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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 943

Last Page: 943

Title: Factors Influencing Sediment Transport at Shelf Break: ABSTRACT

Author(s): H. A. Karl, P. R. Carlson, D. A. Cacchione

Article Type: Meeting abstract


Recent investigations of sediment dynamics at the shelf break suggest that the factors which control the transport of sediment there can be grouped into two major categories: oceanographic and geologic. Oceanographic factors include tides, surface waves, internal waves, fronts, and meteorlogically driven currents that create a wide range of unsteady and quasi-steady water motions whose influences on sediment dispersal is poorly understood. These phenomena affect sediment along the shelf break in zones that have a large spatial and temporal variability. Geologic factors include shelf geometry and physiography, tectonism, and sediment type and supply. These factors influence shelf-break processes either by modifying oceanographic processes or by controlling the geologic set ing of the shelf break. An example of the former is that the physical structure of the bottom boundary layer depends strongly on the shape of the sea floor. An example of the latter is that sediment supply partly determines whether the shelf break is a net depositional or an erosional zone.

Whereas both oceanographic and geologic factors interact to influence sediment transport processes at the shelf break, a particular continental margin may be dominated by one of these factors. For instance, such oceanographic agents as the Gulf Stream and winter storms control sediment dynamics over large segments of the east United States coast, whereas such geologic factors as large sediment supply and active tectonism overshadow oceanographic phenomena in the eastern Gulf of Alaska. Many intermediate conditions also exist. An example is at the complex shelf break off southern California, where active tectonism and oceanographic phenomena nearly equally influence shelf-edge processes.

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