Abstract
Elucidating brine origin and evolution is a fundamental but not easy task especially for coastal geothermal systems with possible marine constituents and multistage evolution, as subsequently physical, chemical and biological alteration processes may mask the original and early-stage signatures. Here chemical and isotopic characteristics of water (D and 18O) and dissolved constituents (13C, 14C, 11B and 87Sr/86Sr) have been utilized to investigate the source and multistage evolution of the Jimo coastal geothermal system in eastern China, with dramatic differences of geochemical characteristics observed within a 0.2 km2 area. Results show that geothermal water is derived from paleo-meteoric water and has undergone a 3-stages evolution that involves: (1) Dissolution of marine halite and potash salts in the deep reservoir; (2) Water-rock reactions especially cation exchange produces a Cl-Na-Ca type water as deep geothermal water upwells along the fault zone; (3) A minor (<0.3%) addition of fossil seawater to the shallow aquifer that produces Cl-Na type waters in the west, whereas sulfide oxidation and dissolution of aluminosilicate and carbonates in the east produces Cl-Na-Ca type waters. The methodology utilized in this study offers a means of examining other similar complex geochemical systems having a multistage evolution.
Highlights
A clear understanding of brine origin and evolution in coastal geothermal systems is necessary for the sustainable management of geothermal waters
This paper investigates the multistage evolution of Jimo coastal geothermal system with dramatic differences of geochemical characteristics within a 0.2 km2 area to discern the origin and evolution of geothermal both water and dissolved constituents
Geothermal water and shallow groundwater in the study area lying on the local meteoric water line (LMWL) indicate the dominated meteoric origin (Fig. 2A)
Summary
A clear understanding of brine origin and evolution in coastal geothermal systems is necessary for the sustainable management of geothermal waters. Numerous chemical and isotopic techniques have been developed, exclusive identification the salinity of coastal geothermal waters with marine or non-marine origin is still difficult like some modern non-marine saline lakes exhibit similar chemical compositions to evaporated water [1, 2]. Research about detailed delineation of geothermal waters evolution pattern at different stage is relatively scarce, which may be contributed to that subsequently. This paper investigates the multistage evolution of Jimo coastal geothermal system with dramatic differences of geochemical characteristics within a 0.2 km area to discern the origin and evolution of geothermal both water and dissolved constituents
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
