Metamorphic type geothermal characteristics study by using integrated geophysical methods–Example from Jinlun geothermal

• Main Authors: Tai-rong Guo, 郭泰融
• Other Authors: Chow-Son Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/88956396072094552498

博士 === 國立中央大學 === 地球物理研究所 === 97 === Geothermal resources exploitation is difficult at Taiwan area because of structure complexity and low permeability in metapelites. The low resistivity anomalies have generally been the main target for geophysical exploration of geothermal resources in many countries. It is worth further study that if there exists low resistivity anomaly in metamorphic geothermal area. Also, temperature and geothermal reservoir distribution are important information in future geothermal exploration in Taiwan area. This study aimed at the characterics study of Jinlun geothermal site which is located at southeast part of Taiwan. The lithology of Jinlun area is composed of slate and metasandstone. Incorporated with Audio frequency Magnetotellurics, gravity, nature gamma methods were conducted in this study to establish geothermal conceptual model. Two significant findings are proposed. 1.High temperature gradient at Jinlun area could be the result of rapid uplift caused by subduction and exhumation at convergent margin. Recharge to the Jinlun geothermal system appears to be from high-elevation meteoric waters originating in the Central Range. These waters circulate to considerable depth where they are heated within the metamorphic basement. Under hydraulic head or buoyancy, hot water flow along RF2 to surface as hot spring. Saline fluid and clay alteration together with the high temperatures associated with geothermal activity tend to result lower resistivity area. The geothermal reservoir may located at the fracture zone which is caused by RF1. 2.The low resistivity anomalies on geophysical exploration are important characteristics both on Jinlun and Chingshui geothermal area. This implies that low resistivity anomalies are also the main target for geothermal exploration at metamorphic area.