Slump Features on the Mississippi Fan, Northeastern Gulf of Mexico

During recent geologic time, the Mississippi River system has been the dominant contributor of terrigenous sediment to the northeastern Gulf Basin. A large mass of sediments has been produced on the continental slope seaward of the mouth of this system. This sedimentary feature has been referred to as the Mississippi Fan. During a recent geophysical cruise in the Gulf of Mexico, several crossings of the fan resulted in seismic records that led to the conclusion that large scale slumps were active on the fan in very recent time. Evidence presented here indicates one slump movement originated near the mouth of the Mississippi Trough and moved about 160 nm toward the southeast. A part of this slump flowed to the south and southwest, or a second slump developed at about the same time and flowed in this direction for a distance of about 130 nm. The southeasterly slump is about 70 nm in width, and the smaller slump, to the west, is nearly 38 nm wide. The maximum measured vertical distance from the point of origin of these features to the downslope limit is about 4000 ft.