Evolution of hot fluids in the Chingshui geothermal field inferred from crystal morphology and geochemical vein data

Lu, Y.-C., Song, S.-R., Taguchi, S., Wang, P.-L., Yeh, E.-C., Lin, Y.-J., MacDonald, J. and John, C. M. (2018) Evolution of hot fluids in the Chingshui geothermal field inferred from crystal morphology and geochemical vein data. Geothermics, 74, pp. 305-318. (doi:10.1016/j.geothermics.2017.11.016)

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Abstract

The Chingshui geothermal field once hosted the first geothermal power plant in Taiwan from 1981 to 1993. After a long period of inactivity, this field is attracting renewed interest to meet the need for clean energy. A 213-m length of cores (IC-21) with continuous recovery, the longest in the Chingshui geothermal field, was recovered from 600 m to 813 m below the surface in 2010. Three types of calcite crystal morphologies have been identified in the veins of the cores of well IC-21: bladed, rhombic and massive crystals. Bladed calcites are generated via degassing under boiling conditions with a precipitation temperature of ∼165 °C and calculated δ18O value of −6.8‰ to −10.2‰ VSMOW for the thermal water. Rhombic calcites grow in low concentration Ca2+ and CO32− meteoric fluids and precipitate at approximately ∼180 °C. Finally, massive calcites are characterized by co-precipitation with quartz in the mixing zone between meteoric water and magmatic or metamorphic fluids with calculated δ18O value of up to 1.5 ± 0.7‰ VSMOW. Furthermore, the scaling and hot fluids at a nearby pilot geothermal power plant confirm a meteoric origin. Based on these observations, we propose that the current orientations of the main conduits for geothermal fluids are oriented at N10°E with a dip of 70°E. This result provides the basic information needed for deploying production and injection wells in future developments of the geothermal power plant in this region.

Item Type:Articles
Additional Information:This work was supported by the Ministry of Science and Technology (MOST), Taiwan [MOST 103-3113-M-002-001, MOST 104-3113-M002-001, and MOST 105-3113-M-002-001].
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:MacDonald, Dr John
Authors: Lu, Y.-C., Song, S.-R., Taguchi, S., Wang, P.-L., Yeh, E.-C., Lin, Y.-J., MacDonald, J., and John, C. M.
College/School:College of Arts > School of Critical Studies > Theology and Religious Studies
Journal Name:Geothermics
Publisher:Elsevier
ISSN:0375-6505
ISSN (Online):1879-3576
Published Online:01 February 2018
Copyright Holders:Copyright © 2017 Elsevier Ltd.
First Published:First published in Geothermics 74:305-318
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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