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Fluid History of the Western Maryland Piedmont

LaFonte, Christopher John
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1435339052

Abstract Details

2015, Master of Science (MS), Bowling Green State University, Geology.
Regional fluid migrations associated with orogenic events have a number of significant geologic consequences in the continental interior, such as the emplacement of hydrocarbons, mineralization, and diagenesis. It is currently believed that fluids associated with the Alleghanian orogeny in the central Appalachians where sourced from the eastern portion of the Piedmont, migrated westward, passing below the Blue Ridge, into the Valley and Ridge region, and finally into the craton. Previous studies have provided details about fluids across much of the central Appalachians, but one gap remains: the western portion of the Piedmont. Using fluid inclusion microthermometry on vein samples throughout the western Piedmont, the trapping conditions and fluid composition were found and used to compare the fluid history of this region with that of other regions to determine if the Piedmont was part of the westward fluid migration. The fluids of the western Piedmont were found to be very uniform in terms of trapping conditions and fluid composition regardless of vein type, rock unit and lithology, and sample location. All inclusions were two-phase (L+V) and were found to consist of a low salinity H2O+NaCl brine with a large majority of them having homogenization temperatures between 140 and 200°C. The age of the veins and fluids cannot be well constrained. While most veins are probably associated with early phases of deformation and metamorphism during the late Ordovician Taconic orogeny and/or the early Silurian Cherokee orogeny, the fluid inclusions in them may be younger and related to recrystallization and/or reequilibration during younger events, such as the late Paleozoic Alleghanian orogeny. Considering the regionally uniform microthermometric properties of the inclusions, their relatively low trapping temperatures and pressures, low salinity fluid composition, the lack of reequilibration textures, and the lack of evidence for significant Alleghanian deformation in the region, the most likely scenario is that the veins trapped the fluids shortly after this region reached peak metamorphic conditions during the Cherokee orogeny in the early Silurian. This timing, along with the significant differences in fluid history with adjacent regions, indicates that the western Piedmont does not record the effects of a late Paleozoic orogen-wide fluid event.
Charles Onasch (Advisor)
John Farver (Committee Member)
Kurt Panter (Committee Member)
72 p.
Geology
Fluid History; Appalachian Geology; Piedmont Geology; Fluid Inclusions; Quartz veins; western Maryland Geology; Ijamsville Phyllite; Sugarloaf Mountain anticlinorium

Recommended Citations

Citations

  • LaFonte, C. J. (2015). Fluid History of the Western Maryland Piedmont [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1435339052

    APA Style (7th edition)

  • LaFonte, Christopher. Fluid History of the Western Maryland Piedmont. 2015. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1435339052.

    MLA Style (8th edition)

  • LaFonte, Christopher. "Fluid History of the Western Maryland Piedmont." Master's thesis, Bowling Green State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1435339052

    Chicago Manual of Style (17th edition)

bgsu1435339052
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This open access ETD is published by Bowling Green State University and OhioLINK.