Sierra de Catorce: Remnants of the ancient western equatorial margin of Pangea in central Mexico
José Rafael Barboza-Gudiño, Roberto S. Molina-Garza, Timothy F. Lawton, 2012. "Sierra de Catorce: Remnants of the ancient western equatorial margin of Pangea in central Mexico", The Southern Cordillera and Beyond, José Jorge Aranda-Gómez, Gustavo Tolson, Roberto S. Molina-Garza
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The Sierra de Catorce in northern San Luis Potosí, Mexico, represents an uplifted block with exposures of the oldest rocks of the region which include Upper Triassic turbidites interpreted as deposits of a submarine fan system (“Potosí Fan”) and overlying Lower Jurassic volcanic and volcaniclastic strata interpreted as a record of the Early-Middle Jurassic volcanic arc (“Nazas Arc”) of western North America. These lower Mesozoic units, recognized in several exposures in the region, are interpreted as remnants of the ancient western margin of Pangea prior to accretion of Late Jurassic—Early Cretaceous magmatic arc complexes and associated marginal basins that constitute the Guerrero composite terrane in western Mexico and that resulted in construction of a new Pacific margin. A field trip in the Sierra de Catorce and surrounding exposures of the Upper Triassic—Lower Jurassic succession allows observation and discussion of key features that demonstrate the sedimentary and tectonic history of the western equatorial margin of Pangea.
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Prepared in conjunction with the 2012 GSA Cordilleran Section Meeting, Querétaro, Mexico, this volume's eight field guides showcase three aspects of the geology of the southern end of the North America cordillera: Mid-Tertiary and Quaternary volcanology, environmental geology, and Mesozoic tectonics. Field Guide 25 explores the Cenozoic stratigraphy of Sierra de Guanajuato, one of the most important Mexican mining districts, and addresses a controversial topic, the accretion of the Guerrero terrane and its possible role in the Late Cretaceous—Early Tertiary orogeny. Three guides related to the Trans-Mexican Volcanic Belt, an active magmatic arc related to subduction of the Rivera and Cocos plates, include new data about the recent volcanic history, physical volcanology, and volcanic hazards in Mexico's most densely populated area. Bringing the geosciences into societal problems, one guide presents data on ground deformation related to water extraction in urbanized areas of the Mexico City basin, and another explores the ghost town of the Mineral de Pozos mining district and the effect of mine tailings on groundwater.