黔西南普安泥堡大型金矿床黄铁矿与毒砂标型特征及金的赋存状态

发布时间：2018-06-20 22:39

  本文选题：金的赋存状态 + 含砷黄铁矿　； 参考：《地质论评》2017年05期

【摘要】：通过系统的显微镜鉴定及扫描电镜观察,将黔西南普安泥堡金矿床中的黄铁矿按形貌特征划分为6种类型,即立方体状、草莓状、细粒状、粗粒状、环带状及长条状黄铁矿。黄铁矿电子探针分析结果表明,主要载金矿物为含砷黄铁矿(环带状黄铁矿、细粒状黄铁矿)和毒砂。环带状黄铁矿核部和环带形成于不同的成岩、成矿阶段,其核部贫Au、As,富Fe、S,属成岩期的产物;环带富Au、As,贫Fe、S,形成于主成矿期。黄铁矿环带中Au与As具有正对应关系,在一定的楔形空间呈正相关,高Au含量往往与中等As含量(2%~6%)相对应;而As与S呈明显负相关,说明富砷环带是As取代S而进入黄铁矿晶格所致。细粒状黄铁矿具有高Au、As,低Fe、S的特点,类似于环带状黄铁矿环带部位的特征,推测富As环带与细粒状黄铁矿同属主成矿阶段的产物。毒砂常穿插或沿含砷黄铁矿边缘分布,表明其形成晚于热液期含砷黄铁矿。因此,泥堡金矿床中载金矿物的结晶顺序大致为:贫砷沉积成因黄铁矿(核部)→迤富砷黄铁矿环带和细粒状黄铁矿→迤毒砂。电子探针点分析和面波普扫描显示,Au在载金矿物含砷黄铁矿和毒砂中具有不均匀分布的特征,根据Au的溶解度极限(Au/As 0.02)和lgw(As)—lgw(Au)图解,推测Au主要以"不可见"固溶体(Au~(+1))形式赋存于含砷黄铁矿和毒砂中,极少量可能为纳米级自然金(Au~0)。
[Abstract]:The pyrite in Pu'an Nibao gold deposit in southwest Guizhou is divided into 6 types according to their morphological characteristics, i.e. cube, strawberry, fine grain, coarse grain, annular and long stripe pyrite. The results of electron probe analysis of pyrite indicate that the main gold bearing minerals are arsenic-bearing pyrite (annular pyrite, fine-grained pyrite) and arsenopyrite. The core and belt of annular pyrite are formed in different diagenetic stages. In the metallogenic stage, the core is rich in Au-As-rich Fe-S, which belongs to the product of diagenetic period, and the annular zone is rich in Au-As-rich and Fe-S-rich, which was formed in the main metallogenic period. In the pyrite ring zone, au and as have a positive correspondence, and there is a positive correlation between au and as in a certain wedge-shaped space. The high au content often corresponds to the middle as content, while the correlation between as and S is obviously negative. The results show that the arsenic rich ring is caused by as replacing S and entering the pyrite lattice. Fine grained pyrite is characterized by high Au2 + as and low Fe2 S, which is similar to that of annular zonal pyrite. It is inferred that the AS-rich annulus and fine granular pyrite belong to the main ore-forming stage. Arsenopyrite is often interspersed or distributed along the edge of arsenopyrite, which indicates that arsenopyrite was formed later than hydrothermal stage. Therefore, the crystallization order of the gold bearing minerals in the Nipu gold deposit is roughly: the arsenic-poor sedimentary pyrite (core) and the fine grained pyrite deposit. Electron probe point analysis (EPMA) and surface pop scanning show that au has the characteristics of uneven distribution in arsenopyrite and arsenopyrite bearing gold ore. According to the solubility limit of au (au / as 0.02) and the diagram of lgwttrium As-lgwfen (Au2), the results show that the au is distributed unevenly in the arsenopyrite and arsenopyrite containing gold ore. It is inferred that au mainly exists in arsenopyrite and arsenopyrite in the form of "invisible" solid solution, and a very small amount may be nano-scale natural gold.
【作者单位】： 贵州大学矿业学院;贵州大学资源与环境工程学院;
【基金】：国家自然基金资助项目(编号:41072072,41503030) 贵州省科技合作计划项目(编号:黔科合LH字[2015]7663号) 贵州省教育厅青年科技人才成长项目(批准号:黔教合KY字[2016]117) 贵州省国土资源厅公益性项目(黔国土资发[2015]34号)的成果~~
【分类号】：P618.51
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本文编号：2045932