INVESTIGATING CLIMATIC EFFECTS ON THE STRUCTURAL AND TOPOGRAPHIC EVOLUTION OF THE HIMALAYAS THROUGH LANDSCAPE ANALYSIS AND THERMOKINEMATIC MODELLING

The interplay between climate and tectonics remains a major research focus with the Himalayas as the ideal locality to study these relationships due to their stark along- and across-strike variations in topography, pronounced precipitation patterns, and differential erosivity of rock units that influence topography. This study systematically explores and leverages these along- and across-strike variations to better understand the governing processes and threshold behaviors. The topography of the Himalayas has long been attributed to interactions between surface and tectonic processes, however, the dynamic linkage between these processes and climate remains enigmatic. Much focus has been placed on an abrupt topographic break between the Lesser and Greater Himalaya that persists along strike with varying relief. Understanding what sustains this topographic break is essential to understanding relationships between climate, tectonic, and surface processes, as it lies at the geographic intersection of focused precipitation, a ramp in the main Himalayan decollement (MHT), proposed out-of-sequence thrust faulting, and a transition zone between differentially erodible units. Along strike variations in precipitation weighted channel steepness (Ksn-q), a common proxy for active uplift, occur within and between laterally continuous rock units of the Himalaya and correlate with mean annual precipitation (MAP) patterns. This study highlights correlations between spatial patterns of Ksn-q, exposure of rock units, and MAP. We show that with intensifying precipitation towards the east, exposure of lithologically resistant units increases while weaker units progressively thin and the zone of high Ksn-q steps southward. We then use thermokinematic and landscape evolution models of proposed tectonic scenarios to compare with observed topographic patterns and compiled thermochronologic data to better understand the dynamic linkage between climate and tectonics in the Himalaya.