Magmatic-like fluid source of the Chingshui geothermal field, NE Taiwan evidenced by carbonate clumped-isotope paleothermometry

Lu, Y.-C., Song, S.-R., Wang, P.-L., Wu, C.-C., Mii, H.-S., MacDonald, J. , Shen, C.-C. and John, C. (2017) Magmatic-like fluid source of the Chingshui geothermal field, NE Taiwan evidenced by carbonate clumped-isotope paleothermometry. Journal of Asian Earth Sciences, 149, pp. 124-133. (doi: 10.1016/j.jseaes.2017.03.004)

Abstract

The Chingshui geothermal field, a moderate-temperature and water-dominated hydrothermal system, was the site of the first geothermal power plant in Taiwan. Many geological, geophysical and geochemical studies using more than 21 drilled wells have been performed since the 1960s. However, there are still controversies regarding the heat and fluid sources due to the tectonically complicated geological setting. To clarify the heat and fluid sources, we analyzed clumped isotopes with carbon and oxygen isotopic compositions of calcite scaling in geothermal wells and veins on outcrops and calculated the 18O values of the source fluids. Two populations of 18O values were calculated: -5.8±0.8 ‰ VSMOW from scaling in the well and -1.0±1.6 ‰ to 10.0±1.3 ‰ VSMOW from outcropping calcite veins, indicative of meteoric and magmatic fluid sources, respectively. Meanwhile, two hydrothermal reservoirs at different depths have been identified by magnetotelluric (MT) imaging with micro-seismicity underneath this area. As a result, we propose a two-reservoir model: the shallow reservoir provides fluids from meteoric water for the scaling sampled from wells, whereas the deep reservoir provides magmatic fluids from deep marble decarbonization recorded in outcropping calcite veins.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacDonald, Dr John
• Authors: Lu, Y.-C., Song, S.-R., Wang, P.-L., Wu, C.-C., Mii, H.-S., MacDonald, J., Shen, C.-C., and John, C.
• Subjects: Q Science > QE Geology
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
• Research Group: Solid Earth Research Group
• Journal Name: Journal of Asian Earth Sciences
• Journal Abbr.: JAES
• Publisher: Elsevier
• ISSN: 1367-9120
• ISSN (Online): 1878-5786
• Published Online: 03 March 2017
• Copyright Holders: Copyright © 2017 Elsevier Ltd.
• First Published: First published in Journal of Asian Earth Sciences 149:124-133
• Publisher Policy: Reproduced in accordance with the publisher copyright policy