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 und...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=axb)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 slopealtitude 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 slopealtitude 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.展开更多
Runnels are characteristic erosional features on karstified soluble rocks and can occasionally develop on less soluble rocks(i.e.sandstones and granites) but are poorly reported in Malaysia.This research summarizes bo...Runnels are characteristic erosional features on karstified soluble rocks and can occasionally develop on less soluble rocks(i.e.sandstones and granites) but are poorly reported in Malaysia.This research summarizes boulder distribution,size,petrology and runnel morphology in a Pleistocene post-glacial mudflow on Mount Kinabalu.The goal is to investigate the runnel formation on granites.Colonization of boulders by cyanobacteria,mosses,lichens and higher plants is observed and related to rock surface meso-scale and micro-scale features.The coarse porphyritic texture of the granite contributes to the fragmentation and mechanical weathering of large K-feldspar crystals in the runnels.The damp runnel micro-environment is preferentially covered with mosses further enhancing weathering and erosion.As runnels deepen,the remnant protruding fins of rock weaken and may break off.The runnels are subaerial pseudokarst features,not the result of dissolution.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.41971003)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant Nos.2019QZKK0205)the Science and technology Project of Tibet Autonomous Region(Grant Nos.XZ202101ZY0001G)。
文摘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=axb)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 slopealtitude 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 slopealtitude 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.
文摘Runnels are characteristic erosional features on karstified soluble rocks and can occasionally develop on less soluble rocks(i.e.sandstones and granites) but are poorly reported in Malaysia.This research summarizes boulder distribution,size,petrology and runnel morphology in a Pleistocene post-glacial mudflow on Mount Kinabalu.The goal is to investigate the runnel formation on granites.Colonization of boulders by cyanobacteria,mosses,lichens and higher plants is observed and related to rock surface meso-scale and micro-scale features.The coarse porphyritic texture of the granite contributes to the fragmentation and mechanical weathering of large K-feldspar crystals in the runnels.The damp runnel micro-environment is preferentially covered with mosses further enhancing weathering and erosion.As runnels deepen,the remnant protruding fins of rock weaken and may break off.The runnels are subaerial pseudokarst features,not the result of dissolution.
