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

Abstract

Geomorphic evidence suggests that shorelines of 100–200 m above the modern lake levels were common across the Tibetan Plateau during late Marine Isotope Stage (MIS) 3. The timing of this lake‐level highstand is mainly based on radiocarbon ages. Problems surrounding the ages of lacustrine sediments at or beyond the limit of the radiocarbon‐dating method have created a need for alternative geochronometers. Chronological advances during the last decade have renewed interest in the timing of events beyond the limit of radiocarbon dating. Here, we synthesize published data for elevated lacustrine landforms of 48 lakes on the Tibetan Plateau, in order to provide a thorough perspective on the timing and pattern of lake‐level changes in this alpine area during the late Quaternary. The ages of these elevated shore features reveal a long‐term trend of relative lake‐level fall from at least MIS 5, instead of a peak in MIS 3, as previously thought. Dating lacustrine terrace sequences reveals that the rate of lake‐level fall ranged from ~1 to 3 mm a−1, comparable with that of related river downcutting across the plateau. Palaeoclimatic proxy records point to a sustained drying since the Last Interglacial, suggesting that long‐term aridification might be the culprit for this widespread and progressive lake‐level fall.

Survival of the Qaidam Mega-Lake System under Mid-Pliocene Climates and its Restoration under Future Climates

“…2.6 Ma BP marked a period of increased variability of climate, lake level and extent, as well as changes in salinity (Huang et al, 1993;Wang et al, 2012;An et al, 2001;Heermance et al, 2013). The mega-lake system finally disappeared during the last 100 ka (Madsen et al, 2014;Yu et al, 2019). Today, only few saline lakes and playas exist, and the low-altitude parts of the basin are hyper-arid deserts (Chen and Bowler, 1986;Huang et al, 1993;Wang et al, 2012).…”

Spatiotemporal complexity of the “Greatest Lake Period” in the Tibetan Plateau

“…Understanding the evolution of lakes in the region on longer timescales, as well as the mechanisms responsible, is important for predicting future lake level variations and changes of regional water resources. As the most direct evidence of lake level changes, geomorphological evidence, including paleo-shorelines, wave-cut benches and littoral sediments deposited during high lake level stands, are widely used in Late Quaternary lake level and paleoclimatic reconstruction [3]. Numerous radiocarbon ages of paleoshorelines, high-stand lacustrine sediments, and cores that were drilled on lake shores were reported from the 1980s to 2000s.…”

“…The results have revealed that radiocarbon dating underestimates sedimentary ages older than~30-40 ka and the GLP likely occurred during MIS 5 [5,6]. Yu et al [3] reviewed studies of the GLP and provided a comprehensive summary of the ages of high lake levels for 48 lakes in the TP, and concluded that the GLP was dated to MIS 5 rather than to MIS 3.…”

“…In the present study, we conducted a comprehensive reassessment of the ages of all of the reported lake level high-stands [3,[7][8][9][10]. We then selected the most reliable ages of the highest lake levels, according to the following two criteria.…”

“…Overall, our reassessment results reflect spatiotemporal complexity of the GLP in the TP, which may be the result of multiple factors. High lake levels in the TP during the Late Quaternary are always attributed to high precipitation [3,7,8,[10][11][12]. The highest lake levels in the northeastern TP and adjacent areas during MIS 5 are related to strong East Asian summer monsoon rainfall [7,11].…”