| 第四系覆盖区深部热液脉型矿体综合地球物理方法定位预测——内蒙古维拉斯托矿区北侧隐伏矿体勘查例析 |
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| 关键词:Weilasituo integrated geophysical methods exploration model hydrothermal vein type of concealed orebody |
| 基金项目:国家自然科学基金项目(编号: 41504063);国家重大科学仪器设备开发专项(编号: B02011YQ05006011);高等学校学科创新引智计划“111计划”(编号: B07011);中国地质调查局地质调查项目(编号: 1212011120202; 121201108000150003-02) |
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| Application of Integrated Geophysical Methods to the Prospecting for Concealed Hydrothermal Vein-type Orebodies beneath Quaternary Sediments: A Case Study of the Northern Area of the Weilasituo Copper Polymetallic Deposit |
| The Weilasituo magmatic hydrothermal vein-type copper-polymetallic deposit, with proven reserves of 8.811 4 million tons, is located in the western part of the southern section of the Da Hinggan Mountains metallogenic belt. The average grade of Cu, Zn and Ag is 0.79%, 4.29% and 65~85 g/t, respectively. The NE–NEE-trending orebodies are strictly controlled by the NE-trending fault zones and dip northward. The existence or nonexistence of concealed orebody on the northern side of the Weilasituo ore district, which is covered by Quaternary cover, is an urgent problem to be solved. On the northern side of Weilasituo, the areas covered by the Quaternary sediments possess similar metallogenetic conditions to the main ore district. In order to investigate the concealed oresbodies, the authors used integrated geophysical methods such as gravity method, magnetic method, induced polarization in median gradient array method and controlled source audio-frequency magnetotelluric method. Firstly, three NE–NNE trending ribbon-shaped negative residual density zones, which indicate the underlying faults F1, F2 and F3, were detected based on directional derivative of gravity anomaly. In these zones, a crescent-shaped anomaly zone, with high values of magnetic reduction to pole and upward extension, was considered to be the target of ore hosting rocks, including multiple beaded magnetic anomaly. Then, two abnormal areas (M1 and M2) with lower apparent resistivity values and high apparent charging rates were recognized by apparent charging rate and apparent resistivity from induced polarization in median gradient array. These anomalies may be caused by ore-bearing rocks. Finally, controlled source audio-frequency magnetotelluric survey was applied to areas with anomalies of gravity value, magnetic value and induced polarization value, and two locations with low inversion resistivity were found. These may be caused by the sulfide-rich orebodies which are located at the intersection of NW- and NEE-trending faults. On the basis of these results, it is inferred that additional large-tonnage concealed orebodies are existent in the depth. Based on the results obtained, it is held that there exists a concealed orebody on the northern area of the Weilasituo ore district, which is covered by Quaternary sediments. |
| MENG Yin-sheng,YANG Li-qiang,ZHANG Rui-zhong,LIU Rui-de,LIN Tian-liang,WANG Wen-guo.2016.Application of Integrated Geophysical Methods to the Prospecting for Concealed Hydrothermal Vein-type Orebodies beneath Quaternary Sediments: A Case Study of the Northern Area of the Weilasituo Copper Polymetallic Deposit[J].Acta Geoscientica Sinica,37(6):745-755. |
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