Boron source and evolution of the Zabuye salt lake, Tibet: Indication from boron geochemistry and isotope

• Published in: Applied geochemistry Vol. 148; p. 105516
• Main Authors: Zhang, Wenjie, Tan, Hongbing, Xu, Wensheng, Huang, Jinquan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2023
• Subjects: boron; Boron isotopes; Boron sources; China; climate; Equilibrium isotopic fractionation; evaporation rate; evolution; geochemistry; isotope fractionation; isotopes; liquids; lithium; salt lakes; watersheds; Zabuye salt lake; China; Boron isotopes; Equilibrium isotopic fractionation; Zabuye salt lake; Boron sources
• ISSN: 0883-2927; 1872-9134
• DOI: 10.1016/j.apgeochem.2022.105516

The Zabuye salt lake is well known for its super enrichment of boron (B) and lithium (Li), and for the natural production of LiCO3, which is unique worldwide. However, it is still unclear that where these giant B deposits were from and how the abnormally depleted B isotopic compositions were formed. In this study, the geochemical compositions and B isotopes of liquid and solid reservoirs in the Zabuye drainage basin were systematically measured to reveal the B isotopic fractionation and provide constraints on potential B sources. The results showed: 1) The brine has greater boron concentrations (1.45 g/L∼ 4.82 g/L) and extremely lower isotopic values (−18.06‰ ∼ −13.63‰) as compared to other salt lakes on the Tibetan Plateau; 2) The homologous evolutionary paths and similar B isotopic compositions of regional water suggested that the enriched B in the Zabuye salt lake was mainly derived from hydrothermal activities rather than the surrounding metamorphic rocks, altered rocks, and Quaternary sediments; 3) Multi-isotope (B and O) data and geochemical analysis indicated that the depleted B isotopic compositions of the brine were caused by the redissolution of B-bearing minerals rather than evaporation, although the evaporation rate can reach up to 87.4%; 4) The dominance of redissolution implies a favourable prospect for liquid B accumulation in the present salt lakes, given the increase of lake area since 2012 in response to climate warming of the Tibetan Plateau. These findings would enhance the understanding of B isotopic fractionation and ore-forming mechanisms on the Tibetan Plateau. •Chemical and boron isotopic data of main waters and rocks in the Zabuye drainage basin were provided.•The enriched B in the Zabuye salt lake was mainly derived from hydrothermal activities.•The depleted B isotopic compositions of the brine were caused by redissolution of B-bearing minerals.