Late quaternary hydrological changes at Tangra Yumco, Tibetan Plateau: a compound-specific isotope-based quantification of lake level changes

Abstract

Lake level fluctuations are important features in paleo-reconstructions that can be linked to past climate changes. Closed-basin lakes on the southcentral Tibetan Plateau record the balance between monsoonal precipitation and evaporative loss. To date, most studies provide only qualitative estimates of past hydrological changes. For the first time, we applied hydrogen isotopes (dD) of aquatic and terrestrial nalkanes to quantify lake volume changes of Tangra Yumco and compared values to newly calculated lake volumes of Nam Co. We also used carbon isotopes of sedimentary n-alkanes to reveal past climate and environmental conditions around the lake. The water volume of Tangra Yumco changed by 146 km3 in the past 17.42 cal ka. Lake volume increased in two steps, the first mainly initiated by glacial meltwater input after 16 cal ka BP, and to a minor extent by first strengthening of the Asian Summer Monsoon (ASM). The second increase was caused by intensified summer monsoon precipitation at 11.45 cal ka BP. After 8.0 cal ka BP, lake volume decreased because of arid conditions, until an increase at 0.8 cal ka BP that was probably linked to a wet spell during the Little Ice Age. The lake level changes of Tangra Yumco and Nam Co were affected simultaneously by the ASM, although their amplitudes differed because of different local conditions, such as basin morphology or the blocking effect of neighboring mountains, which influences the rainout of air masses and wind-induced evaporation

Ostracod‐based reconstruction of Late Quaternary lake level changes within the Tangra Yumco lake system (southern Tibetan Plateau)

“…Tangra Yumco sediments have already been investigated for palaeoecological and palaeoclimatic purposes in the recent years (Long et al ., ; Rades et al ., ; Miehe et al ., ; Ahlborn et al , , ; Akita et al ., ; Günther et al ., ; Henkel et al ., ). Ahlborn et al () reconstructed the lake level history based on OSL dating (Fig.…”

“…In the last decade, several studies of lacustrine sediments from the Tibetan Plateau identified significant lake level changes during the Late Quaternary that are related to monsoon and westerlies variability (Mischke and Zhang, ; Kasper et al ., ; Günther et al , , , ; Mishra et al ., ; Ahlborn et al , ; Henkel et al , ). Due to the role of this area as origin of many large rivers of south‐eastern Asia, the climate variations in this area force environmental, social and economic consequences for millions of people and their better understanding is urgently needed to offer indications of future scenarios.…”

“…), located on the southern–central Tibetan Plateau. Tangra Yumco has been investigated in several studies in recent years to assess lake level changes during the Late Quaternary (Long et al ., ; Rades et al ., ; Miehe et al ., ; Ahlborn et al , , ; Günther et al , ; Henkel et al , ). Akita et al () provided a dataset of the ecology of recent Ostracoda of Tangra Yumco as a groundwork for palaeoecological applications.…”

Climatic and associated cryospheric, biospheric, and hydrological changes on the Tibetan Plateau: a review

“…With a total area of 41 800 km 2 , it has been estimated that more than 1000 lakes distributed on TP are larger than 1 km 2 (Ma et al ., ; Witt et al ., ). Glacier melt has greatly supported the development of many inland TP lakes because these are fed by glaciers located in their catchments (Yao et al ., ; Zhu et al ., ; Günther et al ., ). Conversely, many other climatic factors such as increased precipitation and decreased evaporation from lake surfaces may have contributed significantly to the expansion of lakes which are not fed by glaciers in their catchment (Liu et al ., ).…”

How to Deal With Multi-Proxy Data for Paleoenvironmental Reconstructions: Applications to a Holocene Lake Sediment Record From the Tian Shan, Central Asia

“…An average Lake Surface Temperature of 9 • C was selected for the calculations. A more detailed explanation of the calculation is provided in Günther et al (2016).…”