CGRG Bibliography of Canadian Geomorphology
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Author : Campbell, J.E.; Ashton, K.E.; and Knox, B.
Date : 2006.
Title : -Quaternary investigations West of Fond-du-Lac, northeast Lake Athabasca (part of NTS 74O-5 and -6).
Publication : Summary of Investigations 2006, Volume 2, Saskatchewan Geological Survey, Saskatchewan Industry Resources, Miscellaneous Report
Issue : 2006-4.2.
Page(s) : 19 p.
Abstract
Quaternary geological investigations including 1:50 000-scale mapping of surficial materials and ice-flow indicators, and regional till sampling surveys, were undertaken in the Fond-du-Lac area, northeast Lake Athabasca (part of NTS map sheets 74O-5 and -6), as part of the multidisciplinary, multi-year Fond-du-Lac Project. Multiple ice-flow directions indicate complex spatial and temporal variations in ice flow. Four main phases of flow were identified. Indicators related to intermediate stages of ice-flow shifts and local variations due to topographic controls are common. The oldest flow was to the west (Phase I), followed by a shift to the southeast and then southsouthwest (Phase II). By the onset of deglaciation, ice flow had swung to the southwest (Phase III), the main iceflow direction. During the last stages of deglaciation, ice again flowed to the west (Phase IV). Rare, faintly preserved striae sets trending northwest-southeast were also recorded; however, the direction of flow is unknown. On a regional scale, the “Athabasca Low” played a significant role in channelling early- and late-stage ice flows. Drift cover in the area west of Fond-du-Lac is very sparse. The terrain is rugged, dominated by exposed bedrock outcrop ridges with thin (less than 1 m), discontinuous drift cover on the lower slopes and in low-lying areas. Following the retreat of the ice, Glacial Lake Athabasca inundated the region to as high as 365 m above sea level. The dominant surficial deposits are lake sediments (silt, sand, and clay) and till. Boulder lags, winnowed till, sand and cobble beaches, terraces, and wave-cut notches all indicate reworking of surficial deposits by the waters of Glacial Lake Athabasca. Minor sand and gravel are associated with meltwater channels of both subglacial and proglacial drainage systems and ice-contact deposits. Sandy glaciolacustrine deposits were derived from wavereworked glacial sediments. Sandstone pebbles, cobbles, and/or boulders were found in till, on beaches, and as perched boulders on outcrops north of Lake Athabasca. If these erratics are from the Athabasca Group, then the Athabasca Basin originally extended north of its present limit and outliers were likely present prior to the last glacial advance. A large part of the study area is not suitable for drift prospecting as bedrock, lake sediments, and wave-reworked deposits dominate the terrain.
Bibliography of Canadian Geomorphology