Holocene lake-level fluctuations of Selin Co on the central Tibetan plateau: Regulated by monsoonal precipitation or meltwater?

Abstract

Abstract Over the Tibetan Plateau (TP), lakes as paleoenvironmental archives have been the most extensively investigated for their sensitivities to climate change on different timescales. Well-preserved shoreline and terrace remains surrounding these lakes provide critical geomorphological and sedimentary evidence that can be used to infer past lake levels over geological timescales. These features can offer an analogue for understanding how future lake-levels respond to global warming. In this study, we investigated a series of water level-related depositional profiles around the Selin Co basin from the central TP, by dating 28 samples using K-feldspar luminescence techniques. Combining the obtained chronological data with sedimentological, stratigraphic evidence and differential GPS survey observations, the Holocene history of lake-level fluctuations in Selin Co was inferred. The results show a stable highstand between 10 ka and 7 ka but a striking subsequent lake-level decline. This pattern appears to follow the solar insolation-forced changes in the intensity of the Indian summer monsoon (ISM), particularly during the early Holocene. However, such gradual weakening of ISM intensity after the early Holocene may not interpret the dramatically rapid shrinking of Selin Co, implying other components are largely underrecognized driving factors accounting for the effective moisture of lakes in the early Holocene. Here, we argue that the increased meltwater input from glaciers and permafrost, together with increased precipitation, might have resulted in the high lake level at 10–7 ka, as the high summer temperature during the early Holocene induced massive melting water flow into the lake. By 7 ka, the abrupt lake-level drop is likely related to the decreased meltwater owing to decreasing regional temperatures documented from glacier landforms, ice cores and lacustrine sediments. Therefore, we highlight that meltwater from glaciers and permafrost poured into lakes on the central TP, particularly during warm periods on the millennial timescales, might also dominate the Holocene high lake levels.