| 复杂地形结构下瞬变电磁三维正演模拟 |
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| 引用本文： | 聂佐夫,陶春辉,沈金松,朱忠民.复杂地形结构下瞬变电磁三维正演模拟[J].海洋学报,2021,43(6):145-156. |
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| 作者姓名： | 聂佐夫 陶春辉 沈金松 朱忠民 |
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| 作者单位： | 1.上海交通大学 海洋学院，上海 200240 |
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| 基金项目： | 国家重点研发计划（2018YFC0309901，2017YFC0306203）；国家自然科学基金（41706042，41906174）；中国大洋十三五课题（DY135-S1-01-07） |
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| 摘 要： | 如何确定海底多金属硫化物的空间分布并对其进行资源量评价至关重要。瞬变电磁法是陆地金属矿床勘探的重要手段，但海底的崎岖地形、硫化物的复杂结构以及不稳定的近底观测条件为瞬变电磁在海洋中的应用提出了挑战。为验证瞬变电磁方法对热液区硫化物的勘探应用潜力，本文采用了有限元方法，结合大西洋洋中脊TAG热液区实测地形数据和硫化物深部剖面进行三维正演模拟，通过对比仪器在不同位置、姿态、离底高度的正演模拟结果发现:重叠回线探测装置在离底高度小于60 m时，可以有效探测到TAG丘体的高电导率异常。海底复杂地形以及仪器拖曳方式都会对二次场早期响应产生干扰，同时仪器姿态变化也会改变所探测到的响应，这表明，应结合研究区域的海底地形、仪器海底定位以及姿态数据才能更好的对实测瞬变电磁数据进行合理解释。
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| 关 键 词： | 瞬变电磁法 三维正演 TAG热液区 海底多金属硫化物 复杂地形与结构 |
| 收稿时间： | 2020-07-24 |
3D transient electromagnetics forward modeling with complex topography and structure: A case study of the TAG hydrothermal field,Mid-Atlantic Ridge |
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| Institution: | 1.School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China2.Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China3.Key Laboratory of Submarine Geoscience, Ministry of Natural Resources, Hangzhou 310012, China4.College of Geophysics, China University of Petroleum (Beijing), Beijing 102249, China |
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| Abstract: | It is crucial to evaluate seafloor massive sulfides (SMS) in terms of their special distribution. Transient electromagnetic method (TEM) is ideal for land mineral deposits prospecting, but the complicated seafloor topography, inner structure of sulfide deposits and measuring conditions in the hydrothermal field pose a great challenge to its application in the ocean. In order to verify the application potential of TEM in deep-sea exploration, a 3D forward modeling scheme was developed with finite element method, combining with bathymetry data and drilling results. The method was then applied to the TAG hydrothermal field, Mid-Atlantic Ridge, and the result was well fitted with acquired TEM data. By comparing the forward simulation results under different instrument positions, attitudes and altitude, we found that the coincident loop system could effectively detect the active TAG mound ore body when the altitude was less than 60 meters. Complex seafloor topography and how the instrument was being towed could significantly disturb the early time response, while the instrument attitude also made an influence on the detected signal. Therefore, it was necessary to combine the bathymetry data, instrument positioning data and attitude data in the research area to better interpret the measured TEM responses. |
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