OSL dating of past lake levels for a large dammed lake in southern Tibet and determination of possible controls on lake evolution

摘要: Fluvio-lacustrine terraces along Phung Chu (river) on the central southern Tibetan Plateau indicate that a large palaeo-dammed-lake formerly existed in this area. Based landscape survey, optically stimulated luminescence (OSL) dating and sedimentary analyses, research shows was blocked dammed-lake over 2500 km size formed before 30 ka ago. OSL analysis suggests fluvio-lacustrine sediments were well bleached yield accurate age estimates for two lake drainage events. The first event took place after ka, resulted river incision high terrace at 50 m height from present level. second happened 3.7 further 25 According to distribution of sediments, active normal faults (particularly Kharta Fault) region gradient slopes enters Yo Ri gorge, seismically-induced landsliding is regarded as highly likely have been cause blockage associated formation dammed-lake, although glacial damming also possible cause. volume drainages may led catastrophic flooding analogous modern lakes represent significant geo-hazard risks down-river human settlements. As dammed-lakes are special phases fluvial evolution, often involving blockage, breakthrough drastic catchment change, these processes can reveal how tectonic or climatic events modify landforms. However, such tectonic-derived landform changes impact palaeo-climate region. Thus study has added new evidence regarding evolutionary history dammed including its formation, duration, extent final drainage, which crucial understanding general process mechanisms better assessing risks.