Search

Hydrogeochemistry of 32 hot springs in the western Sichuan Province after theWenchuanMS 8.0 earthquake was investigated by analyzing the concentrations of cation and anion and the isotopic compositions of hydrogen and oxygen. The water samples of the hot springs were collected four times from June 2008 to April 2010. Hydrogeochemical data indicated the water samples can be classified into 9 chemical types. Values of δD and δ18O indicated that the spring waters were mainly derived from meteoric precipitation and affected by water-rock interaction and mixture of deep fluids. Concentrations of K+and SO4- of the samples from the Kangding district exhibited evident increases before the Wenchuan earthquake, indicating more supplement of deep fluids under the increase of tectonic stress.The chemical and isotopic variations of the water samples fromthe area closer to the epicenter area can be attributed to variation of regional stress field when the aftershock activities became weak. [ABSTRACT FROM AUTHOR]

The chemical components, He, Ne, and C isotropic ratios of gas samples collected thrice from 32 hot springs in western Sichuan Province, southwestern China in June and October 2008 and June 2009 were investigated in order to discuss the relationship between hot spring gas geochemistry and the Wenchuan Ms 8.0 earthquake. The data showed that the ³He/4He and ... values in spring gases in the Longmenshan fault (LMSF), Xianshuihe fault (XSHF), and Minjiang fault (MJF) zones increased obviously after the great earthquake. It was estimated that up to 62% of mantle helium contributed to the spring gas in the Kangding region based on the maximum ³He/4He (7.42 x 10-6) in June 2008. Over time the mantle derived fluid contribution to the hot springs gradually decreased, but the crustal gas components: CO2 and CH4 derived from organic matter and radiogenic He increased. The gas geochemical data suggested that more mantle fluids migrated into the crust in western Sichuan Province after the Wenchuan Ms 8.0 earthquake. [ABSTRACT FROM AUTHOR]