Late Quaternary ice flow, stratigraphy, and history of the Babine Lake-Bulkley River region, central British Columbia, Canada.

摘要

Examinations of glacial and nonglacial sediments, and landforms in central British Columbia indicate a complex late Quaternary history. Successive erosional and depositional cycles exposed subsurface geological units, but also buried geomorphic landforms. Damming of outlets by ice and sediment controlled modern and past drainage patterns.; The reconstruction of the late Quaternary history of the Babine Lake-Bulkley River region was undertaken using genetic interpretations of unconsolidated sediments. These sediments include: Olympia Nonglacial Interval lacustrine deposits (Unit 1), ice expansion glaciofluvial, glaciolacustrine and waterlain deposits (Unit 2), Fraser Glaciation till (Unit 3), deglacial glaciofluvial (Unit 4) and glaciolacustrine (Unit 5) sediments, and postglacial colluvial and fluvial deposits (Unit 6). Glacial lake development and associated reversals in drainage during glacier expansion and retreat were dependent upon the position of ice margin/sediment dams and drainage outlets. Locally, mapping near the Fulton River identified geomorphic landforms and sediments used to reconstruct the glacial and deglacial history of an area near the centre of the Late Wisconsinan Cordilleran Ice Sheet.; Ice flow during the Fraser Glaciation in central British Columbia occurred in three distinct phases: (1) ice expansion, (2) maximum and (3) late-glacial phases. The ice expansion phase, a prolonged period of glacier growth in valleys and over plateaux, lasted late into the Fraser Glaciation. In the maximum phase, ice buildup over the interior culminated with the development of a Cordilleran ice divide east of the Coast Mountains. At this time, the ice sheet surface extended well above 2500 m asl, and glaciers flowed westward over the Hazelton, Skeena, and Coast mountains to beyond the Pacific coast, and east northeastward across the Rocky Mountains into Alberta. Widespread reversal in flow documented here resulted from fluctuations in centres of accumulation and ice sheet thickness, in response to climate change, rapid calving, ice streaming, and drainage of ponded meltwater. Upslope flow westward through the Hazelton and Coast mountains continued until the end of the late-glacial phase.; Knowledge of the late Quaternary history was utilized in applied geological studies. These studies included the failure potential of glaciolacustrine sediments in the Bulkley River region, and modeling of glacial dispersal at the Bell Mine.