Hydrogeochemistry and genetic mechanisms of the geothermal system in the Xi'an depression of the southern Weihe Basin, China

Abstract

Investigating hydrogeochemistry in geothermal fluids is a valuable approach to comprehending the intricate process of deep geothermal water circulation and uncovering the underlying mechanism behind the formation of geothermal systems. The article presents a thorough investigation of the hydrogeochemical and stable isotope characteristics of geothermal fields situated on both the southern and northern sides of the Xi'an depression. This study elucidates the process and progression of deep geothermal water, thereby offering theoretical backing for the exploitation of geothermal resources in the Weihe Basin. The data indicates the following points. The predominant chemical composition of geothermal water consists of SO₄·HCO₃–Na and SO₄·HCO₃·Cl–Na types. The ionic components are mainly impacted by the dissolution of Silicate and evaporite minerals, as well as the alternating adsorption of cations. The geothermal water is replenished by rainfall from the Qinling Mountains, with the recharge elevation varying from 677.94 m to 1,467.65 m. Various techniques are employed to determine the temperature and depth of the reservoir, which helps to understand the behavior of the deep thermal water. Thus, the study determines that the geothermal water in the Xi'an depression originates from laminar-controlled geothermal reservoirs, lateral flow recharge, and an unusual deep thermal structure.