Ice flux of alpine glaciers controls erosion and landscape in the Nianbaoyeze Shan, northeastern Tibetan Plateau

The evolution of mountainous topography is the result of the interactions of climate, topography, and erosion. Glaciers are one of the most active erosional forces sculpting mountainous regions. However, our ability to understand this erosional force is limited by the controversy regarding the major factors controlling glacial erosion. We selected the Nianbaoyeze Shan, which is occupied by subcontinental glaciers (likely cold-based or polythermal glaciers) in the northeastern Tibetan Plateau, to study how erosion by alpine glaciers sculpts the landscape. We first applied a power law model (y = ax(b)) fit to the cross-profiles of glacial valleys and analyzed the controlling factor of glacial erosion; we then identified the morphometric characteristics of the cirques to analyze the influencing factors, and investigated the development patterns of glacial valleys and cirques. Finally, we used hypsometry and the slope-altitude curves and reconstructed the palaeo-glacier surfaces and palaeo-Equilibrium Line Altitudes (ELAs) to determine if the glacial buzzsaw effect had impacted this glaciated region with subcontinental glaciers. Our findings show that ice flux is the main factor controlling glacial erosion. In this region, decreasing temperatures promote an increase in glacier mean size (i.e., ice flux), which enhances the rate of glacial erosion. Cirque morphology is mainly influenced by aspect and the ELA. The development patterns of glacial valleys and cirques were dominated by a widening process. The ELAs of Marine Isotope Stage (MIS)-3 derived from the cirque floor altitudes or the Accumulation Area Ratio (AAR) and Area-Altitude Balance Ratio (AABR) coincide with the hypsometric maximum and the reduction in slope-altitude curves, which indicates that glacial buzzsaw has impacted this region. Furthermore, the glacial buzzsaw effect has profoundly influenced the mountain heights and topographic evolution in this subcontinental glaciated region.