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dc.contributor.advisorFisher, W. L. (William Lawrence), 1932-
dc.contributor.advisorRuppel, Stephen C.
dc.creatorPierce, John Donalden
dc.date.accessioned2014-10-27T19:03:13Zen
dc.date.issued2014-08en
dc.date.submittedAugust 2014en
dc.identifier.urihttp://hdl.handle.net/2152/26920en
dc.descriptiontexten
dc.description.abstractThe Eagle Ford Shale and equivalent Boquillas Formation (Late Cretaceous) contain abundant volcanic ash beds of varying thickness. These ash beds represent a unique facies that displays a range of sedimentary structures, bed continuity, and diagenetic alteration. They are prominent not only in West Texas outcrops, but also in the subsurface of South Texas where hydrocarbon production is actively occurring. The ash beds have the potential to be used for stratigraphic correlation for understanding early diagenesis and — most importantly — for obtaining high-resolution geochronology, which can then be used for defining depositional rates and chronostratigraphy. Study of the ash beds was conducted at outcrops along U.S. 90, west of Comstock, Texas, the subsurface in Atascosa and Karnes County, and at a construction site in South Austin. Bed thicknesses range from 0.1–33 cm and were collected throughout the entirety of the Eagle Ford succession. Mineral separation yielded abundant non-detrital zircons for U-Pb dating. Dating was conducted using LA-ICP-MS at The University of Texas at Austin, to attain a base level understanding of the age range for the Eagle Ford. High-resolution ages for the base and top of the Eagle Ford were obtained, in addition to radioisotopically defining the Cenomanian-Turonian boundary within the section. U-Pb ages for the Eagle Ford Shale range from Early Cenomanian to Late-Coniacian near Comstock, Mid-Cenomanian to the Turonian-Coniacian boundary in the subsurface, and Early Cenomanian to Late Turonian in Austin area. These findings contrast with many of the regional biostratigraphic studies across the Eagle Ford and indicate a more prolonged period of Eagle Ford deposition than previously observed.en
dc.format.mimetypeapplication/pdfen
dc.language.isoenen
dc.subjectEagle Forden
dc.subjectU-Pben
dc.subjectGeochronologyen
dc.subjectLA-ICP-MSen
dc.subjectSouth Texasen
dc.subjectWest Texasen
dc.subjectCentral Texasen
dc.subjectCenomanianen
dc.subjectTuronianen
dc.subjectOAE2en
dc.titleU-Pb geochronology of the Late Cretaceous Eagle Ford Shale, Texas; defining chronostratigraphic boundaries and volcanic ash sourceen
dc.typeThesisen
dc.date.updated2014-10-27T19:03:13Zen
dc.description.departmentGeological Sciencesen
thesis.degree.departmentGeological Sciencesen
thesis.degree.disciplineGeological Sciencesen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Science in Geological Sciencesen


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