NEW OBSERVATIONS ON THE CRUSTAL STRUCTURE OF THE US GULF OF MEXICO BASIN BASED ON DEEP-PENETRATION SEISMIC REFLECTION DATA, GRAVITY AND PLATE RECONSTRUCTIONS

We use a grid of 17,000 km of deep-penetration seismic data reflection and gravity modeling to define crustal provinces in the eastern Gulf of Mexico (GOM) and then use PaleoGIS software to reconstruct the positions of these same blocks during Mesozoic opening of the GOM. Main results from this study include: 1) definition of the continent-oceanic boundary for the area along the Florida escarpment, the northeastern GOM, and the Sigsbee escarpment; 2) recognition of a discontinuous Moho reflector that defines thinned 10-27-km-thick, continental crust beneath the Western Florida platform consistent with estimates based on previous refraction and gravity models; 3) recognition of a semi-continuous Moho reflector that defines 3.5-10-km-thick oceanic crust beneath the central GOM; 4) recognition of seaward-dipping reflectors inferred to be volcanic flows of Jurassic age marking the continent-ocean boundary (COB) in the northeastern GOM; SDR's indicate that the western margin of the Florida peninsula is a volcanic rift margin that perhaps formed as part of the Mesozoic Central Atlantic Magmatic Province (CAMP), a plume head magmatic event accompanying the breakup of Pangea; 5) delineation of the edge of the Louann salt layer at the COB indicating that the central GOM oceanic crust formed after the salt layer was formed and rifted into two halves to form the Louann province in the northern GOM and the Campeche province in the southern GOM. Plate reconstructions predict locations of the COB and SDR-influenced areas outside of the US GOM study area in the Mexican and Cuban GOM.