Tectonostratigraphy and Petroleum Systems Potential of the Frontier Basins of the Central and Eastern Gulf of Mexico
R. Pascoe, P. Nuttall and M.C. Mejía-Hernández
Event name: First EAGE Workshop on Deepwater Exploration in Mexico: Foster collaboration to unlock potential
Session: Overcoming Subsurface Challenges Part II
Publication date: 15 May 2018
Info: Extended abstract, PDF ( 3.74Mb )
Price: € 20
The crustal architecture of the central and eastern Gulf of Mexico is well imaged on modern, deep-penetrating reflection seismic data, due to thinner or absent Jurassic salt, relative to the northwestern and southern parts of the greater basin. Within the zone of hyper-extended continental crust on both the US and Mexican margins 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. A consistent observation along the margins is that the base salt surface is a monoclonal ramp from beneath the Mesozoic shelf edge to the oceanic crust. We do not interpret the step-up in level that occurs between the base salt and the top of the oceanic crust as a fault, but rather 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. Corrected bottom hole temperatures from wells of the Florida shelf indicate geothermal gradients 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 are 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.