--> Abstract: Form and Composition of Mississippi Fan, by Charles J. Stuart, Charles A. Caughey; #90975 (1976).
[First Hit]

Datapages, Inc.Print this page

Abstract: Form and Composition of Mississippi Fan

Previous HitCharlesNext Hit J. Stuart, Previous HitCharlesTop A. Caughey

The Mississippi fan is a lobe-shaped prism of muddy Quaternary sediments extending for about 800 km from near the present Mississippi River delta to the Sigsbee abyssal plain. The Mississippi trough and smaller, filled depressions notch the shelf edge near the fan apex. These depressions apparently channeled detritus across the outer shelf and upper slope and acted as point sources of fan sediment. Upper, middle, and lower subdivisions of the fan are identified on the basis of seafloor gradient and relative smoothness, seismic character, and influence of salt structures. The upper fan is in water depths from about 1,000 to 2,500 m and has an irregular, hummocky topography with an average surface gradient of about 1°. Structural and topographic complexities in this pa t of the fan have resulted from salt diapirism, slumping, and possibly current scour. Dart-core lithologies consist of clay, silt, and uncommon, very fine-grained sand.

The middle part of the fan is characterized by a low gradient (<0.25°), moderately smooth surface, and complex internal structures as shown by seismic profiles. Mid-fan deposits thin from 1,300 to 800 m toward the southwest and southeast, and near-surface sediments are clays and silts. Widespread intervals of chaotic seismic response--interpreted as slump and slide deposits--are present adjacent to the depositional loci of the fan. Interbedded units of continuous reflectors probably are turbidites, hemipelagites, and possibly contourites.

The lower fan is very smooth, nearly flat, and grades into the Florida and Sigsbee abyssal plains. Quaternary silt and clay in the lower fan are interpreted as turbidites and pelagites. Associated seismic reflections are continuous and converge toward abyssal-plain areas.

AAPG Search and Discovery Article #90975©1976 GCAGS- GC Section SEPM Annual Meeting Shreveport, Louisiana