| EH4连续电导率成像仪在隐伏矿体定位预测中的应用研究 |
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| 引用本文：.2007.Application of stratagem EH4 system to prediction of hidden ore bodies[J].Mineral Deposits,26(1):70~78 |
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| 基金项目:中国科学院创新工程项目(KZC3-SW-137)、国家科技攻关“305”项目（2001BA609A-07-08和2003BA612A-06-19） |
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| 中文摘要:EH4连续电导率成像仪是近几年美国生产的快速高效的数字化地球物理探测仪器，其基本配置（10～100 kHz）的装置能测量地表以下1 000 m深度范围内地质体的连续视电导率值，作者对25个不同类型的金属矿床进行了隐伏矿定位预测，取得了显著的效果。经钻孔验证后显示：① 岩浆熔离型铜镍硫化物矿床，很好地反映了基性_超基性杂岩体的形态和规模，并识别了岩体的不同岩相，得出矿化异常岩相呈盆状，电阻率为130～300 Ω·m的结论；②斑岩型_浅成低温铜金矿床，区分了隐伏斑岩和矿化蚀变带，确认矿化异常在隐伏斑岩外围呈面状分布，矿化异常体的电阻率小于100 Ω·m；③韧性剪切带型金矿床，明显区分了矿化蚀变构造带和围岩，矿化异常形态呈脉状，电阻率小于200 Ω·m。这3个矿床实例研究表明，EH4连续电导率成像仪测量所得的二维视电阻率_深度剖面图能清晰地反映地下不同地质体的精细电阻率结构，判读含矿构造带以及矿化异常在空间上的展布，因此，EH4连续电导率成像仪在隐伏矿定位预测方面将起到重要的作用。 |
| 中文关键词:地球物理 EH4连续电导率成像仪 矿化异常 隐伏矿体 铜镍矿床 斑岩铜矿 金矿床 |
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| Application of stratagem EH4 system to prediction of hidden ore bodies |
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| Abstract:The Stratagem EH4 system, made by Geometrics & EMI Electromagnetic Instruments, Inc., is a unique magnetotelluric system using both natural and man_made electromagnetic signals to obtain a continuous electrical sounding of the earth beneath the measurement site. It can be utilized to measure the electrical conductivity of the earth over the depth range from a few meters to more than one kilometer by 10 Hz～100 kHz. The authors have applied the Stratagem EH4 system to the exploration of various types of metallic deposits in China in search for new resources since 2001, with good results acquired. The results obtained can be displayed by a 2D model map (resistivity_depth map). The 2D model map can clearly identify fine resistivity structures of different resistivity bodies. The EH-4 inversion tested by drilling has yielded some new results: ① the shape and size of the studied mafic_ultramafic intrusion are displayed, and different intrusion facies and magma channels are identified. This intrusion is 800 m wide and up to 450 m deep, assuming a funnel_shaped cross-section. The smaller resistivity (130～300 Ω·m) for the magmatic liquation Cu-Ni deposit, corresponding to mineralized altered lithofacies, shows a basin in section; ② a concealed porphyry with high resistivity (higher than 300 Ω·m) is detected. What is most important is that the mineralization anomaly resulting from the epithermal copper_gold deposits may be defined by the smaller resistivity (lower than 100 Ω·m), with the anomaly assuming planar distribution; ③ the concealed gold ore body of the shear type gold deposit can be detected by the resistivity value of lower than 200 Ω·m, with its shape being veinlike in section. The resistivity value of the wall rock is higher than 360 Ω·m. The three examples of the studied deposits show that the electrical conductivity imaging of EH4 data can not only clearly identify different resistivity anomalies but also reflect the shape and size of the buried mineralized body or the deep geological structure. Therefore, the Stratagem EH4 geophysical technique can play an important role in locating mineralization systems and defining drilling targets at depth, and this is surely most important in subsequent drill_site positioning and potential resource prediction. |
| keywords:geophysics,Stratagem EH4 system, mineralization anomaly, hidden ore body, Cu_Ni deposit, porphyry Cu deposit, gold deposit |
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