A New Temporal Model for Eastern Gulf of Mexico Mesozoic Deposition

John Snedden, Gail Christeson, Drew Eddy, Patricia Ganey-Curry, Ian Norton, Hilary Olson, and Harm van Avendonk
[email protected]

The Mesozoic history of the eastern Gulf of Mexico (GOM), including Florida, is mainly known through early vintage reflection seismic data acquired over the Florida shelf, DSDP core sites in the Florida Straits, and limited older well control. We have formulated a new model for the temporal evolution of the Florida outer margin, using a combination of new reflection seismic data and integration with new refraction data. Reinvestigation of the original biostratigraphic reports from 1970's and 1980's vintage well tests in addition to new analyses in Mississippi Canyon wells facilitated development of a more tightly constrained sequence stratigraphic framework. In our model, the mixed carbonate/siliciclastic Haynesville-Buckner supersequence (152 to 155ma) is the first to develop a shelf margin and prograde that outer margin, downlapping onto newly created oceanic crust in the eastern GOM spreading center. This is followed by progradation of the Cotton Valley-Bossier supersequence (142 to 152ma), including the key Tithonian age marine source rock, which laps out further basinward. The final unit deposited onto the accreting oceanic crust is the Cotton Valley-Knowles supersequence (138 to 142ma). Termination of sea-floor spreading is more or less synchronous with basinward shift of the Hosston (133 to 138ma) siliciclastic system, suggesting a major tectonic reorganization in the source terrane areas of the Ocala Uplift and possibly the Appalachians. Aptian-age (+/-122 ma) carbonates of the Sligo form a basin-wide platform margin as the GOM transitions into the next phase of structural and depositional development. Understanding this temporal evolution supports new exploration efforts in the eastern GOM planning area as well as portions of adjacent Mississippi and Desoto Canyons, as it impacts hydrocarbon reservoir, source, and seal evaluation here.

AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63^rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013