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首页> 外文学位 >Time-Space Relationships between Sediment-Hosted Gold Mineralization and Intrusion-Related Polymetallic Mineralization at Kinsley Mountain, NV.
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Time-Space Relationships between Sediment-Hosted Gold Mineralization and Intrusion-Related Polymetallic Mineralization at Kinsley Mountain, NV.

机译：内华达州金斯利山的沉积物金矿化与入侵相关的多金属矿化之间的时空关系。

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摘要

Carlin-type gold deposits (CTGDs) in north-central Nevada contain a large endowment of gold, making Nevada one of the world's leading gold producers. Most CTGDs occur in four distinct clusters, known as the Carlin Trend, Cortez, Getchell, and Jerritt Canyon. These four camps of CTGDs are estimated to contain >200 million ounces of Au and share common features, including the occurrence of gold in solid solution or as submicron particles in disseminated arsenian pyrite in large carbonate replacement bodies where alteration is dominated by decarbonatization and silicification of silty carbonate host rocks. CTGDs can be confused with other disseminated gold deposits hosted by predominantly carbonate-bearing sedimentary rocks that share many features with CTGDs, but also have many distinctly different characteristics and generally have lower endowments of gold. These similar deposits, referred to as here sediment-hosted gold deposits (SHGD), include distal-disseminated deposits temporally and spatially associated with upper crustal felsic intrusions, epithermal deposits hosted by carbonate rocks, and epizonal orogenic deposits hosted by carbonate rocks. A very important question to resolve is whether CTGDs and SHGDs represent a spectrum of deposits with a shared origin, in which CTGDS are an endmember, or whether they have different origins that ultimately resulted in similar looking alteration and mineralization.;Kinsley Mountain lies approximately 150 km east of the majority of large CTGDs in Nevada. SHGDs, intrusion-related tungsten skarn, and polymetallic carbonate replacement vein deposits have been mined from Kinsley Mountain, proximal to an Eocene intrusive center. Stratigraphically and structurally controlled SHGDs occur as replacement bodies in Cambrian shelf carbonates and siliciclastics. The SHGDs at Kinsley are broadly similar to the large CTGDs to the west, but key differences are highlighted in this paper.;Kinsley Mountain underwent multiple episodes of contraction and extensional deformation in the Mesozoic. During the Eocene, a granodiorite stock and associated dikes were emplaced at ∼40 Ma, with slightly later Eocene extension and volcanism. High-angle basin and range faulting began in the Miocene continues through the present. Quartz veins containing polymetallic mineralization cut the stock and polymetallic veins replace carbonate country rock proximal to the stock. Molybdenite in skarn near the stock returned a Re-Os age of 37.88 +/- 0.3 Ma. Numerous cogenetic dikes extend up to 4 km north of the stock into the area of the SHGDs. SHG mineralization is primarily hosted by the Cambrian Dunderberg Shale and Secret Canyon Shale. These units contain interbedded shale and limestone with up to 50% ferroan dolomite in shale beds. In strongly mineralized intervals, ferroan dolomite has been replaced by quartz and pyrite. A 39.7 +/- 0.6 Ma mineralized dike places a maximum age constraint on mineralization, whereas ∼36--37 Ma unmineralized dacite to rhyolite flows that flank both sides of Kinsley Mountain and onlap Cambrian stratigraphy, place a minimum age on mineralization.;SHG mineralization is characterized by diagenetic or hydrothermal pyrite cores surrounded by euhedral, oscillatory zoned Au-bearing arsenian-pyrite rims. Locally, pyrite cores are surrounded by stibnite or tennantite-tetrahedrite, which are enveloped by arsenian-pyrite rims. Gold strongly correlates (correlation coefficient >0.5) with Ag, As, Hg, Sb, Te, and Tl. The ore-stage pyrite at Kinsley contrasts with ore stage pyrite in CTGDs, where the arsenian-rims are typically "fuzzy" in appearance and do not display zoning. Additionally, the presence of early base metals has not been documented in Carlin-type mineralization. Sulfur isotope data on pyrite revealed delta 34S values of ∼3‰--8‰ for pyrite proximal to the stock, while pyrite from the SHGDs were significantly heavier (16‰--25‰). The differences suggest a magmatic source of sulfur for pyrite proximal to the stock and a sedimentary source or mixed magmatic and sedimentary source of sulfur for pyrite in SHG mineralization.;The hydrothermal system at Kinsley had two sulfur sources---a magmatic source that formed the intrusion-related polymetallic mineralization and a sedimentary crustal source that formed the SHGDs. In the SHGDs, carbonate-bearing shales rocks were preferentially sulfidized by the ore-fluid, forming Au-bearing arsenian-pyrite as Fe was liberated from ferroan dolomite during decarbonatization. The presence of euhedral pyrite, carbonate in ore zones, and lack of marcasite, kaolinite, or dickite suggests ore fluids that were higher in temperature and less acidic than ore fluids that form the large CTGDS in Nevada. Aluminum in hornblende geobarometry, typical formation depths of tungsten skarn deposits, and the lack of faulting between the stock and the SHGDs suggest depths of ≥3 km for ore formation. However, such depths require significant uplift between 40 Ma and 36 Ma. Shallower depths for the SHGDs are possible if the range was tilted northward.
机译：内华达州中北部的卡林型金矿（CTGD）蕴藏着丰富的黄金资源，使内华达州成为世界领先的黄金生产国之一。大多数CTGD分布在四个不同的类群中，即Carlin Trend，Cortez，Getchell和Jerritt Canyon。估计这四个CTGD阵营包含> 2亿盎司的Au并具有共同特征，包括在大型碳酸盐替代体中弥散的砷黄铁矿中的固溶态或亚微米颗粒形式的金矿的发生，其变化主要由碳酸盐的脱碳和硅化作用引起。粉质碳酸盐岩。 CTGD可与其他散布的金矿床相混淆，这些金矿床主要由含碳酸盐的沉积岩组成，这些沉积岩与CTGD具有许多特征，但也具有许多明显不同的特征，并且通常具有较低的金end赋。这些相似的沉积物在这里称为沉积物托管金矿床（SHGD），包括在时间和空间上与上地壳长英质侵入有关的远距离散布的矿床，由碳酸盐岩主生的超热矿床和由碳酸盐岩主生的上带造山矿床。要解决的一个非常重要的问题是，CTGD和SHGD是否代表了具有共同起源的一系列矿床，其中CTGDS是其最终成员，还是它们的起源不同，最终导致了相似的蚀变和矿化作用。金斯利山地带大约有150个内华达州大多数大型CTGD的东侧1公里。 SHGDs，与侵入有关的钨矽卡岩和多金属碳酸盐替代矿脉矿床是从始新世侵入中心附近的金斯利山开采的。在寒武纪陆架碳酸盐岩和硅质碎屑岩中，地层和结构控制的SHGDs可以作为替代体出现。 Kinsley的SHGD与西部的大型CTGD大致相似，但本文突出了主要区别。金斯利山在中生代经历了多次收缩和伸展变形。在始新世期间，花岗闪长岩及其伴生堤防在〜40 Ma发生，随后始新世伸展和火山作用稍晚。从中新世开始的高角度盆地和范围断层一直持续到现在。含有多金属矿化作用的石英脉削减了储量，多金属脉替代了储量附近的碳酸盐岩。靠近矿床的矽卡岩中的辉钼矿的Re-Os年龄为37.88 +/- 0.3 Ma。许多同基因堤防一直延伸到种群以北4公里处到SHGDs区域。 SHG矿化主要由寒武纪的邓德伯格页岩和秘密峡谷页岩主持。这些单元包含层状页岩和石灰岩，页岩床中含高达50％的亚铁白云岩。在强烈矿化的时间间隔内，亚铁白云石已被石英和黄铁矿所取代。 39.7 +/- 0.6 Ma的矿化堤防对矿化有最大的年龄限制，而在金斯利山和上覆寒武纪地层两侧的〜36--37 Ma的未矿化的辉绿岩到流纹岩流，对矿化作用的最小年龄。矿化的特征是成岩或热液性黄铁矿岩心，被正反面，振荡带状的含金亚砷铁矿-黄铁矿边缘包围。在局部，黄铁矿芯被辉锑矿或球铁矿-四面体包围，并被砷铁矿-黄铁矿边缘包围。金与Ag，As，Hg，Sb，Te和Tl密切相关（相关系数> 0.5）。金斯利（Kinsley）的矿石级黄铁矿与CTGDs中的矿石级黄铁矿形成鲜明对比，在后者中，砷化缘的外观通常“模糊”且不显示分区。此外，在卡林型矿化中尚未记录到早期贱金属的存在。黄铁矿中的硫同位素数据显示，靠近储层的黄铁矿的δ34S值为〜3‰-8‰，而来自SHGDs的黄铁矿则重得多（16‰-25‰）。这些差异表明，在储层附近是黄铁矿的岩浆硫来源，而在SHG矿床中，黄铁矿的沉积岩浆源或混合岩浆和沉积源。金斯利的热液系统有两个硫源-形成了岩浆源侵入相关的多金属矿化作用和形成SHGD的沉积地壳源。在SHGDs中，含碳酸盐的页岩岩石优先被矿石流体硫化，当Fe在脱碳过程中从亚铁白云石中释放出来时，形成了含金的砷黄铁矿。在内华达州，存在矿化的黄铁矿，碳酸盐矿，以及缺乏镁铁矿，高岭石或地开辉石，这些矿液的温度较高，而酸性较低，这构成了内华达州大型CTGDS的矿液。角闪石地质大气中的铝，典型的钨矽卡岩矿床形成深度，以及在储层和SHGD之间缺乏断层，表明矿石形成深度≥3km。然而，这样的深度需要40 Ma至36 Ma之间的显着隆升。如果范围向北倾斜，则SHGD的深度可能更浅。

著录项

  • 作者

    Hill, Tyler J.;

  • 作者单位

    University of Nevada, Reno.;

  • 授予单位 University of Nevada, Reno.;
  • 学科 Geology.;Mineralogy.
  • 学位 M.S.
  • 年度 2016
  • 页码 213 p.
  • 总页数 213
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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