Determination of the age of lake terraces, the last glacial advance, and rates of normal faulting in the Tangra Yum Co graben using 10Be exposure and optically stimulated luminescence dating

青藏高原许多湖泊周围的梯田和湖滩记录了水位的显著变化，并记录了过去气候和环境条件的显著变化。本文提出了在西藏南部一个活动地堑体系中的深湖唐格拉Yum Co的古岸线序列中，用现场产生的宇宙成因10Be和发光定年法进行定年。保存完好的湖泊阶地延伸至比唐格拉Yum Co当前水位高出约200米的高度，然而，不知道相关的湖泊水位高地是发生在全新世早期气候最佳时期，还是在最后一次消冰过程中，甚至更早。除了测定湖泊阶地和阶地的年代外，我们还将通过测定冰碛岩体的年代来确定末次冰期推进的年龄。最后，我们的目标是推导出湖边缘主要正断层的滑动速率。后者将通过结合断层陡坡的地形测量、位移面测年、沟中暴露断层的古地震学调查以及断层下盘流域范围内侵蚀速率的测定来实现。计划中的研究将揭示湖泊水位变化、气候变化和正断层之间的关系，并结合其他TiP小组的结果，解决这些过程对典型藏南活动地堑系统的沉降和沉积模式的影响。

Terraces and benches around many lakes on the Tibetan Plateau record significant changes in water level and document pronounced variations in past climatic and environmental conditions. We propose to date a sequence of paleo-shorelines at Tangra Yum Co – a deep lake situated in an active graben system in southern Tibet – with in situ-produced cosmogenic 10Be and luminescence dating. Wellpreserved lake terraces extend to a height of about 200 m above the present water level of Tangra Yum Co, however, it is unknown whether the related lake level highstands occurred during the early Holocene climate optimum, in the course of the last deglaciation, or are even older. In addition to dating lake terraces and benches, we will constrain the age of the last glacial advance by 10Be dating of granitic boulders from moraines. Finally, we aim to derive slip rates for major normal faults at the margin of the lake. The latter will be achieved by combining topographic surveying of fault scarps, dating of displaced surfaces, paleoseismologic investigations of fault exposed in gullies, and determination of catchment-wide erosion rates in the footwalls of the faults. The planned research will unravel the relationship between lake-level variations, changes in climate, and normal faulting, and – combined with the results of the other TiP groups – resolve the impact of these processes on the subsidence and sedimentation patterns in an active graben system typical for southern Tibet.