Geology of Mina Plomosas area, Chihuahua, Mexico


Geology of Mina Plomosas area, Chihuahua, Mexico

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dc.creator Bridges, Luther Wadsworth, 1931- 2010-09-20T22:20:31Z 2010-09-20T22:20:31Z 1962-06 2010-09-20
dc.description.abstract Three 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.
dc.format.medium electronic
dc.language.iso eng
dc.rights Copyright © 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.subject Geology of Chihuahua, Mexico
dc.subject Chihuahua, Mexico
dc.title Geology of Mina Plomosas area, Chihuahua, Mexico
dc.description.department Geological Sciences
dc.type.genre Thesis
dc.type.material text Geological Sciences Geological Sciences The University of Texas at Austin Doctoral Doctor of Philosophy

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