We present a shoreline-based, millennial-scale record of lake-level changes spanning 12.8-2.3. ka for a large closed-basin lake system on the southwestern Tibetan Plateau. Fifty-three radiocarbon and eight U-Th series ages of tufa and beach cement provide age control on paleoshorelines ringing the basin, supplemented by nineteen ages from shell and aquatic plant material from natural exposures generally recording lake regressions. Our results show that paleo-Ngangla Ring Tso exceeded modern lake level (4727. m asl) continuously between ~. 12.8 and 2.3. ka. The lake was at its highstand 135. m (4862. m asl) above the modern lake from 10.3. ka to 8.6. ka. This is similar to other closed-basin lakes in western Tibet, and coincides with peak Northern Hemisphere summer insolation and peak Indian Summer Monsoon intensity. The lake experienced a series of millennial-scale oscillations centered on 11.5, 10.8, 8.3, 5.9 and 3.6. ka, consistent with weak monsoon events in proxy records of the Indian Summer Monsoon. It is unclear whether these events were forced by North Atlantic or Indian Ocean conditions, but based on the abrupt lake-level regressions recorded for Ngangla Ring Tso, they resulted in significant periodic reductions in rainfall over the western Tibetan Plateau throughout the Holocene.
Bibliographical noteFunding Information:
This research was funded by grants from the Comer Science and Education Foundation to JQ and AMH and the Henry Luce Foundation to JWO, NSF Grants 1211299 , 1103403 , and 0908792 to RLE and HC, and a student grant to AMH from the Geological Society of America . GL was supported by NSF-China grant 41101189 . The authors thank the editor and anonymous reviewers for comments that improved the manuscript.
- Indian Summer Monsoon
- Shoreline dating
- Tibetan Plateau
- U-Th series dating