The spectacular glacial erosional and depositional landforms on the Tibetan Plateau （TP） and its surrounding mountains are direct imprints of the Quaternary glaciations and contain essential information of palaeoclimate change and landscape evolution. According to the glacial sequences in the TP and its surroundings， the moraine complexes with fresh-looking tills， distribute beyond the modern glacial landforms are assumed to be formed during Little Ice Age （LIA） glacial advance. The timing and extent of this glacial advance is critical to understand the spatiotemporal variation of ancient glaciers and palaeoclimate change during the past millennium. Here， the first moraine complexes in the west （main） and east （hanging） valleys of Yongqu River valley， which originates from the southern slope of Bujia Gangri were investigated by terrestrial in situ cosmogenic nuclides （TCN） 10Be surface exposure dating techniques. Their ages are （203±52） years （MW1， n=4） and （162±58） years （ME1， n=3）. Our dating results， position， geomorphological and sedimentary relationship， characteristics of boulders and moraines， soil development and vegetation coverage and other features demonstrate that the first set of moraines were formed during the LIA glacial advance. This glacial event is synchronous with those in the TP and its surroundings. Combining the climate proxies in the TP and its surroundings， it is reasonable to infer that the cooling during LIA was a main control factor to force this glacial advance.
Zheduoshan Mountains is located in the eastern margin of the Qinghai-Tibet Plateau， in the transition zone from plateau to mountains and valleys， with well-preserved glacial landforms. It is of great significance to study the glacial landforms to reveal the coupling mechanism between the evolution of topography and paleoclimate change in the eastern margin of the Qinghai-Tibet Plateau. On the basis of field investigation， combined with Google Earth remote sensing image， The Second Glacier Inventory Dataset of China （Version 1.0）， glacial landforms and its characteristic parameters are identified and calculated. A total of 189 ancient glaciers were identified， covering an area of 497 km2. Based on the available chronological data， the glacial landforms in the study area are mainly remains of glaciations since the last glacial maximum （LGM）. The results show that the height of LGM glacier equilibrium line （ELA） is 4 380 m on the west slope and 4 110 m on the east slope， with a difference of 270 m， indicating that the east side of the watershed is more favorable for glacier development. The widely developed glacial lakes， glacial bedrock surface， roche moutonnée， etc.， and deep glacial trough （U-shaped Valley） indicate the characteristics of temperate （marine） glaciation； the positive glaciation amplitude， glacial valley orientation and erosion landforms reveal that the terrain conditions and water vapor sources in the accumulation area have an important impact on the development of glaciers in the study area.
The environmental information recorded by the stable carbon isotope compositions of soil organic matter （δ13C） is crucial to the study of climate change， but the mechanism by which the soil δ13C responds to climate change at high altitude remains unclear. A systematically analysis on the δ13C of 36 surface soil samples in the upper and middle reaches of the Yarlung Zangbo River， southern Qinghai-Tibet Plateau （altitude between 3 500 and 5 100 m） was carried out， and the responses of δ13C to climatic factors were discussed. Results showed that the δ13C values ranged from -24.6‰ to -15.2‰， with an average value of -20.8‰， indicating that the aboveground vegetation is C3/C4 vegetation type.With the increase of altitude， the proportion of C4 plants decreased but C3 plants increased， which dominated the difference of δ13C composition. when the altitude increased by 100 m， the δ13C became lighter by 0.5‰. Further analysis suggested the growing season temperature may be the main climatic factor affecting the variation of δ13C， and the contribution of precipitation and atmospheric pressure were lower.
Different information is contained in fine or coarse among earth surface loose sediments. These differences were coursed by the sources of the sediments， processes of transport and deposition of the sediments， and the weathering of sediments after they deposited. We can trace the sources of the sediments， or reconstruct the past environment of study area by the different information. Tracing sources of aeolian sediment is key to reconstructing earth surface processes in arid areas and interpreting the paleoenvironmental significance of aeolian sequences. The Qaidam Basin， Co Nag Lake， and Yarlung Zangbo River in the Qinghai-Tibet Plateau （QTP） were chosen as our study area because of their important significances both in climate and landform. Loose sediment samples， including aeolian dune sand， loess， lacustrine deposits， fluvial sediments， proluvium， and eluvium-deluvium， were collected from the three areas. The sediment samples were separated into two parts by dry sieving： a coarse part with grain size between 75 and 500 μm， and a fine part less than 75 μm in grain size. Laboratory measurements of rare earth elements， trace elements， and Sr-Nd isotopic composition were made. Multidimensional scaling （MDS） represents the proximity of data （e.g. measures of similarity， closeness， relatedness） as distances among points in a multidimensional （typically two-dimensional） space. We calculated the Euclidean distance of every two samples in our samples and then applied classical MDS model to fit the data. The results show that the coarse and fine particles of sediment samples， the loose sediments in our study areas， QTP， differ in light mineral composition， trace and rare earth element composition. Compared to the coarse particles， the fine particles are rich in clay minerals that are easily affected by chemical weathering， and minerals with low hardness such as calcite， which is easily to be abraded. The fine part of the sediment contains more environmental information， suggesting that the fine part cannot be directly compared between different climate zones for provenance identification. To trace sediment sources， using the coarse part based on the grain-size distribution of the targeted sediment would be more appropriate.
Under the background of the transition from Quaternary glaciation to interglacial period or modern global warming， glacier retreat will cause instability of bedrock and till slopes， and even glacier debris flow and other paraglacial surface processes. Therefore， these processes have become important factors driving the geomorphic evolution in paraglacial area and its downstream valley. However， there are still two problems in the study of the temporal and spatial variation characteristics and driving factors of paraglacial processes. Firstly， there is a lack of discriminating methods between various paraglacial deposits， till and other diamictons. Secondly， insufficient attention has been paid to the effects of paraglacial processes on downstream valley evolution. Therefore， we studied the till and paraglacial deposits on the eastern slope of Mt. Gongga， a typical temperate glacial area， and compared the grain size and quartz grain microtextures with two continental glacial tills. The results show that all kinds of paraglacial deposits have formed certain uniqueness when inheriting various characteristics of the till in the source area， indicating that the comprehensive comparison method of these two indicators can realize the effective discrimination of various paraglacial deposits and till. At the same time， due to the type of glacier， action period and lithology could affect the grain size of till and quartz grain microtextures in the source area， the discrimination based on these two indicators should be limited to the same area， and the common characteristics of deposits should be avoided. Based on the comparison and cluster analysis of till on the eastern slope of Mt. Gongga， various paraglacial deposits and grain size and quartz grain microtextures in different layers on the Moxi Platform， it is confirmed that the bottom of the platform is MIS3 till， the middle is debris flow deposits since MIS3， and the upper may be fluvial deposits or glacial debris flow deposits transformed by rivers. The accumulation and exposure age of paraglacial process in the Moxi Valley indicate that the intense paraglacial process caused the Moxi Valley to continue accumulating during the transition from the last glaciation to the Holocene， even until about 6~7 ka， and then turning into incision.
Equilibrium line altitude （ELA） is a direct reflection of glacier response to climate change. Analyzing its variation characteristics is of great significance to understand the current and past climate. However， because there are only a few glaciers in the Qinghai-Tibet Plateau and its surrounding areas with long-time scale continuous observation data， the height of the equilibrium line of most other monitored glaciers is only the observation data in recent years， and the time series is relatively short. At the same time， the distribution of plateau meteorological stations is mainly concentrated in the eastern edge， and there is no station detection data in some glacier distribution areas， which largely limits the comparative analysis and research on the height variation of glacier equilibrium line and its climate sensitivity in different regions. The middle part of Nyainqêntanglha Mountains as the southwest monsoon channel and the watershed of the Nu River and the Yarlung Zangbo （Brahmaputra） River， the study of ELA variations and characteristics can provide a reference for the interrelationship between glacier changes and climate in different basins. In this study， the natural domain method is used to select the glacier distribution area in the middle of Nyainqêntanglha Mountains as the research point. Through the extraction and analysis of remote sensing images， glacier cataloging data and meteorological data， and using air temperature， solid precipitation data and ELA as input parameters， we try to establish multiple linear regression equations， reconstruct the glacier ELA in the study area from 1984 to 2019， and discuss and analyze the variation trend of ELA on its interannual scale regional heterogeneity and climate response. The results show that the multi-year average ELA in the study area is 5 360 m a.s.l.， showing an overall upward trend. The research on the annual variation of ELA shows the characteristics of fluctuation. The fluctuation range of ELA is 5 360~5 420 m a.s.l.， the fluctuation range is about 60 m， and the average rising rate is 1.57 m·a-1. Analysis of ELA variations in different watersheds shows that from 1984 to 2019， the ELA ranges of Xiaqu， Yigong Zangbo and Maiqu are 5 178~5 492 m a.s.l.， 4 855~5 120 m a.s.l. and 5 150~5 485 m a.s.l.， respectively. Under the background of climate warming， the variations of ELA are generally increasing， but the variations of ELA in different basins are different. Among them， the ELA variation in the Maiqu basin is the largest， with an average increase of 335 m， the Xiaqu basin and the Yigong Zangbo basin increased by 265 m and 314 m， respectively， with a rising rate of 9.57 m·a-1， 7.57 m·a-1， and 8.97 m·a-1， respectively. At the same time， statistical analysis shows that the annual average ELA elevations of the Xiaqu， Yigong Zangbo and Maiqu watersheds are 5 335 m a.s.l.， 4 987 m a.s.l. and 5 317 m a.s.l.， respectively， showing a decrease in the northwest-southeast direction， and a higher elevation on the north slope. Based on the statistics of average air temperature， solid precipitation and glacier ELA in the middle of Nyainqêntanglha Mountains from 1984 to 2019， the analysis of the response of glacier ELA variation to climate shows that the glacier ELA in the study area is mainly controlled by air temperature variation. With the air temperature variation of 1 ℃， the fluctuation range of ELA is 126.02 m. Moreover， with the continuous increase of air temperature， the glacier ELA in the middle of Nyainqêntanglha Mountains rises and the glacier will continue to retreat.
After a detailed field investigation in the Zoige Basin， a clear， representative and complete sedimentary stratigraphic profile was discovered on the bank of the first bend of the Yellow River. Through the observation and analysis of sedimentological and stratigraphic characteristics and sedimentary facies， combined with laboratory grain size analysis， data processing and dating. The results show that the blue-gray paleolacustrine sedimentary layer in the lower part of the profile reflects the deep closed lake in the basin before the OSL age of 35 ka. The alternate layer of sand and peat covered on it reflects that after the disappearance of the paleolake at 30 ka， peat swamps appeared at the bottom of the paleolake， and the effect of sandstorms prevailed at the same time.The turbid yellow-orange paleoflood sedimentary layer （OFD1） reflects that between 30~27 ka， large-scale floods from the source area of the Yellow River entered the Zoige Basin， flooded at the bottom of the paleolake and carried good sorting. Fine sand and silt sand are accumulated. The floodplain-aeolian sand layer with a thickness of 5~7 m in the middle of the section can be seen as undulating paleo-sand dunes when traced along the river bank.This strongly indicates that during the last glacial peak and deglacial period， the climate was arid and cold， the Yellow River had been cut down to form its channel， and its floodplain sediments were blown up by the strong wind to form rolling sand dunes. The turbid yellow-orange paleo-flood sedimentary layer （OFD2） covered on this layer reflects that in the 9.86~8.28 ka of early Holocene， the flood from the source area of the Yellow River entered the basin again and deposited on the paleo lake bottom on both sides of the first bay of the Yellow River. Good sorting of fine sand and silty sand. After the mid Holocene， wind-sand action was still prevailing in the Zoige Basin， the Yellow River trough was deep cut， and both banks of the First Bay received sandstorm deposits. Under relatively warm and humid climatic conditions in the mid-Holocene， sand-dust storm sediments were transformed into subalpine meadow black soil at any time， with extremely high maturity. Since the late Holocene， the process of wind-sand and sand-dust storm deposition has continued， and the sand-dust storm sediments have also been transformed into subalpine meadow black soil layers. The research in this paper has important scientific significance for the in-depth understanding of environmental changes and the evolution of surface processes in the source region of the Yellow River and the climate and hydrological changes since the Late Pleistocene.
The research in this paper mainly focuses on the banks of the Tangke section of the Yellow River in the Zoige Basin， and studies the natural sedimentary profiles directly exposed by the lower cut of the Yellow River. The purpose is to establish the stratigraphic sequence and age frame of soil sediments， and to deeply explore the upstream erosion of the Yellow River into the interior of the Zoige Basin. The characteristics of regional surface process changes during the process provide chronological and stratigraphic evidence for the Yellow River running through the Zoige Basin. Through field investigation of the Zoige Basin， a sequence of riparian soil sediments containing deep lacustrine sediments was found on the right bank of the Tangke section of the Yellow River in the middle of the basin， and in-depth observations and systematic sampling were carried out. In the laboratory， the chronological framework was established by using the optical luminescence and AMS14C dating techniques. Combined with the macroscopic characteristics and physicochemical properties of soil sedimentary facies at various levels， the environment and surface processes were thoroughly analyzed and discussed in the Zoige Basin since the demise of the last glacial paleolake. The research results show that the ancient Yellow River eroded headward along the Maqu rift valley at 37 ka， which connected the Zoige ancient lake water system， while the interior of the basin was a deep lake environment before 30.9 ka， and a blue-gray lacustrine silt layer was deposited stably. After 30.9 ka， the Yellow River penetrated through the interior of the Zoige Lake Basin， the ancient lake water leaked out and disappeared， and the original ancient lake water system was completely transformed into the Yellow River source water system. A large amount of turbid yellow-orange sediment carried by the Yellow River from the upper reaches of the lake basin was deposited in large quantities， covering the paleolacustrine sediment， and aeolian sand action prevailed in the lake basin. During the Last Glacial Maximum （LGM）， the loose sediments in the basin were generally transformed by the freezing and thawing of the periglacial environment， forming freeze-thaw folds. From 14.6 to 12.5 ka， in response to the warm climate in the B?lling-Aller?d （B/A） period， the mountain glaciers around the basin melted and melted water flowed into the basin. Various shallow depressions at the bottom of the ancient lake basin formed shallow lakes of different sizes. Sand layers of littoral-shallow lacustrine facies were deposited. From 12.5 to 11.7 ka， corresponding to the global Younger Dryas （YD） event， the climate became cold again and transformed into a permafrost environment in the basin. Paleo-earthquake disturbances have formed complex double-fold folds. In the Holocene， the climate gradually became warm and humid from 11.7 to 4.8 ka， and the shallow depression at the bottom of the ancient lake basin became a silty swamp environment， and a muddy soil layer was developed. In the middle and late Holocene 4.8~1.8 ka， it transformed into a swamp meadow environment and developed swamp meadow black soil paleosols. After 1.8 ka， the marshes in the basin shrank， aeolian sand activities prevailed， the floodplain sand was transformed into sand dunes by wind， and the near-source sandstorm sediments in the riparian highlands were transformed into subalpine meadow black soil modern soils by pedogenesis.
Lakes over the Qinghai-Tibet Plateau are considered as the important indicators of regional climate variability. Since the mid-1990s， the expansion caused by the increasing precipitation due to the warming and humidifying environment and the accelerated melting of glacier and frozen soil has been the most prominent environmental change feature of Qinghai-Tibet Plateau. It is worth mentioning that the spatial distribution characteristics of lake water level changes are highly consistent with the precipitation changes in the affected areas of Westerlies and Indian monsoon zone. The harsh natural environment makes it difficult to achieve the field observations of inland lakes on the Qinghai-Tibet Plateau. Currently， the development of remote sensing technologies can overcome the above-mentioned limitations， which has become the main research means of lake change monitoring on the Qinghai-Tibet Plateau. Based on the remote sensing monitoring technologies and methods， this paper summarized the research progress on the aspects of lake extent extraction， water volume change， water environment and ice phenology. Some studies have applied multi-source remote sensing and hydrological models to quantitatively evaluate water balance in the basin scale. The results have shown that the main contribution factor of lake water increase in inland areas of Qinghai-Tibet Plateau was the increase of precipitation， while the contribution of glacier melting， frozen soil melting and other factors was relatively small. Currently， academic circles generally believe that the annual variation of precipitation is the main reason for the recent changes of lakes in Qinghai-Tibet Plateau， and the accelerated melting of glacier and frozen soil further accelerates the expansion of lakes or inhibits the contraction of some lakes. The previous research on the climate response mechanism of lake changes in the Qinghai-Tibet Plateau was mostly limited to the qualitative description of climate factors， such as precipitation， evaporation， temperature， wind speed and glacier melting， etc. Now， in the aspect of lake water balance， more and more researches are making progress in quantification. In the future， with the open sharing of more remote sensing data as well as the building of more hydrological and meteorological stations， better data conditions will be provided for the quantitative research on water balance of lakes on the Qinghai-Tibet Plateau.
The warming rate of the Tibetan Plateau in recent decades is about twice the global average warming rate in the same period， with a great impact on the vegetation and adding many uncertainties to the fragile ecological environment. It is particularly important to accurately assess vegetation changes in the region. Different sources of satellite remote sensing data can introduce some uncertainty into the assessment results， and past studies on the variability of multi-source data assessment in the region are unclear. Therefore， in this study， the NDVI datasets from MODIS， GIMMS and SPOT were used to evaluate the vegetation change on the Tibetan Plateau region from 2000 to 2014 through Sen’s slope estimator and Mann-Kendall trend test， and to assess the differences among different datasets. The results illuminated that SPOT NDVI reflected significant and rapid vegetation greening， with 27.44% of the image pixels significantly greening， exceeding MODIS and GIMMS NDVI by 4.10% and 15.89%， respectively， and the significant greening trend in the growing season reached 0.0182 （10a）-1， higher than the other data 0.0078~0.0090 （10a）-1. The percentage of significant greening pixels and the greening trend of MODIS NDVI gradually decreased as the resolution increased， and the difference in the percentage of significantly greening pixels between MODIS data is less than 2.80%. The proportion of significantly browning pixels in GIMMS NDVI averaged 5.83%， exceeding the other data by 3.37%~5.51%， with the most significantly browning pixels in spring （7.88%） being comparable to the proportion of significantly greening pixels. The regional mean NDVI had a minimum significant greening trend of 0.0092 （10a）-1 and showed vegetation browning in spring and summer. Therefore， when exploring the characteristics of vegetation change on the Tibetan Plateau based on GIMMS NDVI， especially for spring phenology studies， it may cause greater uncertainty in the results. In contrast， SPOT and MODIS NDVI show a high degree of agreement and can complement each other in exploring vegetation change on the plateau.
Glacial models have been widely used in simulating and predicting the impact of climate change on glaciers in the future. With the development of geomorphological mapping， digital elevation models， geochronology， and palaeo-climate records， glacial models have also been used in simulate palaeoglacier evolution and reconstruct palaeo-climate conditions. In this paper， we reviewed the two types of glacial models： landform-ice surface profile models and coupled mass balance-glacial dynamic models， which have been used for palaeo-glacial reconstruction. We first introduced the principles and framework of using these models for palaeoglacier simulation， as well as the methods to calibrate model parameters and validate model outputs using geomorphic evidence. We then summarized the studies and major findings in using glacial models to reconstruct the extent， volume， and equilibrium-line altitude （ELA） of palaeoglaciers， estimate palaeo-climate conditions during different glacial stages， and evaluate the results derived from geochronological datasets on the Tibetan Plateau and its surrounding mountains.The landform-ice surface profile models interpret ice thickness， area， and volume of a palaeoglacier based on the steady-state ice surface profile derived from the principles of ice physics and flow dynamics， as well as the geomorphic landforms to constrain ice boundary （e.g.， moraines） and local heights （e.g.， trimlines）. The commonly used model is the one-dimensional flowline model， which has been implemented in Excel and ArcGIS. The landform-ice surface profile models are relatively easy to use but cannot directly derive the palaeo-climate information associated with glacial stages. Indirect methods are necessary for the palaeo-climate reconstruction based on the estimated ELA of the palaeoglacier.The coupled mass balance-glacial dynamic models simulate glacial evolution based on mass balance and ice flow dynamic models using climate data or scenarios. The mass balance of a glacier can be determined by the energy and mass balance model， positive degree-day model， and the ΔT-ΔP empirical relationships at the ELA. The ice dynamic models can be one-dimensional， two-dimensional， and three-dimensional based on model complexity. These models can be used to reconstruct palaeoglaciers based on the steady-state simulation of a set of ΔT-ΔP scenarios and the continuous simulation using long-term climate records， such as the proxy records reconstructed by tree rings， ice cores， and lake sediments， and the climate records simulated by the GCM models.The coupled mass balance-glacial dynamic models require the calibration of a lot of parameters， limiting the use in areas where required data are unavailable. The simulated glaciers have been mainly validated with field-observed geomorphic evidence by visual comparison. Several methods have been developed to validate the simulations by quantifying the overlap-fit percentage or measuring the offset between model-simulated and field-reconstructed ice boundaries for large ice sheets， which also have the potential to be implemented in the reconstruction of mountain glaciers. The coupled mass balance-glacial dynamic models are driven by the climate data or scenarios； thus， these models can be used directly to estimate suitable palaeo-climate conditions associated with glacial evolution.Both landform-ice surface profile and coupled mass balance-glacial dynamic models have been applied to the palaeoglacier reconstructions on the Tibetan Plateau and its surrounding mountains. The studies have been mainly from the marginal mountains on the southern， southeastern， and northeast Tibetan Plateau， whereas few studies have been conducted on the central and northern plateau. In terms of glacial stages， most reconstructions have focused on the Last Glacial Maximum， lacking the reconstructions of other glacial stages. Due to the requirement of long-term climate records， the continuous simulation of glacial evolution based on the coupled mass balance-glacial dynamic models are still in the early stage.Future studies are necessary to continuously improve model structure and efficiency， integrate model input/output with ArcGIS or other GIS packages， encourage the share of source codes and data， and establish standard test datasets for model comparison. The integration of geomorphic evidence to calibrate model parameters and the investigation of the relationships between changing climate systems， glaciated topography， and mass balance during different glacial stages are also critical to improve the applications of glacial models on palaeo-glacial reconstruction. This review provides a solid foundation to promote the applications of glacial models on palaeo-glacial reconstruction and improve the understanding of the extent， evolution， and climate-driven mechanism of palaeoglaciers.
Glaciers are sensitive to climate change， and the Tibetan Plateau （TP） is known as the third pole， where the most extensive glaciers develop on it. The Last Glacial Maximum （LGM） occurred between 18 and 24 ka， during which the glaciers expanded on a large scale as the global cooling. It is of great significance for understanding the evolution of glacial water resources and the paleoclimate conditions of TP to reconstruct the LGM glaciers. Basongcuo Catchment and Pai valley are located in the southeastern TP， which is mainly controlled by the Indian monsoon and is a key area for understanding the relationship between the Indian monsoon and glacier changes. The cosmogenic 10Be exposure dating method has been used to date the moraine in the Basongcuo Catchment and Pai valley， and the results show that there were LGM glacial activities in both places. Based on the glacial geomorphology and their existing 10Be exposure age in Basongcuo Catchment and Pai Valley， a glacier surface profile model was applied to quantitatively reconstruct the ice volume and glacier extent， while previous studies have roughly estimated the glacier area only based on the glacial geomorphology. And the equilibrium line altitude （ELA） of the glaciers during the Last Glacial Maximum was calculated by using the accumulation area ratio （AAR） and area altitude balance ratio （AABR） methods. The 1998—2019 meteorological observation data of eight meteorological stations near the study area obtained from the National Meteorological Data Center showed that the summer temperature lapse rate in the area is 4.0 ℃·km-1， and the precipitation gradient is 224 mm·a-1·km-1. Based on these parameters， the climatic conditions in LGM were reconstructed by precipitation-temperature （P-T） empirical regression model and temperature lapse rate （LR） model. The results show that the glacier area of the LGM period in the Basongcuo Catchment is about 982.3 km2， which is 4.5 times the area of modern glaciers， and the ice volume is about 274.4 km3， there is no modern glacier distribution in the Pai Valley， and the glacier area in the LGM is 5.76 km2， the ice volume is about 0.51 km3 The ELAs of the two glaciers in the LGM period were 4 472~4 497 m and 3 619~3 669 m， respectively， which is 535 m and 1 034~1 184 m lower than modern glaciers. The reconstructed ELAs are broadly similar to that of nearby paleoglaciers. In order to better reconstruct the LGM temperature， this study takes into account the influence of tectonic activities on the depression of ELAs. The block of the study area has been eroded at a rate of at least 5 mm·a-1 since the LGM. Therefore， this study used a denudation height of 120 m to correct the reconstruction of ELA， so the ΔELA result may be underestimated （by no more than 4%）. In addition， considering the uncertainty of the temperature change caused by erosion at the temperature lapse rate （4.0 °C·km-1）， the final temperature drop was underestimated by about 0.48 °C. Therefore， when the LGM precipitation is roughly 60% lower than that at present and considering the effect of tectonic denudation， the average summer temperature of the glaciers of Basongcuo Catchment and Pai Valley during the LGM period was about 2.96~4.89 °C lower and 5.09~6.99 °C lower than that now. Obviously， the value of ΔELA and temperature changes in the Basongcuo Catchment are relatively small， which may be because the glaciations in the two places occurred at different stages of the LGM period. But on the whole， the reconstruction results of the LGM temperature drop values in the two regions are within the range of that reconstructed from previous studies and are comparable to other paleoclimate records.
Knowing what controls glacial erosion and their interactions is not only very important for understanding the physical mechanisms of glacial erosion and glacial landform evolution， but also the fundamental for exploring the relationships between climate， tectonics and topography. However， researchers before just analyze the main controlling factors of glacier erosion in areas under similar tectonics， which leads to few knowledge about the impact of tectonics. Then， whether tectonics is the main controlling factor of glacier erosion？ And how does it affect glacial erosion？ The Quaternary glaciation in the northern Tianshan Mountains are spectacular， and sculpts abundant glacial relics under various climate and tectonics in different regions， which make the northern Tianshan Mountains an appropriate study area for discussing the key problems above. We select 7 glacial basins on the north slope of the northern Tianshan Mountains from east to west， and then compare the distribution of glacial erosion and its influential factors based on the Hkr values and qualitative or quantitative data of all factors in each basin. Results show that the glacial erosion in the 7 basins generally decreases from west to east， which mainly induced by the comprehensive effect of tectonics， climate， and topography. Among all the factors， peak elevation and precipitation have the most significant impact on glacial erosion through ice flux， and tectonics may affect glacial erosion by influencing peak elevation， accumulation area， and thus ice flux， but what extent of tectonics on glacial erosion need more investigation. Therefore， maybe the ice flux is the fundamental factor which results in the difference of glacial erosion in the northern Tianshan Mountains.
The Last Glacial Termination marks the transition from the global Last Glacial Maximum （LGM） to the interglacial Holocene. This transition is the most striking climate reorganization on Earth， over the past 100 ka. The global LGM termination has been widely regarded as nearly synchronous around the world， yet， proposed mechanisms behind this synchroneity remain contentious. Mountain glaciers in the mid-latitude regions， such as those in the Tibetan Plateau （TP）， are highly sensitive to climate change， and hence can provide invaluable information for clarifying this conundrum. However， glacial chronologies as regards the LGM termination remain extremely limited in the TP and its surrounding mountains. This impedes a full understanding of potential climatic mechanisms forcing glacial fluctuations in the vast TP. In this study， we examined the lateral moraine remnants formed near the valley-mouth of the Yudongqu valley， Gangrigabu Range， southeast TP， using 10Be surface exposure dating. Apparent 10Be exposure-ages （n=14） obtained from four out of six lateral moraine relics there range from （13.3±1.0） ka to （19.3±1.4） ka. On the basis of statistical test， we identified six potential outliers with the aid of probability density function plots. We then examined whether the clustering of remaining 10Be exposure-ages were merely caused by measurements or not using the reduced chi-square test and P value. After excluding the potential outliers， the two geomorphologically younger moraines were robustly dated to （17.0±0.5） ka and （18.4±1.0） ka， representing two glacial culminations that correspond well to the LGM termination. We then compared the 10Be-based moraine chronologies with climatic proxies， such as Northern Hemisphere summer solar insolation， ice-volume equivalent sea level， stalagmite δ18O record， chironomid-inferred mean July temperature record， sea surface temperature （SST）， and atmospheric CO2 concentrations. We conclude that the two glacial events identified in the Yudongqu Valley were in response to changes in summer air temperature connected with SSTs in the Indo-Pacific Warm Pool （IPWP）.
North America is rich in late Quaternary glaciation remnants. Over recent years， a large number of exposed ages of glacial boulders or bedrock have been obtained using cosmogenic radionuclide （CRN） dating， allowing a potential reconstruction of the North America’s late Quaternary evolutionary glaciation sequence. In this paper， the 10Be exposure ages of 4 357 independent samples from North America were compiled and classified according to confidence classes （A-C）. All exposure ages were grouped according to the original literature and recalculated using the latest version of the exposure age calculator. Since the erosion rate of each study area could not be determined， the calculation of exposure ages in this study was based on a zero erosion assumption. We considered the ages we adopted to be minimum exposure ages. After division into confidence classes， 424 groups of 1 956 exposure ages with well-clustered and moderately-clustered classes were obtained. Due to considerable overlap of data， the overall range in glaciation in North America appeared too wide. We therefore constructed an evolutionary glaciation sequence and determined the peak age of the probability density curve for four large regions and 15 subregions in North America. The subdivision of regions at all levels was based on glacier shape， scale and topographic conditions. Combining these results with paleoclimate data， we compared and analyzed the response of the resulting evolutionary glaciation sequence to high-resolution climatic events， thereby summarizing the characteristics of each stage of the North American evolutionary glaciation sequence. The results showed that North America has experienced many glaciations in the past 150 ka. It is conservatively estimated that the glaciers in North America have experienced large-scale glaciations during at least marine isotope stage （MIS） 6/5， MIS 4/3 and MIS 2. The evolution of glaciers before the Last Glacial Maximum （LGM） was regional. Of these glaciations， the MIS 6/5 glaciation was concentrated in the western part of the United States， with peak ages of 138.7 ka and 118.7 ka， corresponding to the late MIS 6 and early MIS 5. Traces of a MIS 4/3 glaciation are only preserved in Alaska， possibly related to the atmospheric effect of the Laurentian Ice Sheet. The times when the LGM reached its maximum range may not be regionally synchronous. In addition to the principal mechanisms driven by the global climate change， changes in regional climates， the internal dynamics of different glaciers， and atmospheric effects brought about by the Laurentian Ice Sheet may also have been secondary factors. The responses of glaciers to the high-resolution climatic events known as the Heinrich Stadial 1 （HS-1）， the B?lling-Aller?d （B-A） interstadial and the Younger Dryas （YD） event， during the last period of deglaciation， appear to be synchronous， possibly affected by a significant change in the Atlantic meridional overturning circulation （AMOC）. The 10Be exposure ages of North American glaciers also correlate well with the high-resolution ‘Bond’ events that have occurred during the Holocene. In the future， more 10Be exposure age data and climate data are needed to enrich the study of the evolutionary glaciation sequence in North America during the late Quaternary.
Yarlung Tsangpo River is easily dammed， and the relationship between damming events are important for understanding the evolution of the landform in the valley. Many lacustrine are exposed in the terraces in the middle Yarlung Tsangpo valley. Lacustrine terraces in the broad Mailing， Zetang， and Xigazê valley are studied， which indicated dammed palaeo-lake occurred during late Pleistocene in all three broad valleys. However， the spatio-temporal relationship between three palaeo-lakes remain unknown. Based on previous studies， herein analysis the dam locations， genesis， elevations， and ages of the palaeo-lakes. During late Pleistocene， three independent separate dammed palaeo-lakes happened in the middle Yarlung Tsangpo River. They are Gega palaeo-lake （3 180 m a.s.l.） in the broad Mailing valley， Jêdêxoi palaeo-lake （3 585 m a.s.l.） in the broad Zetang valley， and Dazhuka palaeo-lake （3 811 m a.s.l.） in the broad Xigazê valley and the Dazhuka-Yueju gorge. It’s likely advance of glaciers have dammed the Yarlung Tsangpo River during late Pleistocene. The advance rates of the glaciers are different due to the geomorphological difference and the precipitation decrease from Nyingchi to Xigazê， and the time of dam formation were different. The Gega palaeo-lake was dammed by the Zelunglung Glacier at the entrance of the Yarlung Tsangpo Gorge. The Jêdêxoi palaeo-lake was probably dammed at the entrance of the Gyaca gorge. On the contrast， the Dazhuka palaeo-lake was likely dammed at the outlet of the Dazhuka-Yueju gorge. However， the extinction age of three dammed palaeo-lakes were similar （about 13 ka）， indicate strong relationship between the failure events.
As one of the most intensive internal and external dynamics areas of the Tibetan Plateau （TP）， southeastern Tibet is a high-risk area for river damming and outburst flood. Thus， it is of great significance to analyze the evolution process of the paleo-dammed lake for understanding and assessing disaster risk from outburst flood caused by river blockage. southeastern Tibet is one of the most extensively glaciated areas of the TP， both now and during the Quaternary， however， few paleo-moraine dammed lake has been reported in this region. During our recent field investigation， widely distributed lacustrine deposits has been first found from the Baiyu Village to Linqiong Village reaches of the Bodui Zangbo River Valley， eastern Nyainqêntanglha Range， southeastern Tibet. This study used optically stimulated luminescence （OSL） technique to date the lacustrine sediments which are preserved on the surfaces of moraine and terraces near to the Linqiong Village. The OSL ages range from ~6 to ~10 ka，corresponding to the early Holocene. Based on geomorphology mapping and OSL dating， and combined with previous dating results about moraines located at the Baiyu Valley， we speculated that a paleo-dammed events may have occurred during the Heinrich event 1 （H1） in the Bodui Zangbo River Valley. The paleo-dammed lake was caused by a debris landslide originating from H1 moraine at the Baiyu Valley， triggered by the intensive downcutting and lateral erosion by the Bodui Zangbo River. The maximum lake area and volume were ~18.8 km2 and ~0.13 km3， respectively. According to the dating results from moraines and lacustrine deposits， we inferred that the formation time of this paleolake was about between the H1 and 10 ka， and its failure time would be after 6 ka， implying that the paleolake was at last stable for 4×103 years. The Bodui Zangbo River incision lacustrine sediments later， forming multilevel lacustrine terraces.
Chatter mark is crescentic or arc-shaped fracture patterns formed on the bedrock or striated boulder by periodic or intermittent movement of debris carried by glaciers in glaciated area， ranging in size is generally no more than 1 m. In China， the identification markers and terminology of chatter mark are still confusing， quantitative studies are especially lacking， and a systematic disciplinary knowledge has not yet been formed. Therefore， it is necessary to explore the morphological classification， geomorphological characteristics， formation mechanism， distribution pattern， discrimination method and environmental significance of chatter mark based on relevant reports in foreign literature and measurement data obtained from fieldwork， in order to establish a conceptual system to deepen the cognitive framework of chatter mark. From the perspective of terminology， we classify the chatter mark into narrow and broad sense in this paper. The broad conception of chatter mark including five types： curved-cone crack， lunate fracture， crescentic gouge， crescentic fracture， and crescentic scar. The results of Kolmogorov-Smirnov and Jarque-Bera tests of the spacing of 23 crescentic scars are arranged in accordance with normal and gamma distribution at 95% confidence level， which is consistent with the spacing characteristics of rock joints （fractures）. The spacing of 25 crescentic gouges and 35 crescentic fractures are arranged in accordance with normal and gamma distribution by Kolmogorov-Smirnov test， but not by Jarque-Bera test at 95% confidence level. The conclusion is as follows： （1） The main formation mechanism of chatter mark analogous to （R） shear fracture and （T） tensile fracture in the Riedel Shear structure mode and follows the principle of brittle fracture. The chatter marks developed on the glacial polish surface are mainly R fracture， R′ fracture and T fracture. The forward dip of the principal fracture surface of various chatter marks is the key to reveal the mechanism of their formation. （2） Whether curved-cone crack， lunate fracture， crescentic gouge， crescentic fracture or crescentic scar is produced specifically may be related to the thickness and sliding velocity of the glacier， the concave and convex nature of the rock surface and the strength， location， shape and mode of movement （e.g.， rotation， rolling） of the rock frozen in basal ice. （3） The linear arrangement of chatter marks in groups in space， maintaining roughly equal rupture spacing， is basically consistent with the saturation mode theory. （4） The directional and group distribution characteristics of the chatter mark have definite environmental significance. The combination of chatter mark， striae and the polish is an important indicator of glacial relics. The isolated so-called “chatter mark”， without the combination of the glacial erosional landforms， is worthless in indicating glacial action. （5） The “first disclosed chatter mark” in Lushan Mountain， Shandong Province， in recent years are not “direct evidence of Quaternary glacial abrasion”， and there is no “complete evidence group”. The article “Lushan” misinterpreted the relationship between the two corners or arcs of the chatter mark and the direction of glacial movement， which led to an unrealistic misjudgment of the fracture structure of a migmatite surface affected by differential weathering in Lushan. The main peak of Lushan is only 1 108 m a.s.l. and does not have the climatic conditions for the formation of late Quaternary glaciation.
Glacial valley is a typical landform formed by glacial erosion. Studying the morphological characteristics of the cross-section of the glacier valley is helpful to distinguish the causes of different valleys and analyze the erosion process and erosion capacity of the glacier. Glacial erosion valley has many morphological characteristics. In addition to the most common glacial valley being U-shaped valley， box shaped and inverted trapezoidal valley forms are also developed. In the previous studies， researchers mostly focused on qualitative and quantitative analysis of the morphological characteristics of the partial U-shaped valley， while few quantitative studies on the morphological characteristics of other forms of valley； At the same time， the specific performance of the wide and shallow valley of Tanggula Mountain can be further deepened. When Zimmer studied the Quaternary glacial erosion geomorphologic features of the Sierra Nevada in the United States， he proposed a V-index （
Frost cracking is the major physical weathering process in paraglacial environments and alpine mountains. Scree supplied by frost cracking is the major source of hazards such as collapse. The rock damage by frost cracking is an accumulation process controlled by temperature， so the past temperature change means a lot in landscape evolution. But the influence of different temporal scale of past temperature change on spatial distribution of scree in the arid to semiarid alpine mountain is not clear. Here we analyze the spatial correlation of scree and different temporal scale of past temperature change controlled time averaged frost cracking intensity （Fci ） to explore factors that control scree spatial distribution in Qilian Mountains. The results show that there is a good spatial correlation between scree and both 104 and 105 temporal scale temperature change controlled time averaged Fci . In the western Qilian Mountains， the spatial correlation between scree and 104 temporal scale temperature change controlled time averaged Fci is better than that with 105. We also point out that the increase in temperature induces frost cracking moving to high elevation range and generates new areas with high hazard risk. We also highlight the importance of frost cracking in controlling hazards such as collapse. Our research provides a new thought to predict hazards in the background of global warming， our results can be an important reference for disaster prevention and mitigation decisions.
The spatiotemporal patterns of catchment basin erosion rate is vital for understanding the geomorphic evolution of active orogenic belts. Based on the hydrological data from 1964 to 2011， decadal-scale erosion rates of eight rivers （Haba River， Burjin River， Kelan River， Zhuolut River， Kuyiltes River， Zingali River， Burgun River and Ulungu River） basins are estimated by river sediment transport method. The contributions of suspended load， bed load and solute load to river sediment transport are first determined， and then decadal-scale erosion rates are calculated for each analyzed catchment basin. Here， we focus on the decadal-scale catchment basin erosion rate and its controlling factors in the Altai Mountains. The results show that the average erosion rate of the eight basins is 0.03 mm·a-1， among which the minimum erosion rate of 0.01 mm·a-1 is in Ulungu River， and the maximum erosion rate of 0.05 mm·a-1 is in Klan River， a tributary of the Irtysh River. Furthermore， in order to explore the potential effects of climate， topography， lithology， tectonics and vegetation on catchment basin erosion， correlation analyses were conducted between these factors and the erosion rate. It is found that there is a strong correlation between erosion rate and topographic factors （basin area， slope， and basin relief） and climatic factors （runoff depth and mean temperature）， which may indicate that these factors have a major impact on erosion in the Altai Mountains. Compared with the million-year scales erosion rate （0.07~0.3 mm·a-1） existed now， the low decadal-scale erosion rate could imply that the continuous arid climate since late Cenozoic limited the surface erosion process of the Altai Mountains.
Glaciotectonism is an important part of the “erosion-deposition-deformation” triad of glaciers. Compared with the simple glacial landform and sedimentary records， glaciotectonics has wider distribution and stronger potential of preservation， but the study degree in the middle and low latitudes is low. Using the methods of geomorphology， kinetic stratigraphy and luminescence chronology， this paper investigates the glaciotectonics in source area of the Yuqu River in eastern Tibet. The results show that there are two periods of glaciotectonics with different dynamic properties and directions in the region， and their characteristics have significant temporal and spatial differences. Temporally， they are mainly related to the differences in glacial scale and derived glacial dynamic conditions， and spatially， they are mainly related to the properties of underlying bedrock， regional and local reliefs and drainage conditions； According to the dating data from the overlying strata and others， it is speculated that the regional glaciotectocs are not later than the penultimate glacial age. According to the comprehensive regional data， since the late Middle Pleistocene， the river source area has experienced four stages dominated by icefiled process， valley glacier process， paraglacial process and alluvial process， respectively. This study is helpful to the identification and reconstruction of older glaciation in the region， and provides theoretical and methodological support for distinction of traditional tections from glaciotectonics， interpretation and historical reconstruction of regional deformation characteristics and effective identification of fault activity.
On March 12， 2004， a large-scale rock-ice avalanche occurred on the south side of Yulong Snow Mountain in Lijiang， Yunnan Province. The slide body consists of the upper ice mass and the lower rock mass， with a total volume of 9.1×106 m3. The maximum high drop of the landslide is 1 971 m， the longest movement distance is 4 860 m， and the apparent friction coefficient （H/L） is 0.40. The rock-ice avalanche with the volume of 11.2×106 m3 and the movement length of 3 170 m developed in Ganheba. This paper presents a detailed study of topographic and geomorphological characteristics through remote sensing images and field investigation.
The lithology of the study area consists mainly of limestone with two sets of structural faces. Although seismic activity data indicate that the occurrence of the Ganheba rock-ice avalanche is not directly related to earthquakes. The Yulong Snow Mountain is tectonically active， and historical earthquakes likely caused structural damage to bedrock along the joint surface in the source area. Besides， the temperature in the Lijiang area showed an increasing trend from 1951 to 2005. Yanggongjiang No. 5 Glacier near the study area decreased dramatically. The long-term freeze-thaw cycling is likely to aggravate the rock damage in the source area. Therefore， the triggering factors of the Ganheba rock-ice avalanche are highly fractured limestone， freeze-thaw cycle， and historical seismicity.
According to the topographic and geomorphological characteristics， the Ganheba rock-ice avalanche can be divided into three zones： the source area， the circulation zone， and the accumulation zone. The slope in the source area is significantly steep， and the average slope angle is 48°. There are two groups of structural planes developed in the bedrock. A small number of debris remains at the platform in the circulation zone. The ice mass is mainly distributed in the accumulation area III-1， while the surface of the accumulation area III-2 is widely distributed with glacial milk pits and a unique “boat rock” structure. The directional arrangement of boulders can also be observed in this section. The movement process of landslides can be divided into two stages： the pre-collisional fragmentation stage and the post-spreading accumulation stage. In the first stage， the destabilized rock body is violently broken by a high-speed impact on the platform. In the second stage， the debris flow moves as a flexible sheet with all displacement taking place in the fluvioglacial deposit and the inter-particle fragmentation is not significant.
Based on the above analysis， we believe that the emplacement process of the Ganheba rock-ice avalanche is as follows： （1） The bedrock joint of the permafrost area tended to expand under the freezing and thawing cycle. Until March 2003， glacial snowmelt water in the fissure led to a decrease in basal friction and the effective stress in the bedrock， which eventually caused sliding damage along the structural surface of the limestone. （2） The overlying ice mass and underlying rock mass formed a double-layer sliding structure. They collided with platform at the circulation area， and was significantly broken under the control of the structural surface of the bedrock. （3） The ice mass stopped in the accumulation area III-1 and formed several arcuate lateral ridges within a few years. Constrained by the topography， the debris flow in the accumulation zone III-2 first extends toward SE120°， and then turns to NE85° with the valley shape. （4） After the valley turns， the velocity of the debris flow drops abruptly and the thickness of the deposit gradually becomes thinner， forming a unique “boat rock” structure.
An in-depth study of the geomorphic features and kinematic processes of the Ganheba rock-ice avalanche is of great significance to revealing the kinematic mechanism of high-speed remote landslides. It is also of importance to the prediction and early warning of large-scale landslide disasters in alpine mountains of western China.
Incomplete/heterogeneous bleaching is a great challenge for glacial sediment luminescence dating， which hinders the application of traditional luminescence method using sand and silt-size grains in glacial environment. The latest developed rock luminescence burial dating technique is able to judge whether the cobble has been fully exposed to daylight according to the luminescence-depth profile， which is one of the solutions to the problem of heterogeneous bleaching of glacial sediment luminescence dating. In front of the modern glacier in Yingpu Valley， eastern Qinghai-Tibetan Plateau， 130 young glacial cobbles were collected， including 93 modern samples and 37 Little Ice Age （LIA） samples， 20 of the modern samples were collected from the ground surface. Firstly， surface~2 mm/saturated signal method was used to distinguish the degree of bleaching of cobble samples， and SAR and SGC methods were used to preliminarily estimate the equivalent dose （De） and their overestimations. Then， the relationship between the characteristics of cobble samples （roundness， sphericity， color， grain size， relative grain size， average diameter of cobbles， etc.） and the degree of bleaching was explored， to find well bleached cobbles and their characteristics. The results indicated that there are cobbles showed characteristics of being bleached at most sampling sites. On average， 20.6% of cores of the buried cobbles were well bleached， and show very low De overestimations. Samples from different types of sedimentary environment show different degrees of bleaching. The cobble samples from the top of lateral moraine have the best degree of bleaching， followed by glaciofluvial terrace and modern glaciofluvial cobbles. The glaciofluvial cobbles collected from small depression between modern recessional moraines in front of modern glacier show the worst degree of bleaching， and De is relatively seriously overestimated. Granite cobbles with poorer roundness， lower sphericity and lighter color were better bleached. To sum up， the degree of bleaching of glacial cobbles is related to sedimentary environment， deposit process， transport distance and characteristics of cobbles. The above conditions should be comprehensively considered when sampling cobbles for rock luminescence burial dating.
