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.
Shuai HE,Bing-Nan YANG,Shuai RUAN, et al. Fine Interpretation of the exploration results of diamond-bearing rock masses in Maping area, Guizhou using the 3D AMT forward modeling and inversion technologies[J]. Geophysical and Geochemical Exploration,
2022, 46(3): 618-627.
Li Y G, Xiang L, Huang Y C, et al. Re-understanding of diamond-bearing parent rocks in Zhenyuan area, Guizhou Province[J]. Geological Bulletin of China, 2019, 38(1): 103-109.
Li Y G. Petrological and ore-bearingproperties of the diamond-bearing pluton in Zhenyuan Area of Guizhou Province[D]. Wuhan: China University of Geosciences(Wuhan), 2019.
Huang Y C, Shi R, Lin Z Y, et al. Discovery of lamproite tube and Its prospecting significance in Cangputang of Zhenyuan, Guizhou Province[J]. Guizhou Geology, 2015, 32(1): 32-36.
Zhang X G, Shi R, Wu S N, et al. New discovery of lamproite and its significance for diamond exploration in Wengshao Area of Shibing,Guizhou Province[J]. Guizhou Geology, 2015, 32(1): 37-40.
Huang Y C, Li Z X, Qiu Z L, et al. Mineralogical characteristics oflamproite-hosted and placer diamonds from Zhenyuan, Guizhou and their significance for primary deposit prospecting[J]. Acta Scientiarum Naturalium Universitatis Sunyatseni, 2016, 55(5): 108-118.
Tian Z F, Mao X, Luo X, et al. The application of AMT method to the electrical structure study: A case study of Suqian sector of Tan-Lu Fault Zone[J]. Geophysical and Geochemical Exploration, 2016, 40(4): 732-736.
He S, Yang B N, Li H L, et al. Identification of Ⅳ graben tectionics of southeast Chongqing by AMT method and its significanc[J]. Geological Science and Technology Information, 2019, 38(1): 270-276.
[9]
Simpson F, Bahr K. Practical magnetotellurics[M]. Cambridge: Cambridge University Press, 2005.
[10]
Saraev A K, Larionov K A. 音频大地电磁测深在金伯利岩勘探中的应用[J]. 石油地球物理勘探, 2004, 39(S1):144-145.
[10]
Saraev A K, Larionov K A. Application of audio geomagnetic bathymetry in Kimberley rock exploration[J]. Petroleum Geophysical Exploration, 2004, 39(S1): 144-145.
[11]
Saraev A K, Antaschuk K M, Nikiforov A B, 等. AMT测深法在金刚石矿勘探中的应用[J]地球物理学报, 2010, 53(3): 657-676.
[11]
Saraev A K, Antaschuk K M, Nikiforov A B, et al. Audiomagnetotelluric soundings for the diamond exploration[J]. Chinese J. Geophys., 2010, 53(3): 657-676.
[12]
Zhdanov M S, Fang S, Hursan G. Electromagnetic inversion using quasi-linear approximation[J]. Geophysics, 2000b, 65(5): 1501-1513.
[13]
Siripunvaraporn W, Egbert G, Lenbury Y. Numerical accuracy of magnetotelluric modeling:a comparison of finite difference approximations[J]. Earth Planets Space, 2002, 54(6): 721-725.
Liang M, Liu S, Hu X Y. AMT numerical simulation of fault model and its applications[J]. Geological Science and Technology Information, 2016, 35(5): 231-237.
[15]
Zhdanov M S, Tolstaya E. Minimum support nonlinear parametrization in the solution of a 3D magnetotelluric inverse problem[J]. Inverse Problems, 2004, 20(3): 937-952.
Tang J T, Zhang L C, Wang X Y, et al. Subsurface electrical structure of the Fanshan-Jiangjunmiao region in the Lujiang-Zongyang Ore District derived from 3-D inversion of audio-magnetotelluric data[J]. Chinese J. Geophys., 2018, 61(4): 1576-1587.
[17]
孙士军, 杨松平. 贵州金刚石成矿条件初探[J]. 贵州地质, 1998, 15(1):1-8.
[17]
Sun S J, Yang S P. A discussion on prerequisites to search for primary diamondsin Guizhou[J]. Guizhou Geology, 1998, 15(1): 1-8.
[18]
Hayman P C, Kopylova M G, Kaminsky F V. Lower mantle diamonds from Rio Soriso (Juina area, Mato Grosso,Brazil)[J]. Contributions to Mineralogy & Petrology, 2005, 149(4): 430-445.
[19]
Tappert R, Stachel T, Harris J W, et al. Diamonds from Jagersfontein (South Africa): Messengers from the sublithospheric mantle[J]. Contributions to Mineralogy & Petrology, 2005, 150(5): 505-522.
[20]
Bulanova G P, Walter M J, Smith C B, et al. Mineral inclusions in sublithospheric diamonds from Collier 4 kimberlite pipe, Juina, Brazil: Subducted protoliths, carbonated melts and primary kimberlite magmatism[J]. Contributions to Mineralogy and Petrology, 2010, 160(4): 489-510.
Wang L, Tao P. Ore-search prospecting areas of diamond-bearing lamproite in southeastern Guizhou Province[J]. Geology and Exploration, 2012, 48(4): 775-783.
Wang L, Tao P. Determination of Diamond Parent Rock in Eastern Guizhou By Regional Geophysical Prospecting Gravity and Magnetic Information[J]. Guizhou Geology, 2011, 28(4): 254-259.
Fan H F, Wang L. Volcano-tectonic characteristics of diamond ore prospects in southeast Guizhou[J]. Chinese Journal of Engineering Geophysics, 2016, 13(3): 389-398.
[24]
阮帅. 三维大地电磁有限内存拟牛顿反演[D]. 成都: 成都理工大学, 2015.
[24]
Ruan S. Three-dimensional geomagnetic finite memory is intended for Newtonian inversion[D]. Chengdu: Chengdu University of Technology, 2015.
Ruan S, Zhang J, Sun Y B, et al. AMT impedance phase invariant correction based on 3D MT modeling technology[J]. Chinese J. Geophy., 2015, 58(2): 685-696.
[26]
Mackie R L, Madden T R, Wannamaker P E. Three-dimensional magnetotelluric modeling using difference equations: Theory and comparisons to integral equation solutions[J]. Geophysics, 1993, 58(2): 215-226.
[27]
Newman G A, Alumbaugh D L. Three-dimensional magnetotelluric inversion usingnon-linear conjugate gradients[J]. Geophys. J. Int., 2000, 140(2): 410-424.
[28]
Byrd R H, Nocedal J, Schnabel R B. Representations of quasi-Newton matrices and their use in limited memory methods[J]. Mathematical Programming, 1994, 63(1-3): 129-156.
Deng Y, Tang J, Ruan S. Adaptive regularized three-dimensional magnetotelluric inversion based on the LBFGS quasi-Newton method[J]. Chinese J. Geophy., 2019, 62(9): 3601-3614.
Ruan S, Tang J, Chen X B, et al. Three-dimensional magnetotelluric inversion based on adaptive L1-norm regularization[J]. Chinese J Geophy, 2020, 63(10): 3896-3911.
