Petrogenesis and geochemistry of kyanite-bearing pegmatites in the Buncombe Pegmatite District, North Carolina

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dc.contributor.authorWood, Keith Yatesen
dc.contributor.committeecochairTracy, Robert J.en
dc.contributor.committeecochairBodnar, Robert J.en
dc.contributor.committeememberWise, Michael A.en
dc.contributor.departmentGeologyen
dc.date.accessioned2014-03-14T20:44:01Zen
dc.date.adate2008-08-22en
dc.date.available2014-03-14T20:44:01Zen
dc.date.issued1996-08-01en
dc.date.rdate2010-10-04en
dc.date.sdate2008-08-22en
dc.description.abstractKyanite is generally considered to be a product of metamorphism. This study investigates a set of kyanite-bearing pegmatites that represent a case in which kyanite crystallized directly from melt. The pegmatites intrude spinel orthopyroxene hornblendite in the Buncombe Pegmatite District in the Eastern Blue Ridge of North Carolina. One site was studied in detail and survey studies of two other occurrences were made. The pegmatites contain quartz, large euhedral crystals of plagioclase, biotite, and kyanite, as well as apatite, muscovite, tourmaline, and microscopic primary sillimanite. Potassium feldspar is notably absent. One site, the Thomas Mine, was examined in detail in order to determine the mode of occurrence for these rocks. Excavation revealed pegmatite with two texturally and mineralogically distinct zones. Biotite-rich rocks surrounding the pegmatite indicate strongly potassic alteration of the host hornblendite. Trace element data obtained for kyanite and biotite from the pegmatite show clear patterns related to chemical fractionation of these components during crystallization. Major element geochemistry of the pegmatite and host ,I rocks are consistent with magmatic intrusion. Reaction of the pegmatite melt with the host rocks led to the formation of large amounts of biotite, and depleted the melt in potassium. The remaining melt became saturated in aluminum silicate and crystallized kyanite and sillimanite. Wallrock assemblages, fluid inclusions in pegmatite quartz, the coexistence of kyanite and sillimanite as primary phases, and geothermobarometry on nearby unaltered rocks all indicate conditions of formation of approximately 600-800 MPa and 625-675°C, near those of peak metamorphism for the region.en
dc.description.degreeMaster of Scienceen
dc.format.extentviii, 56 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-08222008-063115en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08222008-063115/en
dc.identifier.urihttp://hdl.handle.net/10919/34704en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1996.W663.pdfen
dc.relation.isformatofOCLC# 36436300en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectpegmatiteen
dc.subjectkyaniteen
dc.subjectmagmaticen
dc.subjectbiotiteen
dc.subject.lccLD5655.V855 1996.W663en
dc.titlePetrogenesis and geochemistry of kyanite-bearing pegmatites in the Buncombe Pegmatite District, North Carolinaen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineGeologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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