Geologic framework of gravity anomaly sources in the central Piedmont of Virginia

dc.contributor.authorKeller, Mary Ruthen
dc.contributor.committeechairRobinson, Edwin S.en
dc.contributor.committeememberGlover, Lynn IIIen
dc.contributor.committeememberCostain, John K.en
dc.contributor.departmentGeophysicsen
dc.date.accessioned2014-03-14T20:47:15Zen
dc.date.adate2008-10-30en
dc.date.available2014-03-14T20:47:15Zen
dc.date.issued1983-06-15en
dc.date.rdate2008-10-30en
dc.date.sdate2008-10-30en
dc.description.abstractBouguer gravity anomalies at 1870 locations on the central Piedmont of Virginia from 37° 37' N to 37° 52' N and 77° 44' W to 78° 23' W display patterns of variation produced by upper crustal density contrasts and thickening of the crust in a WNW direction. No other deep sources are evident. Upper crustal density contrasts are associated with rock units known from geologic mapping. ‘The subsurface distribution of these rock units interpreted from seismic reflection data was confirmed by measured variations in gravity. A two-dimensional model analysis indicates the following average in situ density values for the principal formations: Arvonia Formation-2.77 gm/cc, Columbia Granitoid-2.75 gm/cc (tonalite) and 2.73 gm/cc (pegmatite), Chopawamsic Volcanics- 2.77 gm/cc (felsic units), and 2.79 gm/cc (mafic units}, Catoctin/ Lynchburg-2.815 gm/cc, Maidens Gneiss-2.775 gm/cc, Grenville Basement- 2.71 gm/cc. Gravity and seismic data are consistent with the existence of a major thrust fault at depths between 9 km and 16 km that separates Grenville Basement rocks from younger Catoctin/Lynchburg rocks. The slight eastward dip of this thrust fault beneath the western part of the area increases significantly east of 78° 05' W. Gravity anomalies suggest the existence of several mafic inclusions within the Columbia Granitoid that were not identified by geologic mapping.en
dc.description.degreeMaster of Scienceen
dc.format.extentv, 83 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-10302008-120444en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10302008-120444/en
dc.identifier.urihttp://hdl.handle.net/10919/35535en
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1983.K453.pdfen
dc.relation.isformatofOCLC# 10381504en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1983.K453en
dc.subject.lcshGeology -- Virginiaen
dc.subject.lcshGravity anomalies -- Virginiaen
dc.titleGeologic framework of gravity anomaly sources in the central Piedmont of Virginiaen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineGeophysicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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