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Stages of Jurassic Rifting, Magmatism, and Salt Deposition in the Eastern Gulf of Mexico Inferred from a Grid of Deep-Penetration Seismic Reflection Data Tied to Wells


Previous investigations on the Mesozoic rift history of the Gulf of Mexico (GOM) have focused on the pre-rift, geometrical fits of continental crust in North America, Mexico, Chiapas, and Yucatan. Less emphasis has been placed on inferring the process of lithospheric thinning known from other, better studied, rifted margins including: 1) mantle plume vs. crustal controls on rifting; 2) magma-poor vs. magma-rich style; and 3) linking stratigraphic and/or uplift events to each stage of the rifting, including the deposition of early source rocks and massive halite. Observations based on interpretations of 17000 km of deep-penetration 2D seismic lines tied to wells lead to the following interpretations: 1) massive lava flows of ∼8 km in thickness and with eastward dips (seaward-dipping reflectors or “SDR's”) are mapped across a ∼16,600 km2 area around Lloyd ridge and formed prior to the formation of ocean floor; 2) stratigraphic correlations show that the SDR's show they are coeval or slightly later than massive salt deposition and late Jurassic source rock deposition, but younger than the formation of oceanic crust in the central GOM; 3) SDRs is within ∼600 km of the calculated center of the CAMP mantle plume head that created thickened oceanic crust beneath the Bahamas area; for this reason the presence of SDR's is a likely consequence of the CAMP plume although no core samples have been recovered to test their age and geochemistry; and 4) GOM opening was completed by late Jurassic, as a consequence, the prolific Jurassic source rocks overlay both continental and oceanic crust.