Cosmogenic 10Be and 26Al dating of paleolake shorelines in Tibet

We have used in situ produced cosmogenic nuclides 10Be and 26Al to date lacustrine shorelines around eight lakes in Tibet. Two lakes located south of the Yarlung Tsangpo River discharged at high lake levels. One of them, Drolung Co (Co is a local term, meaning lake), became closed (its water level fell below its outlet channel) at ∼3.8 ka and lowered over 120 m vertically since then. This implies a significant change in intensity of precipitation driven by the Indian monsoon over southern Tibet in the middle-late Holocene. Nam Co and Dajia Co, located to the north of the Yarlung Tsangpo River, also drained at high lake levels and became closed ∼53–36 ka and ∼48 ka, respectively. Of four other lakes developed closely in the Qiangtang basin, north of the Yarlung Tsangpo River, Tangra Yum Co and Siling Co (located at 31–32°N) show exposure ages for high lake shorelines of over 220 ka, the oldest lake shorelines reported for Tibet, while towards the north and west, the high lake of Zhari Nam Co appeared after the Last Glacial Maximum (LGM). The different pattern of lake development to the north of Yarlung Tsangpo River may reflect regional climate effects.

► The intensity of precipitation driven by the Indian monsoon may have significantly changed in southern Tibet during the middle-late Holocene.
► There were no synchronous high lake levels in the analyzed area of Tibet.
► The results argue against the assumed combined lake within east Qiangtang at 120 ka.
► The patterns of lake development in the north of the Yarlung Tsangpo River may result from regional climatic control.