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首页> 外文学位 >Interpretation of mineralization styles, alteration, mineralogy, paragenesis, and geochemistry at Gold Quarry, Carlin trend, Nevada: Implications for Northern Nevada-rift related, Miocene, intermediatesulfidation, base-metal mineralization.
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Interpretation of mineralization styles, alteration, mineralogy, paragenesis, and geochemistry at Gold Quarry, Carlin trend, Nevada: Implications for Northern Nevada-rift related, Miocene, intermediatesulfidation, base-metal mineralization.

机译：内华达州卡林趋势金矿场的矿化样式，蚀变，矿物学，共生作用和地球化学的解释：与内华达北部裂谷有关的中新世，中间硫化作用，贱金属矿化。

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摘要

Newmont's Gold Quarry deposit is a world class Carlin-type deposit located on the southern portion of the Carlin trend. The deposit is hosted primarily in the Rodeo Creek unit, which is extensively faulted and locally exhibits multiple types and intensities of alteration and mineralization. The majority of the remaining ore is sulfidic-refractory consisting of Eocene Carlin-type mineralization where the gold is hosted as a solid solution within the structural lattice of arsenian pyrite. Extensive Miocene base-metal mineralization locally overprints Eocene Carlin mineralization and contains rare local arsenian pyrite and widespread small, generally less than 1 to 10 microm, late free gold grains. Miocene gold may also be sequestered locally in other sulfides such as arsenopyrite. Silver is constrained to Miocene base-metal mineralization and is not represented above trace element levels in Eocene Carlin mineralization.;Miocene base-metal sulfides and sulfosalts are common throughout the Gold Quarry deposit. Massive sulfide veins ranging in size from less than 1 cm to over half a meter in width cut earlier Eocene Carlin-type mineralization including cutting up through reactivated mineralized Eocene structures. Carlin-type mineralization immediately bounding the base-metal veins is generally destroyed by Miocene vein-associated alteration. Base-metal mineralization occurs in four primary styles at Gold Quarry: fracture/fault controlled massive sulfide veins; replacement base-metal mineralization; hydrothermal breccia base-metal sulfide matrix mineralization; and weak disseminated base-metal mineralization.;Miocene massive sulfide base-metal mineralization is divided into three phases separated by two quartz events. The three mineralization events are preceded by an argillization event that locally ranges from weak to intense. Argillization locally overprints or destroys Eocene Carlin mineralization and is itself cut or replaced by Miocene base-metal mineralization. Eocene Carlin gold, however, does not appear to be remobilized by the overprinting argillization. Base-metal Phase I mineralization is iron sulfide-dominant comprised primarily of pyrite and marcasite with minor As and Ni iron sulfides and late sphalerite. Phase II mineralization is base-metal sulfide-and sulfosalt-dominant with a clear metallogenic progression from early copper dominant minerals to silver-rich minerals and terminates with late sphalerite and greenockite. Phase I sphalerite has a low Fe content and commonly exhibits chalcopyrite disease, while Phase II sphalerite in contrast has a high Fe content and no accompanying chalcopyrite disease. The primary Ag-bearing minerals include tetrahedrite, proustite-pyrargyrite, galena-associated Pb-Sb sulfosalts, and aramayoite. Phase III represents system shutdown and is gangue mineral (quartz, barite, and carbonate) dominant with only minor local pyrite and sphalerite. Phase III also contains the majority of the free gold complement with rare encapsulated free gold also associated with the end of the Phase II quartz event. Local supergene alteration primarily consisting of oxidation is generally in close proximity to structures, especially at depth. Base-metal sulfide/sulfosalt paragenesis is consistent throughout the deposit. The full paragenetic sequence is represented in all of the mineralization styles except for hydrothermal breccia base-metal sulfide matrix mineralization zones, which have been found to be primarily restricted to Phase I mineralization.;Select sample 50-element geochemistry was used to derive the unique geochemical signatures for the various mineralogy and alteration styles. This allows for the interpretation of the mineralogy of structures or zones that have been altered or that were decomposed. It also provides a template for the interpretation of the 20-foot interval composite geochemical data. The geochemical correlations consistently support the mineralogical associations and paragenesis. The select sample massive sulfide vein correlations indicate that most of the veins experienced mineralization episodically throughout the Miocene mineralization event. However, several vein samples showed tight correlation even with large separation distances. Massive sulfide veins of only one inch in width exerted sufficient influence on the geochemical signature of a 20-foot interval to be recognized and tentatively identified mineralogically.;Miocene base-metal mineralization style, sulfide assemblage and paragenesis are indicative of a relatively deep seated intermediate sulfidation source. Moderate to intense argillization is locally extensive at Gold Quarry. High to intermediate sulfidation systems are commonly initiated by an early magmatic vapor phase resulting in barren argillized zones. Locally, the argillized zones are not barren due to residual Eocene Carlin Au. The gradational transition of the Miocene base-metal sulfide and sulfosalt assemblage from a higher-sulfidation state to a lower-sulfidation state is represented in the paragenetic sequence. Two distinct sphalerite mineralization styles, low-iron Phase I and high iron Phase II, along with intervening chalcopyrite-tennantite-tetrahedrite support this interpretation. The high Se values, alunite date and intermediate sulfidation state of the Miocene base-metal mineralization suggest a direct relationship with the northern Nevada rift. This is also supported by the spatial association of the Carlin trend with the northern Nevada rift. (Abstract shortened by ProQuest.).
机译：Newmont的Gold Quarry矿床是位于Carlin趋势南部的世界一流的Carlin型矿床。该矿床主要存在于Rodeo Creek单元中，该单元被广泛断层，并且局部表现出多种类型和强度的蚀变和矿化作用。其余的大多数矿石是由始新世卡林型矿化组成的硫化耐火材料，其中金以固溶体形式存在于砷黄铁矿结构晶格中。广泛的中新世贱金属矿化覆盖了始新世卡林的矿化作用，并含有稀有的局部亚砷黄铁矿，并分布着较小的，通常小于1至10微米的晚期游离金晶粒。中新世金也可能被局部隔离在其他硫化物中，例如毒砂。银被限制在中新世贱金属矿化中，并且在始新世卡林矿化中没有被微量元素含量所代表。中新世贱金属硫化物和亚硫酸盐在整个金矿开采中很常见。尺寸从不到1厘米到宽度超过半米不等的大型硫化物脉切开了较早的始新世卡林型矿化带，包括切碎了重新活化的始新世的始新世构造。通常，与中新世脉相关的蚀变破坏了紧接在贱金属矿脉上的卡林型矿化作用。黄金采石场的贱金属矿化有四种主要类型：断裂/断层控制的块状硫化物脉；替代贱金属矿化；热液角砾岩贱金属硫化物基质成矿作用；中新世块状硫化物贱金属矿化分为三个相，由两个石英事件隔开。在这三个矿化事件之前，发生了一次局部性从弱到强烈的泥质化事件。雾化作用局部覆盖或破坏了始新世卡林的矿化作用，而本身被中新世贱金属矿化作用所切割或替代。然而，始新世卡林金似乎并没有被叠印的渗析作用所修复。贱金属第一阶段的矿化是主要由黄铁矿和镁铁矿以及少量的As和Ni硫化铁和晚闪锌矿组成的硫化铁。第二阶段的矿化是贱金属的硫化物和亚硫酸盐的主要成矿作用，从早期的铜占主导地位的矿物向富银的矿物有明显的成矿作用，并终止于晚闪锌矿和绿辉石。 I相闪锌矿具有较低的Fe含量，并且通常会出现黄铜矿病，而II相闪锌矿却具有较高的Fe含量，并且没有伴随的黄铜矿病。含银的主要矿物包括四面体，普氏体-硫铁矿，方铅矿相关的Pb-Sb硫盐和天青石。第三阶段代表系统关闭，是石矿物（石英，重晶石和碳酸盐）占主导地位，仅有少量局部黄铁矿和闪锌矿。第三阶段还包含大部分的游离金补体，以及与第二阶段石英事件结束有关的稀有包封的游离金。主要由氧化组成的局部超基因改变通常非常靠近结构，尤其是在深度。贱金属硫化物/亚硫酸盐共生在整个矿床中是一致的。除水热角砾岩母金属硫化物基质矿化带外，所有的成矿顺序均以所有矿化方式表现出来，发现该热化角砾岩贱金属硫化物基质矿化带主要限于第一阶段的矿化。选择样品50元素地球化学来得出独特的各种矿物学和蚀变样式的地球化学特征。这可以解释已改变或已分解的结构或区域的矿物学。它还为解释20英尺间隔的复合地球化学数据提供了一个模板。地球化学相关性一贯支持矿物学上的联系和共生作用。选择的样品大块硫化物脉动相关性表明，大多数脉在整个中新世成矿事件中经历了矿化。但是，即使分离距离较大，几个静脉样本仍显示出紧密的相关性。仅一英寸宽的大型硫化物脉对20英尺层段的地球化学特征产生了足够的影响，以便在矿物学上得以识别和初步确定。中新世贱金属的矿化方式，硫化物的组合和共生作用指示了相对较深的中间岩体硫化源。 Gold Quarry在当地广泛进行中度到强烈的渗碳作用。高到中度的硫化系统通常由早期的岩浆汽相引发，从而导致贫瘠的隆起带。在本地，由于残留的始新世卡林金，所以该隆起带并不贫瘠。中新世贱金属硫化物和亚硫酸盐组合物从较高的硫化态到较低的硫化态的梯度过渡以亚基因序列表示。两种不同的闪锌矿矿化样式，即低铁I期和高铁II期，以及中间的黄铜矿-钙钛矿-四面体的支持。中新世贱金属矿化的高硒值，亚铝酸盐日期和中间硫化状态表明与内华达州北部裂谷直接相关。卡林趋势与内华达州北部裂谷的空间联系也支持了这一点。 （摘要由ProQuest缩短。）。

著录项

  • 作者

    Sherlock, Wesley K.;

  • 作者单位

    University of Nevada, Reno.;

  • 授予单位 University of Nevada, Reno.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 535 p.
  • 总页数 535
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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