Geomorphic and chronometric evidence for high lake level history in Gahai Lake and Toson Lake of north-eastern Qaidam Basin, north-eastern Qinghai-Tibetan Plateau

摘要

Palaeoshorelines, highstand lacustrine sediments and lakeshore terraces are preserved around saline lakes in the arid Qaidam Basin. Previous research indicates that the chronology of a mega-paleolake in the Qaidam Basin during the late Pleisotocene is controversial. Here we report quartz optically stimulated luminescence (OSL) age estimates of highstand lacustrine sediments, shoreline features and geomorphic exposures that contribute to a revision of the lake level history of Gahai and Toson lakes in the north-eastern Qaidam Basin, on the northeastern Qinghai-Tibetan Plateau (QTP) margin. The results imply that: (i) high lake levels at Gahai and Toson lakes based on quartz OSL dating occurred at 85-72, 63-55, 31, 5.4 and 0.9-0.7 ka, probably corresponding to periods of warm and wet climate; (ii) periods of high lake levels are almost synchronous with other lakes on the QTP (e.g. Qinghai and Namco lakes), with the highest late Pleistocene levels occurring during Marine Oxygen Isotope Stage 5; and (iii) highstand phases on the QTP are out of phase with those of low-latitude lakes in the southern hemisphere, possibly driven by solar insolation variability in the low-latitude region.