Geochemistry and Petrology of Dikes and Enclaves of the Mesoproterozoic Enchanted Rock Batholith, Llano Uplift, Central Texas

dc.contributor.advisorGodet, Alexis
dc.contributor.authorPoujardieu, Amber
dc.contributor.committeeMemberGray, Walter
dc.contributor.committeeMemberWhittington, Alan
dc.date.accessioned2024-02-12T19:51:56Z
dc.date.available2024-02-12T19:51:56Z
dc.date.issued2021
dc.descriptionThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.
dc.description.abstractThe Enchanted Rock Batholith (ERB) is a Mesoproterozoic-aged undeformed intrusive igneous body forcefully emplaced into the south-central portion of the Llano Uplift, Central Texas as the product of a Grenville-aged orogenic event. It is a metaluminous to marginally peraluminous fractionated A-type granite hosting ferroan to marginally magnesian, calc-alkalic to marginally alkali-calcic, peraluminous enclaves elongated parallel to the ERB's margins and a grouping of ferroan, calc-alkalic, peraluminous dikes, termed Marschall Creek Dike Complex, in the central-western portion of the batholith. Field, petrographic, and geochemical analysis suggests that the Marschall Creek Dike Complex and the enclaves of the ERB evolved through recharge fractional crystallization with limited magma mixing from ERB, undergoing similar processes during evolution evident by disequilibrium textures present in nearly every sample and correspondingly negative trends of all major oxide vs. SiO2 plots, apart from K2O vs. SiO2, consistent with the fractionation of calcic plagioclase and biotite and, to a lesser extent, zircon, apatite, and titanite. This is supported by the negative trends in the compatible trace elements (i.e., Sr, Ba, Co, V, Zn, and Zr), the partition of LREE and HREE, and negative europium and cerium anomalies of REE. Biotite-rich margins, entrained host material, rapakivi texture, deformation of the enclaves, and undulated surfaces on the dikes are consistent with emplacement into a partially molten host. The doming and zonation of the ERB and orientation of the enclaves parallel to the structure's perimeter suggests that the batholith was emplaced by ballooning.
dc.description.departmentGeosciences
dc.format.extent141 pages
dc.format.mimetypeapplication/pdf
dc.identifier.isbn9798538139392
dc.identifier.urihttps://hdl.handle.net/20.500.12588/5177
dc.languageen
dc.subjectMinerals
dc.subjectCooling
dc.subjectQuartz
dc.subjectOpen systems
dc.subjectTrends
dc.subjectRocks
dc.subjectTrace elements
dc.subjectGeochemistry
dc.subjectClassification
dc.subjectAluminum
dc.subjectCrystallization
dc.subjectSilica
dc.subjectMineralogy
dc.subjectMetamorphism
dc.subjectLead
dc.subjectAlkalinity
dc.subjectBallooning
dc.subjectDikes
dc.subjectEnchanted Rock Batholith
dc.subjectEnclaves
dc.subjectOpen systems
dc.subjectLlano Uplift, Central Texas
dc.subject.classificationGeology
dc.titleGeochemistry and Petrology of Dikes and Enclaves of the Mesoproterozoic Enchanted Rock Batholith, Llano Uplift, Central Texas
dc.typeThesis
dc.type.dcmiText
dcterms.accessRightspq_closed
thesis.degree.departmentGeosciences
thesis.degree.grantorUniversity of Texas at San Antonio
thesis.degree.levelMasters
thesis.degree.nameMaster of Science

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