| Popis: |
In palaeoclimate research concerning central Asia, up to now the focus was set on regions as Russia, northern Mongolia and China. Therefore only a few palaeoclimatic data are pub-lished on southern Mongolia. In order to understand the climatic development of central Asia and to get an impression of future environmental conditions, information on minor in-vestigated areas are important. This study sets focus on palaeoclimate and the sedimentological and morphological processes of two catchment areas of southern Mongolia (Orog Nuur, Bayan Tohomiin Nuur). The multiparameter analysis of three sediment cores yields information to reconstruct lake level changes, processes of transport, sedimentation and weathering during the last 50ka within the catchment of the lakes. Optical stimulated luminescence (OSL) data from selected sections (fluvial and aeolian sediments) give additional information on palaeoenvironmental conditions of the drainage area. Investigations on terrace sections hint towards cold and arid conditions during 150-120ka. Between 80-70ka a warm and humid climate cloud be recon-structed from lake transgressions. The sedimentological analysis of the lacustrine cores indi-cate low lake levels, accompanied by several phases of increased aeolian activity during 50ka and 13ka, pointing towards predominantly arid and cold climatic conditions. During 35-26ka a change towards a more humid climate could be reconstructed by a lake transgression, accompanied by declining aeolian sedimentation. The proxy data show a more warm and humid climate during the onset of the Holocene (13-11ka). A maximum of temperature and moisture occurred during 9-6ka, interrupted by several short time drying events. Within the investigation area a trend of aridization and remobilization of dune sand can be observed since 6ka. This study offers the first continuous set of palaeoclimatic data from southern Mongolia. The results show a general consistence to adjacent investigation areas of central Asia. Yet, more palaeoclimatic archives from southern Mongolia are required to understand the complex development of climate during the late Quaternary. |
