Palaeo-hydrochemistry reconstructed from fossil mollusc shells from dammed palaeo-lake sediments in the Yarlung Tsangpo valley, Tibet

• Published in: Applied geochemistry 2021-09, Vol.132, p.105069, Article 105069
• Main Authors: Hu, Hai-Ping, Feng, Jin-Liang, Liu, Jin-Hua, Wu, Xiao-Ping, Chen, Feng, Zhang, Ji-Feng, Pei, Le-Le, Wang, Kun-Yin, Ye, Chang-Sheng
• Format: Article
• Language: English
• Subjects: Dammed palaeo-lake; Mollusc shells; Palaeo-hydrochemistry; Vital effects; Yarlung Tsangpo River
• ISSN: 0883-2927; 1872-9134
• DOI: 10.1016/j.apgeochem.2021.105069

Radix sp., Gyraulus sp. and Pisidium sp. are aquatic mollusc taxa. Although their fossil shells occur widely in dammed palaeo-lake sediments in the Yarlung Tsangpo valley in Tibet, their hydrochemical and hydrological implications are not fully understood. Moreover, vital effects on the trace element and stable isotope composition of the aragonite shells of these molluscs are unclear. We measured the values of δ13Cshell, δ18Oshell, Sr/Cashell and Mg/Cashell of the fossil shells of Radix sp., Gyraulus sp., and Pisidium sp. collected from the dammed lake sedimentary sequences at Xigazê and Lhainxiang in Tibet, with the aim of reconstructing the palaeo-hydrochemistry and palaeo-hydrology of the dammed palaeo-lake. The results show that the values of δ18Owater, Sr/Cawater and electrical conductivity (EC) of the dammed palaeo-lake water are higher than those of the modern Yarlung Tsangpo River water. Nevertheless, the dammed palaeo-lake still exhibited a through-flow status, together with freshwater characteristics. The values of δ18Oshell and δ13Cshell of Gyraulus sp. and Radix sp. have a positive relationship, but their ratios of Sr/Cashell and Mg/Cashell are not correlated. Moreover, δ18Oshell in the Radix sp. shells is ~2.97 ‰ more enriched and has a stronger relationship with δ18Owater than is the case for shells of Gyraulus sp. The values of δ18Oshell and δ13Cshell of Pisidium sp. are similar to those of the shells of Radix sp., and we conclude that the shells of Radix sp. are the most suitable mollusc shell for recording the δ18Owater of the ambient water of water bodies in the Tibetan Plateau. •δ18O, Sr/Ca, and EC relationships between Radix sp. and water are strong.•Reconstructed δ18O, Sr/Ca, and EC of palaeo-lake is through-flow status.•δ18Oshell and δ13Cshell of Pisidium sp. are similar to Radix sp.•δ18Oshell of Radix sp. are ~2.97 ‰ more enriched than Gyraulus sp.•Radix sp. shell is most suitable for recording δ18Owater in Tibet.