Geology Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2774

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    CONSTRAINTS ON THE DEPOSITIONAL AGES OF LESSER HIMALAYAN ROCKS IN CENTRAL NEPAL AND THEIR STRUCTURAL IMPLICATIONS
    (2009) Burgy, Katherine Diane; Martin, Aaron; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The lack of good exposures and paucity of datable horizons in central Nepal has hindered the ability of geologists to piece together a relatively cohesive and straightforward stratigraphic succession within the Lesser Himalaya. U-Pb isotopic analyses of detrital zircons from the Modi Khola valley indicates maximum depositional ages of ~1875 Ma for the Kuncha Formation, ~1800 Ma for the Fagfog Formation, and ~ 1780 Ma for the Kushma Formation. The intrusive 1831 ± 17 Ma Ulleri augen gneiss provides a minimum depositional age bound for the Kuncha. Combined, these data suggest the Kuncha Formation is the oldest member of the Lesser Himalayan series in central Nepal. Additionally, 13C data suggest the Malekhu Formation of the Lakharpata Group was deposited before ca. 1250 Ma. A field mapping comparison based on the redefined stratigraphy indicates the Ramgarh thrust is located >10 km farther south than previously mapped, potentially reducing regional shortening estimates.
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    Topographic signatures in the Himalaya: A geospatial survey of the interaction between tectonics and erosion in the Modi Khola valley, central Nepal
    (2009) Walsh, Lisa Schleicher; Martin, Aaron J; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Spurred by the recognition that lithologic resistivity to erosion influences the steepness of terrain, the purpose of this study is to enhance our understanding of feedbacks between erosion and tectonics in the Himalaya. Using spatial statistics, within a Geographic Information Systems (GIS) framework, this study extracts steepness and curvature values from the terrain to identify the unique spatial signature of lithologic units in the Annapurna Range. The spatial relationship of faults and significant changes in river steepness (ksn) and concavity (θ) are examined in this project using high resolution digital elevation models (DEMs), derived from a variety of interpolation methods. Through these quantifications, I explore the possibility of a new model for tectonic activity in central Nepal, in an effort to improve our understanding of how surface processes sculpt the landscape.