PhD, University of Cincinnati, 2017, Arts and Sciences: Geology

Models attempting to define the links among climate, tectonics, erosion, and topography in high mountain environments have continued to evolve in recent years. Quantitative studies of the rates of catchment and bedrock erosion and the ages of significant depositional or erosional events are still needed to illuminate these complex links and their positive and negative feedbacks. Underlying climatic and tectonic forcings may exert significant control on the interplay of surface and tectonic processes and how mountain landscape systems develop. Regional variability poses an additional challenge to researchers in environments that are already dynamic and complex. To investigate how the interplay of these tectonic and climatic factors affect arid, mountainous regions and how they have affected the evolution of landscapes in mountain systems during the Quaternary, I present quantitative data bearing on the ages of moraines, strath and fluvial terraces, and alluvial fan surfaces using 10Be terrestrial cosmogenic nuclide (TCN) methods in the Pamir Range of western China and the Precordillera of Argentina, where optically-stimulated luminescence (OSL) dating was also applied. 10Be TCN methods were also used to determine catchment and bedrock erosion rates for a part of the Zanskar Range in the Indian Himalaya. My study examines the ages of these landforms within the context of each field area's climatic and tectonic setting. Dating and erosion results were analyzed within their geologic context, building a whole-basin sedimentary history in China, a regional climatic framework in Argentina, and a line between erosion rates and basin morphology and tectonics in India. In the Pamir Himalaya, results illustrate the presence of remarkably well-preserved alluvial fan surfaces dating back to ~580 ka, despite evidence of significant Quaternary basin change, including the development and drainage of a large paleolake and multiple glaciations since >80 ka. In the Zanskar (open full item for complete abstract)

Committee: Lewis Owen Ph.D. (Committee Chair); Marc Caffee Ph.D. (Committee Member); Craig Dietsch Ph.D. (Committee Member); Thomas Rockwell Ph.D. (Committee Member); Lindsay Schoenbohm Ph.D. (Committee Member) Subjects: Geology

PhD, University of Cincinnati, 2013, Arts and Sciences: Geology

The lower Ohio River valley is a terraced fluvial landscape that has been significantly influenced by the advance and retreat of glaciers in its upper drainage basin and by changes in the Holocene climate. The lower Ohio Valley is also susceptible to crustal deformation and seismic shaking produced by the Wabash Valley (WVSZ) and New Madrid (NMSZ) seismic zones. Geomorphic mapping, sediment coring, geophysics, and optically stimulated luminescence (OSL) dating were used to develop a chronostratigraphic framework of sediments and landforms in the valley and to evaluate fluvial responses to glaciation, Holocene climate change, and neotectonic deformation. Sediments deposited during marine oxygen isotope stage (MIS) 6 or earlier were only found in the subsurface. The elevation of the last interglacial (MIS 5) Sangamon paleosol preserved on the valleys edges indicates that MIS 6 alluvium filled the valley to within 7 m of the modern floodplain. The river incised ~22 m into MIS 6 outwash before the end of MIS 5e, and was aggrading by 114 ± 11 ka (MIS 5d). OSL ages indicate the river aggraded 8-14 m by the middle of MIS 3, and had incised ~10 m and started aggrading again by 29.9 ± 2.7 ka before MIS 3 ended. Aggradation continued into MIS 2, and maximum aggradation occurred by 21.4 ± 1.0 ka, which is synchronous with the last glacial maximum in Ohio. The Ohio River incised the MIS 2 outwash and formed a suite of fill-cut terraces that decrease in age as elevation decreases, recording the river's adjustment to fluxes in sediment load and meltwater discharge during deglaciation. From 13.5 ± 2.1ka to 11.7 ± 2.7 ka the Ohio river incised up to 3 m, possibly in response to the Bølling Allerød interstadial, and began meandering at ~11.7 ± 2.7 ka which at the beginning of the Holocene. From 5.4 ± 0.7 ka to ~4ka, roughly the timing of the Holocene atlithermal, the river incised ~5 m, and since ~4ka the river has aggraded at least 4 m, which corresponds to the Neoglacial. The (open full item for complete abstract)

Committee: Lewis Owen Ph.D. (Committee Chair); Roy Van Arsdale Ph.D. (Committee Member); Thomas Lowell Ph.D. (Committee Member); David Byer Nash Ph.D. (Committee Member); Paul Potter Ph.D. (Committee Member) Subjects: Geomorphology