THE EVOLUTION OF SMALL LAKE BASINS IN THE GOBI DESERT IN MONGOLIA  

作　　者：J. Grunert C. Stolz N. Hempelmann A. Hilgers D. Htille F. Lehmkuhl T. Felauer D. Dasch 

机构地区：[1]Universitat Mainz, Geographisches Institut, Becherweg 21, 55128 Mairtz, Germany [2]Universltat Koln, Geographlsehes Institut,Albertus-Magnus-Platz,50923 Koln, Germany [3]RWTH Aachen, Geographisehes Institut, WullnerstraBe, 52056 Aachen, Germany [4]Mongolian Academy of Science,Sect. Geoecology,Ulan Bator,Mongolia

出　　处：《第四纪研究》2009年第4期678-686,共9页Quaternary Sciences

基　　金：supported by the German Research Fund(DFG)

摘　　要：In order to investigate pluvial lakes in the Gobi two places were selected for field studies: Khongoryn Els inSouth- and Mongol Els in West-Mongolia. In the eastern and central parts of Khongoryn Els two small endorheic basins,Bayan Tukhem and Khongoryn Gol depressions were studied. Pluvial lake deposits and beach ridges both supposedly mid-Holocenein age give evidence of a 9m and a 15m deep freshwater lake,respectively. Today both depressions are nearlydried out and exposed to wind deflation. A different situation was found at Uujin Sair river valley which cuts through thedune field at its lowest and narrowest (3 km) part. Here, a 22.5 m thick fossil accumulation of at least 20 layers of fine sand(dune sand)alternating with silt(fluvial playa sediment)was exposed and OSL dated. 12 dates ranging between 14ka and17ka reveal the accumulation as Late Glacial which correlates well with the aridity at that time reported for Central Asia byseveral authors. Interpreting the dates it seems obvious that the whole sediment was quickly deposited in a period of about16ka,and shortly after dissected by the Uujin Sair during a similar short time due to increasing humidity of the climate.Another situation was found at the eastern rim of Mongol Els. Two rivers,Shurgiyn Gol and Zavran Gol are impinging hereon the high dunes which have damed both rivers in the past. A younger, shallow lake existed during mid-Holocene( ^(14)C-dated to some 5.5ka)and a large, 17m deep lake( ^(14)C -- dated to some 39ka) probably during stage 4. Expected OSLdates will hopefully support this hypothesis. Anyhow, the palaeogeography of the dune field was different from today; itmoved eastward daming the large river Shurgiyn Gol.In order to investigate pluvial lakes in the Gobi two places were selected for field studies： Khongoryn Els in South- and Mongol Els in West-Mongolia. In the eastern and central parts of Khongoryn Els two small endorheie basins, Bayan Tukhem and Khongoryn Gol depressions were studied. Pluvial lake deposits and beach ridges both supposedly midHoloeene in age give evidence of a 9m and a 15m deep freshwater lake, respectively. Today both depressions are nearly dried out and exposed to wind deflation. A different situation was found at Uujin Sair river valley which cuts through the dune field at its lowest and narrowest （3km） part. Here, a 22.5m thick fossil accumulation of at least 20 layers of fine sand （dune sand）alternating with silt（fluvial playa sediment）was exposed and OSL dated. 12 dates ranging between 14ka and 17ka reveal the accumulation as Late Glacial which correlates well with the aridity at that time reported for Central Asia by several authors. Interpreting the dates it seems obvious that the whole sediment was quickly deposited in a period of about 16ka,and shortly after dissected by the Uujin Sair during a similar short time due to increasing humidity of the climate. Another situation was found at the eastern rim of Mongol Els. Two rivers,Shurgiyn Gol and Zavran Gol are impinging here on the high dunes which have damed both rivers in the past. A younger, shallow lake existed during mid-Holoeene （ ^14C-dated to some 5.5ka）and a large, 17m deep lake （ ^14C - dated to some 39ka） probably during stage 4. Expected OSL dates will hopefully support this hypothesis. Anyhow, the palaeogeography of the dune field was different from today; it moved eastward daming the large river Shurgiyn Gol.

关 键 词：MID-HOLOCENE late-Glacial playa stage 4(?)-lake 

分 类 号：P941.73[天文地球—自然地理学] P736.41