ABSTRACT: Subsidence and tectonic controls on glacially influenced continental margins: examples from the Gulf of Alaska and the western Scotian Shelf and Slope.

CGRG Bibliography of Canadian Geomorphology
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Abstract

The glacial record on continental shelves and slopes at mid- to high latitudes is dominated by marine strata, 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 western portion of the Nova 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. The processes of deposition (including ice rafting, suspension rain-out, debris flows, and turbidity currents) are the same on both the Gulf of Alaska and the Scotian Shelf and Slope, yet the large-scale depositional architecture of glacially influenced marine deposits on both margins differs because sediment preservation is strongly influenced by the impact of tectonics on relative sea-level changes. Eustatic sea level was lower during major glaciations, enabling ice sheets to advance across the Scotian Shelf, whereas rapid ongoing subsidence in the forearc basin of the Gulf of Alaska restricted glacial advances to shallow, nearshore areas until the forearc basin filled with sediments to create a broad shelf. Both shelf and slope deposits are preserved in the Gulf of Alaska, which has developed by both progradation and aggradation, whereas slope deposits are selectively preserved on the Nova Scotia continental margin, which has developed by propagation.

Bibliography of Canadian Geomorphology