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Abstract

The Mesozoic Gulf of Mexico Basin is considered in this discussion as the set of contiguous, Triassic and Jurassic sub-basins directly involved in the counterclockwise rotation of the Yucatan Block from North America in the Late Jurassic. The rifting and seafloor spreading history of the basin is less well understood than analogous salt basins of the Atlantic margins, largely because the base salt surface is significantly deeper and has hereto widely been considered acoustic basement.

In 2012, 17,000 km of 2D PSDM reflection seismic data (SuperCache) were acquired across the deep water of the U.S. Gulf of Mexico. The unique acquisition configuration of long-offset, powerful source, and deep-tow of both source and receivers was designed to optimize the imaging of the presalt architecture of the basin to a depth of 40 km. On these seismic data, the base of the salt and its correlative unconformity, continental and oceanic basement, and the Moho are evident. In combination with vintage, reflection seismic data, shipboard and regional gravity data, and regional refraction profiles, a crustal interpretation has been extended to the greater Gulf of Mexico Basin.

The continental crustal architecture is described in terms of crustal thinning: from low (<30%) to transitional (>70%). Synkinematic sequences are recognized within the Late Triassic to the Middle Oxfordian (~70 my). The final break-up phase occurred within 15 my, ending with a basin-wide open marine transgression and initial emplacement of oceanic crust at 160±1 Ma; continued extension may have occurred in the eastern part of the basin in the latest Jurassic. The basin margins are considered to be intermediate between magmapoor and volcanic end-members. The ocean crust tapers from a maximum width of 700 km in the west, where it is anomalously thin, to anomalously thick as it approaches the pole of rotation in the Straits of Florida. The architecture of extinct spreading valleys and fracture zones is analogous to the modern, slow spreading mid-Atlantic ocean, suggesting that spreading continued until the latest Jurassic (~142 Ma), possibly as late as within the early Cretaceous (~132 Ma).

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