CGRG Bibliography of Canadian Geomorphology
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Author : Gipp, M.R.
Date : 2001.
Title : Development of glacially influenced continental margins in active and passive tectonic settings.
Publication : St. John's 2001. Geological Association of Canada - Mineralogical Association of Canada 2001 Joint Annual Meeting / l'Association géologique du Canada - l'Association minéralogique du Canada réunion annuelle conjointe. Memorial University, St. John's, Newfoundland, May 27-30 2001.
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Abstract
The Pre-Pleistocene glacial record is dominated by glacially influenced marine strata that have accumulated on continental shelves and slopes, but little is known regarding the large-scale architecture of such deposits. Models showing the gross architecture and facies successions of Late Cenozoic deposits in the Gulf of Alaska and on the Scotian Shelf and Slope of southeastern Canada have been developed to guide the interpretation of ancient glacially influenced marine sequences and to illustrate the influences of their tectonic setting. Both of these margins were characterized during the Pleistocene by warm-based ice with similar discharge rates, and the recent (<150 kyr) glacial history of both margins is similar. Typical deposits include poorly-sorted rain-out diamictites, debris flows and turbidites, marked with ice rafted debris. Larger scale features, such as olistoliths and submarine canyons, are also observed on both margins, but the large-scale depositional architecture of glacial marine deposits differs because sediment preservation is strongly influenced by the impact of tectonics on relative sea-level changes and water depths. Eustatic sea level was lowered during major glaciations, enabling ice sheets to advance across the Scotian Shelf, whereas rapid subsidence in the Gulf of Alaska restricted glacial advances to shallow, nearshore areas. Slope deposits are therefore selectively preserved on the Scotian margin, whereas both shelf and slope deposits are preserved in the Gulf of Alaska, with shelf deposits increasing in importance upsection. An example of an ancient analogue for the modern-day Scotian margin is the nearby Gaskiers Formation, which is dominated by slope sediments and shows glacial influence through the presence of dropstones and diamictites.
Bibliography of Canadian Geomorphology