Hydrogeochemical Characteristics of Hot Springs and Their Short-Term Seismic Precursor Anomalies along the Xiaojiang Fault Zone, Southeast Tibet Plateau

Abstract

Significant hydrogeochemical changes may occur prior- and post-earthquakes. The Xiaojiang fault zone (XJF), situated in a highly deformed area of the southeastern margin of the Tibetan Plateau, is one of the active seismic areas. In this study, major and trace elements, and hydrogen and oxygen isotopes of 28 sites in hot springs along the XJF were investigated from June 2015 to April 2019. The meteoric water acts as the primary water source of the hot spring in the XJF and recharged elevations ranged from 1.8 to 4.5 km. Most of the hot spring water in the study area was immature water and the water–rock reaction degree was weak. The temperature range was inferred from an equation based on the SiO2 concentration and chemical geothermal modeling: 24.3~96.0 °C. The circulation depth for the springs was estimated from 0.45 to 4.04 km. We speculated the meteoric water firstly infiltrated underground and became heated by heat sources, and later circulated to the earth’s surface along the fault and fracture and finally constituted hot spring recharge. Additionally, a continuous monitoring was conducted every three days in the Xundian hot spring since April 2019, and in Panxi and Qujiang hot springs since June 2019. There were short-term (4–35 d) seismic precursor anomalies of the hydrochemical compositions prior to the Xundian ML4.2, Dongchuan ML4.2, and Shuangbai ML5.1 earthquakes. The epicentral distance of anomalous sites ranged from 19.1 to 192.8 km. The anomalous amplitudes were all over 2 times the anomaly threshold. The concentrations of Na+, Cl−, and SO42− are sensitive to the increase of stress in the XJF. Modeling on hydrology cycles of hot springs can provide a plausible physicochemical basis to explain geochemical anomalies in water and the hydrogeochemical anomaly may be useful in future earthquake prediction research of the study area.

Geochemical Characteristics of Thermal Springs and Insights Into the Intersection Between the Xiaojiang Fault and the Red River Fault, Southeastern Tibet Plateau

“…The RRF is the northeastern boundary of the Indo-Chinese block (ICB) and the southwestern boundary of the SYB, with a distinct arcuate division in the geomorphology (Replumaz et al, 2001;Schoenbohm et al, 2006); the and RRF, and within the ICB, respectively. The black and white borders of the numbered points represent the sampling points in this study and the ones from previous studies (C. Li et al, 2021;L. Shen et al, 2007;Y.…”

“…Numbered triangles, circles, and diamonds represent sampling sites along or near the XJF (including Qujiang fault and SJF) and RRF, and within the ICB, respectively. The black and white borders of the numbered points represent the sampling points in this study and the ones from previous studies (C. Li et al., 2021; Z. Li et al., 2022; L. Shen et al., 2007; Y. Wang, 2021; Y. Wang et al., 2020; K. Zhao et al., 2005; X. Zhou et al., 2020), respectively.…”

“…The frequent occurrence of strong earthquakes along the eastern boundary of the SYB has intensified the rotation of the block with ongoing southward compression, making it necessary to further investigate the tectonic activity of the front edge of the SYB. Some studies on geothermal fluid geochemistry in the area have focused on the hydrothermal circulation characteristics and volatile origin at both a single fault and limited locations at the front edge of the SYB (He et al., 2023; C. Li et al., 2021; Shao et al., 2022; Y. Wang, Zhao, et al., 2014; X. Zhou et al., 2020). Nevertheless, fluid geochemistry research on the intersection relationship between the XJF and RRF is lacking, and the relationship between fluid geochemistry and regional tectonic features in the front edge of SYB remains unclear.…”

Hydrogeochemistry of Hot Springs and the 2018 Mojiang M 5.9 Earthquake-Related Chemical Changes in the Simao Basin, China

“…During the entire sampling period, most of the cations and anions varied with the two sigma relative standard deviation (2σ). Before the earthquake, ionic concentration increased slightly (only 10-20% above the background value) and was considered insignificant (Toutain et al, 1997;Li et al, 2021). In the springs, Ca 2+ and HCO 3 − ions exhibited significant changes before the Mojiang M5.9 earthquake; however, other ions stayed relatively stable in the springs.…”

Microbial diversity and abundance in the hot springs on the west coast of Saudi Arabia as a potential source of novel industrial products

“…The chemical and physical features of hot springs, which are consistently among the hottest sites in the world, allow for the growth of thermophilic bacteria (Li et al 2021;Simmons et al 2021). A thermophile is an organism that has evolved to thrive in temperatures ranging from 45°C to 80°C.…”