Lithologic heterogeneity of the Eagle Ford Formation, South Texas

dc.contributor.advisorMilliken, K. L.
dc.creatorErgene, Suzan Mugeen
dc.date.accessioned2014-09-04T17:07:47Zen
dc.date.issued2014-05en
dc.date.submittedMay 2014en
dc.date.updated2014-09-04T17:07:48Zen
dc.descriptiontexten
dc.description.abstractGrain assemblages in organic-rich mudrocks of the Eagle Ford Formation of South Texas are assessed to determine the relative contributions of intra- and extrabasinal sediment sources, with the ultimate goal of producing data of relevance to prediction of diagenetic pathways. Integrated light microscopy, BSE imaging, and X-ray mapping reveal a mixed grain assemblage of calcareous allochems, biosiliceous grains (radiolaria), quartz, feldspar, lithics, and clay minerals. Dominant fossils are pelagic and benthic foraminifers and thin-walled and prismatic mollusks; echinoderms, calcispheres, and oysters are present. Early-formed authigenic minerals, including calcite, kaolinite, dolomite, albite, pyrite, quartz, and Ca-phosphate, some reworked, add to the overall lithologic heterogeneity. Point counting of images produced using energy-dispersive X-ray mapping in the SEM provides observations at a scale appropriate to classifying the mudrocks based on the composition of the grain assemblage, although grains and other crystals of clay-size cannot be fully characterized even with the SEM. Each sample is plotted on a triangle, whose vertices correspond to terrigenous and volcanic grains (extrabasinal components), calcareous allochems, and biosiliceous grains. As a subequal mix of grains of intrabasinal and extrabasinal origins the detrital grain assemblage of the Eagle Ford, presents a formidable challenge to the task of lithologic classification of this unit, as neither conventional limestone nor sandstone classifications can be readily applied. The abundant marine skeletal debris in the Eagle Ford is accompanied by abundant calcite cementation and the dissolution and replacement of biosiliceous debris is accompanied by authigenic quartz, suggesting that mudrock grain classification has potential for yielding diagenetic predictions.en
dc.description.departmentEarth and Planetary Sciencesen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/25752en
dc.language.isoenen
dc.subjectEagle Ford Formationen
dc.subjectDiagenesisen
dc.subjectMudrocksen
dc.subjectClassificationen
dc.subjectDetritalen
dc.subjectAuthigenicen
dc.subjectSouth Texasen
dc.subjectLithologic heterogeneityen
dc.subjectGrain assemblagesen
dc.subjectSediment sourcesen
dc.titleLithologic heterogeneity of the Eagle Ford Formation, South Texasen
dc.typeThesisen
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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