Quaternary International 65/66 (2000) 171}192 Paleoclimatic evolution of the Uvs Nuur basin and adjacent areas (Western Mongolia) Jo K rg Grunert, Frank Lehmkuhl*, Michael Walther Geographisches Institut der Universita ( t Mainz, Becherweg 21, D-55128 Mainz, Germany Geographisches Institut der Universita ( t Go ( ttingen, Goldschmidtstr. 5, D-37077 Go ( ttingen, Germany Freie Universita ( t Berlin, Institut fu ( r Geographische Wissenschaften, Malteserstr. 74-100, D-12249 Berlin, Germany Dedicated to Prof. Dr. F. Scholz, FU Berlin, on the occasion of his 60th birthday Abstract The investigations presented in this paper focus on the shifts in Pleistocene glaciations and the geomorphic changes in landforms, as well as lake level changes and aeolian deposits of the last glacial}interglacial cycle, including the Holocene. Geomorphic evidence and high lake levels show that the climate was more humid before the last glacial maximum (LGM); however, at least one arid phase also occurred. During the second half of the LGM the climate was dry and cold, turning to wet and cold during the Late Glacial of the last Ice Age. Fluctuations in humidity and temperature occurred during the Holocene. Since about 2000 yr BP the impact of human activity has increased.  2000 Elsevier Science Ltd and INQUA. All rights reserved. 1. Introduction The Uvs Nuur Basin in the northwestern part of Mongolia stretches from 92330N to 96350N, and from 49347E to 50330E. At its maximum, it measures 312 km from west to east and 135 km from north to south. The northern part of the basin is surrounded by the Tannu Ulu Mountains with the Baruun Tagnyn Nuruu in the northwest, the 4000-m-high foothills of Kharkhiraa in the west, and the 2300-m-high Khan Kho K hiyn Nuruu range in the south. The latter comprises several indi- vidual massifs; of these, the Togtochyn Schil is con- sidered to be a separate mountain. Eastwards, the basin interior rises gradually to elevations of about 1500 m and is bounded in the east by a lower mountain range, about 1900 m high, in the vicinity of Tes Somon. In the climatic classi"cation according to Ko K ppen (1923) the medium and higher mountainous parts of the study area belong to the Dw climate (cold snowy forest with dry winters) and the lower basin zones to the Bs (steppe) region. According to Troll (1964), the study area is situated near the boundaries between the strongly * Corresponding author. Fax: 551-398-006. E-mail address: #ehmku@gwdg.de (F. Lehmkuhl). continental boreal climates with permafrost and the steppe climates with cold and dry winters and moist summers. The recent continental climatic conditions are characterised by a wide annual range of temperature, with winter values of below !20 to !303C and sum- mer values up to and exceeding 203C (for example, the mean temperature at Ulaangom is !32.93C in January and 19.23C in July with an annual average of !3.73C). Annual rainfall averages about 200 mm at the altitude of 2000 m and is estimated to exceed 300 mm in the high mountain areas, whereas precipitation in the basins is less than 100 mm per year (Academy of Sciences of Mongolia and Academy of Sciences of USSR, 1990). The research work was part of the Uvs Nuur joint research project supported by the Deutsche Forschungs- gemeinschaft (DFG, German Science Foundation). First results of the Mongolian}German joint research work including these topics were presented in a volume of Die Erde in the German language, with contribu- tions by Grunert, Lehmkuhl, Naumann and Walther. In addition papers have been published by Lehmkuhl (1998) on the Pleistocene glaciations of Mongolia, and by Walther (1998), Walther and Naumann (1997) and Naumann and Walther (2000, in press) on the lake level changes and other geomorphic features of the Uvs Nuur Basin. 1040-6182/00/$20.00  2000 Elsevier Science Ltd and INQUA. All rights reserved. PII: S 1 0 4 0 - 6 1 8 2 ( 9 9 ) 0 0 0 4 3 - 9