Tracing and identification of concealed Luoboling copper-molybdenum deposit in Fujian Province using trace elements and isotopes in fine-grained surface soils
LI Jian-Ting1(), LIU Xue-Min1(), WANG Xue-Qiu2, HAN Zhi-Xuan2, JANG Yao1
1. College of Earth Sciences,Chengdu University of Technology, Chengdu 610059, China 2. Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang 065000, China
This paper collected surface soil above the known concealed deposit the Luoboling porphyry-type copper-molybdenum deposit and acquired samples of ore and surrounding rocks from typical boreholes of the deposit. Then, it analyzed the changes in the contents of six trace elements (Cu, Mo, Ba, Pb, Zn, and V) and the isotopic composition of S and Pb, aiming to verify the ore prospecting effects of the measurement technology of mobile forms of metals in soil and full analysis of fine-grained soil in concealed deposits and to identify the sources of surface geochemical anomalies according to the isotopic composition of Pb and S. The study results are as follows. The total analysis of fine-grained soil showed the best effects in indicating deep ore bodies in the Luoboling deposit, and the areas with high contents of Cu, Ba, and Mo correlated strongly with the distribution of deeply concealed ore bodies. Both the mobile forms of metals in the soil and the total analysis of fine-grained soil showed that it is quite possible that concealed ore bodies occur below sampling points No.14 and 15. Meanwhile, the changes in the contents of V, Pb, and Zn obtained using both methods can accurately delineate the scopes of mineralized rock masses close to the ground surface. However, most of the total sulfur isotopic composition in the soil of anomaly zones inherits from the non-ore-hosting surrounding rocks and masked the contribution from the deep ore bodies. Consequently, sulfur isotopes showed poor effects in indicating the sources of anomalies in the surface soil in the Luoboling deposit. Therefore, it is more reasonable to measure the sulfur isotopic composition according to the mobile forms of metals in the soil. In contrast, the total Pb isotopes in the soil of the anomaly zones inherit the characteristics of the Pb isotopes of deep ore bodies. This serves as direct evidence of full analysis of fine-grained soil in the mineral exploration of coverage areas.Moreover, the changes in the 206Pb/204Pb ratio in the full analysis of surface fine-grained soil correlated strongly with the distribution of underlying concealed ore bodies and thereby can effectively indicate the deep concealed ore bodies.
李建亭, 刘雪敏, 王学求, 韩志轩, 江瑶. 地表土壤微细粒测量中微量元素和同位素对福建罗卜岭隐伏铜钼矿床的示踪与判别[J]. 物探与化探, 2022, 46(1): 32-45.
LI Jian-Ting, LIU Xue-Min, WANG Xue-Qiu, HAN Zhi-Xuan, JANG Yao. Tracing and identification of concealed Luoboling copper-molybdenum deposit in Fujian Province using trace elements and isotopes in fine-grained surface soils. Geophysical and Geochemical Exploration, 2022, 46(1): 32-45.
Ryss Y S, Goldber G I S. The partial extraction of metals (CHIM) method in mineral exploration[J]. Method and Technique, 1973,84:5-19.
Kristiansson K, Malmqvist L. Evidence for nondiffusive transport of 86Rn in the ground and a new physical model for the transport[J]. Geophysics, 1982,47(10):1444-1452.
Clark J R. Enzyme-induced leaching of B-horizon soils for mineral exploration in areas of glacial overburden[J]. Transactions of the Institution of Mining and Metallurgy Section B-Applied Earth Science, 1993,102:B19-B29.
Mann A W, Birrell R D, Mann A T, et al. Application of the mobile metal ion technique to routine geochemical exploration[J]. Journal of Geochemical Exploration, 1988,61:87-102.
Wang X Q, Cheng Z Z, Lu Y X, et al. Nanoscale metals in earthgas and mobile forms of metals in overburden in wide-spaced regional exploration for giant deposits in overburden terrains[J]. Journal of Geochemical Exploration, 1997,58:63-72.
Wang X Q. Leaching of mobile forms of metals in overburden: development and application[J]. Journal of Geochemical Exploration, 1998,61:39-55.
Xu Y, Wang M Q, Gao Y Y, et al. Tracing the source of geogas mathrials with the leaad isotope method in the Wangjiazhuang copper ore deposite of Zouping, Shandong Province[J]. Geophysical and Geochemical Exploration, 2014,38(1):23-27.
Liu X M, Chen Y L, Wang X Q. Research on isotope identification for anomalous sources of deeppenetration geochemistry: two cases of Jinwozi Au deposit, Xinjiang and Bairendaba-weilasituo polymetallic deposit, Inner Mongolia[J]. Modern Geology, 2012,26(5):1104-1116.
Saunders J A, Mathur R, Kamenov G D, et al. New isotopic evidence bearing on bonanza (Au-Ag) epithermal ore-forming proceses[J]. Mineralium Deposita, 2015,51(1):1-11.
Matthew I L, Brian L C, Wayne D G. Lead isotopes in ground and surface waters: fingerprinting heavy metal sources in mineral exploration[J]. Geochemistry: Exploration, Environment, Analysis, 2009,9:115-123.
Caritat P D, Kirste D, Carr D, et al. Groundwater in the broken hillregion, Australia: Recognising interaction with bedrock and mineralisation using S and Pb isotopes[J]. Applied Geochemistry, 2005,20(4):767-787.
Lin D Y, Cheng Z H. Relationship between Shanghang pull-apart basin in Fujian and Zijinshan copper-gold deposit mineralization[J]. Journal of Xi’an University of Science and Technology, 2011,31(4):438-442.
Pan T W, Yuan Y, Lyu Y, et al. The early-cretaceous tectonic evolution and the spatial-temporal framework of magmatismmine ralization in Zijinshan ore-field,Fujian province[J]. Journal of Geomechanics, 2019,25(1):61-76.
Guo X Q. The characteristics of alteration and mineralization zone and the prospecting indicator in the Luoboling porphyry Cu-Mo deposit, Shanghang, Fujian[J]. World Nonferrous Metals, 2020,11(8):58-61.
Liu H L, Wang X Q, Zhang B M, et al. Geochemical exploration for concealed Cu-Ni deposit, Shaquanzi, Xinjiang[J]. Computational Techniques for Geophysical and Geochemical Exploration, 2014,36(6):200-206.
Liu H L, Zhang B M, Liu D S, et al. The application of soil geochemical measurement method to the Huaniushan Pb-Zn deposit, Gansu Province[J]. Geophysical and Geochemical Exploration, 2016,40(1):33-39.
Han Z X, Zhang B M, Qiao Y, et al. Validity experiments of fine-grained soil geochemical survey for exploring concealed copper deposits: A case study in the Tongjiangling copper deposit, Jiangxi province[J]. Acta Geoscientica Sinica, 2020,41(6):977-986.
Chen Z J, Chen C X, Liu Y Q, et al. Background values and characteristics of soil elements in Fujian province[J]. Environmental Monitoring in China, 1992,12(3):107-110.
Zhang B M, Wang X Q, Ye R, et al. Geochemical exploration for concealed depositesat the periphery of the Zijinshan copper-gold mine, south-estern China[J]. Journal of Geochemical Exploration, 2015,157:184-193.
Chang H J, Chu X L, Huang J, et al. Sulfur isotope fractionation accompanying bacterial action under sedimentary condition[J]. Geological Review, 2007,53(6):807-813.
Habick K, Canfield D E, Rathemeier J. Sulfur isotope fractionation during bacterial reduction and disproportionation of thiosulfate and sulfite[J]. Geochimica et Cosmochimica Acta, 1998,62(15):2585-2595.