Geologia Guatemala
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Publicado: 1 de noviembre de 2012
LA OROGENIA LARAMIDE EN MÉXICO: EDAD Y CINEMÁTICA DE LA DEFORMACIÓN Y MAGMATISMO ASOCIADO
GEOS, GEOS Vol. 24, No. 2, Noviembre, 2004
SE04-1 MÉXICO: LA DEFORMACIÓN LARAMIDE EN MÉXICO : UNA EVOLUCIÓN GEOLÓGICA RESUELT EVOLUCIÓN GEOLÓGIC A NO RESUELTA Cerca Martínez Mariano1, Ferrari Luca 2, Chávez Cabello Gabriel2 y Calmus Thierry3
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SE04-2 NORTHERN THE LARAMIDE IN NORTHERN SONORA: TIMINGAND EVOLUTION BASIN EVOLUTION Jacques Ayala César
ERNO, Instituto de Geología, UNAM jacques@geologia.unam.mx The Laramide orogeny (s.l.) has been widely documented in northern Sonora. Early and Late Cretaceous rocks have been folded, metamorphosed and thrust by units as old as the Proterozoic. Age constraints have been more or less established, even though there is still disagreement on how theorogenic process evolved, as well as its distribution. The Lower Cretaceous is represented by marine to marginal marine deposits of the Bisbee Group; the Upper Cretaceous by continental deposits (El Chanate and Cabullona groups plus other informal units) overlain by andesitic flows and breccias (Tarahumara Formation and other equivalent units). Geochronology of igneous rocks (Tarahumara Formationand intrusive rocks) brackets the age of the Laramide between 75 and 40 Ma. The age of the metamorphic belt that extends from south of Santa Ana to Sonoyta and further northwest is within the same age bracket, but in the younger side. This belt is interpreted as the most important shear zone related to this orogeny. Stratigraphic relationships indicate that deformation began probably in the earlyLate Cretaceous. The youngest marine deposit identified in the Cintura Formation is late Albian. The age of the lowermost Upper Cretaceous has not been determined, but could be as old as Cenomanian. The stratigraphic relationship of the Lower and Upper Cretaceous is unconformable, but varies regionally from angular in the east to parallel in the west. Further more, the basement for the UpperCretaceous varies regionally in relationship to the metamorphic belt. North of this belt, the Upper Cretaceous overlies the Lower Cretaceous. South of the belt, the Upper Cretaceous was deposited upon Precambrian, Paleozoic and Triassic units, thus suggesting strongly the presence of piggy back basins. Structurally, the authocthonous basins are more strongly deformed, locally in overturned folds, andmetamorphosed, whereas the allocthonous ones are not as deformed and are not metamorphosed. More work needs to be done to better separate different stratigraphic and structural domains in the region to understand this orogeny in its full extent.
Instituto de Geología, UNAM Centro de Geociencias, UNAM ERNO, Instituto de Geología, UNAM marianoc@geologia.unam.mx
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El objetivo de este trabajoes plantear algunos problemas no resueltos sobre la tectónica de acortamiento activa durante el Cretácico Superior y Terciario Inferior en México. Esta deformación se manifiesta como plegamiento y cabalgamiento en la corteza superior con dirección de transporte predominante hacia el este-noreste, así como desplazamientos transcurrentes asociados. Localmente, se presentan complejidadesestructurales tales como salientes y vergencias en sentidos diferentes al sentido general de transporte tectónico. En el centro y sur de México, la edad de inicio de la deformación se ha ligado al cambio abrupto entre la sedimentación carbonatada y siliciclástica (Fms. El Doctor y Soyatal o Morelos y Mezcala) que ocurrió alrededor del Turoniano (ca. 93 Ma). La hipótesis que explica la deformación comoproducto del acoplamiento mecánico y tracción entre la placa de Farallón subduciendo de forma horizontal y la corteza de la placa de Norteamérica durante un periodo de convergencia rápida, presenta inconsistencias cuando se aplica en México. Existen diferencias importantes en los estilos de deformación y los patrones espaciotemporales de la actividad magmática asociada a la subducción entre el sur y el...
GEOS, GEOS Vol. 24, No. 2, Noviembre, 2004
SE04-1 MÉXICO: LA DEFORMACIÓN LARAMIDE EN MÉXICO : UNA EVOLUCIÓN GEOLÓGICA RESUELT EVOLUCIÓN GEOLÓGIC A NO RESUELTA Cerca Martínez Mariano1, Ferrari Luca 2, Chávez Cabello Gabriel2 y Calmus Thierry3
3
SE04-2 NORTHERN THE LARAMIDE IN NORTHERN SONORA: TIMINGAND EVOLUTION BASIN EVOLUTION Jacques Ayala César
ERNO, Instituto de Geología, UNAM jacques@geologia.unam.mx The Laramide orogeny (s.l.) has been widely documented in northern Sonora. Early and Late Cretaceous rocks have been folded, metamorphosed and thrust by units as old as the Proterozoic. Age constraints have been more or less established, even though there is still disagreement on how theorogenic process evolved, as well as its distribution. The Lower Cretaceous is represented by marine to marginal marine deposits of the Bisbee Group; the Upper Cretaceous by continental deposits (El Chanate and Cabullona groups plus other informal units) overlain by andesitic flows and breccias (Tarahumara Formation and other equivalent units). Geochronology of igneous rocks (Tarahumara Formationand intrusive rocks) brackets the age of the Laramide between 75 and 40 Ma. The age of the metamorphic belt that extends from south of Santa Ana to Sonoyta and further northwest is within the same age bracket, but in the younger side. This belt is interpreted as the most important shear zone related to this orogeny. Stratigraphic relationships indicate that deformation began probably in the earlyLate Cretaceous. The youngest marine deposit identified in the Cintura Formation is late Albian. The age of the lowermost Upper Cretaceous has not been determined, but could be as old as Cenomanian. The stratigraphic relationship of the Lower and Upper Cretaceous is unconformable, but varies regionally from angular in the east to parallel in the west. Further more, the basement for the UpperCretaceous varies regionally in relationship to the metamorphic belt. North of this belt, the Upper Cretaceous overlies the Lower Cretaceous. South of the belt, the Upper Cretaceous was deposited upon Precambrian, Paleozoic and Triassic units, thus suggesting strongly the presence of piggy back basins. Structurally, the authocthonous basins are more strongly deformed, locally in overturned folds, andmetamorphosed, whereas the allocthonous ones are not as deformed and are not metamorphosed. More work needs to be done to better separate different stratigraphic and structural domains in the region to understand this orogeny in its full extent.
Instituto de Geología, UNAM Centro de Geociencias, UNAM ERNO, Instituto de Geología, UNAM marianoc@geologia.unam.mx
1 2
El objetivo de este trabajoes plantear algunos problemas no resueltos sobre la tectónica de acortamiento activa durante el Cretácico Superior y Terciario Inferior en México. Esta deformación se manifiesta como plegamiento y cabalgamiento en la corteza superior con dirección de transporte predominante hacia el este-noreste, así como desplazamientos transcurrentes asociados. Localmente, se presentan complejidadesestructurales tales como salientes y vergencias en sentidos diferentes al sentido general de transporte tectónico. En el centro y sur de México, la edad de inicio de la deformación se ha ligado al cambio abrupto entre la sedimentación carbonatada y siliciclástica (Fms. El Doctor y Soyatal o Morelos y Mezcala) que ocurrió alrededor del Turoniano (ca. 93 Ma). La hipótesis que explica la deformación comoproducto del acoplamiento mecánico y tracción entre la placa de Farallón subduciendo de forma horizontal y la corteza de la placa de Norteamérica durante un periodo de convergencia rápida, presenta inconsistencias cuando se aplica en México. Existen diferencias importantes en los estilos de deformación y los patrones espaciotemporales de la actividad magmática asociada a la subducción entre el sur y el...
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