Chemical and isotopic compositions of boron in the geothermal waters in the Xianshuihe Fault Zone, Western Sichuan Province, China

In this study, boron contents and boron isotopic compositions of geothermal waters are first reported in the Xianshuihe Fault Zone (XSHFZ), Western Sichuan. The results show that boron contents of geothermal water are 0.03-10.50 mg/L, and the delta B-11 values range from -6.75 to 4.01 parts per thousand, indicating the non-marine origin. The delta B-11 values and Cl/B molar ratios reveal that boron in geothermal water is mainly leached from reservoir rocks, such as carbonate and igneous rocks. Comparing it with other geothermal systems in the Yunnan-Tibet Geothermal Belt, we found that the samples from XSHF have the largest variations of Cl/B molar ratio and the intermediate delta B-11 values.