CLIMATE-TOPOGRAPHIC FORCING AND MOUNTAIN GEODYNAMICS IN THE CENTRAL KARAKORAM HIMALAYA

Understanding the complexities of mountain geodynamics in the Karakoram Himalaya requires an assessment of the scale-dependencies associated with the coupling of climatic, surficial and tectonic processes. Operational scale-dependencies of erosion and uplift are very difficult to ascertain, given the polygenetic overprinting of glaciation, river incision, mass movements, uplift and neotectonics. Furthermore, the nature of climate-topographic forcing as it relates to topographic anisotropy and surface processes has not been adequately examined. Consequently, we examined atmospheric circulation patterns and multi-scale topographic parameters to determine if orographic precipitation zones explain high-magnitude glacier erosion, uplift zones and lithological variation. To accomplish this, we determine orographic precipitation patterns based upon climate-reanalysis data from 1979-2016 (wind-direction and velocity) and Shuttle Radar Topography Mission (SRTM; 30m). First-order topographic parameters were used to assess terrain wind exposure that depicts high-altitude mass loading zones. We also performed spatial network analysis of topographic relief to evaluate areas of relief production and tectonic uplift/deformation. Preliminary results depict significant variation in wind-direction patterns over time that result in significant spatial variation in orographic precipitation governed by the interplay between the Westerlies and the Monsoon. Simulated orographic precipitation zones are spatially coincident with basin and glacier size, location of large tributary glaciers, as well as glacier erosion histories that have produced significant meso-scale basin relief. Network analysis reveals spatial anomalies of relief that highlight uplift zones because of coupled erosion-uplift dynamics. Our results reveal that climate-topography relationships must be accounted for in order to explain mountain dynamics in the Karakoram. In combination with paleoclimate simulations from the Last Glacial Maximum and through the Holocene, which indicate significant changes in monsoon strength and location, our results may explain regional variability in glacier geochronology.