Abstract

Three canyon systems which enter into the northern one third of the Hatteras Abyssal Plain are the principal sources of Late Pleistocene and Holocene sediment for the entire abyssal plain. The Hatteras Canyon System enters as a point source via a small fan built directly on the ocean basin floor. The Wilmington Canyon mouth is somewhat wider and disgorges its load from a lower continental rise fan. The Hudson Canyon empties across the 110-km wide Sohm Gap, a feature which is on the true ocean basin floor. Because sedimentary processes are different, each basin entry point has produced unique topographic features, as well as unique sediment distribution patterns and sedimentary structures. The relative importance of turbidity current, pelagic and contour current processes, is variable from system to system. Southward flowing contour currents contribute very little, if any, sediment to the Hatteras Fan, but are an important sediment source for fine materials on the seafloor at the mouth of the Wilmington Canyon and Sohm Gap. Provenance is also responsible for differences in the sediments in each canyon system. As an example, the Hatteras Canyon material is much more calcareous than material from the other two basin entry points, because of the relatively calcareous nature of the continental shelf source area near Cape Hatteras.

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