Evolution of the Canadian Cordillera; a plate-tectonic model

“…The bedrock within the Trench ranges from Oligocène and Miocene elastics in the south (Clague, 1974;Hopkins et al, 1972) to Cretaceous low-grade metamorphics and Pliocene conglomerates in the north (Bobrowsky, 1989a;Rutter and Taylor, 1968). Detailed bedrock data for the Rocky Mountains can be found in Allan (1914), Bauerman (1884), Beach and Spivak (1943), Daly (1912), Dawson (1877Dawson ( , 1881bDawson ( , 1890b, Dolmage and Campbell (1963), Gabrielse and Yorath (1989 and references therein), Hedley and Holland (1941), Henderson (1954), Hughes (1967), Irish (1965Irish ( ,1970, McLearn and Kindle (1950), Monger et al (1972), Mountjoy (1958), Rice (1941) and Selwyn (1877).…”

Section: Photo Aérienne Oblique De La Chaîne Continentale (Photo Bc89mentioning

confidence: 99%

The Quaternary Geologic History of the Canadian Rocky Mountains

Bobrowsky¹,

Rutter²

2007

gpq

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The Canadian Rocky Mountains figured prominently during the glacial history of western Canada. First as a western limit or boundary to the Laurentide Ice Sheet, second as an eastern margin of the Cordilleran Ice Sheet, and finally as a centre of local Montane ice. Throughout the Quaternary, complex interactions of glacier ice from these three ice sources markedly changed the physical form of the Rocky Mountains, Trench and Foothills areas. Investigations into the Quaternary history of this region have been ongoing since the beginning of the last century. Since about 1950, the number of studies performed in this area have increased significantly. This paper briefly reviews the historical accomplishments of Quaternary work in the region up to the period of about 1950. From this time to the present, individual study efforts are examined in detail according to the three geographic regions: 1) the northern Rocky Mountains (from the Liard Plateau south to the McGregor Plateau), 2) the central Rocky Mountains (from the McGregor Plateau south to the Porcupine Hills) and 3) the southern Rocky Mountains (from the Porcupine Hills south to the international border). In the northern region, geologic data suggest a maximum of two Rocky Mountain glaciations and only one Laurentide glaciation and no ice coalescence. In the central region, three of four Rocky Mountain events, and at least two Laurentide events are known. Only in the central region is there good evidence for ice coalescence, but the timing of this event is not clearly established. In the south, at least three Rocky Mountain episodes and a variable number of Laurentide episodes are recognized. There is no evidence for ice coalescence. A number of facts support the proposal that Cordilleran ice crossed the Continental Divide and joined with local Montane ice at several locations. However, this expansion of western ice occurred before the Late Wisconsinan in all areas but Jasper. In general, the chronological data presented suggest that the Late Wisconsinan glaciation in the Rocky Mountains was a short-lived event which started around or after 20 ka years ago and ended before 12 ka ago.

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“…The rocks underlying the alkaline province belong to the Middle Proterozoic Purcell Supergroup and comprise primary clastic and carbonate rocks >20 km thick deposited between 1700 and 780 Ma (Monger et al, 1972;Sears and Price, 1978;Monger and Price, 1979). Late Proterozoic (780-570 Ma) strata comprising gritty feldspathic sandstones, locally also volcanic rocks, and carbonate rocks lie unconformably over the Purcell Supergroup.…”

Section: Geological Settingmentioning

confidence: 99%

The Nature and Origin of the REE Mineralization in the Wicheeda Carbonatite, British Columbia, Canada

et al. 2016

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In response to rising demand of the rare earth elements (REE), recent exploration of the British Columbia alkaline province has identified the Wicheeda Carbonatite, which contains an estimated 11.3 million tons of light REE-enriched ore grading 1.95 wt.% TREO, to be the highest-grade prospect known in British Columbia. However, research of the deposit is restricted to one paper describing mineralization in carbonatite dikes adjacent to the main plug. This study describes the nature and origin of REEmineralization in the Wicheeda plug.The carbonatite was emplaced in metasedimentary limestone and argillaceous limestone belonging to the Kechika Group, which has been altered to potassic fenite immediately adjacent to the carbonatite and to sodic fenite at greater distances from it. The carbonatite comprises a ferroan dolomite core, which passes outwards gradationally into calcite carbonatite. Three texturally distinct varieties of dolomite have been recognized. Un modèle est proposé dans lequel la carbonatite calcitique est la phase magmatique la plus précoce. Cette phase a atteint la saturation en niobium très tôt, entrainant la précipitation du pyrochlore. Le magma a évolué plus tardivement vers une composition de carbonatite dolomitique qui, lors de son refroidissement, a exsolvé un fluide aquocarbonique altérant les métasédiments de Kechika en fénite potassique et se mélangeant avec les eaux formationelles, plus distales, pour produire les fénites sodiques.Le fluide aquo-carbonique a mobilisé et transporté les ETR sous la forme de complexes chlorurés, au sein de la porosité et des fractures de la carbonatite dolomitique. A la suite des interactions fluide-roche prolongées, les ETR ont précipité du fait du refroidissement et de l'augmentation du pH ; la présence d'apatite a entrainé la formation de monazite-(Ce). La concentration hydrothermale a permis une répartition homogène des teneurs, avec la carbonatite dolomitique contenant dans son ensemble plus de 1 % TREO, faisant de Wicheeda un gisement très attrayant. Contributions of AuthorsThis thesis has been written in manuscript format in accordance with the regulations put

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Evolution of the Canadian Cordillera; a plate-tectonic model

Cited by 181 publications

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A unified model for gold mineralisation in accretionary orogens and implications for regional-scale exploration targeting methods

A unified model for gold mineralisation in accretionary orogens and implications for regional-scale exploration targeting methods

The Quaternary Geologic History of the Canadian Rocky Mountains

The Nature and Origin of the REE Mineralization in the Wicheeda Carbonatite, British Columbia, Canada

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