中国东部中生代浅成热液金矿的类型、特征及其地球动力学背景

中国东部中生代浅成热液金矿可以划分为与花岗岩和与碱性岩有关的两种类型；也可以分为高硫型和低硫型两大类，而且以后一种为主。这些金矿的形成和分布受区域构造制约，具体地说是受破火山口、火山角砾岩筒以及与火山机构有关的断裂控制。成矿围岩为火山岩类及同源花岗质岩石和周围地层。主要的蚀变组合为冰长石一玉髓一绢云母或明矾石一高岭石一石英(玉髓)。成矿年龄分布在180～188Ma，135～144Ma，127～115Ma和94～105Ma四个区间，前三组年龄分别响应于中生代华北板块与扬子克拉通的造山碰撞后陆内造山的伸展过程、构造体制大转折以及岩石圈大减薄，后一组为华南地区岩石圈再一次强烈伸展期间的产物。虽然这些矿床的形成时间有差异，但都是发育于大陆伸展环境中。     

浅成低温热液型金矿床研究的某些进展

浅成低温热液型金矿床成矿流体在较深处(3～4km)发生相分离的同时导致不同成矿元素和载矿元素进入不同的相态,从而形成不同性质流体,其中富挥发S的气水相在高压下有很强的载矿能力,对特定矿化类型形成具有决定性意义。流体在向浅成低温环境演化过程中,携带大量成矿物质的气水相必须转化成液相才可能导致浅成低温成矿(深度1～2km),这个过程与含水的岩浆房冷却密切相关。通过冷却加压,富挥发S的气体在水盐体系的两相界面以上可转变为液体,将成矿元素Au等运移至浅部。浅成低温热液矿床与卡林型矿床均可形成于大陆裂谷环境,前者的高硫化类型与后者在流体性质、蚀变特征、成矿特征等方面具有明显的相似性和可比性。富碲型矿床的Te很可能是在相分离过程中以Te2(g)和H2Te(g)的形式进入气相,并在浅部被地下水吸收,形成Ag(HTe)2-和Au(HTe)2-络合物,伴随着流体的冷却和环境变化,使得碲化物沉淀。少硫(碲)化物特富金的浅成低温热液型矿床金可能以金硅络合物或是金硅合金氢化物形式进行搬运,在浅部SiO2和Au沉淀形成特富金矿。     

基于遥感短波红外技术的三维蚀变填图——以低硫化浅成低温热液型矿床斯弄多为例

斯弄多银(金)-铅-锌矿床是冈底斯南缘林子宗群火山岩中发现的首例低硫化浅成低温热液型矿床,其发现对于完善区域成矿系列,开拓区域找矿方向都具有重要的意义。本文采用遥感技术与短波红外技术相结合的方法,通过三维建模重现了地表-地下的蚀变矿物组合,形成了星-空-地一体化的三维蚀变填图。本文采用多光谱遥感ASTER数据提取了地表围岩蚀变信息,通过遥感波段比值算法的铁染指数(b2+b3)/b1、镁羟基指数(b6+b9)/(b7+b8)、铝羟基指数(b5/b8)+(b6/b9)分别圈定了矿区地表含有Fe~(3+)、Fe~(2+),Al-OH和Mg-OH等基团的蚀变矿物信息;采用短波红外技术提取了岩心中的绢云母、蒙脱石和伊利石等矿物,并确定了地下的蚀变矿物组合。研究表明,(1)地表蚀变中的Al-OH蚀变信息与钻孔中绢云母的分布非常吻合,遥感的Al-OH信息可作为重要的找矿线索;(2)根据地下蚀变矿物的种类分布,能够确定地表铁染蚀变矿物主要表现为大量褐铁矿化(野外特征明显)、少量黄钾铁矾及绢云母;(3)绢云母形成环境的不同导致其二八面体结构发生变化:Al~ⅥAl~Ⅳ?Mg~ⅥSi~Ⅳ和Fe?Mg,是Mg-OH基团与Al-OH信息在地表部分叠合的重要原因;(4)钻孔中伊利石反射光谱特征参数计算表明,伊利石结晶度(SWIR-IC)在钻孔中呈规律性变化,近矿部位SWIR-IC(1.1~1.4)值域较低,说明伊利石形成温度较低,可能是黏土矿物成岩过程中蒙脱石向伊利石的转化递进反应,远矿段SWIR-IC(1.6~2.1)值域较高,说明该矿物较近矿段而言形成温度相对较高,是绢云母伊利石化的具体反映。     

Genesis of the Ciemas Gold Deposit and Relationship with Epithermal Deposits in West Java, Indonesia: Constraints from Fluid Inclusions and Stable Isotopes

The Ciemas gold deposit is located in West Java of Indonesia,which is a Cenozoic magmatism belt resulting from the Indo-Australian plate subducting under the Eurasian plate.Two different volcanic rock belts and associated epithermal deposits are distributed in West Java:the younger late Miocene-Pliocene magmatic belt generated the Pliocene-Pleistocene epithermal deposits,while the older late Eocene-early Miocene magmatic belt generated the Miocene epithermal deposits.To constrain the physico-chemical conditions and the origin of the ore fluid in Ciemas,a detailed study of ore petrography,fluid inclusions,laser Raman spectroscopy,oxygen-hydrogen isotopes for quartz was conducted.The results show that hydrothermal pyrite and quartz are widespread,hydrothermal alteration is well developed,and that leaching structures such as vuggy rocks and extension structures such as comb quartz are common.Fluid inclusions in quartz are mainly liquid-rich two phase inclusions,with fluid compositions in the NaCl-H20 fluid system,and contain no or little CO_2.Their homogenization temperatures cluster around 240℃-320℃,the salinities lie in the range of 14-17 wt.%NaCl equiv,and the calculated fluid densities are 0.65-1.00 g/cm~3.The values of δ~(18)O_(H2O-VSMOW)for quartz range from +5.5‰ to +7.7‰,the δD_(VSMOW) of fluid inclusions in quartz ranges from-70‰ to-115‰.All of these data indicate that mixing of magmatic fluid with meteoric water resulted in the formation of the Ciemas deposit.A comparison among gold deposits of West Java suggests that Miocene epithermal ore deposits in the southernmost part of West Java were more affected by magmatic fluids and exhibit a higher degree of sulfldation than those of Pliocene-Pleistocene.     

Chemistry and Occurrences of Native Tellurium from Epithermal Gold Deposits in Japan

The chemistry and mode of occurrences of native tellurium in the epithermal gold ores from Teine, Kobetsuzawa, Mutsu, Kawazu, Suzaki and Iriki in Japan are examined. Mineral assemblages in contact with native tellurium are: quartz‐sylvanite at Teine, quartz‐hessite‐sylvanite‐tellurantimony at Kobetsuzawa, quartz at Mutsu, quartz‐stutzite‐hessite‐sylvanite‐tetradymite at Kawazu, quartz at Suzaki, and quartz‐goldfieldite at Iriki. The peak patterns of XRD for native tellurium from these six ores are nearly identical to that of JCPDS 4–554. Their chemical compositions of Te range from 98.16 to 100.73 wt.%, showing nearly pure tellurium. Other elements detected are: Se of 0–0.85 and Cu of 0–0.74 at Teine, Sb of 0.45–0.47 and Se of 0.19–0.27 at Kawazu, Se of 0.22–1.11 and Sb of 0–0.49 at Suzaki, and Cu of 0.69–0.98, As of 0.22–0.28 and Bi of 0–0.22 wt.% at Iriki. No other elements are detected in the ores of Kobetsuzawa and Mutsu. The ranges of associated minor compositions are consistent with those of the experimental phase. The differences would be related to associate minerals. The mineral assemblages in these ores agree well with the previously proposed experimental phase relations in Au‐Ag‐Te ternary system for 120–280°C. The Suzaki ore has high Te‐Au assemblage: from calaverite‐sylvanite‐krennerite via native tellurium to petzite, with changing mineralization stage, whereas the Kobetsuzawa and the Kawazu ores have high Te‐Ag assemblage of tellurium‐hessite, and native tellurium‐stutzite‐hessite‐sylvanite, respectively. The Teine ore has intermediate assemblage of native tellurium‐sylvanite. The mineral assemblages in the Au‐Ag‐Te system are related to the hydrothermal environment especially to the pH condition, i.e. Au rich assemblages under acidic and Ag rich assemblages under intermediate pH conditions, being supported by alteration mineral species. The other telluriferous epithermal gold deposits not in association with native tellurium such as Agawa, Date, Takeno, Chugu, Chitose, Sado and Kushikino are estimated to have been formed under higher pH conditions as adularia and calcite occur in these deposits. The pH‐Eh diagram for aqueous tellurium species and tellurium minerals at 250°C indicates that the region of native tellurium occurs between those of aqueous telluride and tellurous species at lower pH, being consistent with their mineral assemblages in ores and alteration envelopes.     

Types, Characteristics, and Geodynamic Settings of Mesozoic Epithermal Gold Deposits in Eastern China

Mesozoic epithermal gold deposits in eastern China are divided into calc‐alkaline and alkaline magma‐related gold deposits, and are also grouped as low‐sulfidation, intermediate‐sulfidation and high‐sulfidation types, of which the first two predominate. These gold deposits are distributed in the Tianshan–Yinshan–Great Xing’anling Variscan fold belt of North China craton, Qinling‐Dabie Indo‐Sinian fold belt of Yangtze craton, and South China fold belt or Cathaysian block, from north to south along the eastern China continent. Most of the epithermal gold orebodies are hosted either in volcanic rocks or their related granitoids, and volcanic breccia pipes. These orebodies are mainly associated with adularia–chalcedony–sericite, and alunite–kaolinite–quartz alteration. These orebodies formed in four mineralization pulses at 175, 145–135, 127–115, and 110–94 Ma. The first three pulses correspond to the post‐collision period between the North China and Yangtze cratons, an extension period during late‐stage rotation of the principal compressional stress from N‐S to E‐W, and a dramatic thinning period of the lithosphere, respectively. The last mineralizing pulse was the result of another extension in South China. Although the mineralizing pulses occurred at different times, they all occurred in extensional settings and were accompanied by crust and the mantle interaction.     

福建紫金山铜金矿床类型与环太平洋浅成低温矿床的比较

福建省上杭紫金山铜金矿床是我国大陆发现的首例高硫型浅成低温热液矿床,在矿床深 继发现了斑岩型铜矿、中低温热液型铜矿和低硫浅成热液型银（金、铜）矿。可与环太平洋带上一系列特大型斑岩铜金和低温热液型金（铜）矿对比,它们有若干共同特征,但紫金山矿床与它们的一些不同之处,启示我们开拓找矿的新的时空领域。     

Gold Grade and Tonnage Models of the Gold Deposits, China

Abstract: The gold grade and tonnage modelling is applied to some types of the gold deposits in China, including placer, Archaean lode, slate belt, Carlin, volcanogenic, skarn and Shandong Peninsula, among others. The Shandong Peninsula type denotes the gold deposit, which was formed in an intensely reshaped Archaean greenstone belt. The modelling results show: (1) the Archaean lode gold deposits of China are similar to the Homestake type in gold grades. (2) The Chinese slate belt type gold deposits are marked by moderately lower gold grades but considerably larger ore volumes than the similar type elsewhere. (3) The Carlin style gold deposits of China are identified by higher Au grades but evidently smaller sizes in comparison with their counterparts in western North America. (4) The volcanogenic (continental) style is similar to Sado epithermal veins in gold grade‐tonnage models and general characteristics while volcanogenic gold deposits of the oceanic subgroup contrast with Kuroko‐type deposits in the gold grade model. But the Chinese volcanogenic (oceanic) subtype (Palaeozoic age) shows similar higher gold grades to those of the Palaeozoic Kuroko‐type deposits elsewhere. (5) Porphyry and skarn gold deposits tend to have a large size but low grade. (6) Less than half of the Shandong Peninsula gold deposits are of ore volumes exceeding the 50th intercept of the relevant gold tonnage model, implying possible undiscovered gold deposits with a larger size in the peninsula. (7) In general, Chinese gold deposits of larger sizes tend to have lower gold grades in relation to gold grade models. (8) Gold grade‐tonnage models can be effectively influenced by how to include or exclude non‐economic gold resources in the modelling. Ore volumes of gold deposits actually to some extent depend on gold grades. Consequently, the way of including or excluding low‐grade values may effect a gold grade‐tonnage model and cause different interpretation of the modelling results. This is particularly true to the gold deposits, which generally show an inverse correlation between gold grade and tonnage.     

Characteristics and Mineralization Age of the Fukusen No. 1 Vein,Hishikari Epithermal Gold Deposits,Southern Kyushu,Japan

The Fukusen No. 1 vein is located in the southeastern part of the Yamada deposit, Hishikari epithermal gold deposits, southern Kyushu, Japan. ⁴⁰Ar/³⁹Ar plateau ages of adularia from the margin and the center of the Fukusen vein are determined to be 0.617 ± 0.024 Ma and 0.606 ± 0.009 Ma, respectively. The Fukusen No. 1 vein shows banding structure composed mainly of quartz, adularia and clay minerals. Colloform texture is displayed by cryptocrystalline to amorphous silica material that is associated with fine-grained electrum and sulfides near the center of the vein. Pyrite in the Fukusen No. 1 vein often shows acicular shape resulting from inversion from marcasite. Near the center of the vein, primary marcasite occurs associated with colloform texture of silica. The Fukusen No.1 vein preserves primary texture and materials which were deposited from the ore-forming hydrothermal solution. The Fukusen No. 1 vein was formed in a short period and is one of the youngest veins in the Hishikari deposits.     

Genetic Aspects of the Manto-type Copper Deposits Based on Geochemical Studies of North Chilean Deposits

Recent studies on mineralogy, geochronology, fluid inclusion and stable isotope (Pb, Os, S, C, O, Sr) characteristics were reviewed to determine constraints for genetic models of the Chilean manto‐type copper deposits. The Chilean manto‐type deposits are divided into the two geologic categories of the northern areas (Arica–Iquique, Tocopilla–Taltal) and the central areas (Copiapó, La Serena, Santiago). The former is distributed in the coastal range composed of Jurassic andesite‐dominated volcano‐sedimentary piles and younger plutonic intrusions, and yields chalcocite (‐digenite) and bornite as the principal hypogene copper sulfides. The latter is hosted mostly in Lower Cretaceous volcano‐sedimentary sequences, and has chalcopyrite‐rich mineral associations. The fluid inclusion data indicate that the primary copper mineralization was commonly generated in the temperature range 150–360°C under low‐pressure conditions near the boiling curve, mediated with relatively saline brines. Generally, homogeneous Pb and S isotope compositions for primary copper minerals imply direct magma source or leaching of igneous rocks. Pb and Os isotope data published for some deposits, however, suggest that ore‐forming metals were derived mainly from the volcano‐sedimentary host rocks. The noticeably negative isotope ratios of primary sulfide sulfur and hydrothermal calcite carbon of some central area deposits indicate influx of sedimentary rock components, and the high ⁸⁷Sr/⁸⁶Sr initial ratios of hydrothermal calcite from the Tocopilla–Taltal area deposits imply contribution of the contemporaneous seawater or marine carbonates. These isotopic constraints imply a formation mechanism in which the Chilean manto‐type copper deposits formed epigenetically in the process of hydrothermal interaction of non‐magmatic surface‐derived brine with the volcano‐sedimentary host rocks, which is inferred to have been induced by a deep‐seated plutonic complex as the possible heat source.     

Concentration of Gold(I) Thiosulfate Complex Ions on the Surface of Alumina Gel and their Change in Chemical State: Preliminary Experiment in the Elucidation of the Formation Mechanism of Epithermal Gold Deposits

In order to elucidate the formation mechanism of low‐sulfidation epithermal gold deposit, the adsorption of [Au(S₂O₃)₂]^3? (a model compound for gold(I) complex ion) on alumina gel (a model compound for the aluminum‐bearing minerals) and change in chemical state of [Au(S₂O₃)₂]^3? after adsorption on the surface of alumina gel were investigated as a basic model experiment. In the pH range from 4 to 6, the amount of [Au(S₂O₃)₂]^3? adsorbed on alumina gel decreased with increasing pH and decreased drastically between pH 6 and 7, and then approached zero above pH 8 at 30°C. At 60°C, the amount of gold adsorbed above pH 7 was enhanced compared with that at 30°C. This adsorption tendency indicates that [Au(S₂O₃)₂]^3? is mainly adsorbed by electrostatic interaction between negative charges of [Au(S₂O₃)₂]^3? and positive charges of alumina gel because of its isoelectric point around pH 9. The chemical state of gold after adsorption of [Au(S₂O₃)₂]^3? on alumina gel was examined using X‐ray absorption near edge structure (XANES). The result showed that [Au(S₂O₃)₂]^3? was spontaneously reduced to elemental gold even in the absence of specific reducing agents after adsorption on alumina gel. This reduction reaction might occur by two steps: (i) disproportionation of the adsorbed [Au(S₂O₃)₂]^3? at the surface of alumina gel, and (ii) spontaneous reduction of the resulting gold(III) complex ions on the surface of alumina gel. The experimental results suggest that aluminum plays an important role in the concentration of gold(I) complex ions and subsequent reduction of gold during the formation of low‐sulfidation epithermal gold deposits.     

Geology and Alteration-Mineralization Characteristics of the Cibaliung Epithermal Gold Deposit, Banten, Indonesia

Abstract. The Cibaliung gold project is located at the central portion of the Neogene Sunda‐Banda magmatic arc. Gold‐silver mineralization in the area is hosted in a thick sequence of sub‐aqueous basaltic andesite volcanics with intercalated sediments intruded by sub‐volcanic andesite to diorite plugs and dykes, and subsequently cut by a cluster of diatreme breccias. These host rocks are unconformably overlain by dacitic tuffs, younger sediments and basalt flows. The gold prospects in Cibaliung occur within a NW‐trending structural corridor that is 3.5 km wide by at least 6 km long. It is fault‐bounded and is considered to be a graben. Two aligned NNW‐trending sub‐vertical shoots, Cikoneng and Cibitung, host the currently defined resource within the steeply dipping vein system with a minimum strike length of 1,300 m. As of July 2001, exploration has defined an inferred + indicated mineral resource of approximately 1.3 million tonnes at 10.42 g/t gold and 60.7 g/t silver at a 3 g/t Au cut‐off. This equates to approximately 435,000 ounces of gold and 2.54 million ounces of silver. Gold‐silver mineralization occurs as quartz veins characteristic of the low‐sulphidation epithermal adularia‐sericite type. Progressive dilation with a general increase in gold grade has produced multi‐stage veining and brecciation that grades from early to late stages as: pre‐mineral fluidized breccia, quartz vein stockwork, massive vein, crustiform vein, colloform‐crustiform vein with progressive increase in chloritic clay bands, clay‐quartz milled matrix breccias with a progressive increase in clay content, and synto post‐mineral fault gouge with vein clasts. Wall rock alteration is characterized by pro‐grade chlorite+adularia flooding that is locally overprinted by a low temperature argillic alteration (smectite, illite and mixed layered clays). Generally, the argillic alteration becomes weak with depth. The major mineral constituents of the veins are quartz, adularia and clay. In the early gold‐poor hydrothermal stages, quartz and adularia dominate with minor calcite and clay (smectite, poorly crystalline chlorite, interlayered chlorite‐smectite and illite‐smectite). In the later gold‐rich hydrothermal stages, clay with variable amounts of carbonate increases whereas the abundance of quartz and adularia decreases. Gold occurs mainly as electrum while silver occurs as argentite‐aguilarite‐naumannite and electrum, and rarely as native silver, sulphosalts and tellurides. Sulphides generally comprise <1 vol % of the vein, with pyrite as the most common species. Together with pyrite, traces of very fine‐grained base metal sulphides dominated by chalcopyrite, sphalerite and galena are in most cases intimately associated with electrum and silver minerals. Partial supergene oxidation generally extends down to about 200 m below the surface at Cikoneng and further down to more than 300 m at Cibitung. The hydrothermal system responsible for the gold‐silver mineralization in the area may be related to rhyolitic magmatism focused on a volcanic intrusive center during back arc rifting that formed a graben or pull‐apart basin. The dominant mechanism for the higher grade gold deposition is fluid mixing of up welling metal‐bearing hydrothermal solutions with relatively near surface cool, oxygenated condensate and/or steam‐heated meteoric fluids, as opposed to retrograde boiling. The strongly focused dilational structural environment is thought to have been the mechanism for focusing fluid flows, both up welling and descending, forming pipe‐like mineralized bodies in the rhomboidal dilation zones. It is interpreted that mineralization took place under low temperature conditions (<150–220d?C) at a minimum depth of around 200–250 m below the palaeo‐water table.     

热液金矿床控矿断裂性质与成矿流体的物理化学

热液金矿床的成矿物理化学条件与控矿断裂构造环境有着密切联系。作者对比了不同构造环境（小秦岭、焦家、玲珑和太白金矿）流体包裹体物理化学参数特征,表明韧性剪切带环境中的金矿成矿流体压力大、ＣＯ２／Ｈ２Ｏ数值也高。不同构造环境中流体Ｋ＋／Ｎａ＋、Ｆ－／Ｃｌ－的差别不仅与容矿岩石化学特征有关,也与构造应力作用有关,同一矿田内,甚至同一断裂带内,因所处构造部位不同,成矿流体压力也不同,致使其他物理化学参数的系统变化,这对地质找矿具有实际意义。     

西秦岭地区卡林-类卡林型金矿床及其成矿时间、构造背景和模式

秦岭造山带是世界第二大卡林-类卡林型金矿省,其地质背景与美国西部卡林-类卡林型金矿省明显不同,位于大陆内部的碰撞造山带,而非活动大陆边缘的盆岭省。秦岭卡林-类卡林型金矿主要赋存于板块缝合带及其前陆冲断带的海西-印支构造层中,以泥盆系和三叠系为主,主要岩性为瀉湖-浅海相的含碳细碎屑岩-碳酸盐岩建造,即碳硅泥岩系;成矿元素为Au-As-Sb-Hg-Ag,缺乏T1,共生矿种为Sb,Hg,Ag,U和重晶石等;成矿温度为160～300℃,流体盐度为4％～10％(NaClcq),压力为5～50MPa,深度约0．5～5km,属于中低温中浅成热液矿床,与内华达卡林-类卡林型金矿一致。成矿流体具有建造水特点,C2H6含量较高,显示了有机流体参与成矿。成矿同位素年龄介于220～100Ma之间,以170Ma为高峰,地球动力学背景属碰撞造山过程挤压-伸展转变期的减压增温体制,成矿构造模式为碰撞造山成岩成矿和流体作用模式。陆陆碰撞过程中,沿龙门山、阿坝-黑水-平青、若尔盖-文县、玛曲-勉县-略阳、白龙江、双河-公馆、凤县-镇安、安康等大型断裂带的陆内俯冲作用不仅导致了西秦岭地壳缩短增厚隆升,而且使俯冲板片变质脱水、熔融,派生成矿流体和相关熔体,流体和熔体的上升到仰冲板片次级构造带,形成了卡林-类卡林型和造山型金矿成矿系统。据此提出,西秦岭深部可能存在潜力巨大的造山型金矿省。     

川西甘孜-理塘金矿带形成条件的矿物电子探针与裂变径迹研究

甘孜-理塘金矿带位于青藏高原东部松潘-甘孜造山带与义敦岛弧造山带的交界部位.通过对嘎拉、错阿、雄龙西、阿加隆洼和曲开隆洼等5个金矿区矿石样品中主要载金矿物黄铁矿和毒砂的电子探针分析,试图探讨区内金矿形成温度、深度和成生环境,并结合矿石锆石裂变径迹定年探讨成矿时代.研究区黄铁矿为S亏损型,普遍含Co和Ni,含量分别为0....     

Geology and Geochemistry of the Buerkesidai and Kuoerzhenkuola Gold Deposits in the Sawuershan Region, Xinjiang Uigur Autonomous Region, Northwest China

The Sawuershan region, one of the important gold metallogenic belts of Xinjiang, is located in the western part of the Kalatongke island arc zone of north Xinjiang, NW China. There are two gold deposits in mining, namely the Kuoerzhenkuola and the Buerkesidai deposits. Gold ores at the Kuoerzhenkuola deposit occur within Carboniferous andesite and volcanic breccias in the form of gold‐bearing quartz–pyrite veins and veinlet groups containing native gold, electrum, pyrite, pyrrhotite and chalcopyrite. Gold ores at the Buerkesidai deposit occur within Carboniferous tuffaceous siltstones in the form of gold‐bearing quartz veinlet groups and altered rocks, with electrum, pyrite and arsenopyrite as major metallic minerals. Both gold deposits are hosted by structurally controlled faults associated with intense hydrothermal alteration. The typical alteration assemblage is sericite + chlorite + calcite + quartz, with an inner pyrite–sericite zone and an outer chlorite–calcite–epidote zone between orebodies and wall rocks. δ³⁴S values (0.3–1.3‰) of pyrite of ores from Kuoerzhenkuola deposit are similar to those (0.4–2.9‰) of pyrite of ores from Buerkesidai deposit. δ³⁴S values (1.1–2.8‰) of pyrite from altered rocks are similar to δ³⁴S values of magmatic or igneous sulfide sulfur, but higher than those from ores. ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb data of sulfide from ores range within 17.72–18.56, 15.34–15.61, and 37.21–38.28, respectively. These sulfur and lead isotope compositions imply that ore‐forming materials might originate from multiple, mainly deep sources. He and Ar isotope study on fluid inclusions of pyrites from ores of Kuoerzhenkuola and Buerkesidai gold deposits produces ⁴⁰Ar/³⁶Ar and ³He/⁴He ratios in the range of 282–525 and 0.6–9.4 R/Ra, respectively, indicating a mixed source of deep‐seated magmatic water (mantle fluid) and shallower meteoric water. In terms of tectonic setting, the gold deposits in the Sawuershan region can be interpreted as epithermal. These formations resulted from a combination of protracted volcanic activity, hydrothermal fluid mixing, and a structural setting favoring gold deposition. Fluid mixing was possibly the key factor resulting in Au deposition in the gold deposits in Sawuershan region.     

大瑶山加里东造山带中部与斑岩相关金矿床的特殊 性及构造环境对其制约作用-以大王顶金矿床为例

[摘 要] 广西大瑶山加里东造山带发育的金矿床既具有造山带型矿床的特征,同时又与花岗斑岩 密切相关。位于大瑶山金矿带中部的湾岛矿田的大王顶金矿就是这类金矿床的典型代表之一。本文通 过调查大王顶金矿床的特征以及成矿花岗斑岩体中金的富集分布规律,剖析了加里东褶皱造山变形以 及花岗斑岩对金成矿的控制作用。由于大瑶山加里东造山带所处的特殊的构造环境,造山晚期所形成 的I 型花岗斑岩体在金的成矿中起着重要的作用,但金矿脉的容矿空间的形成却主要还是构造作用的 结果。     

Mineral Paragenesis and Fluid Inclusions of Some Pluton-hosted Vein-type Copper Deposits in the Coastal Cordillera, Northern Chile

Abstract. Formation conditions of some vein-type copper deposits of the Tocopilla district (Deseada, San Jose, Santa Rosa) and the Gatico district (Yohanita, Toldo-Velarde, Argentina) in the Coastal Cordillera of northern Chile were inferred from mineral paragenesis and fluid inclusion data, and were compared with those of neighboring stratiform copper deposits. The vein-type copper deposits are hosted in Late Jurassic dioritic to quartz-dioritic plutons intruding extensively an andesite-dominant volcanic pile of the Jurassic La Negra Formation. Primary mineralization is characterized by chalcopyrite + magnetite + pyrite + bornite, and supergene alteration of these minerals produced anilite, covellite, atacamite and chrysocolla. The hypogene mineral assemblage indicates relatively high sulfur fugacity and weakly oxidized conditions, distinct from the stratiform copper deposits formed under low sulfur fugacity and moderately oxidized conditions. Furthermore, the fluid inclusion data of the vein-type deposits indicate high temperature (401–560C) and high salinity (39–68 wt% NaCl equiv.) ranges in contrast to the stratiform deposits, suggesting that this type of deposits formed by magma-associated hypersaline ore fluids.