APPLICATION OF SEISMIC METHODS TO MINERAL EXPLORATION
APPLICATION OF SEISMIC METHODS TO MINERAL EXPLORATION
复制标题
地震方法在矿产勘查中的应用
DOI：
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发表时间：
2007
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影响因子：
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通讯作者：
M. Salisbury
中科院分区：
文献类型：
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作者：
M. Salisbury
在高围压下岩石的纵波速度(Vp)和横波速度(Vs)随密度的变化曲线表明，硅酸盐岩石的速度随密度的增加而增加。然而，由于它们的高密度，许多矿石落在Nafe-Drake曲线的右侧，表现出比它们的常见宿主更高的阻抗，这表明如果矿床满足反射或衍射所需的大小、厚度和展布条件，就应该有可能使用高分辨率反射技术来探测和找矿。过去十年，加拿大地质调查局、大学和工业界在加拿大各地的硬岩采矿营地进行的实验表明，二维测量非常适合于确定构造和探测矿体，而三维测量可以用于探测和圈定，垂直地震剖面(VSP)可以用于圈定。由于大多数矿床的规模较小，坚硬岩石地体的结构复杂，而且信噪比较低，因此通过使用高频源和定制的处理序列进行精心设计的调查可获得最佳结果，以识别反射和衍射器。二维和三维测量已经成功地探测到大型块状硫化物矿床并对其成像，例如萨德伯里和巴瑟斯特的岩浆和火山块状硫化物(VMS)矿床，也应有助于探测块状沉积喷气(SEDEX)和铁氧化物铜金(IOCG)矿床。其他类型的矿床更有可能被间接探测到：蚀变晕反射的脉金和斑岩矿床，晕和基底偏移的不整合铀矿床，以及由其他反射碳酸盐中的白点形成的密西西比谷型(MVT)矿床。同样，金伯利岩和它们的宿主之间的高阻抗允许使用VSP技术来描绘管道。
Plots of compressional (Vp) and shear (Vs) wave velocity vs. density for rocks at elevated confining pressures show that velocities tend to increase with density along the well known Nafe-Drake curves for silicate rocks. Because of their high densities, however, many ores fall far to the right of the Nafe-Drake curves and display higher impedances than their common hosts, suggesting that it should be possible to detect and prospect for ores using high-resolution reflection techniques if the deposits meet the size, thickness, and presentation constraints required for reflection or diffraction. Experiments conducted by the Geological Survey of Canada, universities, and industry in hardrock mining camps across Canada over the past decade show that 2-D surveys are well suited to the determination of structure and the detection of orebodies, while 3-D surveys may be used for detection and delineation, and vertical seismic profiling (VSP) for delineation. Due to the small size of most deposits, the structural complexity of hard rock terranes and their low signal-to-noise ratios, the best results are obtained from carefully designed surveys using high frequency sources and customized processing sequences designed to identify both reflections and diffractors. 2-D and 3-D surveys have successfully detected and imaged large massive sulphide deposits such as the magmatic and volcanic massive sulphide (VMS) deposits in Sudbury and Bathurst and should also be useful for the detection of massive sedimentary exhalitive (SEDEX) and iron oxide copper gold (IOCG) deposits. Other types of deposits are more likely to be detected indirectly: lode gold and porphyry deposits by reflections from alteration haloes, unconformity Uranium deposits by haloes and basement offsets, and Mississippi Valley-type (MVT) deposits by white spots in otherwise reflective carbonates. Similarly, the high impedances between kimberlites and their hosts allow pipes to be delineated using VSP techniques.