ABSTRACT: Regional 3D Seismic Well-Tie Lines to depict Geology in Ship Shoal, South Marsh Island, and High Island Areas, Offshore Gulf of Mexico

CHOWDHURY, ABU N.

Three regional arbitrary lines were extracted from the 3D seismic data volume in Ship Shoal, South Marsh Island and High Island South additions. These lines were integrated with biostratigraphic studies, to reveal the stratigraphic ages and structural styles along these transects. Twelve to fifteen sequence boundaries associated with nannofossil extinction were recognized and mapped in the Pleistocene - Miocene section.

The forty mile long ship shoal line shows that the Mahogany salt moved to the south into the younger section leaving salt weld and a counter regional fault system to the north and creating the "Ewing bank thrust system" to the south. A turtle structure associated with evacuation of salt from the GC 18 Field ("Boxer") occurs towards the southern end of this line.

The sixty mile long South Marsh Island line shows a major decollement surface indicating gliding of salt during lower Pliocene time. Significant basin rotation above this surface also occurred. A 30 mile long and 10 mile wide "Miocenica Fan", (upper Pliocene) known to be productive across the Gulf of Mexico, occupies the central portion of this line. Palyobathymetric data along the line indicates that the majority of the sediments in the South Marsh Island area were deposited in the slope fan environment.

The forty mile long High Island line shows "Texas Style" large listric fault systems which are not interrupted by numerous salt basins that are prevalent in offshore Louisiana.

AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana