Fine Interpretation of the exploration results of diamond-bearing rock masses in Maping area, Guizhou using the 3D AMT forward modeling and inversion technologies
HE Shuai1,2(), YANG Bing-Nan1,2,3(), RUAN Shuai4, LI Yong-Gang5, HAN Yao-Fei1, ZHU Da-Wei1
1. No. 103 Geologic Team, Bureau of Geology and Mineral Exploration and Development of Guizhou, Tongren 554300, China 2. Engineering Technology Innovation Center of Resources Explorations in Basement Area of China, Ministry of Natural Resources, Guiyang 550001,China 3. Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China 4. Sinoprobe Center-China Deep Exploration Center, Chinese Academy of Geological Sciences, Beijing 100037, China 5. No. 101 Geologic Team, Bureau of Geology and Mineral Exploration and Development of Guizhou, Kaili 556000, China
The "Dongfang No.1" rock mass in the Maping area, Zhenyuan County, Guizhou is the parent rock of a primary diamond-bearing deposit discovered in China for the first time. Studies have shown that the rock mass found in the Maping area is of the shallow facies of the kimberlite magmatic system, and large-scale concealed rock pipes or buckets may exist in the deep part. To reveal the spatial distribution of deep diamond-bearing concealed rock pipes or buckets in the Maping area, this study carried out the audio-magnetotelluric (AMT) data acquisition in the area using a high grid density of 80 m × 40 m. Then it simulated the pure terrain response in the study area using the 3D forward modeling and deducted the pure terrain response from the measured data. The obtained qualitative interpretation results restored the distribution morphology of AMT impedance phase invariants to some extent that was distorted by static effects. Afterward, this study performed the 3D inversion of the data using the AR-QN quasi-Newtonian inversion method. Based on the lithologic statistical results of the study area, the resistivity variation intervals of the underground units were set during the inversion, obtaining a reliable 3D electrical structure. Finally, this study carried out a fine interpretation of the geoelectric model of this area based on geological data such as rock tubes found on the surface and multiple dikes revealed by boreholes, outlining the morphology of concealed rock pipes or buckets. This study will provide a geophysical basis for the future prospecting and prediction of primary diamond deposits in this area.
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HE Shuai, YANG Bing-Nan, RUAN Shuai, LI Yong-Gang, HAN Yao-Fei, ZHU Da-Wei. Fine Interpretation of the exploration results of diamond-bearing rock masses in Maping area, Guizhou using the 3D AMT forward modeling and inversion technologies. Geophysical and Geochemical Exploration, 2022, 46(3): 618-627.
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