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长凳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。我们建议用原位产生的宇宙成因的10Be和发光测年来确定位于藏南活动地块系统中的深湖Tangra Yum Co的古海岸线序列。保存完好的湖泊阶地延伸到高于Tangra Yum Co现在水位约200m的高度，但相关的湖平面高位是发生在全新世早期气候最佳时期，最后一次冰川消融过程中，还是更古老，目前尚不清楚。除了测定湖泊阶地和板凳的年龄外，我们还将通过10Be测定冰川冰川中花岗岩巨石的年龄来限制最后一次冰川推进的年龄。最后，我们的目标是得出湖缘主要正断层的滑动速率。后者将通过结合断层陡峭的地形测量、移位表面的年代测定、对沟壑中暴露的断层的古地震学调查以及确定断层底部的集水区侵蚀速率来实现。这项计划中的研究将揭开湖平面变化、气候变化和正常断层之间的关系，并结合其他尖群的结果，解决这些过程对藏南典型活动地块系统中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.