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TitleSurficial geology mapping of the Bistcho Lake area (NTS 84M), northwest Alberta
AuthorPaulen, R CORCID logo; Smith, I RORCID logo; Plouffe, AORCID logo; Kowalchuk, C; Ward, B C; Tarplee, M; Peterson, R; Fenton, M M; Pawlowicz, J G
SourceProgram and abstracts, CANQUA 2005; 2005 p. A68
Alt SeriesEarth Sciences Sector, Contribution Series 2004458
MeetingCANQUA 2005 Bi-Annual Meeting; Winnipeg, MB; CA; 2005
ProgramNorthern Resources Development Program
During the summer of 2004, the Alberta Geological Survey (AGS) and the Geological Survey of Canada (GSC) completed the surficial mapping of the Bistcho Lake map area (NTS 84M). This was the second year of a four-year collaborative, multi-disciplinary project created under the GSC's Northern Resource Development Program (NRD Project 4450) with additional support from the Federal-Provincial Targeted Geoscience Initiative (TGI-2).
The study area is situated in the very northwest corner of Alberta, and physiographically is characterized by the Cameron Hills Uplands in the north, and the Fort Nelson Lowlands along the southern margin. Uplands in the northern half of the study area are characterized by extensive peatlands, underlain by shallow discontinuous permafrost. Regions with active thermokarst are distinguished by polygonal patterned ground, irregular ground surfaces and a characteristic patterning of ponds. Permafrost in this region appears to be extremely susceptible to ground disturbance and melting. Lowlands in the southeast are characterized by flat topography and expansive fens developed over glacial Lake Hay sediment. Much of the study area is draped by a thick blanket of clay-rich, clast-poor till. In the northeast, this is overlain by stony carbonate-rich till. Several bedrock outcrops were discovered in the region where previous bedrock topography and drift thickness maps had suggested thick (<250 m) drift cover. Shales of the upper Fort St. John Group (Shaftesbury Formation, Lower to Upper Cretaceous) outcrop north of the hamlet of Zama City and form a bedrock high which divides the drainage between the Hay and Petitot rivers.
Field observations and interpretation of prominently fluted terrain visible on satellite imagery indicate that the Laurentide Ice Sheet initially flowed west and then southwest across the region. During deglaciation, thinning ice became increasingly topographically controlled, as indicated by a dense network of ribbed moraines on top and west of Bootis hill that record an ice lobe wrapping around the north side of Cameron Hills. A second ice lobe retreated east and northeastward down the Hay River valley. In the Fort Nelson Lowland to the south, retreating ice impounded the regional drainage, resulting in the formation of glacial Lake Hay. A thin veneer of glaciolacustrine sediments was deposited along the northern margin of the glacial lake. Iceberg scours and a thin deposit of diamicton (interpreted to be a till) overlying contorted glacial lake sediments indicate that ice readvanced briefly into the glacial lake basin during the latter stages of deglaciation.

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