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首页> 外文学位 >The integration of physical rock properties, mineralogy and geochemistry for the exploration of large hypogene zinc silicate deposits: a case study of the Vazante zinc deposits, Minas Gerais, Brazil.
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The integration of physical rock properties, mineralogy and geochemistry for the exploration of large hypogene zinc silicate deposits: a case study of the Vazante zinc deposits, Minas Gerais, Brazil.

机译：岩石物理性质，矿物学和地球化学的综合，用于勘探大型次生硅酸锌矿床：巴西米纳斯吉拉斯州Vazante锌矿床的案例研究。

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摘要

Exploration for large zinc silicate deposits is more challenging than zinc sulfide deposits, as they do not exhibit similar geophysical anomalies. The Vazante deposit, which is the world's largest zinc silicate deposit, occurs in brecciated dolomite and comprises mainly willemite with various proportions of hematite, and minor franklinite and sphalerite. In the Vazante region, the exploration challenge is enhanced as outcrops are rare, bedrock generally sits below 10s of metres of laterite cover and barren hematite-rich breccias have a similar geophysical signature to willemite ore bodies. In order to evaluate the applications of geophysical surveys in the exploration of this type of deposit, data from 475 samples were investigated from drill holes representative of the various types of ore, host rocks and zones of known geophysical anomalies in the Vazante District. Geochemical (ICP-MS and XRF) and mineralogical (optical, EMPA, SEM and MLA) data were integrated with physical rock properties (density, magnetic susceptibility and K-U-Th gamma ray spectrometry) to assist in finding new ore zones. The most distinct physical property of the ore is density (3.0-4.3 g/cm3), compared with the host rocks (2.7-3.0 g/cm3). This is due to high proportion of denser minerals (hematite and willemite) in the ore. However, barren hematite breccias also have high densities (3.0-4.5 g/cm3). The zinc ore and hematite breccias yielded higher magnetic susceptibilities (0.1-38 x10-3 SI) than the surrounding host rocks, with the highest values associated with greater proportions of franklinite and magnetite (7-38 x10-3 SI). The zinc ore has an elevated U concentration (up to 33ppm) relative to the various host rocks (up to 7 ppm), yielding higher gamma spectrometric values. The results of this investigation indicate that an integration of magnetic, gravimetric and radiometric surveys would be required to identify zinc silicate ore zones and potentially differentiate them from barren hematite breccias and host rocks.
机译：大型硅酸锌矿床的勘探比硫化锌矿床更具挑战性，因为它们没有表现出类似的地球物理异常。瓦赞特矿床是世界上最大的硅酸锌矿床，存在于角砾状白云石中，主要由具有不同比例的赤铁矿的硅锌矿，少量的富兰克林石和闪锌矿组成。在瓦赞特地区，由于露头稀少，基岩通常位于红土覆盖层以下10几米，贫瘠的富含赤铁矿的角砾岩具有与硅藻土矿体相似的地球物理特征，勘探挑战更加严峻。为了评估地球物理勘查在这类矿床勘探中的应用，从代表瓦赞特地区各种类型的矿石，宿主岩和已知地球物理异常区的钻孔中调查了475个样本的数据。将地球化学（ICP-MS和XRF）和矿物学（光学，EMPA，SEM和MLA）数据与岩石的物理性质（密度，磁化率和K-U-Th伽玛射线能谱法）结合在一起，以帮助寻找新的矿带。与主岩（2.7-3.0 g / cm3）相比，矿石最明显的物理性质是密度（3.0-4.3 g / cm3）。这是由于矿石中较高密度的矿物（赤铁矿和硅锌矿）的比例较高。然而，贫瘠的赤铁矿角砾岩也具有高密度（3.0-4.5 g / cm3）。锌矿石和赤铁矿角砾岩的磁化率（0.1-38 x10-3 SI）比周围的基质岩石高，最高值与富兰克石和磁铁矿的比例更高（7-38 x10-3 SI）。相对于各种基质岩石（最高7 ppm），锌矿石的U浓度升高（最高33 ppm），产生更高的伽马能谱值。这项调查的结果表明，将需要对磁性，重力和辐射测量进行综合，以识别硅酸锌矿带，并可能将它们与贫瘠的赤铁矿角砾岩和宿主岩区分开。

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  • 作者

    McGladrey, Alexandra Jane.;

  • 作者单位

    Queen's University (Canada).;

  • 授予单位 Queen's University (Canada).;
  • 学科 Geology.
  • 学位 Master
  • 年度 2014
  • 页码 178 p.
  • 总页数 178
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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