--> ABSTRACT: Inner Shelf Deposits of Louisiana-Mississippi-Alabama Region, Gulf of Mexico, by Jack L. Kindinger, Shea Penland, S. Jeffress Williams, and John R. Suter; #91029 (2010)

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Inner Shelf Deposits of Louisiana-Mississippi-Alabama Region, Gulf of Mexico

Jack L. Kindinger, Shea Penland, S. Jeffress Williams, John R. Suter

The late Quaternary morphology, shallow stratigraphy, and sediment distribution of the Louisiana-Mississippi-Alabama inner shelf are the product of a complex set of transgressive and regressive sedimentary processes interacting during the Holocene transgression. Shelf sedimentary facies were deposited by a combination of deltaic progradation followed by shoreface erosion and submergence. This information is based on interpretations and synthesis or more than 3,200 km of high-resolution seismic profiles and 50 vibracores.

The shelf can be divided into two main depositional regions. The southwest region, east and south of the Mississippi River plain, was formed by two ancestral river delta complexes, overlying a late Wisconsin delta. Deposits of the late Wisconsinan delta consist of well-defined coarsening-upward sequences and represent deltaic progradation during low sea level. The relatively recent Mississippi delta complexes have deposits consisting of fine-grained sand, silt, and clay. With the late Holocene rise in sea level, asymmetrical sand ridges (> 5 m relief) have formed due to marine reworking of this shoreline.

The northeastern region offshore the barrier islands in Mississippi-Alabama have been formed by the ravinement of the exposed shelf by Pleistocene fluvial systems and shoreface erosion. Sediments, underlying the relatively thin Holocene sediment, cover fluvial sands deposited during the late Wisconsinan lowstand. Subsequent sea level rise allowed marine processes to rework and redistribute sediments forming the nearshore fine-grained facies and shelf sand sheet.

AAPG Search and Discovery Article #91029©1989 AAPG GCAGS and GC Section of SEPM Meeting, October 25-27, 1989, Corpus Christi, Texas.