Trace element zoning in pyrite determined by PIXE elemental mapping: evidence for varying ore–fluid composition and electrochemical precipitation of gold at the Spitskop deposit, Saldania Belt, South Africa
Trace element zoning in pyrite determined by PIXE elemental mapping: evidence for varying ore–fluid composition and electrochemical precipitation of gold at the Spitskop deposit, Saldania Belt, South Africa
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通过 PIXE 元素测绘确定黄铁矿中的微量元素分带：南非萨尔达尼亚带 Spitskop 矿床矿石流体成分变化和金电化学沉淀的证据
DOI：
10.1002/xrs.680
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
W. Przybyłowicz
中科院分区：
文献类型：
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作者：
R. Belcher;A. Rozendaal;W. Przybyłowicz
采用显微PIXE方法研究了新元古代萨尔达尼亚带中与中隐金矿化有关的黄铁矿地球化学特征。岩石学上观察到的黄铁矿弱分带在这种分析方法生成的元素图上清晰可见。它还允许两代黄铁矿的积极鉴定。早期，不规则的前同构造颗粒是作为穷人和显示强烈分区后，可能后构造，过度生长富含砷，镍，锑和铅。这个晚期阶段也产生了一个单独的一代，明显分区自形颗粒相似的组成。金是非常细粒度和托管的分区黄铁矿颗粒作为亚微观斑点位于贫As和富As带之间的边界。这种关联是金的电化学沉淀的指示。晚期黄铁矿中Ni、Sb和Pb元素的分带是由于成矿流体的成分和物理化学条件发生变化而产生的选择性沉淀作用，成矿流体来源于周围变质火山-沉积岩堆的挥发分。版权所有© 2004年约翰威利父子有限公司。
The geochemistry of pyrite associated with mesothermal ‘invisible’ gold mineralization in the Neoproterozoic Saldania Belt was studied with micro-PIXE. The petrologically observed weak zoning of pyrite was clearly visible on elemental maps generated by this analytical method. It also allowed the positive identification of two generations of pyrite. Early, irregular pre- to syn-tectonic grains are As-poor and display strongly zoned later, possibly post-tectonic, overgrowths rich in As, Ni, Sb and Pb. This late phase also produced a generation of individual, distinctly zoned euhedral grains of similar composition. Gold is extremely fine-grained and hosted by the zoned pyrite grains as submicroscopic specks located on the boundary between As-poor and As-rich bands. This association is indicative of the electrochemical precipitation of gold. Zoning of the elements Ni, Sb and Pb in the late-stage pyrite is attributed to selective precipitation in response to changes in composition and physico-chemical conditions of the mineralizing fluids that have been derived from devolatilization of the enclosing metamorphosed volcano-sedimentary pile. Copyright © 2004 John Wiley & Sons, Ltd.