Sequence Stratigraphic Evolution of the Mensa Minibasin, Mississippi Canyon, Northern Deep Gulf of Mexico

Aaron van den Berg, Paul Weimer, and Renaud Bouroullec
University of Colorado. Boulder, CO

This study documents the stratigraphic evolution of the Mensa minibasin, in the south central Mississippi Canyon, northern deepwater Gulf of Mexico. Analysis is based on the integration of a 378 square mile 3 dimensional seismic data set, wireline logs, and biostratigraphy.

The stratigraphy is divided into eight intervals between 99 and 9.0 Ma. From 99 to 24 Ma the lithologies in the minibasin are interpreted as dominantly deepwater marls with interbedded shales as determined from regional well data and seismic facies. The interval is thin across the area as a consequence of little siliciclastic input. From 24 to 9 Ma, the remaining seven intervals are interpreted and correlated in detail. From, The sediments between 24 and 14 Ma were deposited primarily within a limited area created from the subsidence of salt beneath the Mensa field area. A thick bowl-shaped sedimentary deposit is present much of which was penetrated by deep well, the results of which remain proprietary at this time. Thin shales that were encountered are interpreted as deposits upon paleobathymetric highs.

The area of sedimentary strata began to invert at about 14 Ma from an association with salt extrusion. The result is the formation of a “turtle” structure. Strata onlapped the structure from all directions. At 9 Ma, amalgamated sheets sands were deposited, onlapping onto the crest of the turtle structure. These sands are the primary reservoir at the Mensa Field.

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