The Crawford Bay map-area is fifty square miles on the east side of Kootenay Lake, southeastern British Columbia, and is part of a regional structural belt, the Kootenay Arc, (Hedley, 1955). It is underlain by strongly deformed and metamorphosed strata of Late Proterozoic to possible Middle Paleozoic age. Sill-like bodies and boudins of metamorphosed amphibolite, and subordinate post-kinematic granitic intrusions and basic dykes of probable Mesozoic age are present in the west part of the map-area. Lithologic succession was determined by use of primary structures in the east part of the map-area and by lithologic correlation in the more highly metamorphosed western part. Horsethief Creek Group, Lower Hamill Group, Upper Hamill Group, Mohican and Badshot Formations, and Lardeau Group comprise an apparent conformable succession. Rock-unit nomenclature is the same as used for similar strata in the Kootenay Arc of the Lardeau and Salmo areas. However, fault-bound Upper Hamill is composed of strata which do not have defined lithologic equivalents outside the map-area and more detailed study of this part of the succession is suggested. The sequence is unfossilifereous and and age of the strata is based on correlation of Badshot Formation with Badshot outside the map-area that has yielded Archeocyathids of late Lower Cambrian age. Three phases of deformation, of variable intensity, are recognized within the map-area. Phase one folds are the earliest tectonic event and delineate the main structural trend. Three major folds, outlined by stratigraphic mapping, the Plaid Lake syncline, the Washout Creek syncline, and the Crawford Bay synform, are believed to be phase one structures. Early phase folds are isoclinal "similar" with axial planes parallel to gross lithologic layering. Fold axes and related penetrative mineral lineation plunge up to 20° northward except where locally deformed by subsequent structures. Only small scale phase two folds are recognized. These are asymmetric "similar" folds with southeast trending axial planes which dip moderately to the southwest, and westward plunging fold axes. Major faults may have formed during either phase of deformation. Kinks and related quartz veins formed during phase three deformation. Folding of bedding by phase three kinks is considered to be flexural-slip. Regional metamorphism is synkinematic with phase one and two deformation. Culmination of metamorphism appears to be post-faulting and post-phase two deformation. Phase three deformation is post-metamorphic. Chlorite, biotite, garnet, diopside, and sillimanite zones delineate an increasing metamorphic gradient from east to west. Distribution coefficients, KD= Mg/Fe garnet / Mg/Fe biotite, of Mg and Fe in coexisting garnet and biotite pairs in Mohican Formation, are larger with increasing metamorphic grade from the east limb to the west limb of the Crawford Bay synform. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Guichon Creek batholith is exposed within an elongate area of 400 square miles. Sedimentary rocks of Cache Creek group (Permian) and Nicola group (Karnian of Upper Triassic) are intruded by the batholith. In the few places where outer intrusive contacts are exposed, the older rocks have been metamorphosed to albite-epidote and hornblende hornfels and to epidote-chlorite skarn. Middle and Upper Jurassic sediments, Lower Cretaceous and Tertiary volcanic rocks and sediments unconformably overlie intrusive rocks. Pleistocene glacial and interglacial deposits mantle the batholith leaving less than 3% of the surface of the batholith exposed. The Guichon Creek batholith is a composite, upper mesozonal to epizonal, intrusive pluton consisting of seven major, nearly concentric phases. In shape it is an elongate, semi-concordant dome. The magma was emplaced as a crystal mush in a series of pulses and crystallized during a short period of geologic time. It is suggested that erosion of overlying sedimentary and volcanic rocks, as indicated by absence of Lower Jurassic strata, accompanied emplacement and crystallization of successive phases of the batholith. This may explain the association of mesozonal features of older phases at the batholith margin with epizonal features of younger inner phases. The batholith was emplaced by a combination of sidewall and roof stoping, forceful intrusion and assimilation of older rock. There is, therefore, a variety of contacts between phases including sharp intrusive contacts, intrusive contacts of dyke-like bodies and brecciated contacts. Contacts between two phases, although generally intrusive, may be gradational in some parts of the batholith. Contacts between varieties of a phase are gradational and were not observed in intrusive contact. Effects of assimilation are evident in outer contaminated margins of Hybrid and Highland Valley phases. Textures of these rocks are extremely varied and the rocks range in composition from diorite to quartz monzonite. Inner uncontaminated phases have orderly compositional and textural variations. The outermost uncontaminated rock is granodiorite and is thought to represent closely the composition of the original magma. Compositional differences within the inner phases are the result of differentiation within the magma chamber. The most effective process of differentiation was upward and outward movement of alkalis and silica accompanying diffusion of volatiles to regions of lower temperature and pressure. The differential material collected in cupolas and along the walls of the magma chamber. Pressure buildup at the roof of the magma chamber may have exceeded the confining pressure and resulted in fracturing which allowed emplacement of magma into older crystalline phases and into surrounding country rock. The number of phases may have been largely determined by rate of diffusion of volatiles. Emplacement of differential magma from the margin of the chamber into cooler wall rock produced dyke-like bodies of various textures and compositions. Undifferentiated magma remaining in the magma chamber crystallized more slowly and produced rock of more uniform texture and composition. Twenty-six potassium-argon age determinations for the various phases of the batholith are centered around 198 ± 8 my. It is not possible to differentiate among phases on the basis of potassium-argon apparent ages because variations are within analytical limits of uncertainty of techniques used. No interval of time can be given for period of emplacement. All phases began retaining argon at approximately the same time 198 ± my. ago. The batholith has undergone no significant metamorphism since that time. On the basis of isotopic and geologic considerations, it is probable that the Guichon Creek batholith was emplaced approximately 200 my. ago, after Karnian stage of Upper Triassic but prior to Middle Jurassic. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Coquihalla Serpentine Belt extends north-northwest forty miles from a point southeast of Hope, British Columbia to just south of Boston Bar. Sections of the northern part of this belt and the surrounding rocks from Spuzzum to Boston Bar were mapped. The serpentine belt here consists of partially serpentinized harzburgite with generally more intense serpentinization toward the margins. North of a point east of Spuzzum the belt is found entirely within the probable Permian Hozameen Group of spilitic lava and tuff, chert, and argillite. South of the point where mapped, the serpentine is found between the Hozameen and Jurassic to Lower Cretaceous Ladner Group of predominantly slate with some graywacke. Several sills and a small stock of granitic rock were found in the mapped areas. Field evidence and laboratory data favor intrusion of the material in the serpentine belt into a pre-existing fault either by plastic deformation of solid harzburgite or by squeezing up in the fault. Serpentinization occurred probably during intrusion and most likely involved a volume for volume reaction whereby water from outside was added to the harzburgite and silica and magnesia were carried away. The volcanic and sedimentary rocks of the area show the effects of low grade regional metamorphism. Minerals formed include albite, epidote, calcite, stilpnomelane and tremolite-actinolite. Much of the albite in the spilitic rocks is believed to have formed from a more calcium-rich feldspar whereby the sodium was derived from water and/or included sediments during or after extrusion. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

An 800 foot-square outcrop of a gneiss-breccia body at Pasco creek, 3 miles north along the highway from Horseshoe Bay, B.C. was mapped, and its relationship to the gneiss country rock studied. A survey of the literature of breccias included in the present thesis was used as a basis, together with the field data, for a method of breccia formation proposed as a result of this work. The body was found to be pipe-like in shape, following directions of structural weakness in the rock. The size of breccia fragments and varying amounts of matrix, as well as the border phase dioritic rocks were thought to have resulted from several processes active in the formation of the breccia. Among these explosive action of gases ahead of an intrusive body, together with fluidization of a mixture of these gases and shattered country rock are thought to be of prime importance in the formation of the breccia. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

An area of some 400 square miles between Hope, B.C. and the 49th parallel, covering part of the northern Cascades and southern Coast Mountains, was investigated with the purpose of determining the origin and history of the plutonic rocks. Five separate plutonic complexes, which range in age from Late Cretaceous to Miocene, underlie the area. The oldest complex investigated, the Late Cretaceous Spuzzum Intrusions (103-79 M.Y.) emplaced in the catazone-Mesozone, consists of two phases: diorite and tonalite. The older of the two, the diorite, is a zoned intrusion which occupies the central part of the batholith. Sheared sills and stocks belonging to the early Tertiary Yale Intrusions (59-35 M.Y.) comprise the second oldest complex. These bodies crop out in a narrow belt that separates high grade metamorphic rocks of the Custer-Skagit Gneiss from the low grade metamorphic rocks of the Hozameen Group. The Early Oligocene Silver Creek Stock (35 M.Y.) represents the oldest of three epizonal complexes. The epizonal Chilliwack Batholith (29-26 M.Y.) is composed of seven intrusive phases which range in composition from hypersthene-augite diorite to aplitic alaskite. Each of the phases of this batholith appears to have been emplaced in a pulse from an underlying, differentiating magma that was rising through the crust. The youngest complex, the Mount Barr Batholith (21-16 M.Y.) is composed of four intrusive phases, each of which appears also to nave been emplaced in a pulse from an underlying magma. One of the phases of this batholith is in the form of a 3000-foot-thick sill-like body. These three epizonal plutons appear to be related to the north-trending Cascade volcanic-plutonic province, which overlaps the northwest-trending Coast Crystalline Complex, here represented by the Spuzzum and Yale Intrusions. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The metamorphic rocks of the Breakenridge and Cairn Needle Formations are correlated with the Upper Paleozoic and Mesozoic (Jurassic) strata respectively. Those of the Chilliwack Group - Peninsula Formation range in age from Upper Paleozoic to Lower Cretaceous. A gneissic granodiorite on Mount Breakenridge is cored by a younger (Early Tertiary) porphyritic quartz diorite. The Scuzzy granodiorite (Upper Cretaceous) is the main plutonic rock of the area. Between the Jurassic and Mid-Cretaceous the formations were folded into northwest trending antiforms and synforms. Three phases of folding are recognised. Major faults were produced in Mid-Cretaceous time. Contemporaneous with the folding the rocks were migmatized and regionally metamorphosed to form a kyanite-sillimanite facies series in which the metamorphic grade increases rapidly from South to North. The mineral assemblages in pelitic gneisses are considered to have approached equilibrium. The bulk composition of these gneisses may not only have controlled the presence of staurolite but also, through the opaque minerals present, the fs₂,fo₂ of the coexisting fluid phase. Extreme gradients in fluid phase composition (X CO₂) are demonstrated to have existed during the metamorphism of closely associated calc - silicate and dolomitic limestone. An episode of contact metatnorphism, which produced andalusite and sillimanite bearing schists was associated with the emplacement of the Scuzzy fluton. (U. Cretaceous). / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Thompson Valley between Spences Bridge and Lytton, where it joins the Fraser, merits attention because of the abundance of clear sections of late glacial and postglacial deposits in road and rail cuts, and its position as an important transition zone between the glacial lake deposition of the southern Interior and the dominantly fluvial aggradation of the Fraser. Most attention was paid to the stratigraphy of road and rail cuts, as the only morphological features preserved in the steep and narrow valley are terraces, fans, landslides and talus slopes. Quaternary deposits yield little evidence of the depositional environment prior to the last major advance of ice, but there is a good record of conditions during and following deglaciation. The last ice sheet, which wasted away by down-melting, left a thin mantle of till over the uplands and till deposits up to 50 ft. thick in the valley. The Lower Thompson Valley, close to the glacier sources of the Coast Mountains, was one of the last areas to be free of ice. Consequently major lakes developed in the Thompson and Nicola Valleys and were forced to drain into the Okanagan Valley. When the ice plug south of Spences Bridge failed, some time before 9,000 B.P., drainage was resumed down the Thompson Valley to the Fraser. During deglaciation, up to 300 ft, of silts and deltaic gravels were deposited in the l,230 ft. stage of Lake Deadman, which was dammed by ice south of Spences Bridge. Between Skoonka Creek and Seddall, respectively 4 and 7 miles south of Spences Bridge, are deposits of collapsed silt and flow till and it is suggested that an ice plug remained here separating lacustrine deposition north of Skoonka Creeks from fluvial aggradation south of Seddall, where the valley was by then largely ice-free. Aggradation, which was due to the large supply of material from lateral sources resulting from recent glaciation and weathering, was extremely rapid; more than 500 ft. of cross-bedded and horizontal gravel and sand were deposited in probably little more than 1,000 years. Aggradation ceased well before 7,530 B.P. With amelioration of the climate and stabilization of the slopes, the load of the river was considerably reduced and it degraded its former valley fill creating a series of terraces, with a veneer of imbricate cobbles, from 500 ft. down to 30 ft. above present river level. Most terraces are non-cyclic, but paired terraces, approximately l4O ft. above the river, mark a period of relative stability prior to 7,530 B.P. The river was probably within 50 ft. of its present level by 6,600 B.P., and since then downcutting appears to have proceeded relatively slowly. At least three phases of alluvial fan formation occurred during this period of dominant degradation, the terraces acting as temporary base levels for the mudflows. Mazama ash, deposited on the terraces and fans approximately 6,600 years ago, provides a useful marker horizon. Apart from slow down-cutting by the river and some alluvial fan formation, the dominant processes affecting the topography since 6,600 B.P have been landsliding and slumping. The largest slide, the Drynoch Earthflow, has been active for at least 3,175 years and slumping due to seepage and river erosion has occurred intermittently along the river banks. / Arts, Faculty of / Geography, Department of / Graduate

Alluvial fan construction within British Columbia was dependant upon temporary conditions resulting from deglaciation; there is no significant fan aggradation at present. Five study areas were selected from the semi-arid sections of the Fraser, Thompson, Bonaparte, South Thompson and Similkameen valleys. The Tertiary and Quaternary geo-morphic histories of these areas are similar in many respects--most significantly, one or more phases of Pleistocene glaciation were followed by fluvial and lacustrine aggradation--but vary regarding the amount of subsequent downcutting by major rivers. This ranges from several hundred feet in the Fraser and Thompson valleys to a few feet or none in the Similkameen and Bonaparte valleys. Stratigraphic evidence from the Fraser Valley indicates that fan building commenced soon after the valley floor became ice-free, probably whilst glacial conditions persisted in tributary basins. It continued during aggradation by major rivers and for sometime afterwards. In the Thompson and South Thompson valleys fans were most recently built upon degradational river terraces. The occurrence of Mazama volcanic ash within fans indicates that construction continued until after 6,600 years B.P. Fans were built during a phase of landscape readjustment from predominantly glacial to predominantly fluvial conditions. They resulted from the secondary deposition of glacial drift and locally weathered material by streams and mudflows. Fan composition was dependant upon the nature of the available material and upon the character of the parent basin. For example, the widespread occurrence of glacio-lacustrine silt in the Thompson Valley gave rise to fans composed of silty mudflow gravels. Generally, small, steep basins produced mudflows whereas larger basins had more constantly flowing streams which deposited fluvial gravels. Fan aggradation declined as the drift supply was exhausted; deposition of material derived by current weathering was insufficient to maintain the growth of the fans. After deposition ceased many fans were dissected as a result of local base-level lowering controlled by degradation of major rivers and/or fan-head trenching initiated as the debris supply declined. Fan-head trenching is best developed in the South Thompson Valley; base-level dissection predominates in the Fraser and Thompson Valleys. Where fan building persisted during degradation, multilevel fans were constructed. Statistical correlations among morphometric parameters describing fans and related basins indicate that basin characteristics exerted an influence upon fan geometry through the nature of the fan building stream. There relationships vary regionally, possibly reflecting lithologic, climatic and geomorphic contrasts. British Columbia fans are steeper and display a greater variation of morphometric relationships than fans of the arid American Southwest. Fans resulting from deglaciation are distinguished by use of the prefix "para-glacial". / Arts, Faculty of / Geography, Department of / Graduate

The Eagle Bay Formation in the Adams Plateau-Clearwater area, 35km northeast of Kamloops, hosts several economic and sub-economic mineralized occurrences. The age and genesis of these mineral deposits can be estimated by using a specific growth curve which depicts the lead evolution for the Eagle Bay Formation. This curve, named the remodeled curve, represents a local deviation from the average 'shale' curve of Godwin and Sinclair (1982) for the autochthonous part of the Canadian Cordillera. This remodeled curve is specifically applicable to the Adams Plateau-Clearwater area. The lead isotope data from the deposits of the Eagle Bay Formation plot in three distinct clusters along the curve indicating that the lead isotopic signature of the Eagle Bay Formation is upper crustal, and that three periods of mineralization can be recognized or 'fingerprinted'. Accordingly, mineralization cogenetic with Devonian volcanism, and veins related to Cretaceous magmatism can be distinguished by location of galena-lead isotope values within clusters 1 or 3 respectively. Cluster 2 reflects a Late Triassic pulse of mineralization and includes epigenetic veins and stratiform deposits. These deposits are either replacement or cogenetic with their host. The Triassic model age for mineralization that is apparently stratiform and cogenetic raises questions about the currently assigned Cambrian age of associated host rock. To accommodate the lead isotope data a new Upper Triassic unit (T-EBG) within the Eagle Bay Formation is defined. The distinctive lead isotopic signature between deposits hosted by the Eagle Bay Formation is valuable as a guide for future mineral exploration programs in the Adams Plateau-Clearwater area. Recognition of lead isotopic fields that fingerprint types of mineral deposits, provides a useful and practical framework for the classification and evaluation of new mineralized prospects in the area. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A stratigraphic framework for altered volcanic rocks assigned to the Late Jurassic - Early Cretaceous Gambier Group (Heah et al., 1986) is proposed that correlates units from the abandoned Britannia Mine with strata along the eastern section of Britannia Ridge and the Furry Creek valley. Geological mapping defines three packages, interpreted as volcanic sequences, that represent a continuous succession of mainly mafic to felsic volcanics. From north to south, packages 1, 2 and 3 dip moderately and face consistently southwest. Package 1 is characterized by a mafic flow sequence intruded by rhyolite domes. Package 2 is dominated-by a felsic dome complex and a sedimentary basin, both blanketed by a thick pyroclastic flow unit. Package 3 is characterized by felsic lavas and ash flow tuffs gradational upwards to a thick argillite unit. Developed orebodies occur at two major horizons that are close to the lower and upper contacts of package 2. Sulphides associated with chert horizons occur within altered sheared equivalents of crystal lithic tuff and felsic breccia related to felsic dome complexes. Whole rock analyses define an altered calc-alkaline volcanic suite. Alteration, attributed to hydrothermal solutions accompanying massive sulphides, is most intense in packages 1 and 2 where rocks are MgO-rich, CaO-poor and enriched or depleted in alkalis compared to normal subalkaline rocks. Rocks in package 3 and from later crosscutting dykes are relatively unaltered. Rb-Sr values tentatively define a Jurassic to Early Cretaceous age of 167 ± 37 Ma for the altered volcanic suite. K-Ar dates of 90.5 ± 3.2 Ma and 81.4 ± 3 Ma are interpreted as reset by Coast Plutonic Intrusions surrounding the volcanic pendant and a later deformational or undocumented intrusive event. Massive sulphides associated with felsic volcanic rocks on Britannia Ridge are similar to volcanogenic massive sulphide deposits described in the Canadian Archean greenstone belts and the Miocene Kuroko deposits of Japan. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Accompanied by two oversized thesis maps / Graduate