Abstract

Seven large submarine canyons cut the Beringian continental margin. Three of these are among the world's largest submarine canyons. Bering is 400 km long, Navarinsky and Zhemchug are each 100 km wide at the shelf break, and volumes of sediment removed from these three canyons range from 4,300 to 5,800 km3 an order of magnitude larger than any submarine canyons incised in the margin of the lower 48 states.

Two major events set the stage for the development of the Beringian margin and the dissection of these canyons: (1) the jump of the subduction zone to the Aleutian trench in Late Cretaceous-early Tertiary time that changed the margin from active to passive and (2) the low stands of sea level during the Cenozoic glacial stages. The position and configuration of these canyons have been determined, or strongly influenced, by structural features of the margin. Some of the Beringian canyon systems appear to occupy continental-margin embayments, perhaps residual structural configurations inherited from the time of subduction. The principal mechanisms responsible for cutting and shaping the canyons are extensive slumps and slides that carried large volumes of continental-margin sediment to the base of the slope. Second in importance are sediment gravity flows (debris flows, mud flows, and turbidity currents) that eroded and transported shelf and slope sediment to the rise and far into the Aleutian basin, contributing significantly to the 4- to 11-km-thick rise wedge and >2-km-thick sedimentary sequence of the basin floor.

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