Sequence Stratigraphy and Depositional History of the Eastern Mississippi Fan (Pleistocene), Northeastern Deep Gulf of Mexico

Abstract

The eastern Mississippi Fan is a moderate-size, mud-dominated, Pleistocene submarine fan in the northeastern deep Gulf of Mexico. Analysis of 6900 km of multifold seismic data identified eight discrete depositional sequences interpreted to be coeval to the younger sequences in the western Mississippi Fan. All sequences consist of channel-levee deposits and slides. Channel-fill deposits are characterized by high-amplitude subparallel reflections, and levee-overbank deposits are characterized by interbedded subparallel to hummocky and mounded reflections. All sequences are affected by a series of volumetrically and areally large submarine slides, that are characterized by hummocky to chaotic reflections. Individual slides are up to 5000 km2 in area. The channel-levee systems within six of the sequences are derived from sediment sources located northwest in the Mississippi Canyon lease area. The channel-levee systems within the remaining two sequences are downfan continuations of systems in the western Mississippi Fan. These changing positions of the channels presumably reflect changes in the position of the shallow-marine depocenter that fed the fan throughout the Pleistocene. The eastern Mississippi Fan can serve as an exploration analog for mud-dominated turbidite systems with similar seismic facies and geometries. The fan has four potential reservoir facies: channel-fill sediments with sinuous to linear trends, thin-bedded sands in levee-overbank sediments, sheet sands deposited at the terminus of channels, and one possible basin-floor fan. Channel valley width/thickness ratio values range from 2.9 to 13/1 upfan to 2.9 to 8.8/1 downfan.