Metal remobilization and ore-fluid perturbation during episodic replacement of auriferous pyrite from an epizonal orogenic gold deposit
Metal remobilization and ore-fluid perturbation during episodic replacement of auriferous pyrite from an epizonal orogenic gold deposit
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边带造山金矿床中含金黄铁矿间歇性置换过程中的金属再活化和矿石流体扰动
DOI：
10.1016/j.gca.2018.10.031
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发表时间：
2019-01
影响因子：
5
通讯作者：
Guagliardo Paul
中科院分区：
文献类型：
--
作者：
Wu Ya-Fei;Evans Katy;Li Jian-Wei;Fougerouse Denis;Large Ross R.;Guagliardo Paul
西秦岭大桥造山带造山带金存款矿床中的角砾岩矿石中，存在着结构复杂的黄铁矿、白铁矿和少量毒砂对含金黄铁矿的幕式置换作用。本研究采用激光烧蚀-电感耦合等离子体质谱（LA-ICP-MS），纳米二次离子质谱（NanoSIMS）和二次离子质谱（西姆斯）的新组合来研究金和其他微量元素在这个复杂的置换过程中的再活化和再富集以及可能的机制。几条线的证据，包括一定程度的保存外部形态，尖锐的接触和组成的差异之间的父黄铁矿和产品黄铁矿和白铁矿，反应引起的孔隙度表明，通过两步置换通过溶解和再沉淀机制，加上额外的白铁矿过度生长的父黄铁矿的替代收益。在自形黄铁矿的置换过程中，多孔产物黄铁矿中的Au和其它微量元素（Te、Se、Zn、Co、Tl、Ni、W和As）相对于其前身的贫化表明这些金属从原始黄铁矿晶格中的出溶和再活化。在随后的替代多孔黄铁矿的两种类型的白铁矿和次要毒砂，自形产物白铁矿含有微量元素的含量低，可能是由于高的金属溶解度的酸性流体有利于白铁矿沉淀。相对于多孔黄铁矿，复杂分区的白铁矿显着富含金和其他金属（W、TI、As、Sb、Ag、Se和Zn），被认为是通过进一步氧化和/或阈值过饱和度立即降低引发的沉淀形成的。富杂质黄铁矿的溶解和新的黄铁矿和白铁矿的沉淀可能发生在低pH值加上高浓度的溶解Fe 2+条件下，这是由矿石流体中的H2S和/或S2−水溶液部分氧化引起的。流体氧化作用的证据是δ 34 S值从原生自形黄铁矿逐渐降低，形成多孔黄铁矿、自形白铁矿和复杂环带白铁矿。同位素结果与大桥存款矿床在断阀域多级水力压裂过程中受压力波动控制的成矿流体氧化作用相一致。该定量研究强调，压力驱动的热液过程在浅成造山带金矿系统中脆性流变带含金黄铁矿幕式交代过程中，对金及其它微量金属的微米至纳米尺度的再分布和再富集起着关键作用。
Mineral-scale episodic replacement of auriferous pyrite by texturally-complex pyrite, marcasite and minor arsenopyrite occurred in breccia ores from the Daqiao epizonal orogenic gold deposit, West Qinling Orogen, China. This study uses a novel combination of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), Nanoscale secondary ion mass spectrometry (NanoSIMS), and secondary ion mass spectrometry (SIMS) to investigate the remobilization and re-concentration of gold and other trace elements during this complex replacement process and the probable mechanism. Several lines of evidence including some degree of preservation of external morphology, sharp contacts and compositional differences between the parent pyrite and product pyrite and marcasite, and reaction-induced porosity suggest that the replacement of parent pyrite proceeds via a two-step replacement via a dissolution and reprecipitation mechanism, plus an additional marcasite overgrowth. During the replacement of euhedral pyrite, depletion of gold and other trace elements (Te, Se, Zn, Co, Tl, Ni, W, and As) in porous product pyrite relative to its precursor indicate exsolution and remobilization of these metals from crystal lattice of the original pyrite. In the subsequent replacement of porous pyrite by two types of marcasite and minor arsenopyrite, euhedral product marcasite contains low contents of trace elements, possibly due to high metal solubility in the acidic fluids favorable for marcasite precipitation. The complex-zoned marcasite significantly enriched in gold and other metals relative to porous pyrite (W, Tl, As, Sb, Ag, Se, and Zn) is thought to have formed via precipitation triggered by further oxidation and/or immediate reduction in threshold supersaturation. Dissolution of the impurity-rich pyrite and precipitation of new pyrite and marcasite generations could have occurred at low pH plus high concentrations of dissolved Fe2+condition caused by partial oxidation of aqueous H2S and/or S2−in ore fluids. The fluid oxidation is evidenced by a general decreasing trend of δ34S values from the parent euhedral pyrite, to product porous pyrite, euhedral marcasite, and complex-zoned marcasite. The isotopic results are consistent with ore fluid oxidation controlled by pressure fluctuations during multistage hydraulic fracturing in a fault-valve regime at Daqiao deposit. This quantitative study emphasizes that the pressure-driven hydrothermal process plays a key role in the micron- to nano-scale redistribution and re-enrichment of gold and other trace metals during episodic replacement of auriferous pyrite in brittle rheological zones from epizonal orogenic gold systems.
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影响因子：
4.5
作者：
Geisler, Thorsten;Schaltegger, Urs;Tomaschek, Frank
通讯作者：
Tomaschek, Frank
西秦岭造山带大桥沿带造山金矿床成矿过程：黄铁矿、白铁矿的结构、微量元素、硫同位素和碳质材料拉曼光谱的制约
DOI：
10.5382/econgeo.2018.4583
发表时间：
2018-08
期刊：
Economic Geology and the Bulletin of the Society of Economic Geologists
影响因子：
--
作者：
Wu Ya-Fei;Li Jian-Wei;Evans Katy;Koenig Alan E.;Li Zhan-Ke;O'Brien Hugh;Lahaye Yann;Rempel Kirsten;Hu Si-Yu;Zhang Zhong-Ping;Yu Jun-Peng
通讯作者：
Yu Jun-Peng
影响因子：
5.8
作者：
S. E. Drummond;H. Ohmoto
通讯作者：
S. E. Drummond;H. Ohmoto
影响因子：
5.8
作者：
J. Cline
通讯作者：
J. Cline
影响因子：
5.8
作者：
R. Reynolds;M. Goldhaber;D. Carpenter
通讯作者：
R. Reynolds;M. Goldhaber;D. Carpenter