LAUSR

Received: 28 December 2019 Accepted: 17 March 2020 Ruidian geothermal field is a treasure trove of geothermal resources in Southwest China. This paper probes deep into the hydro-chemical features and isotopic features of geothermal fluids in the geothermal field, and discusses the evolution of the hydrochemical features. The main results are as follows: the geothermal fluids were recharged by the same source, and mixed with cold water through a simple process, that is, the fluids originated from the same high-temperature deep reservoir. The leading hydro-chemical features in Ruidian geothermal field are HCO3·Cl-Na. The Clcontent peaked at 200mg/L, and the O drifted positively by 1.5% to 2.5%. The water-rock interaction in the geothermal fluids is not in the equilibrium state. A good portion of the fluids is surface water. To a certain extent, the underground geothermal fluids have an open circulation condition. The hydro-chemical components mainly come from granite dissolution, the alteration of the magma and hydrothermal fluid, and the mixing with groundwater.