The topographic maps of 1:50,000 scales,aerial photographs taken in 1966,one Landsat image taken in 1999,and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountai...The topographic maps of 1:50,000 scales,aerial photographs taken in 1966,one Landsat image taken in 1999,and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountain,in the northeastern Tibetan Plateau,China in the past 30 years.The total glacier area decreased from 492.9km2 in 1966 to 458.2km2 in 1999.The volume loss of the studied glaciers reached 1.4 km3 from 1966 to 2000.This agrees with documented changes in other mountain glaciers of the whole Tibetan Plateau.展开更多
The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are r...The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are recognized as two types. One was found in sandy gravel beds of the second terrace of the Yellow River. This ice-wedge pseudomorph is characterized by higher ratio of breadth/depth, and are 1-1.4 m wide and about 1 m deep. The bottom border of the ice-wedge pseudomorph is round arc in section. Another discovered in the pedestal of the second terrace has lower ratio of width/depth, and is o.3-1.0 m wide and 1-2 m deep. Its bottom border is sharp. Based on the TL dating, the former was formed at the middleHolocene （5.69±0.43 ka BP and 5.43±0.41 ka BP）, that is, the Megathermal, and the latter was formed at the late Last Glacial Maximum （13.49±1.43 ka BP）. Additionally, the thawing-freezing folders discovered in the late Late Pleistocene proluvium are 39.83±3.84 ka BP in age. The study on the ice-wedge pseudomorphs showed that the air temperature was lowered by up to 6-7℃ in the source area of the Yellow River when the ice-wedge pseudomorphs and thawing-freezing folds developed.展开更多
The Gongga Mountain is the largest area of modern glaciation in the Hengduan Mountains and,with a summit elevation of 7556 m,is the highest mountain on the eastern margin of the Tibetan Plateau.During the Quaternary g...The Gongga Mountain is the largest area of modern glaciation in the Hengduan Mountains and,with a summit elevation of 7556 m,is the highest mountain on the eastern margin of the Tibetan Plateau.During the Quaternary glacial-interglacial cycles the Gongga Mountain was extensively and repeatedly glaciated,and glacial landforms and outwash deposits from multiple glaciations are well-preserved in valleys,in basins,and on piedmonts.To constrain the glacial chronology of the eastern slope of Gongga Mountain,sample sites were selected based on the distribution and weathering of glacial tills,relationships among glacial deposits,and soil development on moraines.Dating of the tills and glaciofluvial deposits was undertaken with electron spin resonance(ESR) and optically stimulated luminescence(OSL).The ages of the glacial deposits can be divided into four clusters:2.2±0.5,11.9±0.6,35.9±2.7-58.0±6.3 and 119.2±15.9-194.2±32.8 ka.Five glacial advances in this region have been identified,which are equivalent in age to the Little Ice Age(LIA),Neoglaciation,marine oxygen isotope stage(MIS) 2,mid-MIS3,and MIS6.The largest local last glacial maximum(LGML) occurred on Gongga Mountain during mid-MIS3,characterized by a cold-humid climate,rather than the global Last Glacial Maximum(LGMG) of MIS2.The Gongga,Nanmenguangou(NMGG) and Yajiageng Glaciations occurred during the late part of the last glacial cycle,the middle of the last glacial cycle and the penultimate glacial cycle,respectively.On the basis of geomorphological,sedimentological,and compositional characteristics,landforms of the Moxi Platform and terraces can be grouped by facies and geochronology.In combination with the dating results,this analysis indicates the basal part of the Moxi Platform between Xinxin and the Moxi Hotel is correlative with the till of the Nanguanmen Glaciation(mid-MIS3).This basal unit has occasional lenses of glaciofluvial sandy gravel and lacustrine sediments.The remainder of the Moxi Platform and the terraces beside the platform are glaciofluvial deposits occasionally mixed with debris flow deposits and range in age from MIS3 to Holocene.展开更多
基金supported by the National Natural Science Foundation of China(40576001 and 40825017)the Chinese Academy of Sciences(KZCX3SW344 and 100 Talents Project)+1 种基金the Korean Research Council of Public Science and Technology(PP07010)the National Key Technology R&D Program(2006BAB18B01).
文摘The topographic maps of 1:50,000 scales,aerial photographs taken in 1966,one Landsat image taken in 1999,and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountain,in the northeastern Tibetan Plateau,China in the past 30 years.The total glacier area decreased from 492.9km2 in 1966 to 458.2km2 in 1999.The volume loss of the studied glaciers reached 1.4 km3 from 1966 to 2000.This agrees with documented changes in other mountain glaciers of the whole Tibetan Plateau.
基金the Ministry of Land and Resource of P.R.China the National Natural Science Foundation of China(No.40172062).
文摘The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are recognized as two types. One was found in sandy gravel beds of the second terrace of the Yellow River. This ice-wedge pseudomorph is characterized by higher ratio of breadth/depth, and are 1-1.4 m wide and about 1 m deep. The bottom border of the ice-wedge pseudomorph is round arc in section. Another discovered in the pedestal of the second terrace has lower ratio of width/depth, and is o.3-1.0 m wide and 1-2 m deep. Its bottom border is sharp. Based on the TL dating, the former was formed at the middleHolocene （5.69±0.43 ka BP and 5.43±0.41 ka BP）, that is, the Megathermal, and the latter was formed at the late Last Glacial Maximum （13.49±1.43 ka BP）. Additionally, the thawing-freezing folders discovered in the late Late Pleistocene proluvium are 39.83±3.84 ka BP in age. The study on the ice-wedge pseudomorphs showed that the air temperature was lowered by up to 6-7℃ in the source area of the Yellow River when the ice-wedge pseudomorphs and thawing-freezing folds developed.
基金supported by National Natural Science Foundation of China(Grant No.41171063)Fundamental Research Funds for the Central Universities(Grant No.LZUJBKY-2010-114)+1 种基金Foundation of State Key Laboratory of Cryospheric Sciences,Cold and Arid Regions Environment and Engineering Research Institute,Chinese Academy Sciences(Grant No.SKLCS2011-03)the Program of Ministry of Science and Technology of China(Grant No.2006FY110200)
文摘The Gongga Mountain is the largest area of modern glaciation in the Hengduan Mountains and,with a summit elevation of 7556 m,is the highest mountain on the eastern margin of the Tibetan Plateau.During the Quaternary glacial-interglacial cycles the Gongga Mountain was extensively and repeatedly glaciated,and glacial landforms and outwash deposits from multiple glaciations are well-preserved in valleys,in basins,and on piedmonts.To constrain the glacial chronology of the eastern slope of Gongga Mountain,sample sites were selected based on the distribution and weathering of glacial tills,relationships among glacial deposits,and soil development on moraines.Dating of the tills and glaciofluvial deposits was undertaken with electron spin resonance(ESR) and optically stimulated luminescence(OSL).The ages of the glacial deposits can be divided into four clusters:2.2±0.5,11.9±0.6,35.9±2.7-58.0±6.3 and 119.2±15.9-194.2±32.8 ka.Five glacial advances in this region have been identified,which are equivalent in age to the Little Ice Age(LIA),Neoglaciation,marine oxygen isotope stage(MIS) 2,mid-MIS3,and MIS6.The largest local last glacial maximum(LGML) occurred on Gongga Mountain during mid-MIS3,characterized by a cold-humid climate,rather than the global Last Glacial Maximum(LGMG) of MIS2.The Gongga,Nanmenguangou(NMGG) and Yajiageng Glaciations occurred during the late part of the last glacial cycle,the middle of the last glacial cycle and the penultimate glacial cycle,respectively.On the basis of geomorphological,sedimentological,and compositional characteristics,landforms of the Moxi Platform and terraces can be grouped by facies and geochronology.In combination with the dating results,this analysis indicates the basal part of the Moxi Platform between Xinxin and the Moxi Hotel is correlative with the till of the Nanguanmen Glaciation(mid-MIS3).This basal unit has occasional lenses of glaciofluvial sandy gravel and lacustrine sediments.The remainder of the Moxi Platform and the terraces beside the platform are glaciofluvial deposits occasionally mixed with debris flow deposits and range in age from MIS3 to Holocene.
