Seismic Tectono-stratigraphy of the Pre-Callovian Sequences of the US and Mexican Gulf of Mexico

Abstract

The offshore Gulf of Mexico basins offer a range of contrasting tectonic settings in which pre-salt sequences can be observed with regional 2D and 3D reflection seismic data sets. The sequences immediately pre-salt are here considered syn-kinematic to the main phase of crustal extension leading to continental break-up and emplacement of oceanic crust. As such, the first order control on these sequences appears to be the magnitude of local crustal thinning. In the northeastern U.S. GOM in the shallow waters of northwest Florida to eastern Louisiana on moderately thinned crust, the sequences are characterized by rotated fault blocks and half graben fills overlain by a draping sag sequence. In the deep water offshore southwest Florida and northwest Yucatan, the late sag sequence expands basin-ward to its limit at the ocean-continent boundary and pinches out landward against a series of basin-ward dipping reflectors that appear similar to Type 1 SDRs from southern Brazil to Argentina. In the shallow and deep-waters of the Salina Basin, off the west coast of the Yucatan and beneath widespread and thick salt, our data are not as clear as to the northeast, but appear to show a sag sequence which is at its thickest in the central part of the basin and thins basin-ward as in West Africa. The transform margin offshore eastern Mexico juxtaposes only moderately thinned continental crust against oceanic crust and the pre-salt equivalent sequences are represented by thinned half-graben fill above rotated fault blocks.

AAPG Datapages/Search and Discovery Article #90369 © 2020 AAPG Hedberg Conference, Geology and Hydrocarbon Potential of the Circum-Gulf of Mexico Pre-salt Section, Mexico City, Mexico, February 4-6, 2020