--> Abstract: Sequence Stratigraphy of Upper-Miocene to Pleistocene Sediments of Southwestern Mississippi Canyon and Northwestern Atwater Valley, Northern Gulf of Mexico, by Ryan Sincavage, Paul Weimer, and Renaud Bouroullec; #90032 (2004)

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Sequence Stratigraphy of Upper-Miocene to Pleistocene Sediments of Southwestern Mississippi Canyon and Northwestern Atwater Valley, Northern Gulf of Mexico

Ryan Sincavage, Paul Weimer, and Renaud Bouroullec
University of Colorado, Boulder, CO

A sequence stratigraphic framework for Miocene-Pliocene sediments of northwestern Atwater Valley and southwestern Mississippi Canyon, northern Gulf of Mexico, was established using a suite of 2 dimensional seismic data, well logs, and biostratigraphic data. Two end-member mini-basin types are observed, supra-salt mini-basins, which are floored by autochthonous salt, and deep mini-basins, which do not contain any evidence of allochthonous salt at their bases. Within the study area, both types of mini-basins are dissected by isolated salt tongues and diapirs to the north, and by the extensive Sigsbee Salt Nappe to the south.

A total of twelve depositional intervals/sequences were correlated throughout the study area between 24 Ma to the Present. Seismic facies analysis, biostratigraphy and well log interpretation were used to generate isochron, seismic facies, and geologic facies maps for six intervals. Eight fields or discoveries are located within the study area. Reservoir sands are principally tabular sheet sands, channel-fill and overbank deposits.

The Neogene geologic and structural evolution of the study area has been divided into four informal phases of sediment delivery. Phase I (24 – 10.75 Ma) is characterized by active withdrawal of a top Cretaceous allochthonous salt system and a period of sediment starvation. Early evolution of the Neogene allochthonous salt system began in Phase II (10.75 – 8.20 Ma), and sediment delivery increased to a maximum during this time period. Phase III (8.20 – 5.4 Ma) consists of continued withdrawal of salt and a return to low sediment input. Final emplacement and burial of the Neogene allochthonous salt occurred during Phase IV (5.4 Ma – present), accompanied by supra-salt deposition above the allochthonous salt canopy.

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