Post Mid-Cretaceous Seismic Stratigraphy and Geologic History, Deep Gulf of Mexico Basin

FENG, JIANHUA, and RICHARD T. BUFFLER, University of Texas Institute for Geophysics, Austin, TX

The deep Gulf of Mexico basin is underlain by up to 10 km of sedimentary rocks. This section is subdivided into two megasequences separated by a prominent, basinwide, mid-Cretaceous sequence boundary (MCSB), which marks a major turning point in the history of the Gulf basin. The post-MCSB section consists of the more distal portions of large siliciclastic wedges that partially fill the basin. A detailed seismic stratigraphic analysis has subdivided the post-MCSB, pre-Pleistocene section into 12 new sequences, which have been mapped throughout the entire deep basin using UTIG and all available industry seismic data.

Correlation with two published Exxon seismic lines on the northeastern shelf provides tentative age control for the five youngest sequences. The correlation across the slope was made using a dense grid of UTIG and industry seismic data with minimum interference from salt structures. These ages were further confirmed by correlation with DSDP sites 90 and 91 in the western Gulf. This study suggests that the base of the Mississippi Fan is Upper Miocene in age, which is older than the Plio-Pleistocene age proposed by previous studies.

Isopach maps of each new sequence document the progressive filling of the deep basin and the shift of major deep water depocenters from the west and northwest to the north. This corresponds to the shift of the deltaic depocenters along the northern Gulf margin. A tentative correlation of the deep Gulf sequences with the major northern Gulf coast depositional episodes is proposed.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)