Fig. 1

Map of sampling sites in the study area. (a) The figure shows the distribution of sampling sites in the study area; (b) Photograph of core samples from the hot spring borehole; Note: The map was independently created by the authors using ArcGIS 10.7 (https://www.esri.com/zh-cn/about/about-esri/company), and there are no copyright issues associated with its use. Figure 1 (a) was produced by the authors using WPS Presentation (Version 12.1.0.20784, Kingsoft, https://platform.wps.cn/), and Fig. 1 (b) is an original field photograph.