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dc.creatorBridges, Luther Wadsworth, 1931-
dc.date.accessioned2010-09-20T22:20:31Z
dc.date.available2010-09-20T22:20:31Z
dc.date.created1962-06
dc.date.issued2010-09-20
dc.identifier.urihttp://hdl.handle.net/2152/8535
dc.descriptiontext
dc.description.abstractThree previously unrecognized outcrops of pre-Carboniferous rock in the Mina Plomosas - Placer de Guadalupe area have a total area of slightly less than four square miles. Six units, ranging in age from Ordovician to Jurassic, are mapped within the Plomosas Formation named by Burrows in 1909; the total thickness is about 8,000 feet. The lower 2,000-foot section of Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian rock, composed predominantly of limestone, resembles contemporaneous formations in west Texas. The 2,000-foot to 3,000-foot section between Pennsylvanian and Late Jurassic rock, composed predominantly of siltstone and conglomerate, consists of a 500-foot to 1,000-foot Permian (Wolfcampian-Leonardian) sequence overlain by beds of undetermined age. The Permian sequence includes a reef. The 3,000-foot section of Late Jurassic rock is composed of shale, sandstone, and limestone. The area lay to the north of the main Ouachita trend, and Paleozoic tectonism was less intense than in the Marathon uplift. Nevertheless, angular unconformities within the Permian sequence indicate Permian movements. Laramide tectonism was extreme, with major overthrusting toward the west. Two large sections are upside-down. Crustal shortening on the order of ten miles can be proved near Mina Plomosas. Probably the sericite and microspar (finely recrystallized limestone), in the Paleozoic and Jurassic rocks, are products of incipient metamorphism resulting primarily from Laramide deformation. Mina Plomosas is an important lead-zinc mine. A little placer gold is found at Placer de Guadalupe. All mineralization in the Placer de Guadalupe - Mina Plomosas area is thought to be Tertiary in age. The petroleum potential of Chihuahua is still untested.en_US
dc.format.mediumelectronic
dc.language.isoengen_US
dc.rightsCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.
dc.subjectGeology of Chihuahua, Mexicoen_US
dc.subjectChihuahua, Mexicoen_US
dc.titleGeology of Mina Plomosas area, Chihuahua, Mexicoen_US
dc.description.departmentGeological Sciencesen_US
thesis.degree.departmentGeological Sciencesen_US
thesis.degree.disciplineGeological Sciencesen_US
thesis.degree.grantorThe University of Texas at Austin
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US


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