Gold and Trace Element Zonation in Pyrite Using a Laser Imaging Technique: Implications for the Timing of Gold in Orogenic and Carlin-Style Sediment-Hosted Deposits
Gold and Trace Element Zonation in Pyrite Using a Laser Imaging Technique: Implications for the Timing of Gold in Orogenic and Carlin-Style Sediment-Hosted Deposits
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DOI：
10.2113/gsecongeo.104.5.635
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发表时间：
2009-08
期刊：
影响因子：
5.8
通讯作者：
R. Large;L. Danyushevsky;Chris Hollit;V. Maslennikov;S. Meffre;Sarah E. Gilbert;S. Bull;R. Scott
中科院分区：
文献类型：
--
作者：
R. Large;L. Danyushevsky;Chris Hollit;V. Maslennikov;S. Meffre;Sarah E. Gilbert;S. Bull;R. Scott
对4个不同沉积型金砷矿床黄铁矿中金等微量元素的激光剥蚀ICP-MS成像研究表明，每个存款中金的富集有两个阶段：早期同沉积阶段，不可见的金沿着其它微量元素，特别是As、Ni、Pb、Zn、Ag、Mo、Te、V和Se，富集在砷成岩黄铁矿中;后期热液阶段，金以自由金颗粒形式存在于增生变质黄铁矿和/或热液黄铁矿的裂隙中，或以狭窄的金砷镶边形式存在于增生热液黄铁矿的最外层。与成岩黄铁矿相比，热液黄铁矿普遍亏损Ni、V、Zn、Pb和Ag，并具有Co、Ni和As富集的循环带。最外面的热液黄铁矿边缘要么富含As-Au，如在中到高级矿床中，如Carlin和Bendigo，要么富含Co-Ni，贫As-Au，如在中到低级矿床中，如Sukhoi Log和Spanish Mountain。金在沉积盆地黑色页岩相含砷同生-成岩黄铁矿中的早期富集，是沉积环境中卡林型和造山型金矿床后期发育的重要条件。品位最好的沉积物型矿床似乎在与变形有关的热液黄铁矿生长和流体流动的最后阶段出现了金的高潮事件。
Laser ablation ICP-MS imaging of gold and other trace elements in pyrite from four different sedimenthosted gold-arsenic deposits has revealed two distinct episodes of gold enrichment in each deposit: an early synsedimentary stage where invisible gold is concentrated in arsenian diagenetic pyrite along with other trace elements, in particular, As, Ni, Pb, Zn, Ag, Mo, Te, V, and Se; and a later hydrothermal stage where gold forms as either free gold grains in cracks in overgrowth metamorphic and/or hydrothermal pyrite or as narrow goldarsenic rims on the outermost parts of the overgrowth hydrothermal pyrite. Compared to the diagenetic pyrites, the hydrothermal pyrites are commonly depleted in Ni, V, Zn, Pb, and Ag with cyclic zones of Co, Ni, and As concentration. The outermost hydrothermal pyrite rims are either As-Au rich, as in moderate- to highgrade deposits such as Carlin and Bendigo, or Co-Ni rich and As-Au poor as in moderate- to low-grade deposits such as Sukhoi Log and Spanish Mountain. The early enrichment of gold in arsenic-bearing syngenetic to diagenetic pyrite, within black shale facies of sedimentary basins, is proposed as a critical requirement for the later development of Carlin-style and orogenic gold deposits in sedimentary environments. The best grade sediment- hosted deposits appear to have the gold climax event, toward the final stages of deformation-related hydrothermal pyrite growth and fluid flow.