Early-Middle Holocene high lake levels of Rinqen Shubtso on the southern Tibetan Plateau and the formation mechanisms

Youhong Gao; Hucai Zhang; Xiaonan Zhang; Lizeng Duan; Guoliang Lei; Yang Pu; Huayong Li; Haoyu Li; Fengwen Liu; Umar Ashraf; Aqsa Anee

doi:10.1016/j.scitotenv.2023.167702

Early-Middle Holocene high lake levels of Rinqen Shubtso on the southern Tibetan Plateau and the formation mechanisms

Sci Total Environ. 2024 Jan 1:906:167702. doi: 10.1016/j.scitotenv.2023.167702. Epub 2023 Oct 11.

Authors

Youhong Gao¹, Hucai Zhang², Xiaonan Zhang¹, Lizeng Duan¹, Guoliang Lei³, Yang Pu⁴, Huayong Li⁵, Haoyu Li¹, Fengwen Liu¹, Umar Ashraf¹, Aqsa Anee¹

Affiliations

¹ Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan 650500, China.
² Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan 650500, China; Southwest United Graduate School, Kunming 650500, Yunnan, China. Electronic address: zhanghc@ynu.edu.cn.
³ State key Laboratory Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, Fujian, China.
⁴ School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China.
⁵ School of Resource Environment and Tourism, Anyang Normal University, Anyang 455000, China.

PMID: 37832691
DOI: 10.1016/j.scitotenv.2023.167702

Abstract

The lake-level highstands on the southern Tibetan Plateau (TP) during the Early-Middle Holocene have traditionally been attributed to increased monsoonal precipitation. However, there has been limited discussion and evaluation regarding how the elevated shoreline indicates the formation of mega-paleolakes and the effects of glacial meltwater on rising lake levels. In this study, we conducted an investigation into the well-preserved paleoshorelines of Rinqen Shubtso, a closed-basin lake system located on the southern TP. By utilizing ¹⁴C dating and analyzing shoreline elevations, the Holocene lake-level fluctuation history of Rinqen Shubtso was reconstructed. Through examining strontium (⁸⁷Sr/⁸⁶Sr) and oxygen isotopes (δ¹⁸O), as well as Rb/Sr ratios in tufa samples from the shoreline, we evaluated the relative contribution of glacial meltwater and East Asian Monsoon precipitation to the lake-level expansion throughout this period. Our findings indicate that prior to 8.5 cal ka BP, the lake level reached its highest elevation before experiencing a rapid drop by approximately 44 m within a short timeframe. Subsequently, maintaining a stable highstand between 8.5 and 5.8 cal ka BP before gradually declining to its present elevation thereafter. We argue that the glacial meltwater induced by rising temperature due to solar insolation likely played a significant role in contributing to these large amplitude high lake levels prior to 8.5 cal ka BP, whereas the maximum East Asian Monsoon precipitation was responsible for sustaining high water levels during 8.5-5.8 cal ka BP when the mean latitudinal position of the summer Intertropical Convergence Zone shifted northward until reached its northernmost point at 8.5 cal ka BP. Following 5.8 cal ka BP, with the weakening of summer monsoon precipitation observed, gradually decreased lake level occurred accordingly. Our results provide valuable insights into understanding past changes in lake level, which are of great importance to predicting future lake variations on the TP.

Keywords: East Asian Monsoon precipitation; Glacial meltwater; Holocene; Shoreline tufa; Stable isotope; Tibetan Plateau.