The Troitsa Lake Property is located at latitude 53º 32¹ north and longitude 127º 20¹ west in the Whitesail Lake Map area. Lower Jurassic andesitic flows, tuffs and breccias and intercalated argillite lenses of the Lower Volcanic Division of the Hazelton Group are intruded by a granodiorite stock. A younger sill-like rhyolite complex occurs to the northwest of the stock. A variety of northwesterly trending dykes, including feldspar porphyries of quartz latite composition, cut all other rocks. The stock is zoned from a coarse-grained quartz monzonite in the centre to a relatively fine-grained granodiorite at the margin.Calculated chemical compositions of the rocks show the stock has followed a calc-alkaline differentiation trend. The compositions of plagioclase, alkali feldspar and biotite systematically vary throughout the stock. The thermal effect of the stock is estimated to have produced hornblende hornfels facies conditions up to 400 feet from the contact. The stock was emplaced in the epizone at a probable depth of about four kilometres and was subject to a load pressure of a little over one kilobar. Compositions of coexisting feldspars allow only a crude estimate to be made of the crystallisation temperatures. This indicates a temperature of 720° to 770°C. Compositions of the biotites indicate the stock crystallised under conditions of constant or increasing f0₂ and the melt may have been water saturated. Biotite compositions and experimental data for the 'granite’ system indicate that the stock crystallised under a PH₂0 of about one kilobar and at temperatures ranging from 730° to 850° C. The PH₂0 must have approached, and perhaps equalled Pload. Potassium / Argon data yield an apparent age for the stock of 75.7 ± 2.3 million years. Several stocks in the Whitesail Lake Map area have closely similar ages. The feldspar porphyry dykes have been subject to hydrothermal alteration. In one major dyke this has a zonal distribution pattern; propylitic type alteration in the north passes southwards through quartz - sericite to biotite - ortho-clase types. Sulphide mineralisation, also showing a zonal pattern, is closely associated with the hydrothermal alteration. Weak propylitic alteration and fracture plane sulphide mineralisation affect the central part of the stock. The dykes appear to have acted as channelways for the hydrothermal ore-bearing solutions. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Driftwood Property is located in the southwest corner of the McConnell Creek map-area, about 87 miles north of Smithers, B. C. The property lies in a northwesterly trending belt of volcanic-sedimentary rocks that were mapped as Takla Group - Upper Division (Lord, 1948). The rocks are more correctly correlated with the Hazelton Group. They are bounded on the west and east by younger sedimentary formations. To the west is the Bowser Group and to the east, the Sustut Group. A Kastberg porphyry of Tertiary age has intruded the Takla Group rocks. Intrusion was into the epizonal environment and produced an irregular dyke-like body having a roof zone with anastamosing dykes and small roof pendants. The composition of the stock varies from granodiorite to quartz monzonite and alaskite. Differences in the stock are observed in textural, mineralogical, and chemical variations. Automorphism of the stock has resulted in propylitic alteration and contact metamorphism has resulted in an enveloping zone of hornfels. Temperatures at the intrusive contact as derived from heat flow calculations were probably a maximum of about 495 to 550°C and varied with respect to the type of rocks intruded.. A biotite hornfels of the albite-epidote hornfels facies has formed an aureole over 100 feet wide. A hornfels of the hornblende hornfels facies has been developed in narrow zones adjacent to parts of the intrusive contact. The porphyry is a metal-enriched intrusion in which some metallic grains formed in an accessory manner but most of the mineralization is epigenetic. The deposit has characteristics of both porphyry copper and quartz stockwork deposits with disseminated, fracture filling, vein, and replacement mineralization in the intrusive rock, hornfels, and skarn. The primary metallic minerals identified were: molybdenite, pyrite, pyrrhotite, chalcopyrite, arsenopyrite, sphalerite, galena, tetrahedrite, marcasite, aikinite, bournonite, and magnetite. Secondary or alteration minerals are rare and only minor goethite, maghemite, malachite, and ferrimolybdite were found. A five stage paragenesis is shown with at least three successive stages of veining. Sulphide deposition is believed to have started at temperatures in the order of 700°C and continued along with re-equilibriation of sulphides down to temperatures below 400°C and possibly 300°C for the sulphosalts. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The stratigraphy and structure of Upper Palaeozoic and Mesozoic sedimentary and volcanic rocks, and of amphibolitic rocks of unknown age, were studied in an area of about 140 square miles in the Cascade Mountains of southwestern British Columbia. The amphibolitic rocks are probably of diverse origins; their stratigraphic relationship to the other rocks is not known, although they may, in part, be equivalent to pre-Devonian rocks in northwestern Washington. Upper Palaeozoic rocks comprise the Chilliwack Group. The base is not exposed. Oldest rocks are volcanic arenites and argillites which are overlain by an argillaceous limestone, about 100 feet thick, in which Early Pennsylvanian (Morrowan) fusulinids occur. Apparently conformably overlying the limestone is a succession of argillites, coarse volcanic arenites, minor conglomerate and local tuff, which contains both marine and terrestrial fossils and ranges in thickness from 450 to 800 feet. A cherty limestone, generally about 300 feet thick, in which there is an Early Permian (Leonardian) fusulinid fauna, is conformable upon the clastic sequence. Altered lavas and tuffs are in part laterally equivalent to this Permian limestone, and, in part, overlie it; these volcanic rocks range in thickness from 700 to 2,000 feet. Disconformably above the Permian volcanic rocks are argillites and volcanic arenites of the Cultus Formation. This formation is apparently about 4,000 feet thick, contains Late Triassic, Early and Late Jurassic fossils and no stratigraphic breaks have been recognized within it. All of these rocks underwent two phases of deformation between Late Jurassic and Miocene time. The first phase, correlated with mid-Cretaceous deformation in northwestern Washington, was the most severe., and thrusts and major, northeast-trending recumbent folds were formed. These structures subsequently were folded and faulted along a northwest trend, possibly in response to differential uplift of the Cascade Mountains. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Near Terrace, British Columbia, the eastern margin of the Central Gneiss Complex (CGC) is a 3-4 km thick, gently northeast dipping, ductile-brittle shear zone with northeast movement of the upper plate. Along Shames River, deformed amphibolite-facies rocks to the west are juxtaposed against lower greenschist to amphibolite facies units to the east along the steep, east side down, brittle Shames River fault (SRF). Gentle to moderate northwest and northeast dips west of SRF contrast with steep southeast dips to the east. Lineations plunge gently northeast and southwest. West of SRF, the Shames River mylonite zone (SRMZ) separates granitoid rocks below from less deformed granitoid rocks, orthogneiss and metasedimentary rocks above. West of Exstew River, the moderately northeast dipping, ductile Exstew River fault, juxtaposes the SRMZ against metamorphic rocks and granitoids of the CGC. The SRMZ is cut by anastomosing brittle-ductile shear zones. Most kinematic indicators show northeast directed shear. Heterogeneous strain in SRMZ accommodates a minimum upper plate movement of 25 km to the east-northeast. Hornblende geobarometry indicates a structural omission of 13.4 km across SRMZ. East of SRF, amphibolite and greenschist facies supracrustal and plutonic rocks of Lower Permian and older Stikine Assemblage are thrust above greenschist facies volcanic strata correlated with Telkwa Formation of the Lower to Middle Jurassic Hazelton Group. Foliation in late synkinematic, 69 Ma granodiorite which intrudes this thrust package dips steeply southeast. Stikine Assemblage is comprised of lower greenstone, granitoid rocks, volcanic breccia and flows overlain by fusulinid-rich marble. A deformed intrusive rock in Stikine Assemblage has a minimum Pb-Pb date of 317 ± 3 Ma. Hazelton Group contains lower andesitic and upper dacitic to rhyolitic packages comprised of agglomerate, volcanic breccia, tuff, and plagioclase porphyry flows. The earliest recognised metamorphism and deformation in the SRMZ, at upper amphibolite grade, affects 188 ± 8 Ma orthogneiss, and occurred before intrusion of a garnet-biotite granite dated by Woodsworth et al. (1983) at 83.5 Ma. Early fabrics are overprinted by Campanian to Paleocene ductile deformation and a second metamorphism. The second deformation waned during intrusion of three granitic intrusions with concordant U-Pb zircon crystallization dates of 68.7 - 69 Ma. A late to post-kinematic granite dyke in the SRMZ has a U-Pb zircon crystallization date of 60 ± 6 Ma. The second phase of metamorphism began before, and outlasted ductile deformation. The SRF and other high angle normal faults cut 69 Ma granodiorite, but do not significantly offset Eocene (46.2-52.3 Ma) K-Ar biotite cooling isothermal surfaces. The 60 Ma granite is deformed by low angle semi-brittle faulting with upper plate movement to the northeast. A 48 ± 3 Ma synkinematic granite dyke in the footwall of SRMZ was intruded during this deformation, which ended before 46.2 - 46.5 ± 1.6 Ma, the K-Ar biotite cooling dates from SRMZ. The entire region is deformed by post-ductile open, upright, east-northeast plunging folds. K-Ar biotite dates for granitoid rocks range from 51.1 Ma in the upper plate to 46.2 Ma in SRMZ, indicating downward progression of cooling. North-northwest trending brittle faults and lamprophyre dykes cut the SRMZ, and are therefore younger than mid-Eocene. Thermobarometry of pelitic and granitoid rocks indicates increasing metamorphic grade with increasing structural depth. Al-j; in hornblende geobarometry indicates slightly lower pressure of crystallization for the interior than the margin of a granodiorite body east of SRF.In the upper plate of SRMZ, west of SRF, sillimanite-staurolite-garnet schist records ductile deformation and metamorphism at 3.8 ± 1.6 kbar and 570 ± 50°C. The schist is intruded by orthogneiss cut by 68.7 Ma granodiorite. The granodiorite crystallized at 3.4 ± 1 kbar, and was deformed at 2.2 ± 1 kbar at 68.7 Ma. In SRMZ, hornblende in pre-kinematic, 188 ± 8 Ma granodiorite crystallized at 5.5 ± 1 kbar. Deformation and synkinematic metamorphism occurred at 4.9 ± 1 kbar, between 83.5 and before 60 ± 6 Ma. East of SRF, greenschist conditions prevailed, except near the southern margin of the 69 Ma granodiorite body, where amphibolite facies was stable during ductile deformation. A metapelitic sample gives near-peak metamorphic conditions of 4.9 ± 1.6 kbar and 700 ± 50°C, and contact metamorphic conditions of 2.9 ± 1.6 kbar and 610 ± 50°C during intrusion of late synkinematic, 69 Ma granodiorite. P-T-time paths for the upper plate of SRMZ west of Shames River indicate initial rapid, near-isothermal decompression beginning before 69 Ma, continuing to 69 Ma, followed by rapid cooling to 0.9-1.1 kbar, at 51.1 Ma. Paleogene to middle Eocene deformation was probably extensional in nature. It occurred in a vigorous magmatic arc, in response to, and possibly coeval with, crustal thickening. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Upper Triassic and Jurassic rocks in the central Graham Island area comprise shale, siltstone, sandstone, and conglomerate of the Kunga, Maude, and Yakoun Groups. Volcanic rocks are common in the Middle Jurassic Yakoun Group. The oldest unit exposed within the study area is the Lower Jurassic Sandilands Formation of the Kunga Group, a more than 250 metre thick sequence of interbedded organic-rich shale, tuff, siltstone, and sandstone. The Lower Jurassic Maude Group conformably overlies the Kunga Group and is divisible into four formations. The Ghost Creek Formation is an organic-rich black fissile shale, and is overlain by calcareous sandstone of the Fannin Formation. The Whiteaves Formation consists of fissile calcareous grey shale that grades upwards into fossil-rich medium- to coarse-grained, sandstone of the Phantom Creek Formation. The base of the Middle Jurassic Yakoun Group is marked by an angular unconformity. The unit is more than 1500 metres thick and is divided into four lithofacies. The lowermost shale and tuff lithofacies is a sequence of interbedded shale, tuff, siltstone, and sandstone, with shale dominating. The sandstone lithofacies overlies and partly interfingers with the shale and tuff lithofacies and comprises medium- to thickly-bedded lithic arenite interlayered with thinly-bedded shale. The conglomerate lithofacies exists within the sandstone lithofacies and consists mostly of thickly-bedded pebble and cobble conglomerate. The volcanic lithofacies interfingers with, and overlies the sedimentary rocks of the Yakoun Group, and includes lava flows, pyroclastic rock deposits, and lahars. The Kunga and Maude Groups record several relative changes in sea level. They formed in a progressively deepening basin. In Pliensbachian time, the basin shallowed and deposition, represented by the upper Fannin Formation of the Maude Group, was near-shore. Toarcian time is marked by an abrupt transgression. The upper part of the Whiteaves Formation and the Phantom Creek Formation of the Maude Group indicate a subsequent regression. The sedimentary rocks of the Yakoun Group were deposited in local shallow marine basins. Volcanic rocks are most abundant in the eastern parts of the map area, and indicate that an igneous source is located in that direction. All rock units in the map area are deformed by major northwest-trending faults and folds, reflecting at least four northeast-southwest oriented deformational events. The angular unconformity at the base of the Yakoun Group restricts one compressional phase to mid-Jurassic time. Abundant southwest-verging folds suggest development of northeast-dipping thrust faults during this compressional event. Northeast-trending normal faults cut through the thrust faults, postdating them and indicating a period of extension. Rocks of the Sandilands Formation are observed thrust on top of the Yakoun Group, thus indicating a second compressional event. Several small-scale strike-slip faults cut through all described rock units and overlying Tertiary sections, suggesting a late Tertiary deformational event. The Middle Jurassic compressional event may be a result of collision of Wrangellia with North America, or could have been caused by changes in relative plate motion between the North American and Pacific plates during the break-up of Pangaea. Lithologic similarities between the Jurassic and older units of Wrangellia on the Queen Charlotte Islands and coeval rocks of the Alexander terrane in southeastern Alaska suggest that there are no clear differences between the two, and that they were contiguous since Upper Paleozoic time. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The lithostratigraphy and Pliensbachian ammonite fauna of a sequence of Pliensbachian to Bajocian sedimentary rocks, informally referred to here as the Spatsizi Group, from the Spatsizi map-area (104 H) in north-central British Columbia are examined in this thesis. Twenty Five species of ammonites representing fifteen genera from Pliensbachian rocks of the Spatsizi Group are described and their stratigraphic ranges in the thesis area determined. The Spatsizi fauna is comprised primarily of ammonites of Tethyan aspect and also contains elements endemic to the East Pacific faunal realm. The Spatsizi fauna is located on the northern half of the Stikine terrane of the western Cordilleran eugeocline, and is surrounded by biogeographically related faunas containing ammonites of Boreal affinity in addition to Tethyan and East Pacific forms, indicating that northern Stikinia occupied a position within the mixed Boreal/Tethyan zone of the eastern Pacific region during the Pliensbachian. Subsequent tectonic displacement of Stikinia transported it northward to its present position. The Spatsizi Group is informally defined and is divided into five informal formations; the Joan, Eaglenest Gladys, Groves, and Walker Formations. Each formation reflects deposition in a different sedimentary environment affected by varying degrees of volcanic (epiclastic or pyroclastic) input Rocks of the Spatsizi Group represent the basinward sedimentary equivalents to the coeval Toodoggone volcanics that formed along the southern flank of the Stikine Arch. Facies transitions from the Stikine Arch in the north to the sedimentary basin in the south are best developed in sediments deposited during Pliensbachian and Early Toarcian times, when epiclastic sands and conglomerates accumulating on the southern flank of the arch graded southward into silts and muds in the basin. Two phases of non-coaxial deformation folded and faulted the rocks in the thesis map area. Deformation was probably related to interaction between the Stikinia and the North American continental margin during accretion. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A well preserved, fossiliferous Middle Triassic to Early Cretaceous section lies on the west side of Harrison Lake in the southern Coast Mountains. The study of this area involves a re-evaluation of the stratigraphic nomenclature first described by Crickmay (1925, 1930a) together with a lithologic description of the units and age determinations based on collected, identified and described fossils by the writer. Discussions on the biostratigraphy, paleogeography, regional correlations and structure of the thesis area and an overview of the regional tectonics of southwestern British Columbia and northwestern Washington, help to better understand the relation of this Mesozoic section to other rock assemblages in this geologically complex region. The oldest unit, the Middle Triassic Camp Cove Formation, comprises conglomeratic sandstone, siltstone and minor volcanic rock. Unconformable7 overlying this unit is the Toarcian to Early(?) Bajocian Harrison Lake Formation, divided into four distinct members by the writer, Celia Cove Member (basal conglomerate), West Road Member (siltstone, shale), Weaver Lake Member (flows, pyroclastic rocks, minor sediments) and Echo Island Member (interbedded tuff, siltstone, sandstone). Thickness of this formation is estimated at 3000 m. A hiatus probably is present between this unit and overlying shale, siltstone and sandstone of the Early Callovian Mysterious Creek Formation which is 700 m thick. Conformably above this are 230 m of sandstone and volcaniclastic rock of the Early Oxfordian Billhook Creek Formation. Late Jurassic fluvial conglomerate, sandstone and siltstone of the Kent Formation, perhaps 1000 m thick south of Harrison River, unconformably(?) overlies the last two units mentioned. Berriasian to Valanginian conglomerate and sandstone, 218 m thick, of the Peninsula Formation overlies the Billhook Creek Formation with slight angular unconformity. The Peninsula Formation is conformably overlain by tuffaceous sandstone, volcanic conglomerate, crystal tuff and flows of the Valanginian to Middle Albian Brokenback Hill Formation which is several km thick. Nine Jurassic ammonite genera are identified and described in this report. Triassic radiolaria and conpdonts and Cretaceous ammonites and bivalves are also present in the section. The most significant structure in the thesis area is the post-Albian to pre-Late Eocene Harrison Fault which strikes north-northwest through Harrison Lake, separating the Mesozoic section along the west side from the northern extension of the Cascade Metamorphic Core on the east side of the lake. A strong sub-horizontal stretching lineation within the fault zone may indicate right-lateral strike-slip movement. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The level of organic maturation, thermal history, and source rock potential of Mesozoic and Tertiary strata in the Queen Charlotte Islands have been investigated with vitrinite reflectance measurements (%Ro rand)> numerical modelling (modified Arrhenius and Lopatin models), and Rock-Eval pyrolysis (source rock potential). The level of organic maturation increases from north to south and is primarily controlled by high heat flow associated with plutonism on Moresby Island. Upper Triassic-Lower Jurassic strata are overmature on Moresby Island with vitrinite reflectance values ranging from 2.40 to 5.80 %Ro rand Jurassic, Cretaceous, and Tertiary strata are immature to overmature on Graham Island with values ranging from 0.15 %Ro rand (Skonun Formation) to 2.43 % Ro rand (Haida Formation). Constant and variable geothermal gradient thermal regimes were numerically modelled with modified Arrhenius and Lopatin methods. Numerical modelling (assuming constant geothermal gradients) predicts high paleogeothermal gradients (45 to 90 °C/km) for up to 180 million years from the Late Triassic to the Tertiary. Variable paleogeothermal gradient modelling (utilizing a 30 °C/km background geothermal gradient) predicts peak geothermal gradients ranging up to 150 °C/km during Yakoun (183-178 Ma) and Masset (35-10 Ma) volcanism. The timing of hydrocarbon generation was estimated with numerical modelling. The levels of organic maturation for Mesozoic and Tertiary strata reflect the timing of plutonism and associated high heat flow. Triassic strata from west Graham Island and Cretaceous strata from north and south Graham Island entered the oil window during the Early Miocene and are still in the oil window. Jurassic strata in central Graham Island and north Moresby Island entered the oil window during the Bajocian and remain within the oil window. The Skonun Formation is generally immature except for strata at west Graham Island (Port Louis well) and at northeast Graham Island (basal strata in the Tow Hill well) which entered the oil window during the Late Miocene. Mean total organic carbon (TOC) contents are generally low (0.06 %) to moderately high (3.6 %) for Mesozoic and Tertiary strata. Some organic-rich horizons with TOC values up to 11.2 % occur in Upper Triassic (black limestone member of the Kunga Group) and Lower Jurassic (Sandilands and Ghost Creek Formations) source strata. Mesozoic and Tertiary strata generally contain gas prone Type III organic matter except for the Lower Jurassic Ghost Creek Formation and the Upper Triassic-Lower Jurassic Kunga Group which contain oil and gas prone Type II organic matter and significant amounts of oil prone Type I organic matter. Lateral variations in TOC and the quality of organic matter (QOM) for Triassic and Jurassic strata are primarily related to the level of organic maturation. The strata have poor to good hydrocarbon source potential on Graham Island. High heat flow associated with plutonism on Moresby Island has overmatured the strata resulting in poor source potential on Moresby Island. Hydrocarbon source potential for Cretaceous and Tertiary strata is primarily controlled by the level of organic maturation and depositional patterns. The Cretaceous Haida and Honna Formation generally contain terrestrially derived Type III organic matter with poor to fair gas source potential. The Skidegate Formation contains a mixture of Types II and III organic matter with decreased (terrestrial) Type III organic matter input and increased Type II (marine) organic matter input relative to the Haida Formation. Cretaceous strata from Moresby Island are generally overmature and have poor source potential whereas equivalent strata from Graham Island are immature to overmature and have fair to moderate gas source potential. Generally immature coal and lignite from the Tertiary Skonun Formation have poor to fair gas source potential. Resinite horizons containing hydrogen-rich organic matter have good oil and gas source potential where mature. Siltstone and shale facies of the Skonun Formation contain moderate amounts of Type II organic matter and have good hydrocarbon source potential. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Detailed structural and petrologic mapping near Azure Lake, British Columbia provides an overview of geologic relations along the northeast margin of the Shuswap Metamorphic Complex. Four phases of deformation have been recognized in the Shuswap Complex and the adjacent lower grade metasediments of the cover sequence. The first deformation consists of west-verging isoclinal folds plunging north and northwest. The second phase resulted in large upright folds with a shallow northwest or southeast plunge. The third and fourth phases are only locally developed as faults, fractures, and brittle folds trending north and northeast, respectively. Mineral assemblages range from garnet-biotite through first sillimanite zones of the Barrovian facies series. Metamorphic grade increases toward the southwest. Regional metamorphism is associated with the first phase of deformation. The Complex is separated from the adjacent cover sequence by a first phase tectonic slide. Structural and metamorphic discontinuities across this slide probably resulted from reactivation of the slide surface during the second phase of deformation. Microprobe analyses have been combined with linear regression techniques to outline probable sillimanite-forming reactions in pelites of the Complex. The regressions show that reaction textures are partly preserved because of the exhaustion of rutile as a reactant phase. Metamorphic conditions in the Complex are estimated from the mutual intersection of experimentally studied mineral equilibria. These conditions are: P=7600 ± 400 bars, T=705 ± 40°C, aH₂O =0.5 ⁺⁰•⁵­₀․₂ . Carbonate mineral assemblages initially buffered fluid phase compositions to high X CO₂ values near 0.75 during metamorphism. Therefore the fluid phase was not homogeneous in composition throughout all rock types during metamorphism. Whole rock Rb-Sr dates of 138 ± 12 Ma (all five samples) and 163 ± 7 Ma were obtained for granodiorite stocks in the Azure Lake area. Two biotite-whole rock ± hornblende dates of 119 ± 11 Ma and 77 ± 20 Ma indicate isotopic resetting. Initial Sr⁸⁷ -Sr⁸⁶ ratios vary from 0.7061 ± 0.0001 to 0.7103 ± 0.0002 for rock and mineral dates. These dated stocks cross-cut structural trends for the first two deformations and impose a hornfelsic contact aureole on regional metamorphic assemblages. Therefore regional metamorphism and deformation were completed by Late Jurassic time. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.