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ABSTRACT: Ice Interaction with the Arctic Shelf and Coast: Constraints On and Implication for Petroleum Development

Peter W. Barnes, Erk Reimnitz

Along the Arctic coast of Alaska, sea ice affects structures placed on and under the seabed and influences the erosion and dispersal patterns of sedimentary particulates and pollutants. Most directly, ice gouges the sea floor to depths of a few meters, with return periods on the inner shelf of tens of years and, in places, annually, primarily during freezeup and breakup. These sea-floor ice-gouge patterns provide information on the motion and characteristics of the local ice canopy. The design and alignment of pipelines and coastal structures should consider that ice gouging extends to the coast and onto the beaches; however, ice gouging is less apparent on beaches owing to lower gouge intensities and vigorous wave reworking. In the long term, gouging contributes to high ates of coastal and shelf erosion. Protruding ice keels extending downward from the sea-ice canopy divert and focus currents causing increased sea-floor scour to depths of a few meters below the sea floor. Sea-ice freezing during the commonly turbulent fall storms causes large volumes of sediment and pollutants to be sorted, resuspended, and, ultimately, incorporated into the ice canopy. Most entrained material is re-released to the nearshore the following open-water season; however, some material may be transported offshore to become part of the Arctic pack. During freezeup and breakup (4-5 months/yr) when these processes are most active, trafficability in the Arctic nearshore is nil owing to the instability of the ice canopy, and so our comprehension of this processes is limited.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990