AAPG Bulletin, V. 82 (1998), No. 6 (June 1998), P. 1207-1232.

Sequence Stratigraphy and Depositional History of the Eastern Mississippi Fan (Pleistocene), Northeastern Deep Gulf of Mexico¹

Barrett T. Dixon² and Paul Weimer³

©Copyright 1998.  The American Association of Petroleum Geologists.  All Rights Reserved

¹Manuscript received January 26, 1996; revised manuscript received April 28, 1997; final acceptance November 20, 1997.
²Energy and Minerals Applied Research Center, Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309-0250.Present address: Exxon Company, U.S.A., Houston Production Organization, P.O. Box 4697, Houston, Texas 77210-4697.
³Energy and Minerals Applied Research Center, Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309-0250.

We are indebted to Halliburton Geophysical Services (now Western Geophysical) for the use of their seismic data, and especially to Robert Graebner, John Anderson, and Gary White. Special thanks to Richard Buffler for use of the University of Texas Institute for Geophysics seismic data. This research has been supported by member companies in the University of Colorado Gulf of Mexico Consortium: Agip, Amoco, Anadarko, BHP, BP Exploration, Burlington Resources, CXY Energy, Chevron USA, CNG, Conoco, Enterprise, Exxon, Marathon, Mobil, Occidental, PanCanadian, Pennzoil, Petrobras, Phillips, Shell, Texaco, Total, Union Pacific, and Unocal. Discussions with Arnold Bouma, Jack Edwards, Robert Mitchum, Harry Roberts, Mark Rowan, Kevin Schofield, Craig Shipp, Chuck Stelting, David Twichell, and Charles Winker helped the final technical content of this paper. Jonathan Irick and Jennifer Crews helped in drafting some of the figures. We thank the following people for their careful reviews, which improved the manuscript: Laurie Lamar, M. S. Wacker, and AAPG reviewers Roy Adams, Brad Macurda, former Elected Editor Kevin Biddle, and an anonymous reviewer. 

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.