Since the Little Ice Age and as a consequence of climate warming,many recently deglaciated forefields have become and will continue to evolve into large ice-debris complexes exposed to periglacial processes and environment.Such transitional processes have significant impli-cations for geomorphologic shaping and water supply for the downstream communities,especially in arid regions,but our understanding of their evolutionary processes and their potential geomorphic and hydrological impacts is still limited.A landform transition from partly debris-covered glaciers to ice-rich permafrost debris undergoing slow viscous creep was revealed in the Aerzailaikunai Valley in the eastern Tianshan Mountains in China based on the results of in-situ observations and measurements(boreholes,ground temperature monitoring,electrical resistivity to-mography surveys,and continuous global positioning system measurements,among others).The internal structure of ice-till mixture contains pure ice layers,supersaturated frozen sands with ice lenses,and ice-bearing blocks with maximum volumetric contents of heterogeneous ice at 35％—60％.Beneath an 1.5-m-thick active layer,permafrost reached far into the underlying bedrock with the mean annual ground temperature of-2.1℃at the depth of 20 m.The higher surface velocities(with an accumulative displacement of 65 mm from October 2019 to May 2020)and extremely high electrical resistivity(several million Ω m)of the debris-covered glacier margin were in sharp contrast to those of the pro-gressively stabilizing ground surface(up to 16 mm)and the lower zones with relatively smaller electrical resistivity(several thousand Ω m).Combined with the borehole stratigraphy(higher rock content),monitored ground temperatures(permafrost environment),lower electrical resistance(ice-rich moraine),and continuous global positioning system results(viscous creeping),this study documents a transition from glacial to periglacial conditions,materials and processes characteristic of cold-dry ice-clad mountains,and reinforces the theory of the transition from debris-covered glaciers into morainically originated rock glaciers.

Yu ZHOU;Guo-Yu LI;Hui-Jun JIN;Sergey S.MARCHENKO;Wei MA;Qing-Song DU;Jin-Ming LI;Dun CHEN

State Key Laboratory of Frozen Soils Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Da Xing'anling Observation and Research Station of Frozen-ground Engineering and Environment,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Jagdaqi 165000,China;School of Civil Engineering and Institute of Cold Regions Science and Engineering,Northeast Forestry University,Harbin 150040,China;Geophysical Institute,University of Alaska Fairbanks,Fairbanks,AK 99775,USA

气候变化研究进展（英文版）

[1]Yu ZHOU;Guo-Yu LI;Hui-Jun JIN;Sergey S.MARCHENKO;Wei MA;Qing-Song DU;Jin-Ming LI;Dun CHEN-.Viscous creep of ice-rich permafrost debris in a recently uncovered proglacial area in the Tianshan Mountains,China)[J].气候变化研究进展（英文版）,2022(04):540-553

proglacial,deglaciated,forefields,periglacial,Aerzailaikunai,gressively,morainically

Viscous,ice,rich,permafrost,debris,recently,uncovered,area,Tianshan,Mountains,China,Since,Little,Ice,Age,consequence,climate,warming,many,have,become,will,continue,evolve,into,large,complexes,exposed,processes,environment,Such,transitional,significant,impli,cations,geomorphologic,shaping,water,supply,downstream,communities,especially,arid,regions,but,our,understanding,their,evolutionary,potential,geomorphic,hydrological,impacts,still,limited,landform,from,partly,glaciers,undergoing,slow,viscous,was,revealed,Valley,eastern,results,situ,observations,measurements,boreholes,ground,monitoring,electrical,resistivity,mography,surveys,continuous,global,positioning,system,among,others,internal,structure,mixture,contains,pure,layers,supersaturated,frozen,sands,lenses,bearing,blocks,maximum,volumetric,contents,heterogeneous,Beneath,thick,active,reached,far,underlying,bedrock,mean,annual,depth,higher,surface,velocities,accumulative,displacement,October,May,extremely,several,million,margin,were,sharp,contrast,those,stabilizing,lower,zones,relatively,smaller,thousand,Combined,stratigraphy,monitored,temperatures,resistance,moraine,creeping,this,study,documents,conditions,materials,characteristic,cold,dry,clad,mountains,reinforces,theory,originated

0.554215