Correlation of Events for the Jurassic and Cretaceous of the Northern Gulf of Mexico Margin Using Mega-Regional Onshore/Offshore-Composited PSDM Seismic Grid

Abstract

Our Gulf of Mexico interpretation shows a new depth map of the mid-Jurassic unconformity at base Louann Salt ranging throughout the Gulf of Mexico Basin. A gradient calculation highlights distinct flexures that separate the historic onshore basins and uplifts. The flexures fan out from southwest to northeast in a pattern consistent with the pull-apart of Africa and Florida, proposing a new view of the basement framework. There is abundant evidence of old Louann Salt movement in the onshore, offshore and deepwater, caused by gravity forces. Onshore growth wedges are numerous in Smackover, Lower Cotton Valley age. Offshore old salt stocks formed in deepwater and show a thinned Mesozoic section.

The stocks were squeezed and salt evacuated, and the Mesozoic thinned section has been drilled in suprasalt canopy positions in numerous offshore locations. In the deepwater environment, a regional Jurassic-age salt nappe extruded over a more northerly position for the continental/oceanic boundary. Florida events seem to correlate with basement movement in the onshore Gulf margin. A second stage rift event interpreted at a Lower Cretaceous unconformity in the southwest Florida shelf region, suggests correlation with Mesozoic basement movements in the onshore uplifts. The Middle to Upper Jurassic shelf edges are regionally interpreted and assist in reconstruction of the early onshore basins to the Florida shelf.

Interpretation of the Gulf of Mexico Basin framework has long been hindered by the separation of datasets west to east and onshore to offshore. This is addressed by a unique pre-stack depth migration (PSDM) onshore and offshore grid of dip and strike composite seismic lines that range from the Texas/Mexico border to the Florida Panhandle, and from the onshore shelf margins to the deepwater abyssal plain. This seamless mega-regional grid is unique to any margin in the world today, and offers advanced correlation of events around the Gulf of Mexico Basin, especially the Jurassic and Cretaceous history.

AAPG Datapages/Search and Discovery Article #90219 © 2015 GCAGS, Houston, Texas, September 20-22, 2015