Wu, Xinxia1, William E Galloway1
(1) University of Texas at Austin, Austin, TX
ABSTRACT: Deepwater Depositional Style of the Upper Miocene Depositional Episode, East-Central Gulf of Mexico
The Upper Miocene (Late Middle to Early Late Miocene) depositional episode (UM depisode), defined by two widespread, transgressive deposits associated with biostratigraphic top Textularia W (12.0 Ma) and Robulus E (6.2 Ma), records a long-lived family of sediment dispersal systems that persisted for nearly 6 m.y. with little modification. In the east-central Gulf of Mexico, this depisode records extensive margin offlap, primarily centered on the ancestral Tennessee River and Mississippi River dispersal axes. Thickest sediments were deposited in the Tennessee River delta beneath modern SE Louisiana. A large volume of sand continuously bypassed the confined minibasin and upper slope at the flank of active deltaic depocenters into the Mississippi Canyon, Atwater Valley and Green Canyon OCS areas throughout the entire UM, forming a long-lived McAVLU submarine fan system in the linked, primary minibasin corridor of the lower slope and basin floor. Canyons, fan valleys, leveed channels, gravity mass transport complexes and structural conduits that focused sediment flow provide various sediment transport elements. The presence of extremely large volumes of high-quality shelf margin delta and deep-water fan sandstones results in the great productivity of the east-central Gulf of Mexico UM. Significant untapped upper Miocene hydrocarbon resources remain in various stratigraphic and structural producing associations.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.