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Tectonostratigraphy of The Frontier Basins of the Central and Eastern Gulf Of Mexico


The crustal architecture of the central and eastern GoM is well imaged on modern, seismic data, due to thinner or absent Jurassic salt, relative to the northwestern and southern parts of the greater basin. The eastern domain comprises the Florida Straits and north Yucatan margins. The central domain includes the US margin east of the modern Mississippi, the northwest Yucatan margin and the interior, shallow-water Salina Basin.

Within the zone of hyper-extended continental crust we observe a progressive west to east transition in key tectono-stratigraphic parameters: 1) an increase in the thickness of oceanic crust from normal (7-7.5 km) to thick (> 8km); 2) increasing depth to the base-salt surface at the limit of ocean crust (with respect to the top of oceanic crust); 3) decreasing amount of salt and degree of basin-ward allochthonous transport; 4) a narrowing of the zone of hyper-extended continental crust and an increase in the dip of the continental Moho beneath the transition from hyper-extended to thinned continental crust; and 5) evidence for compression in the sediments above the base salt surface. Along the length of the margins the base salt surface is a monoclonal ramp from beneath the Mesozoic shelf edge to the oceanic crust. We interpret the step-up in level that occurs between the base salt and the top of the oceanic crust as the marginal, constructional escarpment of oceanic emplacement.

On the thicker continental crust of the basin margins we interpret discrete domain boundaries: the northern margin of the Tampa Embayment of the central Florida margin and in a conjugate position a pronounced dextral step in the north Yucatan margin. Geothermal gradients from wells of the Florida shelf north and west of the domain boundary are 30-35 Co/km, normal to high for continental crust. South and east of the domain boundary geothermal gradients range from 14-24 Co/km, anomalously low for continental crust and possibly consistent with a basement of accreted, Gondwanan, arc terranes. These observations raise the possibility that there may be important differences in crustal type, thermal structure and petroleum potential of the conjugate northwest Yucatan and north Yucatan domains.

Three of the four conjugate segments include undrilled frontier basins, where the significance of an understanding of basin evolution is most impactful for petroleum systems analysis, particularly those of the syn-kinematic and early post-kinematic Jurassic plays.