Geochemistry of the Sykesville diamictite in central Maryland: an investigation of clast-matrix activity during metamorphism with tectonic implications

dc.contributor.authorTamburro, Edie T.en
dc.contributor.departmentGeological Sciencesen
dc.date.accessioned2019-10-10T19:11:57Zen
dc.date.available2019-10-10T19:11:57Zen
dc.date.issued1986en
dc.description.abstractThe Sykesville diamictite is part of the Wissahickon sequence, a polydeformed and metamorphosed sequence of questionable age in the Central Appalachian Piedmont. It occurs in association with thrust stacks of volcanic and mafic units of the Baltimore Mafic Complex and Potomac Valley Sequence in Maryland and Virginia, which are responsible for its formation. The matrix in central Maryland and northern Virginia is a schistose to massive granofelsic unit at biotite ± garnet grade. It contains fragments of quartz, pelitic schist, felsic-gneiss, mafic schist, amphibolite, and metacalcareous rocks. Sharp contacts and mineral chemical affinity between the matrix and pelitic schist and some felsic-gneiss clasts suggests that these inclusions were intrabasinally derived as first suggested by Fisher (1970). Zoned textures, compositional differences, and isotopic disequilibrium with the matrix exhibited by mafic schist, amphibolite, and amphibole-bearing felsic-gneiss clasts suggests these inclusions were derived directly from the allochthon responsible for generating the diamictite. The amphibolite and amphibole-bearing gneisses show textural and mineral chemical affinity with the Baltimore Mafic Complex. Rb-Sr mineral ages suggest the metamorphism in the diamictite matrix is Hercynian. Ordovician ages are estimated for some of the felsic-gneiss and pelitic clasts. Combining these data with existing data for the Wilmington Complex (Grauert and Wagner, 1975), the Bear Island Granite (Muth et. al., 1979), thrusting in northeastern Maryland (Lesser, 1982), and plutonism in the Maryland Piedmont (Sinha, et. al., 1979), suggests deposition of the Sykesville diamictite is Ordovician. Following deposition and overthrusting, a thermal event at 300 my generated the Gunpowder Granite (Olsen, 1972; Grauert, 1973a; Sinha et. al., 1979), and produced the observed metamorphism in the Sykesville diamictite matrix. This model is at variance with a Penobscotian deposition (Drake, 1985a).en
dc.description.degreeM.S.en
dc.format.extentvii, 163 leavesen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/10919/94480en
dc.language.isoen_USen
dc.publisherVirginia Polytechnic Institute and State Universityen
dc.relation.isformatofOCLC# 15062533en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1986.T374en
dc.subject.lcshGeochemistry -- Marylanden
dc.titleGeochemistry of the Sykesville diamictite in central Maryland: an investigation of clast-matrix activity during metamorphism with tectonic implicationsen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineGeological Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameM.S.en

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