The giant Carlin gold province: a protracted interplay of orogenic, basinal, and hydrothermal processes above a lithospheric boundary

Northern Nevada hosts the only province that contains multiple world-class Carlin-type gold deposits. The first-order control on the uniqueness of this province is its anomalous far back-arc tectonic setting over the rifted North American paleocontinental margin that separates Precambrian from Phanerozoic subcontinental lithospheric mantle. Globally, most other significant gold provinces form in volcanic arcs and accreted terranes proximal to convergent margins. In northern Nevada, periodic reactivation of basement faults along this margin focused and amplified subsequent geological events. Early basement faults localized Devonian synsedimentary extension and normal faulting. These controlled the geometry of the Devonian sedimentary basin architecture and focused the discharge of basinal brines that deposited syngenetic gold along the basin margins. Inversion of these basins and faults during subsequent contraction produced the complex elongate structural culminations that characterize the anomalous mineral deposit “trends.” Subsequently, these features localized repeated episodes of shallow magmatic and hydrothermal activity that also deposited some gold. During a pulse of Eocene extension, these faults focused advection of Carlin-type fluids, which had the opportunity to leach gold from gold-enriched sequences and deposit it in reactive miogeoclinal host rocks below the hydrologic seal at the Roberts Mountain thrust contact. Hence, the vast endowment of the Carlin province resulted from the conjunction of spatially superposed events localized by long-lived basement structures in a highly anomalous tectonic setting, rather than by the sole operation of special magmatic or fluid-related processes. An important indicator of the longevity of this basement control is the superposition of different gold deposit types (e.g., Sedex, porphyry, Carlin-type, epithermal, and hot spring deposits) that formed repeatedly between the Devonian and Miocene time along the trends. Interestingly, the large Cretaceous Alaska–Yukon intrusion-related gold deposits (e.g., Fort Knox) are associated with the northern extension of the same lithospheric margin in the Selwyn basin, which experienced an analogous series of geologic events.     

滇黔桂区中三叠世安尼期浊积岩微相划分与金矿关系

对滇黔桂区中三叠世安尼期浊积岩微相的划分,认为区内浊流有3处发源地,形成了3个浊积扇,每一扇中又由中心相、过渡相及末梢相组成,从各微相分布特征和含金性分析,认为浊积岩的过渡相与卡林型金矿密切,并提出了找矿方向.     

正构烷烃的成矿意义——以广西田林高龙卡林型金矿为例

高龙金矿位于西林-百色断褶带西段南西侧的高龙穹隆核部附近, 矿体赋存于石炭—二叠系碳酸盐岩与三叠系细碎屑岩的接触带上.区域性百色-高龙-古障深大断裂及其次级构造构成了矿液流动的通道和矿质沉淀的场所.矿区见有4种正构烷烃: 非含矿地层中的正常成熟型、矿体内部的异常成熟型、热水溶解型和微生物降解型.这些不同类型的正构烷烃提供了丰富的成矿信息, 具有成矿作用的示踪意义.      

中国卡林型金矿成矿构造环境及热液特征

通过对近年来国内质界在卡林型金矿研究方面最新成果的对比总结,认为卡林型金矿多产于大地构造活动地带,如不同大地构造单元接合部位,古裂谷带等;成矿物质和成矿热液流体具有多源性,成矿热液为中－弱酸性的低盐度流体,其中含有一定数量的有机质,有机质在成矿过程中起着重要作用。     

黔西南卡林型金矿床流体包裹体中微量元素研究

用ICP－MS测定了黔西南烂泥沟和丫他卡林型金矿床石英流体包裹体中的Co、Ni、Cu、Pb、Zn和Pt等元素的含量。结果显示，不同成矿阶段石英流体包裹体中均有较高的Co、Ni、Cu、Pb和Zn含量，并首次发现卡林型金矿床成矿流体中富含Pt。据此认为基性火山岩可能是卡林金矿床成矿物质的重要来源之一。     

美国与中国西部卡林型金矿的对比

通过对美国的卡林型金矿与我国的卡林型金矿地球动力学、矿床的地质背景、成矿条件分析,其类似表现为:均发育于地壳活动强烈的部位,具有以硅化、碳酸盐化为主的中低温热液蚀变类型,具有以黄铁矿、雄黄、雌黄、辉锑矿、辰砂、重晶石和石英等矿物组合,且干酪根的成熟度相近;其差异表现为:成矿时代与赋矿围岩的时代相差甚远(矿岩时差),与岩浆岩作用密切程度不同,Au、Hg、Sb、As、Tl的存在形式不同.并根据以上差异,对有关问题进行了探讨.     

贵州省贞丰县那郎金矿点地质特征及找矿远景

文章以那郎金矿点勘查成果资料为依据,通过对该矿床的矿点地质特征、矿体特征等进行分析研究,初步总结了本区成矿控矿条件,并提出了找矿远景区及找矿方法。     

锗、银、金大型超大型矿床的有机地球化学研究

锗、银、金大型超大型矿床的有机地球化学研究庄汉平（中国科学院地球化学研究所，贵阳５５０００２）关键词有机质—金属相互作用褐煤型超大型锗矿床黑色页岩型银钒矿床卡林型金矿床有机地球化学有机质—金属相互作用是有关超大型矿床基础理论研究的重要内容之一。在以往...     

The Nature of Ore‐forming Fluids of the Carlin‐type Gold Deposit in Southwest China: A Case from the Zimudang Gold Deposit

The Zimudang gold deposit is a large Carlin‐type gold deposit in the Southwest Guizhou Province, China, with an average Au content of 6.2 g/t. Gold is mainly hosted in the fault zone and surrounding strata of the F1 fault and Permian Longtan Formation, and the ore bodies are strictly controlled by both the faults and strata. Detailed mineralogy and geochemistry studies are conducted to help judge the nature of ore‐forming fluids. The results indicate that the Au is generally rich in the sulfides of both ores and wall rocks in the deposit, and the arsenian pyrite and arsenopyrite are the main gold‐bearing sulfides. Four subtypes of arsenian pyrite are found in the deposit, including the euhedral and subhedral pyrite, framboidal pyrite, pyrite aggregates and pyrite veins. The euhedral and subhedral pyrite, which can take up about 80% of total pyrite grains, is the dominant type. Au distributed unevenly in the euhedral and subhedral pyrite, and the content of the Au in the rim is relatively higher than in the core. Au in the pyrite veins and pyrite aggregates is lower than the euhedral and subhedral pyrite. No Au has been detected in the points of framboidal pyrites in this study. An obvious highly enriched As rim exists in the X‐ray images of euhedral pyrites, implying the ore‐forming fluids may be rich in As. The relationship between Au and As reveals that the Au may host as a solid solution (Au⁺) and nanoparticles of native gold (Au⁰) in the sulfides. The high Co/Ni ratio (>1) of sulfides and the enrichment of W in the ores all reflect that the gold‐bearing minerals and ore‐forming process were mainly related to the hydrothermal fluids, but the magmatic and volcanic activities cannot be neglected. The general existence of Au and As in the sulfides of both ores and wall rocks and the REE results suggest that the ore‐forming fluids may mainly be derived from the basin itself. The enrichment of Tl suggests that the ore‐forming fluids may be enriched in Cl. The Ce and Eu show slightly or apparently negative anomalies, which means the ore fluids were probably formed under reducing environment. The Y/Ho ratios of ore samples fluctuate around 28, implying the bicarbonate complexation and fluorine were both involved in the ore‐forming process. Combined with the previous studies and our results, we infer that the ore‐forming fluids enriched Au, As, HS^? and halogen (F, Cl) were derived from the mixture of reducing basinal fluids and magmatic or volcanic hydrothermal fluids.     

成矿流体运移的输导体系研究--以右江地区微细浸染型金矿为例

结合石江地区微细浸梁型金矿的矿床地质特征,从成矿流体运移的角度出发,认为该区在４种类型的成矿流体输导体系,断裂系统、古构宵整合面或岩溶不整合面、岩性通道。同时,该区的古炭酸盐岩台地或古生物礁是多种流体输导体系汇集的部位,明显的控制了该区金矿床展布和具体矿体的产出部位,是一种特殊的输导体系。