Evaluating the size and extent of paleolakes in central Tibet during the late Pleistocene

Abstract

Subhorizontal lake shorelines allow a geodynamic test of the size and extent of a hypothesized paleolake in central Tibet, the East Qiangtang Lake (EQL), during the last interglacial period (marine isotope stage (MIS) 5e). Reconstructions based on relict lake deposits suggest that the EQL would have been ~400 m deep and over ~66,000 km2. Models of flexural rebound driven by lake recession predict that shorelines near the EQL center, at the present‐day location of Siling Co, would have rebounded 60–90 m above their initial elevation. New 36Cl chronology of the highest relict shorelines around Siling Co indicates that they reflect lake levels between 110 and 190 ka. These shorelines, however, are presently >300 m below their predicted elevations, implying a substantially smaller water load. Our results reveal that the expansion of Tibetan lakes during MIS 5e was relatively limited. Instead, individual lakes were supplied by river networks, much as they are today.

Late‐Quaternary history of ‘great lakes’ on the Tibetan Plateau and palaeoclimatic implications – A review

“…; Shi et al . ), consistent with the progressive, phased uplift of the plateau during the Late Cenozoic (Amano & Taira ; An et al . ).…”

“…However, recent fieldwork and crustal flexural modelling suggest that a great lake system hypothesized previously as the ‘Qiangtang Megalake’ during MIS 5 did not exist (Shi et al . ). The most recent lake‐level highstand occurred during the Early Holocene.…”

“…), which can be further supported by new 36 Cl ages (Shi et al . ). Also, geodynamic modelling of flexural rebound reveals that the extent of the hypothesized central Tibetan Great Lakes (i.e.…”

“…) or earlier interglacials (Shi et al . ). Resolving this issue is important for understanding the driving mechanisms of long‐term climate changes for the Eurasian landmass and improving the prediction of climate in the future.…”

“…A precipitation record from the Chinese Loess Plateau does not show any anomalous strengthening of the East Asian summer monsoon during MIS 3 (Ning et al 2008). Moreover, an increasing number of OSL ages suggest that terraces around Qinghai Lake, formerly dated to MIS 3 by radiocarbon, may have been deposited during MIS 5 (Madsen et al 2008;Rhode et al 2010) or earlier interglacials (Shi et al 2017a). Resolving this issue is important for understanding the driving mechanisms of long-term climate changes for the Eurasian landmass and improving the prediction of climate in the future.…”