University of Texas – Austin
Gryger, Sean Michael.
Geologic framework of the Sierra Mojada mining district, Coahuila, Mexico : an integrative study of a Mesozoic platform-basin margin.
Degree: MSin Geological Sciences, Geological Sciences, 2010, University of Texas – Austin
The geology of the Sierra Mojada silver-lead-zinc mining district gives new insights into the stratigraphic evolution of the Coahuila Block and the Coahuila Folded Belt and the history of deformation along the basement-rooted San Marcos Fault Zone. Sierra Mojada provides the opportunity for substantial data collection relevant to the interaction of regional tectono-stratigraphic elements in a generally data-poor region of northeastern Mexico. Active mineral exploration has produced an extensive database of closely spaced drill core. Expansive underground workings facilitate subsurface geologic mapping. Sierra Mojada is situated at the northwestern edge of two tectono-stratigraphic provinces, the Coahuila Block, to the south, and the Coahuila Folded Belt, to the north. The San Marcos Fault, a west-northwest-trending regional structure extends through Sierra Mojada and is the informal boundary between these two provinces.
Sierra Mojada is situated on uplifted and deformed late Paleozoic Ouachita siliciclastic strata intruded by Triassic diorites. This basement is diagnostic of the Coahuila Block. Basement rocks are overlain by an immature conglomerate that is interpreted to be the updip equivalent of the Jurassic La Casita Formation. The stratigraphy of Sierra Mojada principally consists of a continuous succession of Barremian through Albian carbonates unconformably overlying the basal conglomerate. The Barremian-Aptian Cupido Formation locally records deepening conditions from a clastic-influenced evaporitic interior to high energy, open water conditions. The shale and lime mudstone of the La Pena Formation were deposited during a Gulf-wide transgression that signals the end of the Aptian. The Sierra Mojada region of the Coahuila Block was inundated throughout the Aptian and was affected by the late Aptian transgression. The Albian Aurora Formation constitutes the bulk of the Cretaceous section. Sierra Mojada exposes the Aurora shelf rim, progressing from platform margin to shelf rim and platform interior facies.
The structural features of Sierra Mojada affect the entire Cretaceous section. The high angle San Marcos Fault was reactivated with reverse motion during the Paleogene as a result of Laramide shortening. This juxtaposed basement and Jurassic conglomerate against the Cretaceous carbonates consistent with offset observed along the southern trace of the San Marcos Fault. A local colluvial unit suggests a lag in Laramide deformation. The carbonate strata and colluvial unit were overridden by a low angle, northeast-dipping thrust fault that placed a Neocomian through Aptian sequence atop the autochthonous Aptian-Albian carbonates. The allochthonous San Marcos Formation suggests regional-scale tectonic transport of this immature fluvial conglomerate from a downdip depozone within the Sabinas Basin. Kinematic indicators are consistent with the southwest-northeast axis for maximum compression established for Paleogene shortening throughout the Coahuila Folded Belt. The thrust fault bisects the principal ore zone…
Advisors/Committee Members: Kyle, J. Richard (advisor), Kerans, Charles (committee member), Lawton, Timothy F. (committee member).
Subjects/Keywords: Coahuila Block; Coahuila Platform; Sabinas Basin; Northeastern Mexico; San Marcos Fault Zone; Laramide Orogeny; Non-sulfide zinc deposits
to Zotero / EndNote / Reference
APA (6th Edition):
Gryger, S. M. (2010). Geologic framework of the Sierra Mojada mining district, Coahuila, Mexico : an integrative study of a Mesozoic platform-basin margin. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-12-2637
Chicago Manual of Style (16th Edition):
Gryger, Sean Michael. “Geologic framework of the Sierra Mojada mining district, Coahuila, Mexico : an integrative study of a Mesozoic platform-basin margin.” 2010. Masters Thesis, University of Texas – Austin. Accessed November 26, 2020.
MLA Handbook (7th Edition):
Gryger, Sean Michael. “Geologic framework of the Sierra Mojada mining district, Coahuila, Mexico : an integrative study of a Mesozoic platform-basin margin.” 2010. Web. 26 Nov 2020.
Gryger SM. Geologic framework of the Sierra Mojada mining district, Coahuila, Mexico : an integrative study of a Mesozoic platform-basin margin. [Internet] [Masters thesis]. University of Texas – Austin; 2010. [cited 2020 Nov 26].
Available from: http://hdl.handle.net/2152/ETD-UT-2010-12-2637.
Council of Science Editors:
Gryger SM. Geologic framework of the Sierra Mojada mining district, Coahuila, Mexico : an integrative study of a Mesozoic platform-basin margin. [Masters Thesis]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-12-2637