s f i n e - to medium-grained (coarser i n t o n a l i t e ) , anhedral, and i n t e r s t i t i a l . I t has pale y e l l o v to deep or reddish brown pleochroism. B i o t i t e generally occurs with hornblende, the two together rimming pyroxene i n d i o r i t e . In d i o r i t e i t i s generally undeformed, but i t i s commonly bent, pinched, or kinked i n t o n a l i t e . C h l o r i t e replaces b i o t i t e s l i g h t l y i n hornblende d i o r i t e , and abundantly i n t o n a l i t e . Accessories include small elongate to large i r r e g u l a r a p a t i t e , rounded to s k e l e t a l or a c i c u l a r opaques and f i b r e s of r u t i l e (?, length slow, st r a i g h t e x t i n c t i o n , high r e l i e f ) i n quartz. Opaque minerals are p r i m a r i l y p y r i t e and p y r r h o t i t e with v a r i a b l e amounts of hematite from weathering. Tourmaline = dark bluegrey, -£ = pink, $*Z .035) occurs i n one t o n a l i t e as bundles of euhedral a c i c u l a r c r y s t a l s . Epidote i s common i n small amounts i n most t o n a l i t e s , occurring i n a few specimens as euhedral incl u s i o n s i n b i o t i t e and p l a g i o c l a s e , and as scattered c l u s t e r s of f i n e grains. Several specimens have textures that appear metamorphic. In one hornblende d i o r i t e specimen (30/7/T5/2a), hypersthene p o i k i l o b l a s t i c a l l y encloses hornblende and b i o t i t e and i s anhedral. I t contains no hematite p l a t e l e t s . Bands of r e c r y s t a l l i z e d mortar are abundant. Several pyroxene d i o r i t e s have granoblastic plagioclase-hornblende-pyroxene matrices, and large plagioclase grains contain rounded to subhedral pyroxene or hornblende i n c l u s i o n s . One of these has large s k e l e t a l hypersthene c r y s t a l s among ordinary pyroxene grains. Quartz i s unstrained i n these specimens. 21 In several pyroxene diorites and one hornblende diorite, large skeletal individual sulphide grains enclose and embay pyroxene and plagioclase. Anhydrous silicates and sulphide are separated by a mono-crystalline, thin but continuous, skin of hornblende. This texture is not abundant, but widespread and conspicuous. 2. Hornblendized Rocks Hornblendized rocks resembling gabbro with hornblende as the only major mafic mineral and showing strong textural evidence of replacement, are irregularly distributed through the Spuzzum Pluton, superimposed on the typical zonation. This type is found in a l l diorites, and in a few localities appears in tonalite. Contact with surrounding rock is gradational over distances of centimetres to tens of metres. It is clearly associated with hornblende veins and hornblendite pods seen most commonly in diorite. Pigage (1975, personal communication) reported gradual variation from tonalite to hornblendite north of Emory Creek. McTaggart and Thompson (1967) described diorite of the Spuzzum Batholith near Spuzzum, B. C, thus: "Medium-grained diorite in which hornblende approaches 50$ of the rock is fairly common and hornblendite is seen occasionally." (p. 1211) Hornblendized rocks are interpreted to result from alteration of diorite or tonalite contemporaneous with the formation of hornblendite dykes, pods, and veins which are described in the next section. Three specimens of hornblendized diorite are classified as transitional to diorite. Two tonalite specimens are unusually mafic and may also be hornblendized. Averaged modes and plagioclase compositions for the three hornblendized diorites are listed in tables Ila and b and shown in fig. 3. Modes and mineralogical data for individual specimens are listed in appendix I. 22 R o c k s o f t h i s u n i t a r e meso - t o m e l a n o c r a t i c , m e d i u m - g r a i n e d , and i n e q u i g r a n u l a r . P l a g i o c l a s e c o m p o s i t i o n s r a n g e w i d e l y and a v e r a g e s l i g h t l y h i g h e r t h a n t h e a v e r a g e o f p y r o x e n e d i o r i t e . S m a l l e r g r a i n s a r e a n h e d r a l , and l a r g e r ones a r e a n - t o s u b h e d r a l and commonly a l t e r e d w i t h i n c l u s i o n s o f e p i d o t e m i n e r a l s , s e r i c i t e , o r h o r n b l e n d e . S m a l l g r a i n s a r e commonly u n z o n e d b u t l a r g e ones have abundan t s t r o n g p a t c h y z o n i n g , w i t h r e l i c t a n - t o s u b h e d r a l o s c i l l a t o r y n o r m a l z o n i n g . C a r l s b a d t w i n s a r e common i n l a r g e r g r a i n s , and d e f o r m a t i o n a l a l b i t e and p e r i c l i n e t w i n n i n g i s a b u n d a n t . P h e n o c r y s t s commonly a p p e a r p o l y g o n i z e d o r b e n t , e n c l o s e d i n a s u b g r a n o -b l a s t i c m a t r i x o f p l a g i o c l a s e and h o r n b l e n d e . H o r n b l e n d e ( s i m i l a r t o t h a t i n t o n a l i t e ) i s f i n e - t o c o a r s e - g r a i n e d and a n - t o s u b h e d r a l , f o r m i n g dense d e c u s s a t e c l o t s o r s t r i n g e r s . S m a l l a n - t o s u b h e d r a l c r y s t a l s a r e commonly s u p e r i m p o s e d o n l a r g e i n t e r l o c k e d i r r e g u l a r g r a i n s . S i m p l e and l a m e l l a r t w i n n i n g a r e common on (100), b u t i n some s e c t i o n s r i m s a r e u n t w i n n e d . C o r e s o f c l o t s commonly c o n t a i n p a t c h e s o f c o l o u r l e s s a m p h i b o l e ( s ee p r e v i o u s s e c t i o n ) s u g g e s t i n g r e p l a c e m e n t o f h y p e r s t h e n e . I n one s p e c i m e n h o r n b l e n d e a p p e a r s t o f o r m pseudomorphs a f t e r g l o m e r o p o r p h y r i t i c p y r o x e n e s (20/8/75/3). I n g e n e r a l , h o r n b l e n d e embays a n d i n c l u d e s c o r r o d e d r emnan t s o f p l a g i o c l a s e . I n some s p e c i m e n s f i n e - g r a i n e d s u b g r a n o b l a s t i c p l a g i o c l a s e i s r e p l a c e d and pseudomorphed b y h o r n b l e n d e , w h i l e l a r g e p l a g i o c l a s e g r a q n s a r e r e l a t i v e l y u n c h a n g e d . B i o t i t e i s f i n e - t o m e d i u m - g r a i n e d , o c c u r r i n g as s c a t t e r e d f l a k e s w i t h h o r n b l e n d e . C h l o r i t e o c c u r s as s m a l l i r r e g u l a r f l a k e s o r b u n d l e s i n h o r n b l e n d e c l o t s . Opaque m i n e r a l s f o r m s m a l l b l e b s i n h o r n b l e n d e c l o t s , o r d u s t y p a t c h e s , some o r i e n t e d , i n l a r g e h o r n b l e n d e c r y s t a l s . S m a l l r o u n d t o e u h e d r a l g r a i n s o f a p a t i t e a r e g e n e r a l l y i n h o r n b l e n d e c l o t s . 23 Quartz forms rare anhedral grains with plagioclase. It may or may not have strain shadows. Pyroxenes are found in transitions to diorite. Most of these are hypersthene and occur as corroded relics in hornblende clots. 3. Ultramafic Bodies Richards (1971) reported 1/2 to 2 inch thick pyroxenite replacement bodies in pyroxene diorite south of the Fraser River. In this study 1 pyroxenite bodies were found only at the head of the north fork of American Creek. These are under 10 centimetres in longest dimension and irregular in shape, occurring in directionless pyroxene diorite with metamor-phic textures (specimen 10/7/75/3; see above, page 20). Hornblendite occurs at many localities as rounded to irregular, commonly complexly interconnected pods less than one metre in largest dimension (plates 1 and 2). These, with few exceptions, have sharp contacts and occur exclusively in hornblendized diorite or tonalite. In some localities pods are elongate in the foliation of the host, but are not foliated internally (plate 3); in other places the foliation is truncated or contorted by irregular pods. More commonly the host rock is direction-less. Hornblendite also occurs as dyke- or pipe-like bodies up to several metres in width, which are accompanied by small pods. Northwest of Odium, large parallel slabs of hornblendized diorite with extremely sharp contacts are surrounded by hornblendite (fig. 5a). A schist xenolith is divided into three parts by the confluence of two hornblendite dykelets (fig. 5b). In the same pipe-like body are rounded to angular, equant to irregular 24 inclusions of hornblendized diorite, some appearing displaced (fig. 5a), others having their foliation concordant with the surrounding foliation suggestive of replacement. Common domelike protrusions of hornblendite into hornblendized diorite, and irregular sutured contacts suggest resorption or assimilation of the latter (figs. 5c and d). Several of these relationships occur in a pipe-like body of hornblendite south of the fork in American Creek (plates 10 and 11). Hornblendite forms stringers parallel to the foliation in large schist xenoliths (fig. 5 e ) , northwest of Odium, and to a lesser degree at the Giant Mascot Mine. In several places, but especially well exposed northwest of Odium, pegmatite dykelets and veins appear to be replaced by hornblendite (plate 8 ) . These are accompanied by very thin veins of hornblende, and host diorite grades to hornblendized diorite close to these veins. This is especially well displayed in pyroxene diorite on the southwestern flank of Zofka Ridge (plates 12 and 13). Hornblendites from the Spuzzum Pluton are medium- to coarse-grained, inequigranular, and decussate. They contain scattered anhedral chlorite, and rare corroded plagioclase. Most large hornblende grains are poikilitic, containing small sub- to anhedral ones. Optical properties appear the same as hornblende of hornblendized rocks, except that hornblende of thin veins is entirely bluegreen whereas hornblende from larger bodies is olive with bluegreen rims. A specimen from northwest of Odium has oriented opaque platelets in a large minority of hornblende grains, suggestive of pyroxene replacement. 25 Plate 1. Irregular hornblendite pods in hornblendized diorite, south fork of American Creek. (19/6/75/5) Plate 2. Hornblendite body in pyroxene diorite southwest of location in plate 1. Hornblende stringers appear to follow fractures in diorite. Note diorite xenoliths. (1/7/75/6) 26 Plate 3. Hornblendite pod elongated i n the f o l i a t i o n of hornblendized d i o r i t e . Note l e u c o c r a t i c patches and f a u l t o f f s e t . (20/6/75/6) Plate k. Dykelets and stringers of hornblendite i n hornblendized d i o r i t e near Odium. (AM#2) 28 Plate 5. Same as Plate 4. Note large hornblendite body i n centre background. Plate 6. Lower part of large hornblendite body in Plate 5 Note xenoliths of hornblendized diorite. 30 Plate 7. Hornblendite veins and pods in hornblendized diorite near Odium. Note pegmatite dykelets at lower l e f t . (AM#2) Plate 9. Same as Plate 8. 33 Plate 10 (above) Hornblendite dykelet in hornblendized pyroxene diorite, south fork of American Creek. Note fine-grained margin and very coarse-grained, plagioclase-cored hornblende centre. (l/T/75/5b) Plate 11 (left) Hornblendite body containing xenoliths of hornblendized diorite, south fork of American Creek. (19/6/75/5) 34 Plate 12. Localized metasomatism producing hornblende along fractures in pyroxene diorite, and replacing pegmatite and mafic dykelet. Note also layering in diorite. (29/7/75/1) \ 35 Plate 13. Same as Plate 12. Note hornblendization of diorite and mafic dykelet near pegmatite dykelet, and parallel fractures. Fig. 5b FRAGMENTED SCHIST XENOLITH IN HORNBLENDIZED DIORITE, CUT BY HORNBLENDITE DYKELETS \ half natural size •. • • ' .*. — — hornblendized schist - hornblendite — — diorite 37 F i g . 5c DOMELIKE PROTRUSION OF HORNBLENDITE INTO HORNBLENDIZED DIORITE one fourth natural s i z e F i g . 5d IRREGULAR CONTACT OF HORNBLENDITE AGAINST HORNBLENDIZED DIORITE 1 metre hornblendite hornblendized d i o r i t e 38 F i g . 5e INJECTION OF DIORITE AND INVASION OF HORNBLENDITE INTO A SCHIST XENOLITH sc h i s t hornblendite - / \- hornblendized d i o r i t e 39 This author concludes that Spuzzum hornblendite is younger than diorite and tonalite. Emplacement of i t appears to be partly magmatic as suggested by dilational features and angular xenoliths, but also partly metasomatic as suggested by vein-like and pod-like bodies and associated hornblendized rocks. C. Structure 1. Internal Structure Richards (1971) described the foliation pattern of diorite south of American Creek as suggesting "the presence of two crude domes, one north of the Fraser River and the other south of Flood" (p. 28). The foliation of tonalite is dominantly steep and northerly striking. His map shows a large dioritic core, crudely rectangular in shape and elongate northward, with about ho per cent of the foliation§ .. . dipping steeply and striking north to northwest, and a somewhat smaller fraction dipping rather shallowly northward. A more detailed map (Richards and McTaggart, 1976), shows two cores of pyroxene diorite within hornblende diorite, roughly corresponding to Richards' dome pattern. Structural data and mineralogical variation are not clearly related, but some correlation can be seen. North of American Creek this correlation becomes less pronounced. Foliations, some with lineation, are developed as aligned "tabular plagio-clase crystals ':, in tonalite and diorite, and aligned elongate pyroxenes in diorite. Cataclastic rocks contain biotite and hornblende strung out in shears, and bands rich in recrystallized mortar. The overall distribution of diorite and tonalite is consistent with a pattern of concentric zonation from pyroxene diorite in the core, through hornblende diorite, to tonalite (see map in pocket). Near the Giant Mascot Ultramafic Body 40 the rim of tonalite is discontinuous and hornblende diorite may be absent, leaving pyroxene diorite in close proximity to tonalite,ultramafic rocks, and schist. Foliations in general do not parallel contacts within the pluton, and only crudely parallel those with surrounding units (fig. 6). The foliation data suggest at least two generations, one a "swirled" flow structure and the other a superimposed northwest striking cataclastic foliation, both being discontinuously developed. Richards (1971) recognized that subdivision of Spuzzum diorite is somewhat arbitrary, for variation within the unit as a whole is gradational. He believed the tonalite unit to intrude diorite, and described its contact at Hunter Creek southwest of Hope as a "100 foot wide zone between diorite and tonalite . . . " i n which "rapid transition from type III diorite to tonalite across this zone is striking and abrupt" (p. 24). North of American Creek continuously exposed gradation from hornblende diorite to tonalite was not found, nor was found a sharp contact of tonalite with diorite. The nearest seen outcrops of clearly recognizable diorite and tonalite are over 30 metres apart. Richards described the evidence of the age of tonalite relative to diorite as inconclusive but suggestive that diorite is older. The fact that large pelitic and calc-silicate schist xenoliths occur in diorite near its margin in a few places lends support of his hypothesis, but this, with the presence of schist xenoliths in tonalite, could also be explained by the intrusion of diorite and tonalite as a single unit into schist. Radiometric ages of tonalite (table I) average four million years younger than those of diorite (which are few in number), but tonalite ages range from 76 to 103 million years. This spread in values is perhaps indicative of resetting, as they are a l l potassium-argon determinations using biotite or hornblende 1+1 Fig. 6 FOLIATION PATTERNS IN THE SPUZZUM PLUTON Scale 1:125,000 42 from rocks in which hornblendite is common. Tonalite of the Spuzzum Pluton is regionally homogeneous, whereas diorite shows continuous variation in mineralogy (south of Emory Creek). Richards (1971) reported that the foliation of tonalite appears to truncate that of diorite in a few places, and structural data from his map show a high angle discordance at one locality. At this locality tonalite is shown in a more detailed map (Richards and McTaggart, 1976) to truncate the mineralogical zonation in diorite, tonalite being in contact with pyroxene diorite rather than separated from i t by hornblende diorite. This author believes these facts are the strongest which suggest diorite is older than tonalite. They, however, do not prove this to be so, and in fact can be explained by a model of fractional crystallization followed by diapiric emplacement of a single pluton of tonalite cored by diorite (discussion in later sections). Local truncation of structural features can be expected, especially i f emplacement occurred in a spasmodic fashion. Further juxtaposition could have been developed as a result of regional disturbances which appear to have affected the northern extension of the Spuzzum Batholith (McTaggart and Thompson, 1967)• 2. Contact Relationships Diorite and tonalite intrude schist. Small dykes and bodies of tonalite can be found in several places, and xenoliths of schist from a few centimetres to at least automobile size are common. Most larger ones retain many of their metamorphic characteristics except that they are generally coarser grained. Small ones tend to lose their identity, being thoroughly recrystallized as hornblende-biotite-quartz-plagioclase granofels. 4 3 Richards (1971) reported calc-silicate xenoliths in diorite but not in tonalite. Calc-silicate layers are found in pelitic xenoliths in both diorite and tonalite north of American Creek. Pigage (1973) described similar calc-silicate layers in schists north of Emory Creek. Read (i960) described sillimanite grade contact metamorphism superimposed on Barrovian regional metamorphism in the large re-entrant which composes the southern arm of Zofka Ridge. The southwest contact of this re-entrant is against diorite and exhibits a wide variety of contact metamorphic rocks not considered in detail in this study. There is considerable uncertainty as to the time relationships between Giant Mascot ultramafic rocks and certain gabbroic and dioritic rocks at the Giant Mascot Mine (Aho, 1956; and McLeod, 1975). These latter rocks can be found intimately associated with a l l types of ultramafic rocks, but only a few are similar to Spuzzum diorite or tonalite. Pyroxene diorite at the mine, however, closely resembles that of the Spuzzum Pluton. Clean contact between these rocks and ultramafic rocks other than hornblendite was seen in three places (fig. 7) : (a) The first is about hOO metres east of the mill, where hornblende pyroxenite is in contact with pyroxene diorite (specimens 27/8/75/2a, b, and c). Alternation between diorite and pyroxenite is discontinuously exposed along a streambed for about 100 metres, the upstream end of which is close to a mutual contact with schist. Contact of diorite with pyroxenite is generally very sharp, but close to schist a heterogeneous, discontinuous "mixed" zone separates them. Pyroxenite consists of medium-grained, subequigranular, hypidiomorphic augite and bronzite in approximately equal amounts, with abundant sub- to kk Fig. 7 LOCAL GEOLOGY MAP OF THE GIANT MASCOT MINE ^ \ ss- v\ *= \\ - i II -II ^//1 ^ - \\ * \\ 45 euhedral large poikilitic hornblende crystals, and minor interstitial plagioclase and quartz. Hornblende also forms skins around pyroxenes and invades them along cleavages, augite being more strongly replaced. Diorite is largely composed of medium-grained, subequigranular, an- to euhedral, plagioclase (zoned An 52 to 82) with sutured grain boundaries, vague relief euhedral zoning in larger grains, superimposed strong patchy zoning, and irregular ragged-looking Carlsbad and albite twinning. Pyroxenes, augite being less abundant than bronzite, are fine-to medium-grained, sub- to euhedral, and loosely clustered. Hornblende forms large anhedral poikilitic grains among pyroxene clusters and interstitial to plagioclase and pyroxenes, and replaces pyroxenes as in pyroxenite. The "mixed" zone is gabbroic in composition and heterogeneous in texture. In general i t is composed of large, anhedral, poikilitic plagioclase crystals (zoned An 40 to 6 l ) with abundant albite twinning and with ra-ee subhedral normal and strong patchy zoning, Bronzite is sub- to euhedral, commonly forming complex skeletal grains included in plagioclase. Augite is an- to euhedral. Hornblende replaces pyroxenes and forms irregular grains as in diorite. It also forms pseudomorphs after pyroxene. This zone appears to pinch and swell along the contact of diorite and pyroxenite, but a thin contact zone of altered pyroxenite appears to be continuous. It contains hornblende crystals similar to those in pyroxenite, as well as sub- to euhedral, fine- to medium-grained pyroxenes in large anhedral poikilitic plagioclase grains (zoned An 68 to 90). This zone appears to grade into unaltered pyroxenite by a steady decrease in amount of plagioclase, but is sharp against diorite. These relationships could be interpreted as assimilation of solid diorite by pyroxenite liquid, forming the mixed zone between them. In 46 this case diorite could be basified by local metasomatism from the crystallizing pyroxenite, causing the prominent alteration and mild recrystallization textures. On the other hand, intrusion of diorite liquid into solid pyroxenite could equally well basify diorite by assimilation of pyroxenite. Local metasomatism could produce the mixed zone. Temperatures of equilibration of pyroxenes (later section) are about 1000° C which supports the latter case. (b) The second contact area is about 000 metres southwest of the mill where round xenoliths of hornblende-rich ultramafic rock can be seen in glomeroporphyritic hornblende diorite (27/8/T5/3b). Exposure is along a series of waterfalls and is: continuous.. Diorite is in sharp contact with coarse hornblendite and hornblende pyroxenite, but these contacts are inconclusive. Xenoliths range from 2 to 30 centimetres in long dimension and are generally ovoid. Several thin, fine-grained hornblendite dykelets cut diorite and appear to cut ultramafic rock as well. These dykelets show that some hornblendite is younger than both diorite and other ultramafic rocks, and the xenoliths show that diorite is younger than these ultramafic rocks. (c) The third contact area is about 150 metres in elevation above the 3550 east portal, where typical hornblende-rich pyroxene diorite is closely associated with pyroxenite, but contacts are not exposed. Xenoliths identical to those described above can be seen in outcrop, and large pieces of float (produced during road building) show fairly large (30 centimetres or so) and angular xenoliths clearly composed of pyroxenite. Thin fine-grained hornblendite dykelets up to several centimetres wide cut diorite and pyroxenite, one cutting what appears to be a xenolith in plate 14. A dykelet of hornblende diorite 15 centimetres wide cuts pyroxenite with 47 sharp contacts, but its extension toward diorite .is covered. This dykelet has hornblende textures similar to comb-layering described by Moore and Lockwood (1973), suggestive of rapid growth in a volatile-rich environment. These rocks show again that hornblendite is younger than diorite and that pyroxenite is older than diorite. Coarse, pyroxene-bearing hornblendite is cut by a fine-grained pyroxene-free hornblende diorite dykelet at the 2 6 0 0 portal. This hornblendite is not clearly the same as that of small dykelets seen elsewhere to cut diorite, but the diorite dykelet appears much like the matrix of glomeroporphyritic Spuzzum diorite. This relationship suggests that either the pyroxene hornblendite is older than Spuzzum diorite,or that old pyroxenite may have been hornblendized during emplacement of the Spuzzum Pluton. A well exposed but inconclusive contact of tonalite against coarse hornblendite lies about 100 metres in elevation above the switchbacks in the mine access road (about 1,0 kilometre northeast of the mill). Moderately foliated tonalite and coarse hornblendite are separated by a fairly continuous, pinching and swelling band of plagioclase-bearing pegmatitic hornblendite (specimens 13/9/75/la and b) up to at least one metre wide. This contact phase is composed mostly of coarse- to very coarse-grained, idiomorphic, somewhat poikilitic hornblende crystals set in an interstitial matrix of medium-grained plagioclase (An 42), augite, and hornblende. Augite forms rounded to elongate, clustered grains included in and among fine- to coarse-grained, interstitial plagioclase grains with weak patchy zoning and rare deformational twinning. Matrix hornblende occurs with clusters of augite, and rims and replaces augite 48 Plate 14. Hornblendite dykelet cutting pyroxene diorite and pyroxenite at the Giant Mascot Mine. Note offset and rounded form of pyroxenite body. (28/8/75/la,b) Plate 15. Mafic dyke in diorite. Note sharp contacts and dilational separation of walls. (29/7/75/6) 49 along cleavages. This contact zone generally grades to coarse hornblendite by a decrease in amount of plagioclase, but its contact with tonalite is sharp. From the evidence of the paragraphs above i t is concluded that the Spuzzum Pluton intrudes the Giant Mascot Ultramafic Body. The relations of other dioritic and gabbroic rocks, not clearly part of the Spuzzum Pluton, are unknown. 50 IV. MINOR INTRUSIONS A. Mafic Dykes and Pipes Fine-grained dykes ranging in composition from mesocratic pyroxene or hornblende diorite to melanocratic amphibolite intrude Spuzzum diorite at several localities and tonalite in at least one locality. They also intrude ultramafic rocks at the Giant Mascot Mine. These dykes have sharp contacts and show dilational features (plate 15), the walls of host rock commonly appearing to f i t together. Some hornblende-rich varieties have weak to strong alignment of subhedral hornblende with polygonal, equant plagioclase. An amphibolitic body near the mill at the mine (fig. 7) has large rounded poikiloblastic plagioclase with hornblende-rich and hornblende-free patches within individual crystals. Hornblende forms a decussate matrix. This texture is also seen in some dykes.* The body contains xenoliths of hornblendized rocks, diorite, tonalite, hornblendite, schist, and pyroxenite, forming a conspicuous intrusive breccia. Plagioclase is strongly normal zoned (An 50 to 80), but poikiloblasts are weakly reverse zoned or unzoned with compositions between An 50 and An 70. Hornblende is olive or brown with 2V^90°, 8 ~ .026, and YAC Z-\7°-B. Pegmatite Dykelets and Veins Coarse-grained chlorite-hornblende-quartz-plagioclase pegmatite cuts tonalite, diorite and mafic dykes. Accessory rutile and tourmaline may be present as rounded crystals or acicular bundles. Northwest of Odium and north of American Creek (plates 8, 9» 12 and 13) this pegmatite is replaced 51 by hornblende. Along Stulkawhits Creek veins of plagioclase pegmatite cut hornblendized tonalite and hornblendite stringers and pods. This pegmatite contains biotite, hornblende, and quartz in small quantities. Dioritic hornblende-plagioclase pegmatites cut and grade into pyroxene or hornblende diorite at several localities. These may be associated with cooling and contraction of Spuzzum diorite during or just after emplacement. C. Tonalite Aplite Dykelets Fine-grained, garnetiferous, muscovite-biotite-quartz-plagioclase aplite intrudes tonalite and schist and cuts dykelets of pegmatite. Small euhedral garnets are poikiloblastic, some with inclusion-free pink cores. Biotite is weakly to strongly aligned forming a foliation, but muscovite forms anhedral unoriented grains. Plagioclase has complex oscillatory zoning, ranging in composition from An 32 to about An 60. It forms fine-to medium-grained equant crystals with abundant deformational and Carlsbad twinning. Quartz and fine-grained plagioclase form a granoblastic groundmass. In tonalite these dykelets appear undeformed except for their foliation and plagioclase twinning, but in schist they appear contemporaneous with broad open folding on northwest trending axes. Some of these dykelets are folded yet cut the foliation of schist, while other dykelets cut them and are planar. Dykelets of these two styles appear identical in a l l other respects. The fact that rocks younger than Spuzzum tonalite are foliated and folded, strongly suggests a deformational event postdating the Spuzzum Pluton. Metamorphic textures in diorite and tonalite could be a result of this event. 52 V. HORNBLENDITE ASSOCIATED WITH THE GIANT MASCOT ULTRAMAFIC BODY Coarse hornblendite forms a discontinuous rim around the main body of the Giant Mascot Ultramafic Body, separating i t from surrounding Spuzzum diorite and tonalite. In only a few places does diorite come in contact with pyroxenite, and in those places the latter is hornblendic, hornblende appearing to form porphyroblasts. Aho (1956) described this hornblendite thus: "In several localities south of the underground workings and at 2400 feet within the 3550 level, hornblendite can be seen in a l l stages of replacement of the anhydrous ultrabasics. Pyroxene cores, relict textures, contact relations, and even plagioclase content are preserved in some rocks while in others the pyroxenes have been fully replaced and the pseudomorphs and relict textures have been reconstituted to form a medium-grained, hypidiomorphic-textured hornblendite composed essentially of prismatic brown hornblende f u l l of small magnetite inclusions. Other bodies of pegmatitic, panidiomorphic textured hornblendite, composed of stubby hornblende crystals up to two inches across, have apparently been formed by similar replacement but perhaps at higher temperatures. These pegmatitic horn-blendites such as those forming the reaction zone around the main ultrabasic intrusion, grade imperceptibly into the pyroxenites and peridotites at most places. All stages of replacement can be traced, yet many of the hornblendite bodies and even the hornblendic pyroxenites show lineation, sharp contacts, inclusions, contact alteration, and dike apophyses suggestive of intrusion into the surrounding^ more anhydrous ultrabasics. Subpoikilitic phenocrysts of labradorite (An 60), labradorite-rich schlieren, and dike-like pegmatitic bodies grading into hornblende gabbro are common near inclusions and contacts of the hornblendites . . ." (p. 452-3) A detailed map of the Giant Mascot Ultramafic Body and vicinity is shown in fig. 1. This map is primarily the work of Aho (1956), but is " modified in outlying areas after the work of this study. 53 Aho interpeted the rim of hornblendite as a reaction zone between a solid-state intrusion of dry ultrabasic rock into wetter diorite and schist. McLeod (1975) interpreted i t also as a reaction zone, but believed that diorite was intrusive into dry ultrabasic rocks. This author i s in agreement with the latter. 54 VI. CHEMISTRY A. Introduction Pyroxenes, plagioclase, and hornblende from several l o c a l i t i e s (table III) vere analyzed by electron microprobe. One specimen of pyroxene diorite was run on two occasions and offers a test of consistency in pyroxene analyses. Elements determined are S i , T i , A l , Fe (as Fe + 2only), Mg, Mn, Ca, Na, and K. Where possible, pairs of ortho- and clinopyroxene from the same specimen were used to calculate approximate temperatures of equilibration according to the method of Wood and Banno (1973). Hornblende analyses from hornblendites were used to calculate C.I.P.W. norms for comparison with basic igneous rocks and other known hornblendite. Since the electron probe does not distinguish the oxidation state of iron, hornblende and pyroxene, analyses were approximately corrected by comparison with analyses from literature. B. Plagioclase Results of plagioclase microanalyses are l i s t e d in table IV. Analyses are arranged in order according to distance from the contact with country rock. Those designated "contact" are from the contact between Spuzzum diorite and pyroxenite at the Giant Mascot Mine (f i g . 7 ) . Results agree well with optically determined compositions. Specimens 27/8/75/2a and c have strong patchy zoning and microanalyses may not show the entire range of composition. C. Pyroxene \ Wood and Banno (1973) provide a semi-empirical equation for determining TABLE III KEY TO SPUZZUM AM) GIANT MASCOT MINERAL ANALYSES Mineral Analys es Symbols Spec. No. Plag. Hbd Cpx Opx Occurrence and Locality 74 rf (Feb.1975)* — — 3 6 Hornblendite dykelet, Giant Mascot Mine 74-7(Apr.1976) — — 1 1 — • 15/6/75/6 2 1 3 4 Px diorite, S side Fraser Canyon, west of Hope A 17/6/75/15 1 2 3 3 Px diorite, 200 m. E. of mill, Giant Mascot Mine 0 18/7/75/5 — — 2 2 Px diorite, 1.25 km. NW of mill, G. M. Mine T l8/7/75/7a — 5 6 — Hornblendite dykelet, 200 m. NE of 3550 portal, Giant Mascot Mine V 24/7/75/11 1 1 4 2 Px diorite, summit of Zofka Ridge, SW of Giant Mascot Mine 27/8/75/2a 1 3 2 2 Pyroxenite, contact with diorite 4.00 m. east of mill, Giant Mascot Mine D same 1 1 2 2 Diorite at same contact X + 27/8/75/2c 6 6 7 2 Diorite several m. away from same contact • AM#2** — 1 — — Hornblendite, several 100 m. NW of Odium • 13/9/75/la — 5 — — Contact of tonalite with UM rocks 900 nu north-east of mill, Giant Mascot Mine 2600 — 5 — — Hornblendite, rim zone of UM rocks, 2600 portal, Giant Mascot Mine * donated by K. C. McTaggart ** donated by K. Nielson TABLE IV PLAGIOCLASE COMPOSITIONS FROM SPUZZUM ANALYSES Locality far far near contact No. 15/6/75/6 24/7/75/H 17/6/75/15 27/8/75/2 a Molar fraction Orthoclase Albite Anorthite >(An/(An + Ab)% core .0175 .4990 .4835 49.21 rim .0176 .5231 .4593 46.75 .0182 .5140 .4678 47.65 .0151 .5241 .4608 46.79 .0125 .2685 .7190 72.81 .0006 .4019 .5975 59.78 Optical An % 42 - 48 48-50 — 55 - 77 No. 27/8/75/2c (contact) Molar fraction Orthoclase Albite Anorthite An/(An + Ab) % .0041 .3840 .6119 61.44 .0075 .3480 .6445 64.93 .0047 .3091 .6862 68.94 .0084 .3005 .6911 69.69 0 .2825 .7175 71.75 .0047 .2727 .7226 72.60 Optical An % 52-82 57 the. equilibration temperature of coexisting ortho- and clinopyroxene as a function of distribution of elements in the two pyroxenes. The equation is derived from a model of ideal mixing in the octahedral (Ml) and cubic (M2) sites of each pyroxene, fitted by additional Mg:Fe terms to experimental data from various sources. The equation is: -•10201. T = *S2L\ + 3 , S 8 X * - 7 . 6 5 X - l U o / . E n <Aor% -173.15 where T = temperature (°C) X = Fe+2/(Mg + Fe + 2) in Opx and a En _ Opx \ M 9 ' \ « i OpX, the same in Cpx where Ml and M2 are site designations. Analyses in this study do not include chromium, and the equation above does not provide for potassium, therefore these elements are neglected in the assignment of formulas and the above calculation. Some ambiguity exists in the discussion of Wood and Banno as to assignment of elements to sites. It is readily apparent that for six oxygens there need not be exactly four electropositive atoms. Wood and Banno do not provide for this situation precisely. For this reason the tetrahedral site is first f i l l e d with silicon and aluminum until occupancy equals two atoms or until aluminum is consumed (less than two atoms). The octahedral site (Ml) is then fi l l e d with a l l remaining Al, Fe + 3, Ti, (Cr), and equal amounts of Fe + 2 and Mg until its occupancy reaches unity. At this state Mg^ -^ and Mg^2 are 58 determined. A l l remaining Fe, Mg, Mn, Ca, and Na atoms comprise the cubic site (M2), which usually will have occupancy unequal to unity. This is done for consistency because structural data for site occupancy is not available. Ortho- and clinopyroxene microanalyses are listed in tables Va and b, and shown in fig. 8 in a C-F-M diagram. For estimation of ferric iron, analyzed pyroxene pairs from various sources were compared with Spuzzum pyroxenes. This comparison shows that chromium-poor pyroxene pairs from Stillwater (Hess, I960), Skaergaard (Brown, 1957), and Bushveld (Hess, I960; and Atkins, 1969) are most similar to Spuzzum pyroxenes. Analyses of these pyroxenes and a key to sources, types of pyroxenes, and their general modes +3 of occurrence are given in Appendix II. Fe contents of these pairs are plotted against Mg/(Mg + Fe) in fig. 9, and estimated curves are drawn for Spuzzum pyroxenes. Corrected formulas are listed for Spuzzum pyroxenes in tables Va and b. Equilibration temperatures calculated from corrected formulas are listed in table VI. Temperatures calculated from corrected analyses range from .53° to 5.54° higher than those from uncorrected ones and average 920°C. Wood and Banno (1973) caution that use of their equation with rocks differing-apprec-iably in composition from those used to derive i t may introduce sizable error. Pyroxene pairs they used were mostly from ultrabasic assemblages, but acid volcanic and basaltic compositions were used also, therefore pyroxenes from Spuzzum diorite should produce results within the given toler-ance bracket. Further, the simplifications associated with their thermodynamic treatment are of uncertain consequence. The authors suggest +3 a tolerance of 70 degrees. Correction for Fe therefore is of no significance. The overall temperature range is about 100 degrees. Considering the tolerance limitation i t can be said with reasonable confidence 59 TABLE Va SPUZZUM ORTHOPYROXENE ANALYSES AND FORMULAS SYMBOL 1 • • A 0 • <r D X Si0 2 53.20 49.21 51.92 51.51 50. 47 52. 04 53.13 53.83 53.11 Ti0 2 .06 .08 .13 .10 .17 .07 .17 .17 .04 A l o O o .91 .59 1.05 1.23 1.47 1.24 2.98 2.88 1.81 c. D FeO 23.59 22.67 23.76 24.27 20.85 21.31 12.53 13.74 16.33 MgO 21.94 21.16 20.72 20.06 22.22 21.89 27.95 27.62 26.03 MnO .46 .1*8 .40 .53 .44 .37 .21 .24 .29 CaO .72 .72 • 77 .72 .98 .88 1.12 .84 .64 Na20 .01 .00 .00 .01 .01 .00 .02 .00 .00 K20 .00 .00 .00 .00 .00 .00 .00 .00 .00 Total 100.89 94.91 98.75 98.43 96.61 97.80 98.11 99.32 98.25 M2 Site .9926 1.0438 .9857 .9855 1.0049 .9818 .9918 .9900 .9897 Na .0008 .0 .0 .0010 .0004 .0 .0011 .0 .0 Ca .0285 .0305 .0312 .0293 .0402 .0355 .0435 .0323 .0250 Mn .0144 .0161 .0129 .0171 .0142 .0117 .0063 .0073 .0087 Mg .6028 .6335 .5832 .5688 .6336 .6155 .7644 .7539 • 7197 Fe+2 .3461 .3637 .3584 .3693 .3165 .3191 .1765 ,19& .2363 Ml Site 1 1 1 1 1 1 1 1 1 Mg .6064 .6110 .5847 .5695 .6357 .6166 .7406 .7204 .7025 Fe+2 .3482 .3507 .3594 .3698 .3176 .3198 .1711 .1878 .2307 Fe+3 .0359 .0359 .0359 .0359 .0359 .0359 .0319 .0329 .0349 Al .0080 .0 .0164 .0219 .0060 .0257 .0519 .0550 .0308 Ti .0015 .0024 .0036 .0029 .0048 .0020 .0045 .0039 .0011 Tetrahedral Site 2 1.9748 2 2 2 2 2 2 2 Al .0315 .0275 .0306 .0336 .0604 .0294 .0751 .0667 .0476 Si I.9685 1.9473 1.9694 1.9664 1.9396 1.9706 1.9249 1.9333 1.9524 60 TABLE Vb SPUZZUM CLINOPYROXENE ANALYSES AND FORMULAS SYMBOL •% • A 0 • V (I 3) Si0 2 52.14 49.18 51.71 50.65 49.96 52.35 51.62 52.13 51.27 52.41 Ti0 2 .39 .44 .31 .41 .48 .22 .33 .35 .47 .30 A1 20 3 2.83 3.04 1.73 2.54 2.98 2.45 2.07 3.06 3.69 2.52 FeO T.99 8.45 10.01 10.96 7.58 6.10 9-33 5.35 5.87 5.94 MgO 14.42 13.85 13.08 12.56 14.78 15.67 13.78 14.91 14.92 15.05 MnO .15 .15 .17 .26 .17 .14 .16 .11 .14 .16 CaO 22.06 20.33 20.92 20.45 20.20 21.07 20.08 21.30 21.21 22.14 Na20 .48 .45 .41 .47 .46 .25 .43 • 49 .Ul .32 K20 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 Total 100.46 95.89 98.34 98.30 96.61 98.25 97.80 97.70 97.98 98.84 M2Site 1.0037 1.0108 .9881 .9990 1.0072 .9826 .9844 .9767 .9868 .9856 Na .0341 .0338 .0304 .0350 .0337 .0183 .0316 .0355 .0297 .0230 Ca .8717 .8439 .8501 .8357 .8277 .8404 .8159 .8523 .8491 .§803 Mn .0048 .0049 .0054 .0084 .0053 .0044 .0051 .0035 .0044 .0049 Mg .0736 .0988 .0740 .0833 .1129 .1015 .0988 .0736 .0879 .0657 Fe+2 .0195 .0294 .0282 .0366 .0276 .0180 .0330 .0118 .0157 .0117 Ml Site 1 1 1 1 1 1 1 1 1 1 Mg .7168 .6987 .6632 .6288 .7271 .7656 .6778 .7539 .7408 .7642 Fe+2 .1900 .2075 .2525 .2762 .1777 .1361 .2261 .1203 .1319 .1367 Fe+3 .0369 .0369 .0369 .0369 .0369 .0359 .0369 .0349 .0359 .0359 Al .0454 .0441 .0385 .0462 .0445 .0564 .0498 .0811 .0783 .0548 Ti .0109 .0128 .0089 .0119 .0138 .0060 .0094 .0098 .0131 .0084 Tetrahedral Site 2 2 2 2 2 2 2 2 2 2 Al .0776 .0947 .0387 .0683 .O898 .0510 .0426 .0534 .0840 .0554 Si 1.9224 1.9053 1.9613 1.9317 1.9102 1.9490 1.9574 1.9466 1 .9160 1.9446 61 Fig. 8 C-F-M DIAGRAM FOR SPUZZUM AND GIANT MASCOT PYROXENES AND HORNBLENDES Horizontal scale: Ca/(Ca + Mg + Fe) Vertical scales: Mg/(Mg + Fe) 62 Fig. 9 FE + 3 ATOMS PER FORMULA UNIT IN SPUZZUM AND GIANT MASCOT PYROXENES Skaergaard CO + fe .07 -.06 . .05 . .0+ . .03 . .01 . .01 . .9 o Bushveld CLINOPYROXENE + Stillwater I .7 Mg/(Mg + Fe) .6 .5 .07 .06 .05 J g .OH •8 + cu fe .03 .01 J .01 .9 ORTHOPYROXENE o o - r .3 — i .7 Mg/(Mg + Fe) .6 T .1 63 TABLE VI CALCULATED EQUILIBRATION TEMPERATURES OF SPUZZUM PYROXENE PAIRS Temperature (°C) from No. Uncorrected formula Corrected formula 74-7 (Feb. 75) 882.99 883.52 7U r7 (Apr. 76) 913.56 917.94 15/6/75/6 873.17 874.30 17/6/75/15 877.43 880.11 18/7/75/5 948.87 954.Ul 2U/7/75/11 922.81 927.55 27/8/75/2c 917.03 918.49 27/8/75/2a (pyroxenite) 965.62 970.15 27/8/75/2a (contact) 975.57 981.04 Range 102.40 106.74 6h that pyroxenes at the contact of Spuzzum diorite with Giant Mascot pyroxenite equilibrated at a somewhat higher temperature than pyroxenes in diorite far from this contact. McLeod (1975) presented microanalyses for 18 pairs of coexisting ortho- and clinopyroxenes from ultramafic rocks from the 3050 level crosscut in the Giant Mascot Mine. These analyses include chromium in addition to elements analysed in this study, and iron is presented as FeO only. Equilibration temperatures calculated as described above average 1026°C and are listed in ascending order in table VII. Histograms of temperature data for Spuzzum and Giant Mascot pyroxene pairs are shown in fig. 10. The properties of these histograms are typical for the data compared to histograms using larger or smaller intervals, or with interval boundaries adjusted higher or lower. The peak at 1120 to l l60°C in the Giant Mascot histogram appears to be real. Whether i t results from collecting bias or shows true temperature distribution is not known. Pyroxenes of diorite are strongly exsolved. A few thin sections of ultramafic rocks show pyroxene to be moderately exsolved. In this study, and that of McLeod (1976, personal communication), care was taken during microanalysis to avoid parts of pyroxene grains rich in exsolution lamellae. If these grains were completely in equilibrium with exsolved pyroxene (when exsolution ceased), then the "clearer" areas should ultimately yield the composition of a single exsolved phase rather than the original pyroxene composition (prior to exsolution). The decrease in calculated temperature in diorite with increased distance from the Giant Mascot Ultramafic Body can be explained by equilibration of pyroxene by exsolution to lower temperatures during post-crystallization cooling. This may have been aided in diorite by increased water content or decreased cooling rate farther 65 TABLE VII CALCULATED EQUILIBRATION TEMPERATURES OF GIANT MASCOT PYROXENE PAIRS Analysis No. Temperature (°C) 3 910.39 27 950.44 8 971.34 28 974.87 22 > 989.07 19 999.50 11 1000.05 15 1007.88 7 1008.90 4 1010.25 2 1018.34 1 1040.21 18 1043.88 25 1003.09 17 1087.59 10 1129.10 16 1130.18 9 1132.59 Pyroxene analyses from McLeod (1975). 66 Fig. 10 HISTOGRAMS OF EQUILIBRATION TEMPERATURES FOR PYROXENE PAIRS S80 ??.0 %0 1000 IOH-0 1030 lllo Temperature (°C) 67 from the ultramafic rocks (which are near a wall of the pluton). High calculated temperatures in ultramafic rocks, may be relict from their original crystallization. Partial to complete re-equilibration of ortho- and clinopyroxenes by exsolution to lower temperatures may have been facilitated by engulfment in the hot Spuzzum Pluton. Deep penetration of magmatic fluids into the ultramafite is suggested by almost ubiquitous development of secondary hornblende in i t (Aho, 1956). If temperatures in the ultramafite approached that of surrounding magma, a histogram of equilibration temperatures might be expected to show a maximum approximating the magma temperature, provided further re-equilibration with decreasing temperature is minor (unlike the model suggested for diorite). The Giant Mascot histogram (fig. 10) has such a peak at 1000 to 1040°C. The high temperature peak (1120 to ll60°C)may represent pyroxene pairs unaffected by reheating. D. Hornblende A key to hornblende analyses listing symbols, specimen numbers, and modes of occurrence is given in table VIII. Analyses and formulas are listed in table IX. Since volatiles were not determined, the ideal two hydrogens for 24 oxygens are assumed in the formula unit. Assignment of elements to sites is as!*"follows: Tetrahedral sites - Si and Al adding to eight atoms or less i f Al is insufficient. Octahedral sites - a l l remaining Al, Ti, Fe + 3, and Mg adding to five atoms or less i f Mg is insufficient. If Mg is insufficient, Fe + 2 is added to five atoms or until i t is consumed. Cubic sites - a l l remaining Mg, Fe + 2, Mn and Ca adding to two atoms or less i f Ca is insufficient. If Ca is insufficient, Na is added to two atoms or until i t is consumed. Alkali sites - a l l remaining Ca, Na, and K. As with 68 TABLE VIII KEY TO SPUZZUM AND GIANT MASCOT HORNBLENDE ANALYSES SYMBOL SPEC. NO. DESCRIPTION SPUZZUM HORNBLENDITE: A AM#2 Type II; homogeneous, medium-grained hornblendite body in diorite GIANT MASCOT HORNBLENDITES: T l8/7/75/7a Type II; pyroxene-bearing medium-grained hornblendite dykelet (average 5) • 2600 Type II; pyroxene-bearing coarse-grained horn-blendite of ultramafic complex (average 5) • 13/9/75/la Type I; plag-bearing very coarse-grained horn-blendite adjacent to tonalite (average 5) "NORMAL" DIORITES: • 15/6/75/6 Anhedral grains and rims of pyroxene in pyroxene diorite A 17/6/75/15 Same as above (average 2) V 24/7/75/11 Same as above PYROXENITE-DIORITE CONTACT: \ 27/8/75/2a Large subhedral porphyroblast(?) in pyroxenite 2 cm. from altered diorite (average 2) \ 27/8/75/2a Different place in same crystal (average 2) X 27/8/75/2c Large anhedral brown-cored crystal in altered diorite (average 2) + 27/8/75/2c Replacing pyroxene as rims and pale green blades with pyroxene (average 4) TABLE IX SPUZZUM AND GIANT MASCOT HORNBLENDE ANALYSES AND FORMULAS SYMBOL • A V o~ -o x + Si0 2 44.58 43.82 45.65 50.09 46.65 43.75 45.99 48.27 43.23 42.73 50.06 Ti02 1.65 1.43 1.36 .72 .78 2.14 .94 1.12 2.43 2.63 .46 A1 20 3 12.00 11.91 11.03 7.17 8.89 9.81 9.57 7.84 11.50 12.48 8.05 FeO 10.11 8.61 9.87 8.76 12.84 14.69 12.30 7.77 8.45 9.17 7.80 MgO 14.55 14.88 15.62 16.61 13.78 11.68 13.24 16.49 14.87 14.16 16.80 MnO .09 .07 .15 .14 .10 .16 .14 .10 .09 .07 .11 CaO 11.15 11.37 11.17 12.40 11.39 11.04 11.52 11.29 10.72 11.25 11.71 Na20 2.32 2.19 2.30 1.71 .90 1.39 -96 1.26 1.93 1.75 .73 K20 .16 .14 .32 .28 .44 .84 .59 .32 .34 .25 .17 Total 96.61 94.42 97.47 97.88 95.77 95.50 95.25 94.46 93.56 94.49 95.89 Alkali Site .538 .537 .578 .425 .295 .428 .299 .258 .466 .439 .126 K .030 .026 .058 .051 .083 .162 .112 .060 .065 .047 .031 Na .508 .511 .520 .374 .212 .267 .187 .198 .402 .392 .095 Cubic Site 2 2 2 2 2 2 2 2 2 2 2 Na .147 .118 .123 .096 .046 .140 .089 .159 .157 .112 .108 Ca 1.739 1.804 1.725 1.887 1.803 1.784 1.833 1.768 1.716 1.790 1.796 Mn .011 .009 .018 .016 .013 .020 .018 .012 .011 .009 .013 Fe+2 .104 .069 .134 .0 .139 .056 .060 .060 .115 .089 .082 Octahedral Site 5 5 5 4.940 5 5 5 5 5 5 5 Mg 3.147 3.275 3.346 3.507 3.026 2.618 2.922 3.582 3.302 3.126 3.574 Fe+2 .912 .793 .836 .836 1.202 1.511 1.222 .694 .739 .841 .659 Fe +3 .215 .204 .219 .205 .246 .286 .246 .195 .202 .209 .192 Al .546 .568 .452 .316 .440 .342 .505 .406 .484 .531 .525 Ti .181 .159 .148 .077 .087 .243 .105 .123 .273 .294 .050 Tetrahedral Site 8 8 8 8 8 8 8 8 8 8 8 Al 1.513 1.511 1.422 .884 1.108 1.402 1.170 .945 1.541 1.654 .834 Si 6.487 6.489 6.578 7.116 6,892 6.598 6.830 7.055 6.459 6.346 7.166 TO pyroxenes this scheme is not thoroughly supported by structural evidence. Fe + 2 is preferentially placed in the cubic site over Mg because i t is larger, yet has the same charge as Mg, and perhaps forces Mg to take the smaller octahedral site. This assignment of atoms is based on an admittedly simplistic argument. Because further calculations were made with hornblende analyses, an estimation of Fe + 3 content was desired. The same procedure used to estimate Fe+3 in pyroxenes was used for hornblende. Hornblende analyses from Deer, Howie, and Zussman (1963) most similar to Spuzzum hornblende analyses were selected for an Fe + 3 vs. Mg/(Mg + Fe) diagram (fig. 11). Analyses of these hornblendes, and their formulas calculated by the above scheme, are listed in +3 Appendix III. A curve was drawn to represent Fe J in Spuzzum hornblende. Formulas given in table IX have been corrected. Several analyses of ultramafic, alkaline, and mafic igneous rocks have been gathered from literature for comparison with that of Spuzzum hornblendite. One analysis of a hornblendite dykelet from South Africa is also included. A key to references, rock types analyzed, and modes of occurrence is given in table X. Analysis h is the average of AM#2 and l8/7/T5/7a (which are very similar) with Ye^>^ calculated from formulas in table IX. Analyses as they appear in their respective sources are listed in table XI with C.I.P.W. norms. Norms were calculated after neglecting volatile elements and normalizing to 100 per cent; effective weight per cent SiOg is also listed. Analyses 1 and 2 show a SiO^ deficiency that cannot be satisfied by forming leucite, and just enough silica has been added to these analyses to satisfy the deficiency (under 5$ added). C.I.P.W. norms are shown in simplified form in fig. 12. It can be readily seen that analyses 3, 8, 9, and 10 are most similar to Spuzzum hornblendite. Good Fig. 11 FE + 3 ATOMS PER FORMULA UNIT IN SPUZZUM AND GIANT MASCOT HORNBLENDES 72 ] TABLE X KEY TO WHOLE-ROCK ANALYSES FROM LITERATURE NO. REFERENCE ROCK TYPE OCCURRENCE 1* Hyndmann, 1972 mafic alkaline average of 105 analyses 2* Hyndmann, 1972 alkaline ultramafic average of 12 analyses 3 Verhoogen, et al., 1970 nepheline basalt Honolulu Series, Oahu, Hawaii k this study hornblendite dykelets, average of 2 analyses 5 Richards, 1971 hornblende diabase gabbroic complex 6 Verhoogen, et al., 1970 high-AlgO^ basalt Medicine Lake highlands, N. E. California 7 Krauskopf, 1967 peridotite average of many analyses 8 Richards, 1971 olivine gabbro gabbroic complex, analysis est. from mode 9 Krauskopf, 1967 olivine basalt average of many analyses 10 Verhoogen, et al . , 1970 olivine basalt Haleakala Volcano, Maui, Hawaii 11 Verhoogen, et al . , 1970 olivine tholeiite Thingmuli Volcano, Iceland 12 Mclver, 1972 hornblendite dykelet in Bushveld Main Zone Gabbro, S. Africa Si0 2 content increased slightly in norm. TABLE XI WHOLE-ROCK ANALYSES AND ADJUSTED C.I.P.W. NORMS OF ROCKS FOR COMPARISON WITH SPUZZUM HORNBLENDITE ). 1 2 3 4 5 6 7 8 9 10 11 12 46.14 48.19 48.OU U7.07 51.38 2.11 1.66 1.83 1.66 .18 11.72 11.91 12.04 14.86 4.57 2.33 2.35 4.08 2.87 9.79 9.86 8.80 7.20 10.46 20.30 14.15 14.41 8.52 14.86 .15 .17 .17 .24 7.78 9-35 8.76 11.47 11.99 1.59 1.67 1.60 2.24 1.14 .58 .5k .30 .20 .26 .19 .12 .18 .10 — — 1.63 2.25 2.39 Total 101.56 100.73 99.94 100.00 98.23 100.47 100.00 100.01 100.00 98.30 99-90 100.44 Le 14.29 18.04 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. Ne 22.09 5.51 10.81 3.94 .56 .31 0. 0. 0. 0. 0. 0. Or 0. 0. 5.55 .88 4.31 .83 1.48 3.43 3.19 1.80 1.21 1.60 Ab 0. 0. 5.84 12.70 22.74 23.07 4.74 13.45 14.13 13.76 19.41 9.82 An 5.81 1.38 15.11 23.06 38.60 36.81 7.72 23.13 23.41 25.19 30.62 6.71 Wo 5.19 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. Di 37.63 33.33 30.13 28.21 11.54 15.27 7.35 12.36 17.49 14.56 21.23 43.08 Hy 0. 0. 0. 0. 0. 0. 15.32 4.58 20.13 27.97 14.49 33.41 01 0. 26.88 20.83 25.29 15.78 20.37 58.08 39.06 14.67 9.45 ,3.33 .56 Mt 7.40 5.13 4.88 2.92 2.87 1.51 3.67 0. 3.38 3.46 6.06 4.25 He 0. 1.25 0. 0. 0. 0. 0. 0. 0. 0/ 0. 0. II 5.13 6.89 5.63 3.00 2.94 1.69 1.54 4.01 3.15 3.54 3.23 .34 Ap 2.46 1.59 1.21 0. ._§3_ .16 .12 0. .kk_ .28 .43 .23 100.00 100.00 99.99 100.00 100.00 100.02 100.00 100.02 100.00 100.01 100.01 100.00 #Mg/(Mg+Fe) 95.33 100.00 82.83 82.69 74.48 68.82 88.05 82.05 77.10 80.33 78.92 74.07 %An 100.00 100.00 70.91 63.13 61.5U 60.06 60.55 61.85 60.96 63.31 59-79 39.19 Wt.#Si02 in norm 43.lk 42.80 43.26 46.20 47-55 48.15 43.89 46.ik 48.19 48.8l 48.20 52.kO Si0 2 41.10 40.28 Ti0 2 2.80 3.67 A1 20 3 13.90 6.77 Fe 20 3 5.30 4.85 FeO 5.30 4.59 MgO 6.90 21.88 MnO .20 .31 CaO 15.30 9.92 Na20 5.00 1.22 K20 3.20 3.93 P205 1.10 .70 Others 1.46 2 .6l U2.86 46.20 45.70 48.27 43.89 2.94 1.58 1.49 .89 .81 11.46 12.50 18.80 18.28 4.02 3.34 2.01 1.90 1.04 2.53 9.03 7.96 6.50 8.31 9.92 13.61 15.39 7.30 8.96 34.27 .13 .08 .14 .17 .21 11.24 11.77 10.60 11.32 3.49 3.02 2.36 2.70 2.80 .56 .93 .15 .70 .14 .25 .52 — .27 .07 .05 .86 2.13 .22 — 74 Fig. 12 VARIATION DIAGRAM OF C.I.P.W. NORMS OF WHOLE-ROCK ANALYSES FOR COMPARISON WITH SPUZZUM HORNBLENDITE Wt./S Analysis No. 3 f 10 ? 8 7 IZ II 5 (, 2. 75 agreement among anorthite content of plagioclase, Mg:Fe in silicates, and effective SiOg supports this choice. It is interesting that a l l four of the most similar analyses are of moderately to strongly undersaturated basaltic composition. This relation-ship suggests that Spuzzum hornblendite could be the result of crystalliza-tion of basaltic magma under elevated water pressure (Mclver, 1972). One possible source of such a "magma" is the reaction of Spuzzum diorite or tonalite with the Giant Mascot Ultramafic Body which is the centre of much hornblendite development (McLeod, 1975). This would require that Spuzzum hornblendite be equal in age to, or slightly younger than, the Spuzzum Pluton. Another possible correlation of Spuzzum hornblendite is with the gabbroic complex of the Yale Intrusions (Richards, 1971), which is contained within the Coquihalla quartz monzonite stock (K-Ar age of 41 m.y.) east of Hope. The gabbroic complex appears to be intruded by quartz monzonite. Analyses 5 and 8 in table XI are from this complex. Hornblendites of this study (table VIII, page 68) appear chemically related to hornblendes in pyroxenite of the Giant Mascot Ultramafic Body and in Spuzzum diorite in contact with i t (pages 43 - 45). Hornblende analyses are plotted with pyroxene analyses in fig. 8, a C-F-M atomic porportions diagram. The most obvious features of this diagram are (l) the compositional parallelism between pyroxenes and coexisting hornblende, and (2) the fact that hornblendites and hornblendes of Giant Mascot pyroxenite and adjacent altered diorite are together in a loose cluster, whereas those of "normal" diorites are more Fe-rich. In fig. 13, Mg/(Mg + Fe) and Al are plotted against Si (atomic proportions in the formula unit). Again hornblendes of pyroxenite and altered diorite cluster around hornblendites. 76 Two distinct types of hornblendite can be recognized, one Si-rich and the other Si-poor, and the Si content of hornblendes of normal diorite falls between them. The Si-rich hornblendite (type I) occurs as a coarse pegmatite adjacent to tonalite at the east margin of the Giant Mascot Ultramafic Body (fig. 7). The Si-poor hornblendite (type II) occurs as dykelets in Spuzzum diorite and Giant Mascot ultramafic rocks. Hornblendite from the south margin of the ultramafic body, adjacent to diorite, corresponds with type II (fig. 13). Large zoned crystals from pyroxenite have compositions ranging from type I to type II hornblendite. Large poikilitic anhedral crystals from altered diorite group with type II hornblendite, whereas rims of pyroxenes and small subhedral grains among pyroxenes group with type I. The graphical relationships above suggest that Spuzzum hornblendite (pages 23 - 39) and some Giant Mascot hornblendites (pages 52 - 53) are genetically related. Further, Giant Mascot hornblendites are also related to the large poikiloblasts/phenocrysts of pyroxenite and altered diorite, as well as to hornblende that replaces pyroxenes in altered diorite. It has been suggested that the hornblendite rim around the Giant Mascot Ultramafic Body originated by reaction with diorite or tonalite (Aho, 1956; and McLeod, 1975). The chemical relationships shown above are consistent with this hypothesis in that hornblendite adjacent to tonalite is richer in Si than that adjacent to diorite. Also the amounts of Al and Si in diorite and tonalite show the same relationship as the amounts in corresponding hornblendites ( -jfc- in fig. 13). In this diagram, Al from diorite is plotted against the number of Si in the formula unit of type II hornblende (6.5). The same has been done for tonalite and type I 77 Fig. 13 MG/(MG + FE) AND AL VERSUS SI PER FORMULA UNIT IN SPUZZUM AND GIANT MASCOT HORNBLENDES V o "normal", diorites A -i 1 i r 7.0 6.0 i 8 II 6.5 Si atoms for 24 Oxygens 75 • I X \ \ Diorite. for 6.5 Si type II "normal" diorites ->fc- Tonalite for 7.1 Si ""\ type I + \ • J —X 1 1 J 1 5 1 1 1 1 X « 1 « h S.o 6.5 7.o 7.5 Si Atoms for 24 Oxygens 78 hornblende (7.1 Si). The value of Al is molar Al/Si in diorite or tonalite multiplied by the number of Si in the formula for corresponding hornblendite. 79 VII. ORIGIN A. Introduction Any hypothesis of the origin of the Spuzzum Pluton must explain the following: (1) Chemical similarities and differences between tonalite and diorite; (2) Mineralogical zonation from diorite to tonalite; (3) Structural patterns in the pluton, configuration and heterog-eneous distribution of phases and foliations; and (k) Radiometric ages. Richards (1971) suggested that dioritic magma first intruded country rocks, followed in about 20 million years by a surrounding intrusion of tonalite which formed by fractional crystallization from the same dioritic parent. Variation in mineralogy was attributed to either decrease in temperature or increase in water pressure from core to margin. Minor variation of the amounts of S i 0 2 and IvV>0 in diorite was explained by water migration either into relatively dry diorite from country rocks, or away from the hotter plutonic core. Tonalite was interpreted to be related to diorite only by the differentiation proces's. He considered the domelike structure pattern to be primary foliation from diapiric emplacement of dioritic crystal mush. The northwest trending foliations in tonalite are thought to be inherited from regional deformation. He suggested that diorite is pre-orogenic whereas tonalite is synorogenic (Richards, 1971, p. kl). Radiometric ages were taken as indicating that tonalite is about 20 million years younger than diorite. 80 As an alternative to Richards' hypothesis, this author suggests a model of diapiric intrusion.! of a partly differentiated quartz diorite magma tody into country rocks, producing a single zoned tongue-like pluton with a dioritic core and a tonalitic rim. Variations in chemistry and mineralogy in diorite can be explained by the same mechanism used in Richards' model. The relatively sharp distinction between tonalite and diorite respresents the boundary between magma without crystals and the same magma with accumulated crystals. Other plutons of apparent diapiric form in the Coast Plutonic Complex (and other parts of the North American Cordillera) have acidic cores and more basic rims (Hutchison, 1970; and others). The reversed distribution in the Spuzzum Pluton is explained by a mechanism of drawing up accumulated crystals. Some of the syntectonic features of tonalite can be seen in diorite (see map in pocket and fig. 6). Regional mapping shows foliations to be heterogeneous and difficult to explain by either Richard's or this author's hypothesis. Syntectonic emplacement of a crystal mush diapir however, could be expected to produce a confusing array of internal structures. Radiometric ages may not indicate the true age of these rocks because of the formation of secondary hornblendite in most parts of the pluton, and because of late deformation (McTaggart and Thompson, 1967). Such alteration and deformation may explain 81 the' fact -that the source - : of the oldest age determination (K-Ar 103 m.y.) is tonalite. Richards attempted to explain this discrepancy as contamination from diorite, its gradational contact with tonalite being 130 metres away. B. Differentiation of Spuzzum Magma 1. Discussion The fundamental difference between Richards' differentiation model and that of this author is illustrated graphically in fig. 14. Richards treated the dioritic core as representative of the parent magma, having been emplaced as a pre-differentiation pluton. Tonalite is later derived by removal of basic constituents of the dioritic parent magma by settling of crystals (54 per cent of its mass as 74 per cent plagioclase An 52, 13 per cent augite and hypersthene, and 13 per cent olivine) which have not been identified in the field (Richards and McTaggart, 1976). In the model proposed in the present study, diorite is considered a cumulate brought up with the rising tonalite diapir. The parent is therefore a mixture of the two. Differentiation is postulated to have been completed at depth before intrusion, thus only the products of i t have risen in the Spuzzum Pluton and the parent is not seeni, _ In estimating the original composition of the hypothetical parent magma, the areal extent of tonalite and diorite was estimated from the map produced in this study and that of Richards and McTaggart (1976). Map areas are assumed to represent cross-sectional areas of concentric Weight Per Cent Oxides Wt.% d i o r i t e Wt.% t o n a l i t e Rocktype Fig. 14 CHEMICAL RELATIONSHIPS IN SPUZZUM DIFFERENTIATION TONALITE MAGMA (thi s study) DIORITE CUMULATE (Richards, 1971) Note: FeO represents a l l i r o n . 83 spheres, diorite being the central one. Volume per cent of diorite is calculated thus: k3/2 x w where X = volume per cent diorite in parent magma, Al = area of diorite only, and A2 = area of pluton as a whole. Volume per cent is converted to weight per cent by the equation: I 00 Y " F . /'ton ('00 - X ) Alio * where Y = weight per cent diorite in magma P ton = ^ e n s ^ y °^ tonalite, and P - density of diorite. Approximate densities of diorite and tonalite are calculated from those of individual minerals from Robie and Waldbaum (1968) and Deer, Howie, and Zussman (1966). This calculation is carried out in table XII, and its results are consistent with densities given in Clarko (1966). The mode of tonalite is the average of a l l twelve thin section estimated modes in Appendix I. That of diorite is the average of pyroxene diorites 15/6/75/6, 24/7/75/11, and 10/7/75/6. Calculated densities are J>ton = 2.84 and^dio" 2 .93. This calculation of the composition of parent magma is only a crude approximation as the configuration of diorite and tonalite is not known at depth, and certainly does not conform to concentric spheres. Values of Al and A2 from both maps each produce volume proportions of 33 per cent diorite. This is converted to 34 weight per cent diorite in parent magma. 84 TABLE XII CALCULATION OF DIORITE AND TONALITE DENSITIES Mineral Pyroxene Diorite Tonalite Mineral Density Contribution to Density Diorite Tonalite Qz tr 16 2.65 — .42 Plag 69 51 50:2.68 1.85 — (An*) (50) (41) 41:2.66 — 1.36 Cpx 15 — 3.35 .50 — Opx 15 — 3.50 .53 — Hbd tr 22 3.2(?) — .70 Bio — 10 3.0 — .30 Opaque 1 .5 5.2 .05 .03 Chl — 1 3.0(?) — .03 TOTAL DENSITY 2.93 2.84 Mineral densities from Deer, Howie, and Zussman (1966). 85 Fig. 14 accurately portrays the compositions of diorite, magma, and tonalite, the line representing magma having been drawn at 34 weight per cent diorite. 2. Test of the Hypothesis A computer program was written by the writer to test the hypothesis of Spuzzum diorite and tonalite forming from a common parent by settling of crystals into a lower fraction (diorite), leaving a crystal-depleted upper fraction (tonalite). The program, given in Appendix IV, is in BASIC and was run on a Digital PDP 11/10 desk computer. It simulates the crystallization of ilmenite, magnetite, plagioclase, orthopyroxene, and clinopyroxene from hypothetical parent magma composed of a combination of chemical analyses of Spuzzum diorite and tonalite. Oxides considered are Si0 2, A1203, Ti0 2, FeO, MgO, CaO, Na20, and KgO. A l l iron is calculated as FeO. The diorite analysis is the average of five Spuzzum diorites, and that of tonalite is the average of three Spuzzum tonalites, a l l given by Richards (1971, p. 35). Analyses have been normalized to 100 per cent after removal of CaO for . apatite. Ilmenite and magnetite are treated as pure phases. Pyroxene compositions (table XIII) are the averages of formulas from tables Va and b of specimens 15/6/75/6, 17/6/75/15, and 24/7/75/11 (all pyroxene diorites). The composition of cumulate plagioclase is determined in the program from the composition of the magma. Plagioclase is considered to contain 1.5 molecular per cent KAlSi^Og. The analysis of the hypothetical melt (34$ diorite and 66% tonalite) is converted to a reservoir of positive ions from which formula units of the various minerals are removed. Crystallization progress is calculated for steps of one per cent of the reservoir, beginning with ilmenite and magnetite. 86 The operator must choose whether plagioclase should equilibrate with liquid or be shielded from i t . Shielding in this case means that plagioclase crystallized during previous steps should not equilibrate with liquid during successive steps, thus preserving normal zoning. Partial equilibration is calculated later by linear interpolation between these two cases. In the case of shielding, cumulus plagioclase composition is determined at each one per cent step, whereas in the case of equilibration the composition is not determined until the end of cumulate crystallization. At a stage of crystallization (per cent atoms as crystals) determined by the operator, analyses of diorite (cumulate crystals plus some liquid) and tonalite (remaining liquid) are assembled and printed. This represents the end of cumulate crystallization, that i s , when diorite and tonalite begin to crystallize independently. The amount of liquid added to crystals to form the diorite analysis is determined by the proportion of original diorite used in making the hypothetical magma. The operator must decide at what stage of crystallization (per cent atoms as crystals) each of the major minerals should begin to crystallize. From these values the proportions of plagioclase, orthopyroxene, and clinopyroxene are determined for each one per cent step. Relative amounts , of pyroxenes and plagioclase crystallizing in any step are assumed propor-tional to the amounts that occur in the pyroxene-richest: diorites. The limiting values are averaged from thin section estimated modes of pyroxene diorites 15/6/75/6, 24/7/65/11, and 10/7/75/6. Volumes of plagioclase and combined pyroxenes are 70 and 30 per cent respectively, in accordance with the mode. The ratio of clinopyroxene over orthopyroxene is .96 by volume. Molar volumes used are for pure diopside, pure clinoenstatite (for six oxygens per formula unit), and plagioclase (An50), taken from Robie and 87 Waldbaum (1968). Plagioclase compositions are determined by estimated melting relationships in the system plagioclase An 60 - enstatite - diopside at 15 kilobars dry pressure (Emslie, 197l). For this calculation only the compositions of coexisting liquid and plagioclase are needed for various bulk compositions. Temperature is of no interest. Emslie (1971) reported that plagioclase in equilibrium with pyroxenes and liquid near the pseudo-ternary piercing point at 15 kilobars has a composition of about An 65 by weight. It is assumed that liquid with normative albite, but no anorthite, will crystallize pure albite; and that liquid with normative anorthite, but no albite, will crystallize pure anorthite. This assumption-. -T '> is .. probably incorrect in detail, but i t serves to simplify calculation of compositions in the middle range where the real plagioclase composition lies (that is An UO to 60). If the liquidus is represented by a straight line, these data allow one to represent the solidus as a smooth curve, and here a hyperbolic curve is chosen for simplicity (fig. 15). 88 Fig. 15 CALCULATION OF PLAGIOCLASE MELTING CURVES Assympto+e I Assymptote 1: T' = -d Assymptote 2: X = 1 + d Liquidus: T' = X Solidus: T' = -k _ d X - (1 + d) where k = d 2 + d Therefore X s = -k + d + 1 X L + d where Xg = composition of plagioclase, weight fraction An, and X L = weight fraction An/(An + Ab) for concentrations of An and Ab in liquid 89 Fig. 16 CALCULATED PLAGIOCLASE MELTING CURVES FOR VARIOUS CONDITIONS 7» 1 1 I 1 I 1 r r • 1 O 10 2P 30 4-0 50 60 70 SO 90 /OO Weight Per Cent Anorthite 90 In order to specify X^ , the program calculates normative amounts of anorthite and albite in the liquid. These amounts are slightly in error, as pyroxenes contain some sodium and aluminum. For comparison, a diagram of T' (function of temperature) against weight per cent anorthite is shown in fig. 16, with the calculated curves for 15 kilobars and 1 atmosphere pressure (Emslie, 19!fi)> and a graphically measured curve for the system albite - anorthite at 1 atmosphere (Bowen, 1913). The output of reconstructed analyses of diorite and tonalite is accompanied by the RMS residual for a l l oxides in both analyses, compared with the original analyses. By varying the input parameters (crystallization sequence, amount of accessories, and end of cumulate crystallization) the RMS residual can be minimized for both shielded and equilibrated plagioclase. 3. Results Results of the test above are shown in tables XTVa and b. Analyses of diorite and tonalite from Richards (1971) are labelled "original." Reconstructed analyses of diorite and tonalite, synthesized according to the computer program for both "equilibrated" and "shielded" plagioclase, are presented side by side with the "original" analyses. For comparison, the mixture of 34 per cent diorite and 66 per cent tonalite is shown under the t i t l e "original magma." In table XlVa the various input parameters used for the cases of "equilibrated" and "shielded" plagioclase are shown along with the resulting RMS residua. These are the minimum values of RMS residua obtained after systematically varying the input parameters during the test. For a l l practical purposes they are equal for the two cases for plagioclase, and in the opinion of the writer they show that the different-iation mechanism considered is consistent with chemical analyses 91 TABLE XIII PYROXENE COMPOSITIONS USED IN THE DIFFERENTIATION TEST Mole Per Cent Anions Anion Orthopyroxene Clinopyroxene Si 49.59 48.94 Ti .07 .25 Al 1.32 2.38 Fe 18.50 8.06 Mg 29.70 18.62 Ca .81 20.93 Na .01 .81 K .00 .00 Equivalent Oxygen 150.32 149.98 TABLE XlVa RESULTS OF THE DIFFERENTIATION TEST: INPUT PARAMETERS AND RMS RESIDUA Case Equilibrated Shielded RMS residual .156 .162 diorite 34 34 Atom* crystals lU .2 13.9 Atom* II -20 .20 Atom* Mt -02 .02 Atom* xals when: Plag begins 1 1 Opx begins 0* 0* Cpx begins 14.2 . 13 * actually calculated after removal of accessories 92 TABLE XlVb RESULTS OF THE DIFFERENTIATION TEST: COMPOSITIONS OF PHASES DIORITE TONALITE ORIGINAL MAGMA Original Equ.il. Shield. Original "Equal. Shield.  Si0 2 56.16 56.29 56.29 60.99 60.73 60.73 59.34 Ti0 2 .86 .87 .87 .73 .73 .73 .78 AlpO 19.52 19.68 19.59 17.75 17.76 17-79 18.36 FeO 3 6.44 6.47 6.U9 5.47 5.49 5.48 5.80 MgO 5.13 5-03 5-07 4.21 4.29 4.28 4.53 CaO* 7.47 7.60 7.66 5.95 5-95 5.97 6.47 Na20 3.91 3.47 3.43 3.91 4.11 4.13 3.91 K^ O .51 .59 .59 .99 .93 .93 .83 Total 100.00 100.00 99-99 100.00 99-99 99.99 100.02 Norms: Qz 3.70 5.61 5.72 11.76 10.58 10.52 8.99 Plag 67.32 65.75 65-34 61.05 62.04 62.20 63.18 Or 3-00 3-49 3.49 5-85 5-50 5-50 4.91 Di 2.34 1.09 1.39 1.26 1.85 1.74 1.65 Hy 22.01 22.41 22.40 18.69 18.63 18.6U 19.81 II 1.63 I .65 I.65 1.39 1-39 1.39 1-48 Mg/(Mg+Fe) .617 .611 .612 .609 .612 .612 .612 %An 49.3 53.9 54.1 44.4 42.5 42.4 46.2 Corrected for apatite according to amount of P90 93 of diorite and tonalite. That i s , the results of this test are consistent with the hypothesis that Spuzzum diorite is a cumulate, and that tonalite is a residual liquid, from an original quartz dioritic magma. This is not to say, however, that the Spuzzum analyses are inconsistent with any other hypothesis. C. Origin of the., Pluton Fyfe (in Newall and Rast, 1969) discussed the i n i t i a l stages in pluton formation, comparing i t to a theory of formation of the core of the by earth^gravitational instability in a dense liquid layer (Elsasser, 1963). This model consists of five stages of development; (1) Melting of metal in upper layers of lower viscosity than a deeper part of the earth. (2) Small droplets f a l l at decreasing velocities and build up a gravitationally unstable layer of dense liquid. (3) Perturbations cause a bulge in the layer, which coalesces into a very large drop. (k) The large drop eventually detaches from the layer and sinks rapidly with Stokesian behaviour. (5) The region where the first drop formed will be a more favourable locus for further drop formation. By considering not a dense but rather a buoyant liquid, one may invert this model and apply i t to pluton formation (Fyfe, 1969; and others). A low viscosity zone of melting in the deep crust would allow small droplets of buoyant magma to form and tend to rise. Liquid would collect in a layer as droplets reach the upper part of the melting zone and are obstructed by increased viscosity. Upward bulges caused by perturbations would grow 9U larger spontaneously, taking in large volumes of liquid from the layer, until they could pull away as diapirs and rise. Most of the above hypothesis can also be applied to partial melting of subducted oceanic crust. Some process is needed in this case to bring magma up from the Benioff zone at a depth of 100 kilometres or more. Marsh and Carmichael (1974) suggested that small diapirs of andesitic magma rise at intervals of about 70 kilometres along the length of a subduction zone from a narrow tube of magma collected along the loci of partial melting of oceanic crust. Their model is designed for island arc volcanism, and this magma is thought to form volcanoes immediately on arrival at the base of oceanic crust, i t being thin. However, i f the same small diapirs were to pass into thick and^probably more viscous continental crust, i t seems reasonable that in a given area they may amass to form a pocket which resembles the collected layer in the Elsasser model. With varying degrees of assimilation, the resulting mixture of crustal rocks and Benioff zone andesite may produce the wide assortment of rocks found in plutonic complexes, the majority of which perhaps, being granodioritic or quartz dioritic in composition. Studies by Ramberg (1969) into conditions that cause diapirism showed that synthetic diapirs can and do draw up their substratum as a core. Depending on the properties of materials used in an experiment and the forces applied to them, substratum cores rose to various levels within their host diapirs, in some cases reaching into the bulbous or flattened heads and appearing as though the heads were blown up like balloons. Ramberg stressed that these results applied only to materials with viscosity contrast ratios ranging from 1 to 1 0 3 , which correspond well with pairs of different types of crystalline rocks or different magmas, but not with crystalline rock and magma together. He also experimented with an aqueous 95 solution and modelling clay to better simulate the supposed viscosity contrast between magma and crustal rock. Diapirs were not produced in these tests. However, l i t t l e is known of the magnitude of the effective viscosity of crustal rocks at depth (Ramberg, 1969), and i t may well be that rocks behave more plastically than assumed in these studies. Depending on the physical conditions in a collected layer and on the evolution in size and shape of a bulge, a plutonic body of given composition may begin to crystallize before separating from the collected layer. Indeed, i f the cause of increased thermal activity originally responsible for melting should wane, i t is likely that the collected layer itself would undergo crystallization. If crystals settled in a bulge as i t formed, then as i t detaches i t may draw up a core of crystal mush with i t in a diapir-like pluton. This is the mechanism proposed for the origin of the Spuzzum Pluton, and i t is illustrated schematically in fig. 17. The conditions necessary for such a process to work include crystallization in the Elsasser bulge before its detachment, so that a cumulate layer may form at the base of the bulge. If crystallization does not begin early enough for crystals to sink through the bulge, any accumulation of crystals in the melt will not be distributed in the same fashion. For example, cooler surroundings at a higher level in the crust may cause crystallization at the margin of a pluton, but i t is difficult to imagine that these crystals would collect as a cumulate core. Rather, they should form a "cumulate" margin, or perhaps sink i f the magma is not too viscous and accumulate at the floor of the pluton. Once a pluton has acquired drop-like form, however, a drawn-up core (Ramberg, 1969) will be nearly impossible. The model proposed for the Spuzzum Pluton requires accumulation of a layer of crystals in the Elsasser 96 Fig. 17 SCHEMATIC DIAGRAM OF THE ORIGIN, RISE, AND EMPLACEMENT OF THE SPUZZUM PLUTON ® o w o " o o Melted droplets collect. ° O °° t>° °S ° °o ° o °° O ° ° Bulge begins to form. Crystals begin to form and settle. Wetter magma flows in faster than more viscous, drier magma. Bulge grows, sucks in lower, drier, more viscous magma. Pluton separates from magma layer with sucked up crystal mush core. CouirA'ry reck xenoliths Pluton rises through plastic rocks, is obstructed by brittle rocks, and spreads as i t becomes less buoyant. H20 rich liquid H20 poor liquid LEGEND W W * © o -liquid droplets in melting rock crystals 4 4 diorite tonalite 97 bulge, and this condition may well be rare in nature. Certainly the plutonic style characterized by a basic core with an acidic rim is rare. Most zoned plutonic bodies known have the reverse relationship. (Compare plutons of the Coast Plutonic Complex - Hutchison:;; 1969; Bald Rock Batholith, California - Larsen and Poldervaart, 196l ; Deep Creek Stock, Idaho -White, 1973; and Guichon Batholith, British Columbia - Northcote, 1969; and Ager, et al., 1972). D. Water in the Spuzzum Pluton It was originally suggested by Richards (1971) that the increase in hornblende and biotite, together with the decrease in augite (* hypersthene), from the core to the margin of Spuzzum diorite resulted from migration of water. In a more recent review of the problem (Richards and McTaggart, 1976), the authors argued that migration of water through the magma by diffusion would only be effective over a few tens of metres. As a result they proposed that the magma originally was stratified in water content, i t being greatest at the highest levels of a magma chamber at depth; and the variation in water content seen at the present level is due to successive intrusions from different parts of this magma chamber. The observed distribution of water is consistent with and perhaps better supports the single diapiric intrusion model of this study. If in a deep magma chamber (or melted layer) water were to collect in the upper parts, a diapir leaving from i t could have a water-rich margin and a drier core. A collected layer with uniform temperature and water content increasing up-ward should be less viscous in its upper parts. An Elsasser bulge would form by relatively rapid lateral flow of water-rich magma toward the bulge, but drier magma would flow more sluggishly. As the bulge forms a pluton and detaches from the collected layer i t should draw up in its core deeper 98 drier magma, but the majority of i t would be the less viscous, wet magma. Any crystals growing in the quartz dioritic parent magma should sink, and those in the water-rich upper portion of the bulge would sink more quickly than those in the more viscous deeper portion. This process is interpreted to be responsible for the chemical differences between tonalite and diorite. Crystals sinking through an increasing viscosity gradient could produce a relatively abrupt transition from crystal-depleted tonalite to crystal-enriched diorite below. This transition should have a strong correlation with any abrupt change in the water content (and thus viscosity) along the gradient. Such a change could be formed as water-rich magma flows laterally into the bulge from the surrounding area, forming a steepening in the viscosity gradient at the shear-like interface between faster-flowing water-rich magma and sluggish drier magma below. The result of the foregoing processes would be a diapir of crystal-depleted water-rich tonalite magma, cored by a crystal mush of drier diorite with its water content steadily decreasing from a value less than that of tonalite (because of added anhydrous crystals) at its rim, to a very low value in the centre. Table XV shows the water contents of rocks of the Spuzzum Pluton to be consistent with this pattern. Water contents of minerals are approximated from analyses in Deer, Howie, and Zussman (1966). Densities are those used in previous sections and volumes are from averaged modes of table Ila. Fig. 17 is a schematic diagram of these processes, charting the evolution of the Spuzzum Pluton from its origin in a collected layer to its emplacement as a differentiated tongue-like pluton. 99 TABLE XV CALCULATION OF WATER CONTENT OF THE SPUZZUM PLUTON Pyroxene Diorite Hornblende Diorite Tonalite P min wt* H20 Yol% Hbd 5.4 14.6 22.1 3.2 2 Yol% Bio .5 6.6 9-5 3.0 4 Vol* Chi 0 0 .8 3.0 11 p> rock 2.93 2.93 2.84 \Jt% HgO of Hbd .118 .319 .498 Wt/S H20 of Bio .020 .270 .401 Wt* H20 of Chi 0 0 .093 Total wt# H20 .138 .589 .992 100 E. Rise and Emplacement of the Pluton A plutonic mass rises because i t is less dense than its surroundings. In order for i t to remain as a diapir-like body, those surrounding must behave plastically as the pluton passes through..- As a pluton rises i t both crystallizes and cools, becoming denser and more viscous. In turn, the rocks at higher levels in the crust are more brittle and cooler than those below. Rocks are poor thermal conductors, and the heat of crystallization of magma may largely keep pace with any drain of heat into the surroundings, so that in general a pluton will be much hotter than the rocks around i t . There will therefore be a considerable thermal gradient near the margin of a pluton. Certainly stocks, plutons, and batholiths of a l l sizes have been emplaced hot, having produced contact metamorphism in the rocks they intrude. The ultimate depth to which a plutonic mass can rise, and its form when i t arrives there, are determined by a l l of the above factors. If a pluton increases in density so that i t no longer is buoyant, i t must cease to rise as a whole (although dykes and s i l l s may be injected higher by gas pressure effects). If surrounding rocks become too brittle, the body may rise by stoping or forceful injection along loci of weakness, and probably lose its coherent form as a diapir. The Spuzzum Pluton appears to have been intermediate between these two cases. It has to a large extent retained its diapiric form (concentric zonation, tongue-like structure), but its shape has been influenced by the strength of its surroundings, having stoped large country, rock xenoliths and flowed around massive reentrants or pendants of country rock. There is no clear evidence in the geology of the region that the pluton ever developed a volcanic pile during emplacement. It has been classified by 101 Richards and McTaggart (1976) as mesozonal. Contact metamorphism in a large schist reentrant indicates emplacement at a depth of about 13 kilometres or 4.5 kilobars pressure (Richards, 1971). Fig. 18 shows the pressure-temperature environment of the Spuzzum Pluton during its evolution. Liquidi for andesite with 0* and 2* water by weight after T. Green (1972) are shown as solid lines labelled "LiqQ1' and "Liq^." The estimated position of the 0.6* water liquidus is also shown and labelled "Liq ^ i" From the same source is the dry solidus shown as a dashed line labelled "SOIQ." The water saturated liquidus and solidus for quartz diorite after Piwinskii and Wyllie (1968,) are labelled " L i q s a t " (solid line) and "Sol 2" (dashed line) respectively. The dashed line labelled "Sol g" is the solidus for granodiorite with a mixture of water-saturated and water-undersaturated phases (e.g. pyroxene with amphibole). This mixture corresponds with composition II of Robertson and Wyllie (1971). The short-dashed line labelled "Satg" represents the loci of points at which quartz diorite with 2* water by weight undergoes second boiling. Borders of the stability fields of tholeiite, garnet granulite, and eclogite after D. Green (1976) are shown as light-weight solid lines. Continental temperature gradients (normal and high) after Bailey (1969) are shown as cross-hatched solid lines. The interpreted trajectory of the evolution of the Spuzzum Pluton through pressure-temperature^ space is shown in heavy dashed lines in fig. 18. The same crystallization data are used in this diagram for tonalite and a l l kinds of diorite; the differences in the behaviour of the various phases are thought to be controlled primarily by water content. Tonalite is considered to have contained 2% water by weight, and diorite contains between 0* and 0.6* water in hydrous minerals. The value for tonalite is arbitrarily 102 Fig. 18 EVOLUTION OF THE SPUZZUM PLUTON PROJECTED IN PRESSURE-TEMPERATURE SPACE (Refer to text for definitions and discussion) Temperature (°C) 103. o o -p a} Vi <u & EH Fig. 19 SCHEMATIC DIAGRAM OF CRYSTALLIZATION VERSUS TEMPERATURE FOR ROCKS OF THE SPUZZUM PLUTON AT 4.5 KILOBARS PRESSURE 1200 1100 4 1000 A 900 800 4 700 Per Cent Crystals Composition II Composition III Roman numerals refer to compositions ("bulk water contents) described by Robertson and Wyllie (1971)• 104 chosen as a water content that would produce second boiling. The relationships of crystallization progress among these phases are illustrated in fig. 19, with temperature plotted against per cent crystals for various water contents in quartz diorite magma. The general curve shape is after a similar curve determined experimentally for water-saturated quartz diorite (Robertson and Wyllie, 1971). The various curves for undersaturated magma are placed on the temperature scale according to liquidus and solidus temperatures at 4.5 kilobars (fig. 18). The curves are labelled after the four major water content categories described by Robertson and Wyllie (1971): (I) No water is present, corresponding to the dry liquidus and solidus temperatures. (II) Water content is less than or equal to the amount necessary to saturate a l l solid phases. The liquidus temperature decreases steadily with increasing water content, but the solidus temperature remains nearly constant and considerably below that of I. ( i l l ) Water content is more than enough to saturate solid phases, but insufficient to saturate the liquid at some stage of crystallization. The liquidus temperature decreases steadily with increasing water content, but the solidus temperature remains constant and equal to the saturated solidus temperature. This is the only range of water contents for which magma may undergo second boiling, at which point the liquid becomes saturated and exsolves a vapour phase. The . open circle in fig. 19 is the point at which tonalite undergoes second boiling, corresponding to the short-dashed line in fig. 18. (IV) Water content is greater than or equal to the amount necessary to saturate the liquid at a l l times. The liquidus and solidus temperatures are minimum values. When magma undergoes second boiling, i t continues to crystallize along curve IV. The breaking point between compositions II and III is chosen as 1% water, which is the water content of solid tonalite (table XV). 105 Crystallization history of the Spuzzum Pluton can be crudely surmised from the data in fig. 18. The open circles labelled a, b, c, c 1, . . . depict isolated points in the history of the pluton, and are described below: (a) A more or less arbitrary point is chosen at which original Spuzzum magma of any water content is completely liquid. This will correspond to collection of andesitic magma droplets into a layer or magma chamber (stages 1 and 2 of fig. 17). Since this may be in the deep crust or upper mantle near the crust base, a depth of about 45 kilometres is chosen as an i n i t i a l depth. (b) The incipient pluton is,ready to rise, corresponding to stage h of fig. 17. Pyroxene diorite has formed by considerable crystallization of drier parts of the bulge, and settling of crystals from the water-richer upper parts. Hornblende diorite will eventually form from the upper, water-richer part of the accumulated crystal mush. Crystallization has occurred in a l l parts of the bulge by the time the pluton detaches, but the marginal parts are depleted of crystals by settling. (c and c') The inside of the pluton retains its high temperature as i t rises, whereas the marginal parts cool by conduction. Crystals may be partly resorbed as load pressure decreases. (d and d') The pluton reaches a level where i t cannot penetrate upward easily. The core is a mush of crystals and interstitial liquid, but the water-richer tonalite margin, though cooler, is dominantly liquid (fig. 19). The rim continues to cool faster than the core. The pluton spreads laterally, developing a tongue-like shape. 106 (e and e') Tonalite boils, producing a reactive vapour that metasomatizes country rocks and produces hornblendite. The pluton is immobile at this stage; tonalite is largely crystalline and the diorites have only small amounts of liquid left in them (fig. 19). There is a considerable difference in temperature between the core and margin of the pluton. (f and f') Diorites are completely solid, even the most hydrated variety, yet tonalite s t i l l contains some liquid. As a result, foliations in tonalite may be locally discordant with those of diorite. The core temperature begins to approach the margin temperature. (g and g') Tonalite is completely solid. The core temperature is nearly the same as the margin temperature. (h) The solid pluton continues to cool, eventually reaching a temperature consistent with the geothermal gradient. F. Origin of Hornblendite In previous sections i t has been shown that hornblendite of the Spuzzum Pluton, hornblendite rimming the Giant Mascot Ultramafic Body, and hornblendite dykelets cutting the latter, are probably chemically related to each other and to hornblende in altered diorite in contact with the ultramafite. Hornblendite in contact with tonalite (type. I) differs in composition from that in contact with diorite (type II) in a manner that parallels the differences between tonalite and diorite (fig. 13). These relationships suggest (l) that hornblendite rimming the Giant Mascot Ultramafic Body originated by reaction with Spuzzum diorite and tonalite, 107 and (2) that hornblendite in the Spuzzum Pluton has its.'source in this reaction. The idea that a reaction of this nature occurred has been discussed by Aho (1956), who believed ultramafic rocks intruded diorite. He suggested that constituents of the hornblendite rim may have been partly derived from diorite by addition of H"20, CaO, and Na20 to the ultramafic rocks, or that ultramafic magma may have assimilated some diorite. McLeod (1975) agreed with Aho as to the origin of the hornblendite rim, but concluded that Spuzzum diorite and tonalite intruded the ultramafic rocks which he said may have been an early phase of Spuzzum igneous activity. The origin of hornblendite in Spuzzum diorite has been discussed by Richards (l97l)- He suggested that hornblendite and pyroxenite bodies formed in part by metasomatism of diorite along pre-existing fractures, either by addition of basic constituents or by subtraction of acidic constituents. He favoured their formation by subtraction of Si0 2, A l ^ ^ Na20 and 10,0 by hot water-rich fluid on the basis of experimentally determined solubilities of these components. He accounted the formation of pyroxenite rather than hornblendite to higher temperature at constant water pressure, although lower water pressure at constant temperature would produce the same result (see his fig. 19B, p. 43). If simple subtraction of acidic constituents from diorite (or tonalite) is the only mechanism in the formation of Spuzzum hornblendite, then there is no reason for the composition of this hornblendite to match that of the Giant Mascot hornblendite rim. This author believes the chemical similarities are more than coincidence, and proposes that the same reaction that produced the hornblendite rim is responsible for ultramafic bodies in the Spuzzum Pluton. 108 This author proposes that the hornblendite rim as well as hornblendite bodies in the Spuzzum Pluton were produced by metasomatism at its contact with ultramafic rocks in the presence of water-rich fluid during emplacement of the pluton. It seems fortuitous that hydrothermal fluid that may have metasoma-tized rocks at the contact of Spuzzum diorite and Giant Mascot pyroxenite should do the same to diorite five kilometres away. This process is made more plausible by the presence of fractures or shears in the nearly solid pluton, which appear to have controlled hornblendization in many places. Hornblendite bodies such as the one northwest of Odium are more likely to be altered xenoliths of ultramafic rock analogous to the Giant Mascot Ultramafic Body, many pods of which occur in the vicinity of the Spuzzum Pluton in rocks of the Settler Schist, Hozameen Group, and Chilliwack Group (McTaggart and Thompson, 1967; and Monger, 1970). The same reaction responsible for conver-sion of up to 100 metres of pyroxenite to hornblendite at the mine would probably assimilate or alter beyond recognition a small pod of the same rock. Another example may be the body of hornblendite south of the fork in American Creek. Hornblendization of parts of the Spuzzum Pluton may have been by diffusion of hydrothermal fluid through diorite or tonalite or more likely along fractures, shears, and xenolith contacts, also producing small wispy pods of hornblendite common in hornblendized rocks. Pyroxenite replace-ment bodies (Richards, 1971) in pyroxene diorite are considered analogous to hornblendite bodies, except that they probably crystallized under conditions of lower water pressure (but equal total pressure) or higher temperature in the core of the pluton. The character of metasomatism between Giant Mascot ultramafic rocks and the Spuzzum Pluton is shown in fig. 20. Ultramafic rocks are represented by dunite (average olivine) and pyroxenite (equal amounts of 109 Fig. 20 CHARACTER OF METASOMATISM BETWEEN THE SPUZZUM PLUTON AND GIANT MASCOT ULTRAMAFIC ROCKS Dunite Pyroxenite Hornblendite Diorite or Tonalite '110 average ortho- and clinopyroxene) calculated from analyses given by McLeod (1975). Hornblendite type I is a single analysis and type II is the average of three analyses given in this study (see chemistry section). Diorite and tonalite analyses are averaged from those given in Richards (1971), after correction of CaO for apatite. The values in fig. 20 are moles of atoms for equal volumes of each rock type. Dashed lines connect type I hornblendite and tonalite, whereas type II hornblendite and diorite are connected by solid lines. Densities used are 2.93 and 2.84 for diorite and tonalite, respectively (calculated previously in this section); and 3.4, 3.2 and 3.3 for pyroxene, hornblende, and olivine, respectively. Moles of atoms are normalized so that the highest value (Mg in dunite) is equal to one. The ordinate is a nonlinear scale meant to magnify low values (K and Ti especially). Linear measure from zero along the ordinate is proportional to the square root of the actual value. From fig. 20 i t can be seen that hornblendites l i e crudely in line with feldspathic rocks and pyroxenite, with some notable exceptions. Further, with the exception of Ca and Mg, the difference between horn-blendites I and II for each element reflects the difference between tonalite and diorite. These relationships suggest that the composition of magma intruding pyroxenite controlled the composition of adjacent hornblendite. This supports a hypothesis of metasomatic origin of the hornblendite rim. At constant volume, diorite or tonalite can be converted to hornblendite by addition of Ti, Fe, Mg, and Ca and removal of Si, Al, Na, and K. Pyroxenite can be converted to hornblendite by addition of Ti, Al, Na, and K and removal of Si, and Mg (Fe and Ca remain nearly constant.) If both ultramafic rock-and feldspathic rock contribute to conversion, hornblendite can be formed by addition of small amounts of Ti, Fe, and Ca and removal of Si. I l l It was shown above, page 74, that hornblendite near Odium and that from a dykelet at the Giant Mascot Mine have compositions similar to silica-undersaturated basalt. If such a hornblendite body formed by metasomatism of ultramafic rock in a hot batholith, i t could melt and be injected into its surroundings. The plausibility of such a mechanism is illustrated by the relationships of undersaturated basalt and diorite melting curves, shown in fig. 18. The water-saturated liquidus and solidus for alkali basalt (Yoder and Tilley, 1962) are shown as broken cross-hatched lines and labelled " L i q " and Sol_." Diorite liquidi and solidi B B for various concentrations of water are shown as solid and broken lines and further discussed above, page 101. At 4.5 kilobars (the postulated depth of emplacement of the Spuzzum Pluton) water-saturated alkali basalt begins to melt 100 degrees below the solidus of hornblende diorite (Sol g), and possibly about 50 degrees below the second boiling point of tonalite (Sat2). Certainly a hornblendite body in hot diorite would not be water saturated. In fact, i t may be a mixture of hornblende and pyroxene, and therefore the melting curves of Yoder and Tilley (1962) do not apply. If tonalite were to boil as shown in fig. l 8 , however, water-rich vapour could follow fractures in the solid diorite and saturate, any ultramafic bodies in its path (as well as any in tonalite). Coursing rof water-rich fluid through fractures in pyroxene diorite produced locallized metasomatism along those fractures (plates 12 and 13). Large bodies of hornblendized diorite in pyroxene diorite (see map in pocket) evidently formed by the same process. It is conceivable that ultramafic xenoliths in tonalite and in diorite near its margin may have been converted to hornblendite and locally melted in the presence of excess water as a result of the second boiling of tonalite. Once mobilized as 112 a magma an ultramafic "body could follow fractures, stope off slabs of diorite, or re-assimilate diorite to some degree. Diorite xenoliths in massive hornblendite near Odium and on American Creek (plates 2, 6, and 11; fig. 5a) and hornblendite dykelets at the mine (plate 14), strongly suggest this behaviour. The age of hornblendites, by the above hypotheses, must be somewhat younger than the age of emplacement of the Spuzzum Pluton. Diorite and tonalite must have been solid enough to fracture or shear, possibly having only interstitial liquid among interlocked crystals. Fluids may have been produced by exsolution from the last fraction of magma during the pneumatolitic stage of crystallization (for tonalite or water-richest hornblende diorite). Dry pyroxene diorite, exsolving no vapour phase with crystallization, could have been in contact with unaltered pyroxenite in such a system. This corresponds with Richards' (1971) interpretation that hornblendite and pyroxenite replacement bodies formed in diorite as i t cooled. This author sees no reason why hornblendite should not have formed in tonalite as well as diorite by the same process. / 113 LIST OF REFERENCES CITED Ager, C. A., McMillan, W. J., and Ulrych, T. J., 1972. Gravity, magnetics, and geology of the Guichon Creek Batholith. British Columbia Dept. of Mines and Petroleum Resources Bull., v. 62. Aho, A. E., 1956. Nickel-copper pyrrhotite deposits at the Pacific Nickel Property, southwestern British Columbia. Economic Geology, v. 51, pp. 444 - 4 8 l . Atkins, F. B., 1969- Pyroxenes of the Bushveld Intrusions, South Africa. Journal of Petrology, v. 10, pp. 222 - 249. Bailey, D. K., 1969. Volatile flux, heat focusing, and the generation of magma. Mechanisms of Igneous Intrusion (Newall, G., and Rast, N., eds.) Gallery Press, Liverpool, pp. 177 - 186. Bowen, N. L., 1913. The melting phenomena of the plagioclase feldspars. American Journal of Science, series 4, v. 35, pp. 577 - 599-Brown, G. M., 1957- Pyroxenes from the early and middle stages of fractionation of the Skaergaard Intrusion, East Greenland. Mineralogical Magazine, v. 31, pp. 511 - 543-Cairnes, C. E., 1944. Hope area. Canada Geological Survey Map, no. 737A, scale 1 in. = 4 mi. Clark, S. P., Jr. (ed.)., 1966. Handbook of physical constants. Geological Society of America Memoir, no. 97. Deer, W. A., Howie, R. A., and Zussman, J., 1963. Rock-forming Minerals, v. 2, Longmans, London. Deer, W. A., Howie, R. A., and Zussman, J., 1966. Introduction to  Rock-forming Minerals, John Riley and Sons, N. Y. Eastwood, G. E. P., 1971. Nl (No. 171, Fig. E). Geology, Exploration, and Mining in British Columbia, B. C. Dept. of Mines and Petroleum Resources^ pp. 258 - 264. Elsasser, ¥. M., 1963. Early history of the earth. Earth Science and Meteorites: (Geiss, J., and Goldberg, E. D., eds.), North-Holland, Amsterdam, pp. 1 - 30. Emslie, R. F., 1971. Liquidus relations and subsolidus reactions in some plagioclase-bearing systems. Annual Report of the Director, Geophysical Laboratory I969 - 1970 (Yearbook 69), Carnegie Institution of Washington, pp. 148 - 155. 114 Fyfe, W. S., 1969. Some thoughts on granitic magmas. Mechanisms of Igneous Intrusion (Newall, G., and Rast, N., eds.), Gallery Press, Liverpool, pp. 201 - 2l6. Green, D. H., 1976. Experimental petrology in Australia - a review. Earth-Science Review, v. 12, pp. 99 - 138. Green, T. H., 1972. Crystallization of calc-alkaline andesite under controlled high-pressure hydrous conditions. Contributions to Mineralogy and Petrology, v. 34, pp. 150 - l66. Hess, H. H., i960. The Stillwater Igneous Complex, Montana. Geological Society of America Memoir, no. 80. Hutchison, W. ¥., 1970. Metamorphic framework and plutonic styles in the Prince Rupert region of the central Coast Mountains, British Columbia. Canadian Journal of Earth Sciences, v. 7, pp. 376 - 405. Hyndmann, D. W., 1972. Petrology of Igneous and Metamorphic Rocks, International Series in the Earth and Planetary Sciences, McGraw-Hill, N. Y. Krauskopf, K. B., 1967. Introduction to Geochemistry, International Series in the Earth and Planetary Sciences, McGraw-Hill, N. Y. Larsen, L. H., and Poldervaart, A., 196l. Petrologic study of the Bald Rock Batholith, near Bidwell Bar, California. Geological Society of America Bull., v. 72, pp. 69 - 91. Lowes, B. E., 1971. Metamorphic petrology and structural geology of the area east of Harrison Lake, British Columbia (unpubl. Ph. D. thesis). Univ. of Washington, Seattle, U. S. A. Marsh, B. D., and Carmichael, I. S. E., 1974. Benioff zone magmatism. Journal of Geophysical Research, v. 79, pp. 1196 - 1206. Mclver, J. R., 1972. Hornblendite from Bon Accord, Pretoria, and a possible komatiite equivalent. Transactions of the Geological  Society of South Africa, v. 75, pp. 313 - 315. McLeod, J. A., 1975. The Giant Mascot Ultramafite and its related ores (unpubl. M. A. Sc. thesis). Univ. of British Columbia, Vancouver, Canada. McTaggart, K. C, and Thompson, R. M. , 1967. Geology of part of the northern Cascades in southern British Columbia. Canadian Journal of Earth Sciences, v. 4 . , pp. 1199 - 1228. McTaggart, K. C, 1970. Tectonic history of the northern Cascade Mountains. Geological Association of Canada Special Paper, no. 6, pp. 137 - 148. McTaggart, K. C, 1971. On the origin of ultramafic rocks. Geological  Society of America Bull., v. 82, pp. 23 - 42. 115 Misch, P., 1966. Tectonic evolution of the northern Cascades of Washington State. Tectonic History and Mineral Deposits of the Western Cordillera, spec. v. 8 , Canadian Institute of Mining and Metallurgy, pp. 101 - 148. Monger, J. W. H., 1970. Hope map-area, west half, British Columbia. Canada Geological Survey Paper, no. 69-47. Moore, J. G., and Lockwood, P. L., 1973. Origin of comb-layering and orbicular structure, Sierra Nevada Batholith, California. Geological Society of America Bull., v. 84, pp. 1 - 20. Morris, P. G., 1955. A petrologicai:.study of intrusive rocks along the Fraser Canyon near Hell's Gate, British Columbia, (unpubl. M. A. thesis). Univ. of British Columbia., Vancouver, Canada. Northcote, K. E., 1969. Geology and chronology of the Guichon Creek Batholith. British Columbia Dept. of Mines and Petroleum Resources Bull., v. 56. Pigage, L. C., 1973. Metamorphism southwest of Yale, British Columbia (unpubl. M. Sc. thesis). Univ. of British Columbia, Vancouver, Canada. Piwinskii, A. J. and Wyllie, P. J., 1968. Experimental studies of igneous rocks: a zoned pluton in the Wallowa Batholith, Oregon. Journal of Geology, v. 76, pp. 205 - 234. Price, R. A., and Douglas, R. J. W., 1972. Variations in tectonic styles in Canada. Geological Association of Canada Special Paper, no. 11. Ramberg, H., 1969. Model studies in relation to intrusion of plutonic bodies. Mechanisms of Igneous Intrusion (Newall, G., and Rast, N., eds.), Gallery Press, Liverpool, pp. 26 l - 285. Read, P. B., i 9 6 0 . Geology of the Fraser River valley between Hope and Emory Creek, British Columbia (unpubl. M. A. Sc. thesis). Univ. of British Columbia, Vancouver, Canada. Richards, T. A., and White, W. H., 1970. K-Ar ages of plutonic rocks between Hope, British Columbia, and the 49th parallel. Canadian Journal of Earth Sciences, v. 7, pp. 1203 - 1207. Richards, T. A., 1971. Plutonic rocks between Hope, British Columbia and the 49th parallel (unpubl. Ph. D. thesis). Univ. of British Columbia, Vancouver, Canada. Richards, T. A., and McTaggart, K. C, 1976. Granitic rocks of the southern Coast Plutonic Complex and northern Cascades of British Columbia. Geological Society of America Bull'., v. 87, pp. 935 - 953. Robertson, J. K., and Wyllie, P. J., 1971. Rock-water systems, with special reference to the water-deficient region. American Journal of Science, v. 271, pp. 252 - 277. 116 Robie, R. A., and Waldbaum, D. R. , 1968. Thermodynamic properties of minerals and related substances at 298.15°K and one atmosphere pressure and higher temperatures. United States Geological Survey  Bull,, v. 1259. Roddick, J. A., and Hutchison, W. W., 1970. Northwestern part of the Hope map-area, British Columbia. Canada Geological Survey Paper, no. 69-1A, pp. 29 - 38. Verhoogen, JV, Turner, F. J., Weiss, L. E. , and Wahrhaftig, C, 1970. The Earth: An Introduction to Physical Geology, Holt, Rinehart, and Winston, N. Y. White, W. H., 1973. Flow structure and form of the Deep Creek Stock, southern Seven Devils Mountains, Idaho. Geological Society of  American Bull., v. 84, pp. 199 - 210. Wood, B. J., and Banno, S., 1973. Garnet-orthopyroxene and orthopyroxene-clinopyroxene relationships in simple and complex systems. Contributions to Mineralogy and PetrologyT v. 42, pp. 109 - 124. Yoder, H. S., and Tilley, C. E., 1962. Origin of basalt magma: an experimental study of natural and synthetic rock systems, Journal of Petrology, v. 3. pp. 342 - 532. ( 117 GUIDE TO APPENDIX I In this appendix, modes and mineralogical data of a l l specimens thin-sectioned in this study are listed. Modes were measured by eye estimate in a standard petrographic microscope. Mineralogical data were estimated in the same way. Modes are presented in order of decreasing pyroxene/hornblende + biotite) for diorites (parts A and B), decreasing hornblende/ plagioclase + quartz) for hornblendized rocks (part C), decreasing biotite/hornblende for tonalites (part D), and basically in order of increasing mafic minerals for others (parts E and F). Three specimens were borrowed from other workers: AM#2 (hornblendite) was donated by K. Nielson; 79A-2 (hornblendite) by J. McLeod; and 75-A and B (breccia) by K. C. McTaggart. LEGEND Qz quartz S/0 sulphide/oxide ratio Plag plagioclase An % % anorthite in plagioclase Or orthoclase Cb carbonate Opx orthopyroxene Cz clinozoisite Cpx clinopyroxene Chb colourless hornblende Px combined pyroxenes Sn sphene Hbd hornblende Sp spinel Bio biotite Ac actinolite Chi chlorite 01 olivine Mu muscovite Tc talc Ep epidote Pr prehnite Gar garnet tr trace Ap apatite si slight SPEC. NO. Qz Plag Or Opx Cpx Hbd Bio Ap Opaque Others APPENDIX I - PART A MODES OF PYROXENE DIORITES U/Z—2177;—Toff 29/7 WT 875 IO7T WJ iBTr 2T77 2/7 29/7 75/6 75/11 75/6 75/2 75/3 75/1 75/5b 75/m 75/5 75/12 75/10 75/lOc t r 1 t r t r t r 6 5 66 70 70 65 60 60 65 60 70 65 16 15 15 18 22 19 22 22 13 13 16 15 13 15 15 18 9 8 13 10 t r t r t r 1 1 1 2 1 3 6 __ t r t r 1 1 1 2 t r t r t r t r t r t r — t r t r t r — t r 2 t r 1 1 t r 1 1 1 1 1 t r 5 66 60 16 16 8 8 8 8 1 1 2 1 Sn-1 Sp-tr S/O » 1 0 »10 >>10 » 1 0 10 » 1 0 >10 »10 » 1 0 » 1 0 » 1 0 >10 ka.% high low Opx: 2V,o< 5 Cpx: 2Vv H b d : 2V* S * A C Bio: 2V* - - - 15 48 50 66 70 85 1+7 55 55 92 60 51 66 1+2 1+8 1+1+ 1+0 1+0 1+3 1+6 1+0 37 37 50 47 <90 70 65 65 ——. 60 60 60 55 55 55 60 .018 .012 .016 — .012 .012 .016 .012 .015 .012 — .015 1+0 60 50 1+5 50 60 50 35 55 45 1+0 50 .033 .032 __ .032 .030 .030 .023 .031 .030 .032 .022 1+3 1+1 1+1+ 45 1+3 1+1 45 1+0 1+1 1+5 1+3 43 85 90 85 80 85 70 80 —— 80 .026 .021+ — — .027 .026 .025 — .026 .027 .025 .022 20 19 17 20 — 21 21 17 19 APPENDIX I - PART B MODES OF DIORITES AND TRANSITIONS TO HORNBLENDIZED ROCKS TYPE PYROXENE DIORITES HORNBLENDE DIORITES TRANSITIONS SPEC. 1/7 18/8 27/8 28/8 8/8 15/6 30/7 25/8 8/8 7/7 20/8 9/7 NO. 75/3 75/1 75/3b 75/la 75/5b 75/3 75/2a 75/15 75/18 75/2 75/lb 75/8 Qz 5 5 2 9 5 15 t r __ 5 Plag 65 65 65 60-50 60 65 60 65 52 50-60 60 55 ur Opx 16 17 14 17-14 7 10 8 1+ 8 20-15 10 1+ Cpx 3 5 5 3-tr 7 t r — 2 4 0? t r t r Hbd 8 13 15 20-35 8 20 9 18 14 30-25 29 25 Bio 2 8 3 9 6 7 — — 1 Ap t r — — t r t r t r t r t r t r t r t r t r Opaque 1 t r 1 t r - 1 5 — 1 t r t r t r 1 t r Others CHb-4 Ac-10 S/O >10 2 >10 2 » 1 0 » 1 0 » 1 0 » i o » 1 0 >10 » 1 0 10 An*: high 49 85 79 51 47 55 60 57 50 71 82 56 low 43 64 1+6 1+6 kk 40 41 39 42 52 52 35 Opx: 2V* — 65 67 60 70 80 55 — 55 65 65 55 S .012 .013 .012 .013 .013; .018 .011 — .011 • OlU .016 .013 Cpx: 1+0 40 — — 50 — 55 — .023 .027 .031 .029 .025 .035 — — .030 — .030 — VAC 35 — 39 1+0 35 38 — — 1+0 Hbd: 2V C < — 80 85 — 75 90 — 80 — 85 80 S .021 .025 .027 — .022 .031 .026 — .025 .023 .028 .027 — 18 18 — — — 16 — 18 18 18 21 APPENDIX I - PART C MODES OF HORNBLENDIZED ROCKS SPEC. 25/6 25/8 29/7 19/6 2/7 20/8 18/8 25/8 28/8 25/8 6/8 29/7 NO. 75/4 75A 75/3a 75/5 75/2 75/3 75/12 75/3 75/1* 75/8 75/15 75/3b Qz Plag tr 2 tr 5 tr kO-tr 40-tr 50 50-tr 50 55 53 60 54 60 60 65-tr Or Px tr tr 38 Hbd 60-100 60-100 50 50-100 47 44 37 40 40 35 35-100 Bio tr — 2 — 6 — — 1 3 tr Chi tr — tr tr — tr tr — Ap tr tr tr tr tr tr 1 tr tr tr tr tr Opaque tr tr 1 tr 1 1 1 tr 1 1 2 tr Others Sn-tr Cz-tr »10 »10 S/O >10 2 — »10 >10 10 >10 5 >io An*: high ? 79 60 78 58 80 53 82 65 53 48 ? low 1 75 0 60 37 53 30 55 47 48 18 ? Hbd: 80 2Vc< s 80 — 83 78 — 85 75 75 .026 .022 .027 .029 .028 — .025 — .024 .021 Y A C 18 — 21 20 17 17 — — 18 — 17 21 Bio: 0 — 0 Chi: 2VV 0 15 — APPENDIX I - PART D MODES OF TONALITES SPEC. NO. 20/8 75/4 21/8 75/10 19/6 75/2 24/7 75/1 15/6 75/1 7/7 75/8 19/8 75/3 17/6 75/1 6/8 75/7 25/8 75/11 24/7 75/6 18/7 75/2 Qz 25 18 20 14 15 20 15 12 13 15 10 11 Plag Or Hbd 55 50 60 50 55 50 55 53 52 50 ko 45 6 10 10 20 15 20 19 27 28 27 ko 40 Bio 14 20 10 15 8 10 9 7 7 4 10 tr Chl —— tr tr — 7 — tr — — 3 tr — Ep — 2 tr 1 tr — tr — — Ap tr tr tr tr tr tf tr tr tr tr tr tr Opaque 1 tr tr 1 — — 1 1 tr 1 — 1 Others To-tr Mu-tr Pr-tr Opx-tr Mu^tr Ac-tr Mu-tr CHb-3 Sn-tr Sn-tr S/O >10 » 1 0 >10 » 1 0 >10 5 » 1 0 >10 10 » 1 0 » 1 0 >10 An*: high 74 38 46 59 55 52 51 41 56 41 50 48 low 23 25 28 30 ko 26 36 38 31 38 33 46 Hbd: 2V* 90 70 66 72 — 70 80 70 85 — 85 90 .023 .023 .018 .025 .019 — .020 .022 .025 — .028 .026 17 16 20 19 Ik 22 18 19 17 — 17 17 Bio: 2VoC 0 0 — 0 — — 0 — 0 — 0 — Chl: 2 VY — 0 25 I APPENDIX I - PART E ULTRAMAFIC ROCKS AND ASSOCIATES TYPE DIORITE GIANT MASCOT ULTRAMAFIC ROCKS 1 HORNBLENDIC ROCKS 27/8 27/8 27/8 8/8 24/8 24/8 27/8 8/8 24/8 13/9 24/8 13/9 AM#2 79A-2 NO. 75/2a 75/2c 75/2b 75/13 75/7c 75/7b 75/2a 75/4a 75/7a 75/2 75/9 75/1* Qz tr 2 tr 24 8 Plag 75 50-80 43 35 tr — tr-39 3 — 50 — —— Or 40 Opx 20 20-10 20 25 15 18 30-15 35 tr-2 Cpx —— 15-8 15 14 5 7 . 30-15 30 35 — — 12 — Hbd 5 15-2 20 25 80 75 40-20 30 10 50 75 80 90 99-97 Bio tr — — tr Chi tr tr 1 — 1 —— Ap Opaque tr tr — — tr tr tr tr tr tr tr 2 tr tr tr tr tr 1 Others Cb-tr Cb-tr Tc-tr Cb-tr Sn-tr 01-15 Mu-tr Sn-tr S/O 10 >10 »10 » 1 0 » 1 0 »10 10 »10 »10 10 5 3 » i o An*: 85 high 80 80 61 72 — — 90 79 — 71 — — — low 55 52 41 57 — — 71 74 — 62 68 42 — — Opx: 85 85 2Voc 80 85 85 70 90 90 90 S .010 .014 .014 .015 .012 .010 .011 .013 .011 Cpx: 65 6o 2Vy 70 6o 60 65 60 60 — — 70 — — 8* .032 .029 .030 .030 .030 .027 .033 .027 — — .031 — — "SAC 40 39 41 41 41 40 40 44 — — 37 — — Hbd: 85 80 2V* 90 85 80 90 90 — 90 £80 — 90 90 s .025 .030 .027 .027 .027 .026 .024 .027 .024 .021 — .027 .026 .025 16 19 18 18 18 18 17 18 18 17 — 18 17 18 Chi: 2V 2' o ~0 APPENDIX I - PART F MISCELLANEOUS ROCKS TYPE MAFIC DYKES BRECCIA APLITES XENOLITHS GRANOFELSb SPEC. 8/8 20/8 27/8 28/8 TC A TI 24/6 23/7 1/7 6/8 2/7 NO. 75/5b 75/3 75/3a 75/la 75-A,B 75/3b 75/3 75/3 75/15 75/4b Qz tr 30 37 ^ 6 0 25 Plag r\t> 60 34-29 48 19 40 58 48 70 25 ur Opx 28 . tr — — 4 — 10 Cpx 10 — — — — — — — — — Hbd — 65-70 50 80 60 — — tr — Bio tr — tr — — 7 12 I 3 5 28 15 Mu — — — — — 3 1 — — Gar — — — — — 2 1 — — 20 Ap — tr tr — — tr tr — — — Opaque 2 1 2 1 tr tr tr 1 1 5 Others Sn-tr Cz-1 Chl -1 S/0 » i o 5 » 1 0 l — >10 > i o >10 » 1 0 » i o An*: high 73 82 69 78 -65 59 58 47 58 low 45 48 47 69 -40 32 32 34 40 Opx: 2V* 75 — — <90 — — — — 65 8 .014 — — — — — — — .012 Cpx: 2V* £50 — — — — — — — — o~ .032 — — — — — — — — — *Arc 42 — — — — — — — — — Hbd: 2V* — — 90 90 80 — — 75 — S — — .021 .026 - .027 — — .024 — — — 15 17 17 — — 17 — 124 APPENDIX II KEY TO PYROXENE ANALYSES NO. REF. TYPES LOCALITY OR OCCURRENCE SA 660 Atkins, 1969 Diop./Bronz. Bushveld gabbro, Critical Series SA 722 ti Diop./Bronz. Bushveld gabbro, Critical Series SA 733 11 Aug./Bronz. Bushveld gabbro, Main Zone a SA 738 11 Aug./Inv.Pig. Bushveld gabbro, Main Zone b SA 6l6 11 Aug./lnv.Pig. Bushveld ferrogabbro, Upper Zone a 7493 Hess, I960 Aug./Inv.Pig. Bushveld gabbro, Main Zone b EB Ul 11 Aug./Inv.Pig. Stillwater Complex, gabbro EB U3 11 Aug./OPX Stillwater Complex U526 Brown, 1957 CPX/OPX Skaergaard gabbroic picrite U385A n CPX/OPX* Skaergaard olivine gabbro U3Ul 11 CPX/OPX* Skaergaard gabbro (middle) UU30 ti CPX/OPX* Skaergaard ferrogabbro * formula suggests these are inverted pigeonite Note: Formulas given are for six oxygens APPENDIX II - PART A CALCIUM-RICH CLINOPYROXENES REF. Atkins, 1969 Hess, i960" Brown, 1957 NO. SA660 SA722 SA733 SA738 SA616 7493 EB41 EB43 4526 4385A 4341 4430 Si0 2 Ti02 AI2O3 C r2°3 Fe203 FeO MgO MnO CaO Na20 K20 Others 52.90 .37 2.41 .26 1.03 5.10 16.18 . .16 21.46 .34 .02 .02 52.93 .26 2.40 .27 1.07 4.61 16.55 .15 21.55 .33 .02 .03 52.17 .29 2.47 .02 1.10 6.15 16. 04 .20 21.14 .26 .01 .03 51.74 .41 2.45 <.01 1.33 9.73 14.50 .26 19.48 .32 .04 .03 50.35 .36 2.21 1.69 16.18 11.15 .37 17-93 .23 .03 .02 51.39 51.86 51.83 51.17 50.66 51.26 50.58 .41 .55 .49 .97 1.30 .84 .61 2.45 2.33 3.07 3.22 2.45 1.98 2.20 .01 .1+2 — < .01 <.01 1.26 1.60 1.38 1.53 1.33 1.25 1.57 11.63 9.45 7.21 4.54 11.24 14.49 15.53 14.21 14.50 16.00 16.68 14.25 12.85 12.60 .32 .24 .17 .13 .29 .35 .28 18.12 5.13 19-21 20.54 18.01 16.91 16.40 .27 .23 .27 .65 .36 .26 .2k .02 .00 .02 .05 .08 .02 .03 — — .58 — — — ~ Total 100.25 100.17 99.88 100.29 100.52 100.18 100.17 100.23 99.90 99.97 100.21 100.04 H ro Si Ti Al Cr Fe+3 Fe+2 Mg Mn Ca Na 1.9370 .0102 .1040 .0075 .0284 .1562 .8806 .0050 .8420 .0241 1.9363 .0072 .1035 .0078 .0295 .1410 .8999 .0047 .8447 .0234 1.9267 .0081 • 1075 .0006 .0306 .1900 . .8804 .0063 .8366 .0186 1.9279 .0115 .1076 .0 .0373 .3032 .8030 .0082 .7778 .0231 1.9253 .0104 .0996 .0 .0486 .5174 .6337 .0120 .7347 .0171 1.9278 .0116 .1083 .0 .0356 .3649 .7923 .0102-.7283 .0196 1.9370 .0155 .1026 .0003 .0450 .2952 ,8050 .0076 • 7572 .0167 1.9175 .0136 .1339 .0 .0384 .2231 ,8798 .0053 .7615 .0194 1.8829 .0268 .1397 .0122 .0424 .1397 .9123 .0041 .8099 .0464 1.9047 .0368 .1086 .0 .0376 .3534 .7963 .0092 .7256 .0262 1.9395 .0239 .0883 .0 .0356 .4585 .7226 .0112 .6856 .0191 1.9269 .0175 .0988 .0 .0450 .4948 .7132 .0090 .6695 .0177 APPENDIX II - PART B ORTHOPYROXENES AND PIGEONITES' REF. Atkins, 1969 Hess, 19DO" Brown, 1957 NO. SA66O SAT22 SA733 SAT38 SA6l6 7493 EB41 EB43 4526 U385A 4341 4430 Si0 2 Ti0 2 A1 20 3 Cr 20 3 Fe 20 3 FeO MgO MnO CaO Na20 K20 Others Total 54.32 54.82 53.26 51.47 48.90 .25 .21 .20 .29 .50 1.83 1.87 1.79 1.56 1.50 .12 .14 .01 <.01 — 1.28 1.22 1.35 1.42 2.10 13.44 11.49 15.25 21.72 28.70 27.56 28.71 26.30 21.68 13.80 .29 .28 .36 • 52 .60 1.18 1.44 1.10 1.45 3.60 .05 .07 .07 .07 .20 .02 .02 .02 .03 .00 .01 .02 .02 .02 — 100.35 100.29 99.73 100.23 99.90 51.40 .37 1.78 1.40 20.68 19.37 .38 4.07 .11 52.81 53.20 53.60 50.35 50.90 50.50 .26 .50 .55 .50 .ko 1.65 2.24 2.30 2.23 1.80 1.30 .10 .30 — — — 1.13 .83 1.30 1.14 .70 .70 18.13 15.15 10.80 21.12 25.10 27.00 19.81 24.58 28.70 20.03 16.40 15.50 .38 .32 .30 .38 .30 .20 5.13 2.61 2.00 4.50 4.20 4.10 .05 .06 .20 — .10 .20 .00 .01 .00 — .00 .10 — .58 — — — — 100.00 100.16 99.94 100.00 100.30 100.00 100.00 Si Ti Al Cr Fe+3 Fe+2 Mg Mn Ca Na 1.9446 .0067 .0772 .0034 .0345 .4024 1.4664 .0088 .0453 .0035 1.9470 .0056 .0783 .0039 .0326 .3413 1.5155 .0084 .0548 .0048 1.9377 .0055 .0768 .0003 .0370 .4640 1.4221 .0111 .0429 .0049 1.9279 .0082 .0689 .0 .0400 .6804 1.2069 .0165 .0582 .0051 1.9221 .0148 .0695 .0 .0621 .9435 .8062 .0200 .1516 .0152 1.9426 .0085 .0748 .0 .0398 .6536 1.0880 .0154 .1648 .0081 1.9700 .0104 .0726 .0 .0317 .5656 1.0983 .0120 .2051 .0036 1.9447 .0072 .0965 .0029 .0228 .4632 1.3355 .0099 .1022 .0043 1.9129 .0134 .0968 .0085 .0349 .3224 1.5223 .0091 .0765 .0138 I.896O .0156 .0990 .0 .0323 .6651 1.1210 .0121 .1816 .0 1.9484 .0144 .0812 .0 .0202 .8036 .9331 .0097 .1723 .0074 1.9540 .116 .0593 .0 .0204 .8737 .8914 .0066 .1700 .0150 127 APPENDIX III KEY TO HORNBLENDE ANALYSES NO. LOCALITY OR OCCURRENCE 27 Tonalite, Idaho 5 Hornblendite, Austria 14 Hornblendite, Sweden 6 Actinolite-Chlorite Schist, South Africa 7 Amphibolite, Australia 30 Amphibolite, Japan 32 ' Charnockite, Norway 11 Gabbro, Pennsylvania Analyses from Deer, Howie and Zussman (1963) pp. 274-281. Note: Formulas are calculated according to the scheme described in the text, and are for 22 oxygens and 2 OH. 128 APPENDIX III HORNBLENDE ANALYSES AND FORMULAS Number 27 5** 14 6 7 30 32 11 Si0 2 44.99 51.63 42.80 52.78 50.08 45.62 42.24 48.71 Ti0 2 1.46 tr 3.80 .43 .36 1.13 2.76 .32 A l o O o 11.21 7.39 12.71 5.77 9.42 8.87 10.47 9.48 Fe203 3.33 2.50 1.85 2.45 1.14 2.85 4.04 2.33 FeO 13.17 5.30 10.70 6.61 6.89 16.09 16.06 9.12 MgO 10.41 18.09 14.24 17.43 16.00 10.13 9.22 14.43 MnO .31 .17 .15 .17 .33 .32 .28 .23 CaO 12.11 12.32 11.36 11.90 12.53 11.42 11.23 11.93 Na20 • 97 .61 1.34 .68 1.09 1.27 1.44 1.16 K20 .76 — .54 .07 .21 .33 .89 .15 H20 1.52 2.31 .28 2.26 1.49 2.08 .72 1.83 Others .17 — — .03 — — .05 .23 Total 100.41 100.32 99.77 100.58 99.54 100.11 99-40 99.92 Alkali Site .358 .119 .493* .055 .269 .349 .481 .237 K .142 .0 .099 .013 .038 .063 .171 .027 Na .216 .119 .374 .042 .231 .286 .310 .210 Cubic Site 2 2 2 2 2 2 2 2 Na .059 .047 .0 .142 .067 .081 .109 .113 Ca 1.902 1.847 1.730 1.786 1.894 1.824 1.808 1.831 Mn .038 .020 .018 .020 .039 .040 .036 .028 Fe+2 .0 .086 .251 .052 .0 .055 .047 .028 Octahedral Site 4.943 5 5 5 4.955 5 5 5 Mg 2.268 3.761 3.044 3.629 3.354 2.244 2.059 3.072 Fe+2 1.615 .534 1.036 .723 .813 1.951 1.971 1.064 Fe+3 < .367 .263 .200 .258 .121 .320 .457 .251 Al .532 .442 .310 .345 .629 .358 .201 .578 Ti .161 tr .411 .045 .038 .127 .312 .034 Tetrahedral Site 8 8 8 8 8 8 8 8 Al 1.405 .777 1.845 .607 .937 1.200 1.653 1.023 Si 6.595 7.223 6.155 7.393 7.063 6.800 6.347 6.977 includes .020 Ca analyses includes 1.2% epidote 129 APPENDIX IV COMPUTER PROGRAM USED IN THE DIFFERENTIATION TEST This appendix is provided so that the reader may verify that the method used to calculate Spuzzum differentiation phenomena is correct. The program was run on a PDP 11/10 desk computer owned by the Department of Geological Sciences, University of British Columbia. *JCMAME 1 4-SEP-~6 BASIC/CAPS V0-1 - 01 1 REM: DATA FOR DIORITE FIRST* THEN TONAL ITE* LINES 20-25 2 REM: L I S T S I 0 2 * T I 0 2 * A L 2 0 3 * F E 2 03 * FEO , V\ U0 * CAO* N A 2 0 , K 2 0 . J * 10 PRINT "SPUZZUi: DIFFERENTIATION 110DEL** 11 p T? J *! f 15 PRINT "RESTART AT L I N E 150 OR 1o 0»" 20 DATA 5 5 . 4 * . 3 43 * 1 9 . 2 6* 1 . 0 4 * 5 . 42 * 5 . 0-6* 7 . 3 7 o r/ ^ O * 6* . 5 21 DATA 5 9 . 7 " * .°1"* 1 4 * 1 . 1 * 4 03"* 4 . 13 * 5.3 3* ^ r. o j o v' O * .9" 30 READ A ( 2 5 * A ( 3 5 * A ( 4 5 * A ( 0 5 * A ( 1 5 * A ( 5 5 * A ( 6 5 * AC 7 ) * AC35 31 READ 3 ( 2 5 * 3 ( 3 5 * 3 C 4 5 * 3 ( 6 5 * 3 ( 1 5 * 3 ( 5 5*3(65* DC "5 * E C 3 5 32 D D T * • T 35 DATA "9.65*71•05* 60.09*"9.9*50.93*40.43* 5 6.G 3*30.99 1 40 READ W < S ) * W C15 41 LET A< 1 )~A< 1 } + A (.0 } *V; (15/W ( 0 5 42 LET AC 0 5-0 43 4 4 L E T CC 1 5~3( 1 5+3(0 5*V/( 1 5/W(0 5 LET 3 ( 0 5-0 45 LET S0-AC 1 5+A(25+AC 35+AC 45+AC 5 5+A(65+A(" 5 + AC n v O / 46 50 LET SI"DC 1 5 +B(2 5 +D(35 +3(45+3(55 +3(65+3(7 5 +3 C O, \ 5 5 T JT J > - p f}-: J7M REA '"5 ( J 5 56 LET A( I 5-1 C-(?*A( I 5/S0 5 " LET 3 ( 1 5 " 1 0 0 * 3 ( 1 5 / S I 53 N EX T .1 60 DATA .3221 *.°36"*1.956* I•9"5*•6101 *2.S0000E-03*.095* 61 DATA ."443*1.133*.3365*.0321*.0324*3.G00 a f, £"«. 0 4*0*0 65 XT 0 P T rr J T C\ (•"< 66 READ C ( I 5* D(15 6" NEXT I 69 LET 3(05-0 "0 LET C(0 5=0 "1 LET W1=V.'(65+2*(V;(45+W(25 5 "2 LET W 2 " w C ° 5 + W ( 4 5 + 3 * Vi C 2 5 " 5 LET S0-CC 1 5 + C ( 2 5 + C ( 3 5 + CC 45+CC5 5 + C ( 6 5 + C ( 7 5 + C ( f \ .09 6 READY 130 76 LET Sl^DC 1 )+DC2>+DC3)+DC43+DC53+DC6)+DC?>+D<85 00 FOR 1-1 TO 8 85 LET CCI3 =100*CCI3/S0 86 LET DC I >- 1 e.£*DC I 3/SI 90 NEXT 1 95 DATA 1.5795,1.5043,2.4046 96 READ V0,V1,V2\ 100 GO TO 20C0 110 LET Se--3.4o/V2 + .6 ieS/.Vl+.594/V0 115 LET G0-.594/C V0*S0.) 116 LET Q1=.61CC/(V1*S0) 11" LET 02=3.43/CV2*S0> 120 PP.!?•!T 150 PRINT "PLAGIOCLASE EQUILIBRATES WITH L I Q U I D C03, 15 1 PRINT " IS SHIELDED (+1>"J 160 INPUT Z 1"0 PRINT 130 LET U-0 200 PRINT "WT. % DIORITE"/ 2G1 INPUT X 2G5 LET S0-0 2G6 LET S l - 0 210 FOR I-1 TO 8 215 LET MCI >-<X*Ac; I .3/ 1 00 + C 1 - X / l 0 0 > * 3 C I )3/WC I 3 216 LET S1=S1+X*ACI3/C100*W(I3>. 220 LET S0-S0+NCI3 22 1 LET NCI 5-0 225 NEXT I 228 LET S1--S1/S0 230 FOR 1-1 TO 3 235 LET MCI>=MC13*100/S0 236 NEXT I 240 PRINT 250 PRINT "DEG I.N GROWTH" 25 1 PRINT "PLA'J"; 252 INPUT P2 255' PRINT "OPX "! 25 6 INPUT PI 260 PRINT "CPX "*• 261 INPUT P0 26 3 PRINT 2"G PRINT "BEGIN PRINTING" I * 2° i I NPUT E 2"2 PR INT 2°3 LET E-E/100 280 LET P-~G-290 LET S-100 29 5 GOSUB 9 00 29G PRINT 300 IF P0'.-Pl^P2>fi GO TO 3 1 " 301 I F P0+P1+P2-0 GO TO 36C 302 I F P0+P1-0 GO TO 320 303 I F P0+P2-0 GO TO 322 304 I F PI +P2--G GO 1 »./ O M 3G5 326 READY 131 306 I F P0-P2 GC TO 323 30" IF P1-P2 GO TO 330 <*% Q rt O ±J o T V I i (P1-P0 5!»=PC5> e GO p r» 340 1 /?. o T TT CP0-P1 )*P1 >.C Grt p *"\ 343 310 T TT ± . <P2-P0)*PG>0 GO **]* O 346 31 1 T TT <P0-P2)*P2>0 GO p 349 31 2 T TP (P2-P1}vPl>0 G° p r» 352 T TT - 1 ( P i -P2 5 *P2> 0 GO p r> 35 5 3 14 PR 315 ;|" FPINT "INVALID CRY STALL I Z AT I DN SEQUENCE* 320 T TT 1 00~S^P2 »• 0 iJJ'- • •j* r» ' - i r, f, 32 1 ''I r* TO 36G op p T TT* 1 0 0 - S P 1 '. - O •p r\ 0 0 xz vj v.J O o O / * r\ TO 360 324 I F 100-S<P0 «•> r» 1* r\ 390 325 GO TO 360 326 I F 1 0C~S<P0 GO 3 65 w c- GO TO 360 328 I F 1 00-S<P0 GO T 0 r> 'i c\ o o o GO TO 3 60 330 I F 1 00-S<Pl GO TO •*\ n r O D j 1 • r\ TO 360 34 0 T TT* A1 1 GG-S^-PE' GO 1* f~\ 365 34 1 I F 1 0G'-S<P1 GO 3S5 342 GO T" 360 34 3 T F i oe-s<p1 ! - ^  'T* r% 365 34 4 T TT 1 0 0-S--.P0 f4 ^  T ^ A p 345 1 • r» •a . TO 360 346 . . i 1GG-S'PG < - 0 •y r\ 370 34° T TT 1.0.0" S<P2 VJ • . TO 330 o /. r> » * ***« fo 360 349 ** r r i ' 1 0 0 - S P 2 ! 4 *"* 3 70 *? c. c T rp i . J 1 0 G " S - p 0 f ; r* To 39 0 351 .• • /"*i *r r\ 0 {. l . . v-- L'. 352 T IT - i 1 G K - S <*• P 1 1 • r» U "• • TO 0, ^ C *~i O O o T TTp 10G-S-P2 , r* •T1 r> 320 35 4 / • /**. u -. To 3 6G 355 T T~*' 1 C 0 - S p 2 GO 35 6 T "-T 100-S^Pl TO 305 3 50 L E T R0-0 0 361 LET P l - G l 3 6 2 T R2-Q2 363 ,; r» TO 40G 365 LE T R0-0 366 LE T Rl-0 »-l f *7 o o 1 T" T R2-1 368 GO T 0 4 0 0 3°e l V T R 0 ~ 0 T P. 1 " 1 r- ^  U --TO 3S2 37 5 LET R0=1 3" 6 LET Rl-0. ' ( i n 1' r\ vJ • I •., 0 CJ r.-READY 132 OC 380 LET P.0-GC/C Q0+G 1 > 301 LET R1--1-R0 382 LET R2-0 383 GC TO 400 T R0-QG/C00+02) 16 LET R l - 0 38" LET R2-1-R0 388 GO TO 400 390 LET R0-0 39 1 LET R 1 -Q 1 /( Q. 1 +02 ) 392 LET P.2~1~R1 400 IF S-100 THEN IF T~1 THEN GOSUB 90 0 40 2 FOR 1-1 TO 8 405 LET I I (13 (I }-.61>?( R0vC ( I > +R 1*D(I 3 3 406 LET NCI ) -N(I )+• 0 1 *< P.e#C C I3+Rl*D<I3J 410. N EX T I 42S LET X3-(ri(4)-!::(?)-?-U3> 3/<!1<43-ric8) 3 421 LET X-X3/CX3+C1-X33*W2/W13 430 IF Z-0 GO T n 455 434 LET DO-4.2 43 5 LET Y-1+ D0-(DC*2 + D0>/CX+D03 436 LET Y~ Y / ( Y + ( 1 - Y 3 1 /'.v2 3 440 LET M ( 2 3 ~M<2 3-R2*C 9.0000CE-03 + .591 * <1-Y 3 + .394*Y 3 441 LET M ( 2 ) - N C 2 ) + P 2 * C 9 . 0 0 0 S 0 E - 0 3 + . 5 9 1 * C 1 » Y 3 + . 3 9 4 * Y ) 442 LET M(43-M'(43"R2*C3.00000E-03+. I9 " v ( 1~Y3+.394*Y3 443 LET N<43-N< 43'+P2*<3.0e000E-03+. 19"*< 1-Y3+•394*Y) 444 LET 1;<6)-!U6 3-R£*. 19"*Y 445 LET N (. 6 3 ~N C 6 3 + P.2* • 1 9"*Y 446 LET 1) C3 ~n< " 3 « R 2 * . 1 97* C 1 -Y 3 44" LET N (7)-NC)+P2=r,19' ,-*( 1-Y) 440 LET ti(33-N(33-R2^3.00000E«-03 449 LET N < 3 3 ~N(8 3 +H2*3.00000E-03 455 LET P-P+R2 460 LET S - S - l 46 1 LET 50-1-S/100 465 LET U = U + "1 4"0 IF U+.1 <1G0*E GO TO 30fi 400 IF Z>0 GO TO ?45 500 LET L1~-•O32 50 5 LET X - X - L l 510 LET X-X+Ll 520 LET D0-4.2 521 LET Y-l+D0-CD0T2+D03/CX+C03 530 LET Y4=Y/<Y+< 1 -Y) *V.: 1 /wg > 531 LET X4-X/CX + C 1 -X 3 *W 1 /'w2 3 540 IF A D S C C X 3 - X 4 3 / < Y 4 - X 4 3 - • 9 3 5 * P / < M < 4 ? - M C 8 3 3 )«=5.00000E-04 G' 545 IF <X3-X4 3 7 < Y 4 » X 4 3 >.985*P/C M< 4 J «M < 3 3 3 GO TO 550 546 GO TO 510 550 LET X - X - L l 551 LET L l - L l / 2 0 TO 5 10 • ET X2-MC 2 3-P*< 9. 000.00E-03 +. 59 1 v ( 1 »Y43 +. 394*Y43 56 1 LET N2-N ( 2 3 +P~ ( 9 * 00 00 0E-03 + • 59 1 ( 1 -Y4 3 + • 3 9 4-?Y4 3 662 LET N4-NC 4 3-P-T< 3. 0060SE-G3+. 1 9°*C 1 ~Y4 )+.'394*Y4> 663 LET H4=M(43+P*C3.00«0OE-03+» 19"=?( 1 »Y4 3• + . 394*Y4 3 664 LET M6=M(6)-P*.19?*Y4 O O VJ 660 READY 133 665 LET M6---NC63+P*. 19"*Y4 666 LET K>KC*'5»P*.19''*(1-Y/|3 66" LET N"~NC " 3+P*. 1 9 ? * C l ~ Y 4 ) 66S LET MG«M<8)-P*3«00e00E-fi!3 669 LET N3-N<8 3 +P*3.00G00E-02 "45 PRINT 746 PRINT 751 PRINT " "U" % CRYSTALS" ""0 PRINT ""1 PRINT "OXIDE","DIORITE","TONALITE" "72 LET U0-0 ""3 LET T0-0 ""4 LET T l - 0 """ IP Z-0 GO TO 80 0 "30 POP. I ~ 1 T0 3 785 LET T0--T0+W ( I } * ( " 5 < I 3 + < S 1 - S0 > *M < I ) ) "36 LET T I - T I +WC I >*C 1 »S 1 3*MC I 3 78" NEXT I "90 FOR 1-1 TO 3 "92 LET U0-U0 + CV(I 3 * ( N ( I 3 + C S1-S0 3*MCI 33 * 100/TO-A(I 3 3 * 2 "93 LET U0-U0 + C V.'< I 3*( 1 -S 1 3*MC I 3 * 1 00/T 1 -EC I 3 3 ' 2" "9 5 PRINT I, "96 PRINT INT(10000*w<I3*(N(I 3 +<S1-S0>*M<I 3 3/T0 + . 5 3 / l 0 0 , 79" PRINT INTC 1 0000*W< I 3 C 1 -SI 3*MC I 3/T1 +.53/l 00 " "93 NEXT I "99 GO TO 340 •000 LET T 0 - W C 1 ) ^  (.N ( 1 3 + ( S 1 -S03*MC 1 ))+W(23*CM2+CSl-S03*M23 80 1 LET T G = T 0 + W ( 3 3 •<• (N C33+CS1-S0 )*M< 3 3 3 + W ( 4 3 * < N 4+ C S 1 -S0 3*M4 3 302 LET T0-T0+VK 5 3 *(N C 5 3 + (S1 -S0 3 *M< 5 3 3 + W(6 3 *CM6 +C S1-SP)*K63 803 LET T0-T0 + WC "3 *CN"+C S 1 -S0 3*M" 3 +w( 8 ) *CM8 + CS1-S0 3 -MS 3 810 LET TI-WC1)*MC13+W( 2 3-M2 + VJC 3 3-M C 3 3 + VC 4 3 *M4 311 LET T l - T l +WC53-MC53+WC63*N6+WC"3*M"+wc33-M8 812 LET T1~C1-S13*T1 82G PRINT 1 , I NT ( 1 0000*WC 1 3 * C M C 1 3 + C S 1 - S 0 3 * H ( 1 3 3/T0 +.53/100, 821 PRINT INTC I0000*w< 1 3-*C ! -SI 3 *K C 1 3 / T 1 +.53/1 00 822 ' PRINT 2, INT ( 1 0000*WC2)*CN2+CS 1 - S 0 3 *M 2 3 /T G + » 5 3 /1 0 0 , 823 PRINT INTC1000O*W(23=*C 1-S1 3*M2/T1+.53/l00 324 PRINT 3,INTC100 00*WC33 *CN C 3 3 + C S1 -S0 3*MC 3 3 3 /T0 + . 5 3 / l 0 0 , 325 PRINT INTC100G0*WC3)*Cl-Sl3 *M C 3 3/T I + . 5 3 / 1 00 826 PRINT 4, INTC 1 00G0*v/< 4 3 * CN4 + C S 1 ~SG 3-N4 3/TR + . 5 3/l 00, 82" PRINT INTC 1 0000*V;( 4 3--:-C 1 ~S 1 3 *M4./T 1+. 5 3 / l 00 328 PRINT 5, I NT C 1 0 0-0 0 '.v < 5 3 * < N ( 5 3 + < S I - S 0 3 v'A C 5 3 3 /T0 + .5 3 / I 00, 829 PRINT INTC 1 0 0 0 0 * * C 5)*C1-S1 3 (. 5 3/T1+.53/1 0 0 830 PRINT 6, INTC 1 0GG0t=V; C 6 3 * CN6+ C S 1 -S0 3 *M63/T0 +. 5 3 / l 00, 831 PRINT INTC10000*WC63-C1-313*M6/T1+.53/1GP 332 PRINT ",INTC10G0G^V.'("3*(N" + CSl-S03*M"3/T0 + .53/100, 833 PRINT I MT < 1 0000* K <"3 * <1 -S 1 3 *V, 7/T I +. 5 3 /1 0 0 834 PRINT 0,INTC10006*W< C3 * C N3 + C S1-S 0 > *MG 3/T0 + .5 3/i 0 0, 835 PRINT INTC 1G000*WCG>: C 1-S1 3*N0/Ti+.53/l00 336 COSUB 9"0 840 PRINT "RNS RESID~"S0R C U0/16 3 845 PRINT 850 GO T" 300 9 0 0 PRINT "ACCESSORIES C ^ ~ l % 3 " READY OJ OJ CJ OJ CJ 3 . CO co <r o r • CJ 135 GUIDE TO APPENDIX V The purpose of this appendix is to relieve cluttering in the map produced in this study. Instead of plotting station locations on the map, they are tabulated in the appendix. The tables are organized thus: Column 1 Column 2 Column 3 Column k Column 5 Station number. Longitude as minutes and seconds west of 121°W (min.-sec). Latitude as minutes and seconds north of 49°N (min.-sec). Elevation in metres Rocktype s schist HPX hornblende pyroxenite T tonalite OPX olivine pyroxenite HD hornblende diorite HB hornblendite PD pyroxene diorite UB ultrabasic rocks PHD transition PD to HD AP aplite HZ hornblendized rocks Grfs granofels HZD transition HZ to PD or HD CGn Custer Gneiss SCB schist contact intrusive Cgl conglomerate breccia Columns 6 and 7 Col. 6 Col. 7 Column 8: Quality of attitude data Attitude, foliation open and lineation in parentheses. Azimuth or strike (degrees true). Plunge or dip (degrees). VG very good G good FG fairly good F fair FP P W D fairly poor poor too weak to measure directionless Column 9: Notes about specimen or station S Specimen thin sectioned P Specimen microanalyzed APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 2 3 1+ 5 6 7 8 9 Number Longitude Latitude Elevation Rocktype Azim. Inclin. Q. Notes 15/6/75/1 27-27.6 23-30.0 88 T __ — — S /2 28-19.1 11.4 91 RD -- — — /3 1+0.8 22-57.6 88 HD — — — S A 29-1+0.4 1+0.4 82 PHD — — — /5 30-17.3 36.3 76 PD+S — — — /6 31-39.0 21-1+9.8 91 PD — — S,P 17/6/75/1 29-30.9 28-05.1 792 T 130 78NE F S /2 39.8 03.3 792 HPX — — D /3 27.7 06.1 792 T (315) (50) P A 22.8 07.3 792 T 100 65NE P /5 19.8 08.6 792 T 80 50N G /6 29.6 03.7 771 T 160 6lNE G (350) (45) P 11 31.1 02.6 762 HZ 100 55N G /8 22.2 27-58.3 774 T — — — /9 16.7 58.7 789 T+S 60 58NW F /10 07.5 .57.2 792 T 25 40NW F / l l 04.8 57.0 792 T+S 110 80NE G /12 02.1 57.1 792 T 165 90 P A 3 28-59.9 57.6 792 T+S (325) (40) G /14a 32.4 28-03.8 792 T — — D /14b 1+0.1 03.3 786 T+AP — — D /15 29-47.3 27-58.9 805 PD 35 65NW G P 19/6/75/la 27-39.1 29-32.1 506 S 70 35NW G /lb 38.5 28.6 503 HPX — — D /2 28-08.5 25-38.5 390 T (0) (40). P /3 29-19-9 34.8 610 T 105 50NE P (330) (43) G A 30-22.1 41.5 655 T 15 50NW F /5 31-10.7 11.7 707 HZ — — D S UJ OS APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 T Azim. Inclin. 0 Q. y Notes 20/6/75/la /lb 12 /3 A 15 /6 /T 21/6/75/1 12 /3 A /5 /6 /7 /8 /9 /10 24/6/75/1 /2 /3a,b 27- 17.3 07.2. 28- 59.7 29- 05.1 1*4.2 49.7 30.0 00.6 27-12.9 11.2 12.9 16.4 14.5 20.4 26.5 44.6 10.7 29.1 27-48.7 52.5 59.2 25-34.8 35.0 34.6 15.4 24- 35.0 22.6 52.0 25- 02.6 28- 54.2 29- 04.5 28.2 19-6 02.6 28-46.7 51.0 45.7 47.4 37-9 28-39.3 32.1 31.5 320 320 546 701 802 835 829 747 411 402 457 457 427 427 457 488 344 372 518 524 533 Cgl. Cgl, T T HZD HZ HZD T S $ s s s s S+UB S S S S s s 150 110 60 110 120 105 140 (335) 10 (285) 145 (35) 5 (0) 40 (320) 130 (330) 0 (325) 110 (315) 0 (320) 175 (330) 0 (330) 7 0 N E 5 0 N E 80NW 6 0 N E 53NE 6 0 N E 6 5 N E (43) 54W (48) 38NE (34) 65W (13) 22NW (21) 40NE (24) 35W (11) 40NE (17) 30W (22) 53W (22) 6ow (25) G F P G G F G G D G G G FG G G G G FG FG FG G . G G FG G G G G S(ofA) APPENDIX V CATALOGUE OF FIELD DATA Attitude ..... . 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 7 Azim. Inclin. 0 Q. y Notes 24/6/75/4 /6a /6b /6c 28-15-3 22.9 25.4 27.3 25/6/75/1 28-31.4 /2 /3a /3c A /5 /6 1/7/75/1 /2 /3 A /5b /6 /7 /8 /9 /10a /10b 2/7/75/1 /2 /3 /4a,b /5 36.5 40.9 42.5 44.7 29-05.3 23.9 27-17-0 31- 28.1 55.2 37.9 31.2 44.2 32- 48.5 39-4 41.0 24.0 16.1 31- 58.9 55.3 32- 10.4 03.8 01.0 28-30.0 28.4 28.0 26.9 28-25.1 22.8 20.5 19-7 18.7 10.4 02.8 26-14.7 24- 57.1 39.9 32.1 44.3 1+3.4 53.6 57.1 25- 04.3 06.6 10.5 25-18.7 25-5 39.8 36.4 32.1 573 600 610 613 625 637 640 640 640 695 728 518 789 927 1009 957 942 1131 1097 1088 1036 1021 • 978 99k 1021 1012 1006 S S T T S S s HZ 170 (340) 0 (315) (330) 25 (290) 20 (320) (335) (320) (330) (335) 6ow (18) 47W (38) (44) 38NW (34) 65NW (58) (35) (35) (45) (27) G G G G G G G G G G G G G T — — — T — — — CGn — — — HD — — — PD+S 130 20NE FG PD 110 35NE FG PD+HB — — — PD 100 14NE FG HZ 130 20NE F HZ 25 40NW FG HD 170 40W G Grfs — — — HD 5 35W FG HD 0 45W G HZ — — — PD (30) (50) FG Grfs+PD 45 50NW G HZ 5 35W FG data in PD,S APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 7 Azim. Inclin. a Q. 9 Notes 2/7/75/6 /7a /7b /8 /9 /10 7/7/75/1 /2 /3 /4 /5 /6 /7 /8 /9 /10 9/7/75/1 /2 /3 A /5 /6 /7 /8 /9 /10 / l l /12 32-35.5 31.0 15.2 31-49.0 40.8 36.7 31-19.4 21.6 21.8 19.3 10.4 26-18.2 20.6 28.6 20.2 12.8 09.6 25-09.1 17.1 27.8 39.8 48.2 924 914 884 850 850 84i 698 701 701 704 716 PD PD PD PD PD PD HD HZD HD HD HD+S 30 50 55 25 30 50 05.7 52.8 716 HD+S — 13.9 26-01.4 725 S 10 (240) 16.8 05.8 725 T ko 06.3 06.7 786 T 25 30-45.7 08.9 860 UB — 30-23.7 25-35.3 732 T+S — 31-54.3 02.2 853 PHD 0 42.0 12.3 811 HD 25 40.7 24.9 817 HD 10 38.2 33.8 847 HD — 37.0 43.3 881 HD 20 47.7 40.0 930 PHD 20 17.4 26-37.1 942 HZD — 34.8 39-8 914 HD — 40.8 42.9 • 893 Grfs — 52.5 42.7 884 PD 105 44.6 29.5 792 PD (55) 45NW 40NW D G — D 40NW FG S , S 45NW F 50NW G 55NW G data ] HD 50W G (40) P 45NW G S 45NW G D 30W G 30NW FG 30W G 40NW FG 35NW FG — D S — D — D 25SW P S (35) F LO APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 7 Azim. Inclin. 0 Q. y Notes 10/7/75/1 31-56.1 26-26.8 /2 33-12.1 03.3 /3 32-51.9 16.7 /4a 58.2 22.0 /4b 51.0 26.6 /4c 47.5 28.9 /4d 44.3 30.7 /4e 41.2 32.6 /5a 37.7 34.6 /5b 31.7 37.2 /6 40.5 24.8 /7a 24.4 36.9 /7b 27.6 34.7 /8 14.9 36.9 16/7/75/1 29-12.6 28-12.3 /2 07.8 14.8 /3 02.1 17.6 A 28-57.1 20.5 /5 48.2 23.4 /6 47.6 27.4 fl 37.7 38.3 /8 32.2 41.6 /9 25.4 44.2 /10 10.5 44.7 / l l 27.1 39-1 16/7/75/12 32.7 35.2 A3 39.5 30.2 18/7/75/2 31-07.2 28-23.0 /3 30-53.6 27.4 /5 39.1 30.4 844 780 844 850 847 850 850 850 856 863 847 850 847 838 792 792 792 792 789 826 832 838 835 753 774 783 789 1414 1402 1433 HZ PD PD PD PD PD PD PD PD PD PD PX PD PD T T T T T T HZ+T S+T S S S HZ T T? HD PD 110 175 25 20 15 15 20 175 75 80 60 55 30 10 (355) 150 155 160 155 10 135 10SW 55W 45NW 50NW 40NW 35NW 40NW 35W 20NW 55N 50NW 60NW 60NW 70W (50) 8 ONE 60SW 55SW 50SW 90 70NE FG D . D G VG VG VG VG VG VG D D D F G G G G G G G G G G D G D FG talus talus data in talus,g p APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 7 Azim. Inclin. 0 Q. 9 Notes l8/7/75/7a 30-39.1 28-03.4 23/7/75/la 28-56.8 27-41.2 /lb 50.1 43.2 /2a 44.1 43.7 /2b 45.4 41.1 /3 36.2 41.7 A 41.6 42.6 /5 53.6 38.8 /6a 50.0 31.1 /6b 54.1 27.3 /6c 29-00.2 23.6 23/7/75/7 29-02.1 27-27.4 /8 12.3 14.3 /9 32.2 00.9 /10 42.6 26-31.8 24/7/75/1 29-55.6 26-36.7 /2 30-17.7 41.5 /3 37.1 47.5 A 47.4 27-08.7 /5 59.4 15.3 /6 31-02.9 17.2 /7 08.6 21.1 /8 22.8 17.0 /9 32.0 14.5 /10 44.3 18.6 / l l 52.2 22.5 /12 53.5 27.7 1106 HB — — — 1091 T+HB 170 45E G 1094 S 150 75SW G 1103 T+HB — — — 1113 S 75 60NW G 1091 S 30 40NW G 1097 T 65 45NW G 1134 T+AP 70 35NW G 1173 S 60 50NW G 1204 S 65 50NW G 1234 S 95 7 ON G 1219 S 135 65NE G (150) (40) G 1375 S 110 55NE G 1341 S 70 25NW G 1372 S+T 5 45W G 1408 S+T 170 65W FG 1301 S+T 110 5 ONE FG 1341 S 145 45NE FG 1387 S 55 40NW G 1338 HZ 5 80W G 1332 T — — D 1341 HD — — — 1353 HD 110 45SW F 1341 PHD 150 45SW FG 1402 PD 160 35SW G 1433 PD 110 60SW G 1384 PD 120 40SW G data in T data in T, S data in S S,P S APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 7 Azim. Inclin. 8 Q. 9 Notes 24/7/75/13 31-45.6 /14 32.7 /15 23.3 29/7/75/1 32-35.2 12 34.1 /3a,b 43.7 A 37.4 /5a 22.2 /5b 17.5 /6 10.2 /7 02.9 /8 31-49.8 /9 59.4 /10a 39.9 /10b 33.2 /10c 26.9 30/7/75/1 30-46.8 /2a 50.6 /3 31-05.4 A 04.5 /5 09.2 /6 16.6 /7 19.6 /8 17.6 19 04.8 /10a 30-57.5 /10b 53.4 /10c 31-00.1 31/7/75/1 30-13.7 /3 12.1 A 09.5 27-38.6 1341 PD 125 50SW G 47.9 1372 PD 75 45SE P 58.5 1402 HD 130 60SW G 26-50.1 1030 PD 40 30NW G 45.8 960 PD 20 30NW G 39.0 945 HZ 175 35W G 41.7 945 HZ 30 45NW G 43.7 927 PD 80 20N G 42.7 908 HZ 100 35N FG 43.1 893 HZ 50 40NW G 40.7 850 PD 155 20NE G 41.1 863 HZ — — — 40.3 853 HZD — — D 36.5 850 HD — — D 35.5 850 HD — — D 33.8 853 PD 45 45NW F 26-19.2 1030 S 60 45NW G 15.8 981 HD 55 40NW G 25.2 930 SCB — — D 40.7 1030 HD 30 90 P 42.9 1042 HD 35 65NW G 44.4 1058 HD 20 90 P 46.1 1094 HD — — D 48.3 1113 HD 140 60SW G 49.9 1128 PD 140 65SW G 46.2 1128 SCB — — — 40.4 1128 S 45 75NW FG 49.4 1128 HD 150 60SW FG 27-59-9 933 HZ 70 90 F 28-01.9 927 KB — — D 02.0 911 HZ — — — s S(3a,b) H ro S S APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 2 3 4 5 6 7 8 9 Number Longitude Latitude Elevation Rocktype Azim. Inclin. Q. Notes 6/8/75/1 30-03.2 29-52.2 607 T D 12 32-17.3 28-26.9 811 HZ 70 70NW FG /3 2 3 . 0 0 3 . 0 890 PD 65 65NW G A 18.8 27-54.1 924 PD 80 90 G /5 17.3 28-02.6 927 PHD — — D /6 13.0 05.4 960 HD 55 75NW FG /7 06.2 27-56.6 997 T 150 5 ONE F S /8 01.5 28-15.8 1042 T 165 60NE VG /9 02 .6 12 .7 1042 T 70 55NW G /io 08.1 10.4 1015 HPX — — D hi.gr.ore /11a 53 .5 26-53.0 945 PD — — D /lib 45.3 27-06.2 948 PD — — D /12 42.2 14.1 966 PD 65 50SE G A3 38 .7 20 .7 969 PD (220) (40) FG /14 35 .9 28.9 972 PD 75 60SE VG A 5 35 .1 40.7 960 HZ 90 80S G S /16 3 0 . 9 53 .9 924 PD 90 70S VG /17 27.2 28-01.1 881 PD 80 70NW VG 8/8/75A 32-26.4 28-12.2 838 PD 75 90 FG S /2a 33-10.1 07.5 884 HD 120 60SW G /2b 0 0 . 3 09.1 878 PHD 95 85S FG / 3 a 3 2 -54.0 10.1 872 PD — — — /3b 45.1 12.7 872 PD 80 80N F A a 17.0 12.1 914 HPX — — D s /5a 17.6 16.0 908 HD — — D /5b 13.4 27-43.0 972 HD 110 55SW G s /6 10.3 52.7 1006 HD 75 55SE FG n 06.8 56.6 1030 HD 80 70S G /8 04.1 28-03.6 1045 HD 75 90 G 19 01.8 07.9 1061 HD 70 90 G APPENDIX V CATALOGUE OF FIELD DATA 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktyp 8/8/75/10 31-38.8 28-03.1 850 UB /13 43.4 04.0 893 UB+HD /15 47-9 04.4 908 HD /l6 53.2 04.2 927 HD /17 55.8 03.8 1030 • HD /18 57.0 27-59.9 945 HD 18/8/75/1 29-48.3 27-50.6 856 PD+HZ /2a 42.0 47.1 884 S /2b 54.9 30.0 1042 S /3 30-04.9 20.1 1097 S+UB A 09-5 18.4 1113 HPX 15 14.2 18.0 1128 S /6 19.1 17.2 l l 6 l T ll 34.5 10.4 1262 S /8 41.1 14.9 1250 S 19 46.8 18.0 1250 S /10 51.2 20.5 1250 -S /11a 55.3 23.2 1250 S / l i b 57.7 21.7 1274 S /12 31-04.5 22.6 1292 HZ 19/8/75/1 32-57.3 26-37.2 887 HD /2 33-10.1 32.6 899 HZ /3 18.7 30.7 887 T 20/8/75/la 30-23.4 27-39.0 875 HPX /lb 25.9 39.9 905 HZD /2 30.7 38.7 920 HZ /3 34.8 36.6 945 HZ A 36.0 33.4 960 T Attitude 6 Azim. 7 Inclin. 8 Q. 9 Notes 100 90 110 130 120 170 (-) 140 150 (135) 55 110 45S 65S 75SW 80SW 90 90 (90) 55NE 60SW (35) 35NW 80NE D G G G G G F FG G D W FG G W W w w w w F D VG D D D data in HD, S S S 120 90 S S APPENDIX y CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 T Azim. Inclin. 0 Q. y Notes 20/8/75/5 30-33.4 27-29-9 /6 29.1 27.3 /7 23.9 26.5 /8 19.1 25.6 /9 10.4 43.9 21/8/75/la 28-45.6 28-59.1 /lb 50.7 58.8 /2 53.5 56.7 /3 29-01.1 50.2 A 05.11 50.5 /5 11.1 51.5 /6 21. 4 52.3 /7 31.5 52.7 /8 38.5 51.5 /9 45.8 52.7 /10 53.0 54.0 / l l 30-02.2 50.9 /12 09.8 51.7 /13 13.4 47.6 /14 21.2 45.7 24/8/75/1 31-18.8 28-02.6 /2 16.5 03.7 /3 17.5 05.9 A 13.9 09.4 /5 09.4 10.2 /6a 30-42.6 27-59-7 /6b (see l8/7/75/7a) 960 T 130 90 G 975 T 130 80NE F 966 T 135 90 FG 981 T 170 90 FG 826 PD — — — 1152 S 150 - 75SW G 1152 S 30 75NW G (340) (65) G 1189 T 145 90 G 1247 T 140 70NE G 1305 T 145 70NE G 1359 T 140 70NE G 1417 T 155 90 G 1U69 T 150 90 G 1506 T 150 75SW G 1487 T 130 90 G 1570 T 125 80NE G 1463 T 140 90 FG 1436 T 135 80NE FG 1457 T 160 80SW G 1433 T 145 • 65NE G 1387 HPX — — D 1402 S+HZ 80 55N G data 1448 S+HZ — — — 1445 S+HZ — — — 1439 HD — — — 1137 PD — — — PD 70 70NW G H APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation 5 Rocktype 6 7 Azim. Inclin. a Q. 9 Notes 2U/8/75/7a 29-58.7 28-10.0 1027 OPX — — D /7b Giant Mascot dump pile HB — —— D /7c Giant Mascot dump pile HB — — D /8a 29-39.7 28-11.9 985 HD 100 90 G /8b 37.4 11.0 951 HD 110 75NE G /8c 41.9 09.8 948 HD 150 55NE G /8d 45.1 09.0 945 HD 40 50NW G 19 30-06.7 27-56.4 853 HB — — D 25/8/75/1 31-15-1 28-06.1 1436 S+HZ 110 90 FG /2 16.5 09.9 1436 HZ 40 90 FG /3 16.5 12.2 1439 S+HZ 60 90 G /4 16.3 14.5 1443 HB+HZ 50 90 F 15 16.6 17.6 1457 HD 75 65N G /6 19.6 16.4 1469 HD 120 70NE G /7 24.7 15-9 1457 HD — — W /8 18.0 23.5 1393 HZ — — — /10 30-58.6 25.7 1430 HD 110 90 F / l l 4 l . l 29.5 1362 T — — D /12 39.5 34.8 1433 T+UB — — W /13 39-5 38.1 1417 T (-) (90) G 25/8/75/14a 30-32.6 28-39.7 1442 T 120 80NE G /14b 30.4 41.4 1448 T 130 75NE G /15 35.6 35-0 1466 HD — — D /16 23.7 32.3 1372 HPX — — — 27/8/75/2a,b > c 29-41.2 27-55.2 792 PD+UB — — — /3a,b (see 20/8/75/lb) • •= HD+UB — —— — 28/8/75/la,b 30-54.0 28-02.2 1274 PD+UB — — — 13/9/75/1 29-28.5 28-10.2 853 T+HB — — — s s s data in HZ data in HZ, S S shears S(2a,b,c), P(2a,c) S(mafic dyke) S(la,b) S APPENDIX V CATALOGUE OF FIELD DATA Attitude 1 Number 2 Longitude 3 Latitude 4 Elevation Rociftype Azim. I n c l i n . Notes 13 / 9 / 7 5 / 2 1 5 / 9 / 7 5 / l a / l b / 2 /3 A / 5 15 / 9 /75 /6 / 7 /8 / 9 / 10 / l l / 1 2 /13 /14 AM#2 2600 30- 02 .4 3 3 - 4 3 . 0 34- 06.4 42 .1 3 5 - 10 .5 13 .6 42.7 3 6 - 14.7 29 .6 3 5 - 59-5 3 6 - 1 6 . 3 1 0 . 9 33-35-8 24 .4 31- 02 .4 19-6 29- 04;8 3 0 - 06 .3 27 -59 .6 2 5 - 57 .3 4 9 . 3 4 5 . 6 3 5 . 0 13.4 4 5 . 8 2 6 - 1 7 . 5 2 7 - 0 6 . 0 2 0 . 3 31 .4 40 .1 2 6 - 0 1 . 7 05 .4 06 .0 2 1 . 7 2 2 - 5 0 . 5 2 7 - 55 .6 869 707 698 732 796 588 683 716 789 954 893 942 744 860 796 792 122 853 UB PD PD PD PD PD PD PD HD HD HD HD PD PD T HD HB HB (220) 45 165 155 170 170 10 35 70 70 50 145 120 125 165 (25) 25NW 5 ONE 40NE 45E 55E 55E 65SE 90 75SE 80SE 25SW 45SW 25NE FP FG VG VG FG VG VG FG VG G G FG VG G P D D S,P P GEOLOGY BETWEEN THE FRASER RIVER AND EMORY CREEK, NORTHWEST OF HOPE, B. C. by Mark R. Vining, 1977 o Q 0 0 o E O C E N E Conglomerate and sandstone U P P E R C R E T A C E O U S LEGEND A G E S UNKNOWN • • • Hornblendized tonalite 1 1 or diorite 4 4 + v v V A A A V _ _ _ _ _ _ T o n a l i t e H o r n b l e n d e d ior i te Pyroxene diorite C R E T A C E O U S ( ? ) Giant Mascot B o d y : H o r n b l e n d i t e , p y r o x e n i t e , p e r i d o t i t e , a n d dunite U P P E R P A L E O Z O I C Chi l l iwack Group: P e l i t e , g r e e n s t o n e , and minor l imestone Gabbro , hornblendite, and pyroxenite Sett ler Sch is t ; S ^ 5 | Pe l i t i c s c h i s t ; minor m a r b l e , q u a r t z i t e , and ca lc s i l i c a t e rock Custer Gne iss : G n e i s s , m i g m a t i t e , a n d a m p h i b o l i t e F A U L T thrust h igh angle v\ v » X Metamorph ic Fo l ia t ion Posit ion known approx . uncertain C O N T A C T Position known approx. uncertain Igneous F o l i a t i o n MINERALOGICAL ZONATION IN THE SPUZZUM PLUTON SCALE 1:125,000 KILOMETRES • i i i i i < D\or-\\e u n d i v i d e d + + _±_ To no. I i ie G e o l o g y a f t e r R i c h a r d s a n d M c T a g g a r t ( 1 9 7 6 ) a n d t h i s s t u d y 1 Z I ° 3 C ) ' W K 25 5 4 + +• + 4 4 \ inn + + + 1 \ \ 4 4 $ 5 $ J { j J 5 $ * » 5 ' ^ J 5 > > 5 S 1 5 5 4--HI + 4 v x X \ ^ \ \ • \ \ \ \ X T 4 |\ \ \ \ ^ I \ \ + + + + + + + + + ~5 _ K> \ + 4- 4 4 4 +• + 4- 4-4 4 + 4 5 S 5 5 * 5 5 4 + + -f 5 < 4 ^ + + + ; + + + + • + + 4 4- + + \ 4 +K x x x ' x W x \ ^ \ ' \ \ \ + 4 + 4 + 4 4- 4 4-+ _ l - 4 + 4 , . / w V + 4 « ? X ^ V v / » 4 4-+ • 4 4 J 4 +s + + 4 4-+ 4 4 + 4 4 + + + + 4 4 •'//',' : .J-"' .•' : ' - T ^ + j . .75 + + + + \ + ^  ^ 4 + + 7 5+ + 4-^V5$ o 5 $ 5 ^  55 5 4-35' . f ' 4- -4-, v h in . I » ^ — - l -4-4 V V v V 4 v v v 7 - V 8 v v v ^ v v v v V v V ^ V v V V . Y . . -A A V , A A A ' x A A A V V '/A A V / A A  V / A A A A A a A A A A A A A A A A A A A A A A A A A A A A A A A A . A A A A A A A + H " 1 ' V »* V V V V V V . A A A A A A A A A A A A A A A A ' A A A A A A \ v\> S J j 7 + m s;i / A A 7 « -f AN| r?' ^ ^ + ^_ ? ^ " ' / ^ 4 +<XJ» IS ' c 5 r 5 c 5 > - » 5  5 5 5 5 5<5 5 5 $ -> s; 5 ^ ; $ i 5 $ s , Jt A A V ^ X A A A A . . . . ^ . A A ^ A ' " . : A A V A A A A 35 v _ v v v Vzy-•^rr— V ..• A , V v v v .:pr?A •••x A v v..,-: :v; ... I v v v A A j / ^ ^ y A A ^ \ A | v V/T,S ^+ J f , A A A . . , . v 5 A A •' v A A A ;. v , ; | A A ; ' V , , v M 5 5 S 5 R<>"^\*4 + + ; 5 5 s 5 A A A 5 5 5 5 J 5 A A A A V 5 5 5 S A $ A A A A A A A A A A A A A A A A A A A A A . A A A A I ' t i s ^ A A  v \ A A A ^ A A A A A A ' A A A A A A A A A • A A A ^55 A ^ H S A A A 5 5 5 5 5 5 5 $ * A A A A A A V 4 4 4 V 4 4 A A V V A V v A A A A A A rA A A A A A - A A A A / A A A r A A / A A A A A A A A A ' A A A A A A A : i \ ••  . .... l- w v _ 5 5 ; 5 5 ^ 5 4k 5 5 5 J 5 5 , 5 , 5 5 5 S 4 5 5 A A A i " . ^ . * ••. . • _ | _ _ | _ ^ — , j A / 2 ^ + + v v . ^^4 - + 4- 4- +• + A A A V * v \ + + + + + + + + + + A A / .... v + . + + + + + + + + + + + + + + + 4- + , 4- + 4-51 + + A A A A f V V 35 V V / 4 + + 4 - 4 -+ 4 4 4 V 4-V V V V V V V 4- 4- 4- 4-4 V A 5 SV 4 ^ c h / S h s 5 // 5 h s 5 5 ^  A A A V V V y\+ + ^ A A \ V V V V V V V N N . A ' V V V V - V V \ 4 V A A N V V V A A > V V S / V + 4-A A A ^ 3S '. V A V V A A 5 5 A 5 ' 5 ^  5 5 5 5 r 5 , 5 5 5 A V\ A A " A 5 \ +V A A A A A A A A A A A A A A A A V V V * to •% v v v v V V V V V V V 4-V v V V V v v • 4-A A A V 5 v "4 4-4-'5 J?l0 ,3o'w G e o l o g y i n o u t l y i n g a r e a s a f t e r ; M o n g e r ( 1 9 7 0 ) , R i c h a r d s ( I 9 7 I ) , L o w e s ( I 9 7 I ) , a n d P i g a g e ( I 9 7 3 ) "fervths SCALE 1 : 2 5 , 0 0 0 0 MILES tenths I K I L O M E T R E S Ba.se rna.p moiiified after Nft+iohal Topoqrflkphic Series Maps: Sheet 7 2 % - H a r r i s o n Loike Sheet 92"/6 'Hope Sheet JzVu -Mount Uro^uhact Sheet VlVu -5puz_wm 

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