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

Yi Chia Lu, Sheng Rong Song, Pei Ling Wang, Chung Che Wu, Horng Sheng Mii, John MacDonald, Chuan Chou Shen, Cédric M. John

Research output: Contribution to journalArticle

7 Citations (Scopus)

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 δ18O values of the source fluids. Two populations of δ18O 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.

Original languageEnglish
Pages (from-to)124-133
Number of pages10
JournalJournal of Asian Earth Sciences
Volume149
DOIs
Publication statusPublished - 2017 Nov

Keywords

  • Calcite veins
  • Chingshui geothermal field
  • Clumped isotopes
  • Magmatic fluid

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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