--> Abstract: Crustal Architecture and Passive Margin Evolution of the Northern Gulf of Mexico Basin, by Pascoe, Robert and Rowan, Mark G.; #90166 (2013)

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Crustal Architecture and Passive Margin Evolution of the Northern Gulf of Mexico Basin

Pascoe, Robert1 and Rowan, Mark G.
1[email protected]

A revolutionary 2D seismic reflection survey, SuperCache, consists of 17000km of PSDM, gravity and magnetic data, acquired across the US deep-water GoM. The source and streamer configurations of long-offset, powerful source and deep-tow, were designed to optimize imaging of crustal architecture. The source was found to be at least 40% more powerful in the 3-40HZ range than recent seismic surveys in the GoM. A 15km single contiguous solid streamer, the first known commercial application of such an ultra-long streamer, improved velocity estimation to 15km.

As a result of these parameters, the crustal architecture of the basin has been illuminated and the Moho is evident from low-extension to highly attenuated continental crust and onto oceanic crust. The ocean-to-continent transition (OCT) exhibits along-strike (~2000km) variations from hyper-extended continental crust and exhumed mantle in the Western and Central GoM, to an area of volcanic seaward-dipping-reflectors (SDRs) in the East. The original extent and thickness of the Louann Salt can be related to these along-strike changes. Stretching, Thinning and Exhumation phases of continental break-up have been identified. The composite surface of the Callovian Louann Salt, its correlative unconformity on the Florida Platform and the top of oceanic crust, in conjunction with the Moho depth surface, have yielded a thickness map representing crustal architecture.

On the Florida Platform, an initial crustal thickness of 32km is consistent with prior work for the southeastern US continental margin; thicknesses of less than 15km suggest thinning across parts of the "platform" (De Soto Canyon and Tampa Embayments). The southern part of the margin (Sarasota Arch and South Florida Basin) saw post-kinematic emergence and non-deposition to the Middle Aptian, followed by slow, shallow-water sediment accumulation to the Mid Eocene, before rapid subsidence and platform edge collapse, attributed to collision with the Cuban Arc.

This crustal architecture has significant implications for exploration in the deep-water GoM. Variations in the OCT are expected to have controlled post-rift, basal heat flow and lateral distributions of hydrocarbon type and quality. Variations in post-kinematic provenance, subsidence and accommodation space, constrains the distribution of potential pre-salt and post-salt Mesozoic sequences, expected to be the focus of new play development.

 

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013