Fluid Geochemistry of Fault Zone Hydrothermal System in the Yidun-Litang Area, Eastern Tibetan Plateau Geothermal Belt

Abstract EN

The geochemical and geothermal characteristics of hydrothermal systems in an area are useful information to appropriately evaluate the geothermal potential.

In this paper, we investigated the chemical and isotopic composition of thermal water in an underexploited geothermal belt, Yidun-Litang area, in eastern Tibetan Plateau.

24 hot spring samples from the Yidun and Litang area were collected and analyzed.

The water chemical types of the hot springs are mainly Na-HCO3-type water.

Water-rock interaction and cation exchange and mixture are the dominant hydrogeochemical processes in the hydrothermal evolution.

The significant shift of D and 18O isotopes from the GMWL indicates that these springs have undergone subsurface boiling before rising to the surface.

Different ratios of Cl to other conservation species can be found for the springs in Litang and Yidun areas, suggesting the different heat sources of the two hydrothermal systems.

The reservoir temperature in the Yidun area is around 230°C while the reservoir temperature in the Litang area is around 200°C.

Both hydrothermal systems are recharged by the meteoric water and are heated by the different deep, thermally and topographically driven convection heat along faults and undergoing subsurface boiling before going back to the surface.