Geochronology, Geochemistry, and Tectonic Setting of the Mesozoic Nazas Arc in North-Central Mexico, and its Continuation to Northern South America
Claudio Bartolini, Harold Lang, Terry Spell, 2003. "Geochronology, Geochemistry, and Tectonic Setting of the Mesozoic Nazas Arc in North-Central Mexico, and its Continuation to Northern South America", The Circum-Gulf of Mexico and the Caribbean: Hydrocarbon Habitats, Basin Formation and Plate Tectonics, Claudio Bartolini, Richard T. Buffler, Jon F. Blickwede
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Volcanic, sedimentary, and granitic plutonic rocks that are part of the early Mesozoic Cordilleran continental magmatic arc are exposed in a belt from the southwestern United States to Guatemala. In the Mexican states of Chihuahua, Coahuila, Durango, Zacatecas, and San Luis Potosí, these rocks form a discontinuous southeast-trending belt across north-central Mexico. Whole-rock geochemical analyses of volcanic and intrusive rocks in north-central Mexico indicate a calc-alkaline suite formed in this continental volcanic arc along the convergent margin of western North America. Paleomagnetism, field relations, and isotopic ages (40Ar/39Ar, K-Ar, Rb-Sr, and U-Pb) of 73 volcanic and intrusive rocks document the Late Triassic–Middle Jurassic age of the arc. In the region, isotopic ages commonly are reset, apparently because of thermotectonic events during the “Laramide” orogeny that led to the development of the Sierra Madre Oriental fold and thrust belt and to deep burial of the arc rocks. Available evidence suggests that the arc underwent two main phases of subsidence. One phase of extensional subsidence created intra-arc basins and a peak of volcanism throughout the arc in the Early–Middle Jurassic. A second phase began in the Oxfordian, with subsidence and initial deposition of the Zuloaga and La Gloria Formations. Continued sedimentation during this phase led to accumulation of 5–7 km of strata above the arc, as Cretaceous seas transgressed westward over inland Mexico.
The similarities in age, depositional environment, clastic composition, magma types, and geochemical affinity and, more importantly, the tectonic settings that gave rise to the Nazas Formation in Mexico and La Quinta and Girón Formations in Venezuela and Colombia suggest that these two volcanic-sedimentary sequences, now hundred of kilometers apart, were once part of the Late Triassic–Jurassic continental magmatic arc. This arc extended from Alaska to South America and evolved during simultaneous subduction along the western margin of Pangea, rifting in the Caribbean–Gulf of Mexico region, and associated large-scale transpressive activity.
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The Circum-Gulf of Mexico and the Caribbean: Hydrocarbon Habitats, Basin Formation and Plate Tectonics
The Circum-Gulf of Mexico and the Caribbean has long been one of the world's most important petroleum provinces, as well as one of the world's most geologically complex regions. These two characteristics have resulted in an extensive amount of ongoing research by both industry and academia. AAPG Memoir 79, The Circum-Gulf of Mexico and the Caribbean, is the first volume in more than a decade to document such a wide range of research on the geology of this vast area. Of the total 44 papers, roughly two-thirds pertain to the Gulf of Mexico, with an emphasis on the Mexican portion of the basin, and to the petroliferous areas of the southern Caribbean, including Colombia, Venezuela, Cuba, and Trinidad and Tobago. The remaining papers relate to the Antilles and Central America, as well as a series of papers that address region-wide topics such as plate tectonic evolution. A significant number of papers were contributed by authors from national oil companies and universities from within the region.