科研之友
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摘要
Magnetotellurics (MT) sounding is one of the most widely used geophysical exploration methods in volcanic areas for its wide exploration range and high sensitivity to geothermal reservoir related information such as temperature of rocks, abundance of geothermal fluid, extent of magma chamber, and lithostratigraphic strata. The electrical structure of the lithosphere is related with its thermal state. By analyzing the correlation, the geological structural model of the crust and the upper mantle can be built to enhance our understanding of the geodynamic mechanism of volcanic processes. In this paper, we first provide a brief introduction to the theoretical foundation of MT technology and the practical procedure from field data acquisition to data processing. The introduction is followed by an overview of the relationship between the electrical conductivity and temperature of the rocks. We then present several case studies from overseas to illustrate the application of the MT method in the geothermal exploration and the study of the thermal structure of the lithosphere in volcano Areas. For examples, in the Taupo volcanic area, New Zealand, MT sounding was used in the exploration of the Ngatamariki high geothermal field for hydrothermal resource in the upper 0 similar to 3km depths for power plant development; while in the Tendaho geothermal field in the Badi volcano in Afar Province, Ethiopia, the correlation between temperature and electrical structure from 0 similar to 20km and 0 similar to 50km were respectively analyzed, and the mechanism of volcanic formation and is discussed; in the Shinmoe-dake volcano in Kyushu, Japan, routine MT and temperature measurements have been used jointly to monitor volcanic activities. In the later part of this paper, we summarize the key MT sounding results from four major Cenozoic volcanic areas in China, namely, the Tengchong volcanic area in Yunnan Province, the Changbaishan Tianchi volcanic area in Jilin Province, the Wudalianchi volcanic area in Heilongjiang Province, and the Alershan volcanic area in the Inner Mongolia. We further employ the empirical temperature-electrical conductivity to constrain the temperatures of the crustal-mantle boundary for the Changbaishan-Tianchi volcanic area and the Alershan volcanic area, and possible magma chambers for the Changbaishan-Tianchi Volcano.
- 出版日期2017-1
- 单位西安交通大学
