Copeland, Peter2019-09-142019-09-14May 20172017-05May 2017https://hdl.handle.net/10657/457240Ar/39Ar ages of detrital muscovites from two adjacent river catchments in eastern Nepal were collected to study the implication of tectonics and climate in the region. The Sun-Koshi and Arun Rivers combine to form one of the largest river systems in Nepal with the combined catchment area of ~51,645 km2. Combining the new data with previously published bedrock ages leads to additional insight on the tectonic effect of landscape evolution in the eastern Himalayas. Muscovite cooling age of both samples from Arun and Sun-Koshi rivers are similar with a mean age of 11.6 Ma. The majority of ages are less than 14 Ma in both catchments. The lack of correspondence of rainfall with bedrock and detrital ages, channel-steepness index, and topography suggests that tectonics is the primary driver of erosion in the eastern Himalayas. The ages of muscovites from both catchments suggest erosional history, which increased in magnitude since 10 Ma due to the initiation of midcrustal duplex system, out-of-sequence thrusting, or the activation of trans-Himalayan normal fault from South Tibetan Detachment system. The detrital ages in Sun-Koshi-Arun catchments, when compared with the bedrock ages (low- and high-temperature thermochronology) show similar ages with central Nepal. The detrital data from both eastern and central Nepal are similar and the ages of late Miocene suggest that a similar average exhumation rates have operated in these regions since about 11 Ma.application/pdfengThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).GeologyGeomorphologyThermochronologyGeochronologyDetrital thermochronologyHimalayasNepalArun RiverArun River ValleySun-Koshi RiverTectonic geomorphology2019-09-14Thesisborn digital