Late Pleistocene genesis of the middle Yarlung Zhangbo Valley,southern Tibet (China), as deduced by sedimentological and luminescence data |
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| Authors: | Knut Kaiser Zhongping Lai Birgit Schneider Frank W Junge |
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| Institution: | 1. German Academy of Science and Engineering, 10117 Berlin, Germany;2. Key Laboratory of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, 810008 Xining, China;3. Department of Geography, University of Leipzig, 04103 Leipzig, Germany;4. Department of Pollutants Dynamics in Catchment Areas, Saxon Academy of Sciences, 04107 Leipzig, Germany |
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| Abstract: | Knowledge on valley formation and palaeohydrology of the Yarlung Zhangbo (named Brahmaputra south of the Himalayas) is still in an early stage. Research was conducted in the middle valley reach around Gonggar in order to investigate the sediment properties, age and palaeoenvironmental implication of a widespread aggradational valley terrace. This heavily dissected terrace, lying c. 25 m above the present floodplain, consists of topping aeolian and colluvial deposits, intermediate lacustrine fines and basal fluvial sands. Sedimentological properties of the lacustrine layers suggest a cold-climate depositional environment. Geochemical data refer to a common provenance of all sediments investigated from a regional catchment area, implying a local provenance of topping loesses and sands by aeolian sorting of nearby fluvial deposits. OSL dates, representing the first luminescence dating effort partly applied to non-aeolian sediments in this valley, cluster closely in the interval 11.7 ± 0.8–17.4 ± 1.4 ka. During the Late Pleistocene (until c. 16 ka) the investigated middle valley reach around Gonggar was occupied by a lake attaining an extension of at least 100 km. |
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