Southern and Central Mexico: Basement Framework, Tectonic Evolution, and Provenance of Mesozoic–Cenozoic Basins
This volume furthers our understanding of key basins in central and southern Mexico, and establishes links to exhumed sediment source areas in a plausible paleogeographic framework. Authors present new data and models on the relations between Mexican terranes and the assembly and breakup of western equatorial Pangea, plate-tectonic and terrane reconstructions, uplift and exhumation of source areas, the influence of magmatism on sedimentary systems, and the provenance and delivery of sediment to Mesozoic and Cenozoic basins. Additionally, authors establish relationships between basement regions (sediment source) in the areas that supplied sediment to Mesozoic rift basins, Late Cretaceous foreland systems, and Cenozoic basins developed in response to Cordilleran events.
Definition of tectonic elements in Tehuantepec, southeast Mexico: An integrated geophysical, geochronological, and stratigraphic perspective
Published:December 09, 2021
Roberto S. Molina Garza, James Pindell, Henry Coombs, Bodo Weber, Tomás Peña Alonso, 2021. "Definition of tectonic elements in Tehuantepec, southeast Mexico: An integrated geophysical, geochronological, and stratigraphic perspective", Southern and Central Mexico: Basement Framework, Tectonic Evolution, and Provenance of Mesozoic–Cenozoic Basins, Uwe C. Martens, Roberto S. Molina Garza
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We redefine the “Chontal arc” of the southern Isthmus of Tehuantepec, Mexico, as the Chontal allochthon. The Chontal assemblage is composed of Upper Cretaceous low-grade metavolcanic and metasedimentary rocks included in the Chivela lithodeme. By means of field observations, laser-ablation detrital zircon geochronology, and trace-element geochemistry, we constrained the provenance and tectonic setting of these rocks. We concluded that they form an allochthon emplaced during a Paleogene transpressive event. Basement structure in the greater Oaxaca-Chiapas area was assessed by qualitative interpretation of Mexican State aeromagnetic maps. Chivela lithodeme sediments include a contribution from Albian–Turonian volcanic arc rocks no longer present in the region, likely sourced from the Chortís block or from the Greater Antilles Arc as it collided with southern Yucatan. Maastrichtian basic intrusive units, basalt flows, and pillow lavas with pelagic sediments in the Chontal are subalkaline, plotting in the normal mid-ocean-ridge basalt (N-MORB) field of discrimination diagrams. The igneous rocks are interpreted as pertaining either to the inception of the paleo–Motagua fault zone (left step in the fault trace), or to local backarc extension behind the Chortís block just before it began to migrate eastward, in a basin we call the Chontal basin. The Chontal allochthon was thrust northward onto parautochthonous strata flanking the Mixtequita and Chiapas Massif basements. Chontal allochthon rocks were later intruded by Miocene granitoids related to the inception of Cocos plate subduction arc magmatism. Rocks of the Chontal allochthon have been previously linked to the Cuicateco belt of eastern Oaxaca, but this is challenged here on the basis of lithologic type, chronology, tectonic associations, structural styles, and discontinuous anomaly trends in aeromagnetic maps.