Cordilleran Section - 108th Annual Meeting (29–31 March 2012)

Paper No. 7
Presentation Time: 08:30-18:30


BAZÁN PERKINS Jr, Sergio Dale, Universidad Nacional Autónoma de México, División de Estudios de Posgrado, Facultad de Ingeniería, Ciudad Universitaria, México, D.F, 04510, Mexico and BAZÁN BARRÓN Sr, Sergio, Indian Mining Industry, S. A. C. V, Paseo de la Reforma 604, 2102 PH, Mexico, DF, 06900, Mexico,

The breakup of Pangea at the end of the Triassic, cortical strain occurred in Jurassic and Lower Cretaceous with intracratonic riftings. Later changed to compressive forces occurred during the Middle Cretaceous, due to the ridge of the Atlantic Ocean or Mid-Atlantic Ridge. Since then, the intensity is continuous, for the Mexican geotectonic cycle, which causes progressive Mexican Orogeny with polarity to the East. Finally, the cycle ends with a taphrogenic phase of grabens and horsts by vertical tectonics reaching to the Holocene, with numerous recent earthquakes.

This Mexican Structural Belt includes large horizontal compressive forces from the East, without the participation of the subduction of the Pacific tectonic plates under the American Craton. More than a thousand works of geology and geophysics at the Pacific continental margin of the craton of North America, do not prove or justify the plutonism and volcanic arcs and Laramide age Nevadian come from the subduction of oceanic plates of the Pacific, Kula, Farallon and Cocos under the North American craton. Geological and structural data determined due to subduction events towards the west, decreasing in age and intensity towards the east. Rather, successive Mesozoic and Cenozoic volcanic arcs involve sliding to the west, by plate Nevadiana Jurassic to Lower Cretaceous, superimposed on plate Laramide Late Cretaceous-Miocene, from the trench of Chilpancingo towards western.

The trench of Chilpancingo, recognized since Astata, Tehuantepec, Oaxaca to Sonora, generated Laramide plutons and volcanic arcs along the American continent. Recognition in the Belt Structural cross Cananeana or Xolapa, warn schist foliation changes migmatites or high-grade gneisses of the previous tectonic nevadiana, spread further west. This change identifies the plate nevadiana of different character batholith plutonic masses. This magmatism is shallow for about four miles deep, of bottom folds or plis de fond, generated by thrust faults, subject to intense horizontal forces from the East. Therefore, Pacific plates always act as a buttress of reaction to the heavy horizontal forces from the Mid-Atlantic Ridge. With these tectonic conditions, then the Caribbean plate from the Pacific was left lateral offset to southeast by transform faults.