SPP 1372 - Subproject: 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

Basic data for this project

Description

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. Well-preserved lake terraces extend to a height of about 200m 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.