Some 220 million years ago, in Late Triassic time, the Gulf of Mexico basin began to form in the wake of the breakup of Paleozoic megacontinent Pangea, and the opening of the North Atlantic Ocean. Igneous processes played a major role in the formation of this basin, as the common occurrence of basaltic rocks in rift basins around the Gulf of Mexico margin indicates. Geophysical evidence indicates that the central basin is floored by oceanic crust, presumably similar to that of oceanic crust elsewhere. Igneous activity was, however, not confined to the early stages of evolution of the basin. During the late Mesozoic, major volcanic fields rimmed the northern margin of the basin, probably the result of intraplate stresses due to global plate reorganization or isostatic adjustment from increased sediment loads along this margin. The eastern margin of the basin may have been affected by a late Mesozoic–early Tertiary Caribbean magmatic arc complex. Throughout the Tertiary the western margin has had a complex history of igneous activity associated with subduction of the Pacific plate beneath the North American Plate. There are numerous volcanic fields on the coastal plain and presently three active submarine volcanoes within the Gulf of Mexico.
Throughout the evolution of the Gulf of Mexico basin, igneous rocks have also been a significant component of sediment being deposited within the basin. In the Late Cretaceous, local basins along the northern margin had adjacent volcanic sources, and during the early Tertiary uplift, these volcanic terrains were the source of
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The Gulf of Mexico Basin
Eighteen chapters deal with the entire Gulf of Mexico basin. Included are significant contributions from Mexican geologists. Nine topical chapters cover regional aspects of physiography and bathymetry, structural framework, the basement crust, salt tectonics and listric faulting, igneous activity, seismic stratigraphy, oil and gas resources, mineral resources and geopressured-geothermal energy, and ground water. Six chapters summarize regional stratigraphy and paleogeography for the pre-Triassic, Triassic-Jurassic, Lower Cretaceous, Upper Cretaceous, Cenozoic, and late Quaternary. Also included is a synthesis of the origin and development of the Gulf of Mexico basin. Six 4-color plates summarize the bathymetry, natural resources, tectonics, and basement structure and subcrop of the region, and provide a stratigraphic correlation chart and geologic cross sections.