大地电磁测深在火山区地热研究中的应用

发布时间：2018-05-06 04:29

本文选题：地热研究 + 火山　；参考：《岩石学报》2017年01期

【摘要】：大地电磁测深(MT)由于勘探深度范围较大,且对温度、流体、岩浆房和岩性等与热储相关的地质条件的敏感度较高,因而成为火山区地热勘探和岩石圈结构研究中常用的一种地球物理勘探手段。地壳和上地幔的电性结构与热结构之间存在着密切的联系,通过解读二者的关系,可以刻画更为精细的岩石圈结构模型,进而掌握火山区的构造特征和热演化过程,了解其岩石圈地球动力学机制。本文着重介绍了MT方法的原理以及从野外数据采集到后期数据处理的过程,综述了MT法的应用特点以及电导率与温度之间的关系,通过实例分析,介绍了国际上这一方法在火山区地热勘探和岩石圈热结构研究中的应用进展,展示了MT法在新西兰Taupo火山区Ngatamariki高温地热田0~3km地热资源勘探中的应用;以埃塞俄比亚Afar省的Tendaho地热田和Badi火山为例,分别讨论了0~20km和0~50km不同深度的电性结构特征及其与温度存在的内在联系,探讨了形成火山的驱动机制;以日本九州岛的Shinmoe-dake火山为例,介绍了大地电磁测深和温度监测在火山监测方面的应用。最后简述了国内MT法在火山区的应用进展以及存在的问题,并利用上地幔电导率与温度的关系以及岩石圈内硅酸盐熔体不同含水量引起的电导率随温度的变化关系,初步估算了长白山天池和阿尔山火山区的莫霍面以下的温度以及长白山天池火山区的高温岩浆房温度。
[Abstract]:Magnetotelluric sounding (MTS) is highly sensitive to temperature, fluid, magmatic chamber and lithology, because of its wide range of exploration depth, and its sensitivity to the geological conditions related to heat storage, such as temperature, fluid, magma chamber and lithology, etc. Therefore, it has become a commonly used geophysical exploration method in geothermal exploration and lithospheric structure research. There is a close relationship between electrical structure and thermal structure of crust and upper mantle. By interpreting the relationship between them, a more precise lithospheric structure model can be described, and then the tectonic characteristics and thermal evolution process of volcanic area can be grasped. Understand its lithospheric geodynamic mechanism. In this paper, the principle of MT method and the process from field data acquisition to late data processing are introduced. The application characteristics of MT method and the relationship between conductivity and temperature are summarized. This paper introduces the international application of this method in geothermal exploration and lithospheric thermal structure research in firearea, and shows the application of MT method in the exploration of 0~3km geothermal resources in Ngatamariki high temperature geothermal field in New Zealand's Taupo fire mountain area. Taking Tendaho geothermal field and Badi volcano in Afar province of Ethiopia as examples, the electrical structure characteristics of 0~20km and 0~50km at different depths and their intrinsic relationship with temperature are discussed, and the driving mechanism of volcanoes formation is discussed. Taking the Shinmoe-dake volcano in Kyushu, Japan as an example, the application of magnetotelluric sounding and temperature monitoring in volcanic monitoring is introduced. In the end, the application progress and existing problems of MT method in fire mountain area in China are briefly introduced. The relationship between the conductivity of upper mantle and temperature and the change of conductivity with temperature caused by different moisture content of silicate melt in lithosphere are also discussed. The temperature below Moho and the temperature of magma chamber in Tianchi mountain area of Changbai Mountain and the high temperature magma chamber temperature in Tianchi Mountain area of Changbai Mountain are preliminarily estimated.
【作者单位】：西安交通大学全球环境变化研究院地热与环境研究实验室;美国密歇根大学地球与环境科学系;
【基金】：国家自然科学基金项目(41374089)资助
【分类号】：P317;P314

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