Sequence Stratigraphy of Upper Miocene to Upper Pliocene Sediments of West-Central Mississippi Canyon and Northern Atwater Valley, Northern Gulf of Mexico

John Martin, Paul Weimer, Renaud Bouroullec, and R. Jay Austin
University of Colorado, Boulder, CO

This study documents the sequence stratigraphic evolution of west-central Mississippi Canyon and northern Atwater Valley protraction areas, northern Gulf of Mexico, through the integration of 2 dimensional, multifold seismic, well log, and biostratigraphic data.

Turbidites of the Mississippi Delta System were deposited upon allochthonous salt and created a series of intraslope mini-basins. These mini-basins are the depositional centers of the study area. Neogene turbidite successions are the major deposits throughout the study area. The main depositional elements that characterize the depositional setting are amalgamated and layered sheet sands, channel-fill deposits, overbank deposits, mass failure deposits (slides), and condensed sections.

Seven depositional age sequences were identified and correlated throughout the study area: 10.75 – 9.0 Ma, 9.0 – 8.2 Ma, 8.2 – 7.45 Ma, 7.45 – 6.2 Ma, 6.2 – 5.4 Ma, 5.4 – 4.1 Ma and 4.1 – 3.6 Ma. These intervals were deposited in bathyal waters and largely correspond to lowstand systems tract deposition. Individual sequence geometry and thickness was largely controlled by salt evacuation rates and large-scale sedimentation patterns. Amalgamated and layered sheet sands that create basin floor fan successions occur predominantly at the base of sequences and in areas of rapid salt withdrawal. Basin floor fan deposition is more common in older sequences. Stacked channel-overbank deposits are the most common depositional succession of each sequence and account for most of the sediment fill in the study area.

AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004