| Title | Deciphering geochemical traits of orogenic Lushan geothermal field in Taiwan |
|---|---|
| Authors | Y. Lu, S. Song, T. Song, T. Peng, H. Lee, L. Lin, M. Chen |
| Year | 2024 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Lushan geothermal field, helium isotopic ratios, chemical components, hydrogen and oxygen isotope composition |
| Abstract | The Lushan Geothermal Field, located within Taiwan's metapelitic orogenic belt, is recognized for its high geothermal gradient, making it a promising site for geothermal power plant development. The Silica geothermometer estimates indicate reservoir temperatures of up to 137℃in Chunyang, 153℃ in Milegu, 183℃ in Lushan/Truwan, and 151℃ in Mahebo. Despite the highest temperatures recorded in the Lushan/Truwan area, the risk of landslides suggests that future drilling should be concentrated in the Chunyang and Milegu areas. Seasonal variations significantly influence the chemical composition of hot springs in the Lushan Geothermal Field. During the dry season, the waters are primarily Na2CO3-rich, whereas in the wet season, they shift to Ca(HCO3)2 or even CaSO4. The δD and δ18O values exhibit a concentrated pattern during the dry season and a more dispersed pattern during the wet season. These isotopic values do not clearly distinguish between the different areas within the geothermal field, such as Chunyang, Milegu, Lushan/Truwan, Mahebo, and Jingying, and variability within the same area suggests possible differences in local water circulation systems. The similarity between the δD values of hot spring water and those of local rivers and groundwater indicates that the geothermal waters are likely derived from heated shallow groundwater rather than deep circulation or recharge from higher elevations. The RA ratio of helium isotopes indicating a crustal source mixed with atmospheric components. Furthermore, the hot spring waters are either saturated or supersaturated with minerals, highlighting the potential for scaling issues that must be addressed in any future geothermal power plant development in the area. |