Nature and Genesis of the Xiaobeigou Fluorite Deposit,Inner Mongolia,Northeast China: Evidence from Fluid Inclusions and Stable Isotopes

The recently discovered Xiaobeigou fluorite deposit is situated in the southern part of the Southern Great Xing'an Range metallogenic belt. Fluorite‐bearing veins are rather common over the whole area. So far, 11 mineralized veins have been delineated at the Xiaobeigou deposit. Orebodies of the deposit are mainly hosted in Permian and Jurassic volcano‐sedimentary rocks. The orebodies in this mining district exhibit a well‐developed vertical zonation: from top to bottom, the orebodies can be divided into upper, central, and lower zones. The central zone is the most important part for mining operations, and it shows lateral zonation of fluorite mineralization. Rare earth element (REE) contents of the investigated samples are relatively low (less than 30.2 ppm). Furthermore, the REE contents of the fluorite grains from early to late ore stages exhibit a decreasing trend. All the fluorite samples show no or slightly positive Eu anomalies. Three types of fluid inclusions (FIs) are distinguished in the quartz and fluorite samples, including pure‐liquid single‐phase (PL‐type), liquid‐rich two‐phase (L‐Type), and vapor‐rich two‐phase (V‐type) FIs. The FIs hosted in early‐stage quartz were homogenized at 159.5–260.7°C (mainly 160–240°C); their salinities range from 0.18 to 1.22 wt.% NaCl eqv. The FIs hosted in early‐stage fluorite yield slightly lower homogenization temperatures of 144.4–266.8°C (peaking at 140–220°C), which correspond to salinities of 0.18–0.88 wt.% NaCl eqv. Homogenization temperatures and salinities for the late stage are 132.5–245.8°C (mainly 160–180°C) and 0.18–1.40 wt.% NaCl eqv., respectively. Laser Raman spectroscopy of FIs shows that both the vapor and liquid compositions of the inclusions are dominated by H₂O. The H–O isotopic compositions at Xiaobeigou suggest that the ore‐forming fluids are predominantly of meteoric water origin. The Xiaobeigou deposit can be classified as a typical low‐temperature hydrothermal vein‐type fluorite deposit. Combined with regional data, we infer that the fluorite mineralization occurred during the Late Mesozoic in an extensional setting.     

内蒙古二道河子铅锌银多金属矿床流体包裹体红外显微测温研究

二道河子铅锌银多金属矿床是得耳布干成矿带具有代表性的铅锌矿床之一。闪锌矿作为主要矿石矿物,可分为早期黑色-中期红棕色或棕色-晚期黄褐色或浅黄色三个世代。采用红外显微镜技术和激光拉曼技术对不同世代闪锌矿及共生石英中的流体包裹体进行显微测温和成分测试,初步认为三个世代闪锌矿基本与石英内的三次流体活动相对应,推测它们形成于同一物理化学条件,捕获同一成矿流体,但闪锌矿流体包裹体能更直观而细致地勾勒出成矿流体的演化过程。从成矿早期至晚期,随着流体演化,流体包裹体的均一温度、盐度及CO2含量均明显下降,流体从中温、中低盐度、CO2-H2O-NaCl体系向低温、低盐度、H2O-NaCl体系演化。此外,在整个主成矿过程中,影响成矿物质沉淀富集的机制也随时间变化有所差异:早期流体沸腾是黑色闪锌矿等硫化物形成的重要因素;中期以流体自然冷却作用为主,形成了红棕色闪锌矿等硫化物;至晚期,随着大气水的混入,流体混合作用是形成晚期闪锌矿等硫化物的重要原因。二道河子矿床为与火山-次火山有关的浅成中低温热液矿床。     

Genesis of the Bangbu Orogenic Gold Deposit,Tibet: Evidence from Fluid Inclusion,Stable Isotopes,and Ar-Ar Geochronology

The Bangbu gold deposit is a large orogenic gold deposit in Tibet formed during the AlpineHimalayan collision. Ore bodies(auriferous quartz veins) are controlled by the E-W-trending Qusong-Cuogu-Zhemulang brittle-ductile shear zone. Quartz veins at the deposit can be divided into three types: pre-metallogenic hook-like quartz veins, metallogenic auriferous quartz veins, and postmetallogenic N-S quartz veins. Four stages of mineralization in the auriferous quartz veins have been identified:(1) Stage S1 quartz+coarse-grained sulfides,(2) Stage S2 gold+fine-grained sulfides,(3) Stage S3 quartz+carbonates, and(4) Stage S4 quartz+ greigite. Fluid inclusions indicate the oreforming fluid was CO_2-N_2-CH_4 rich with homogenization temperatures of 170–261°C, salinities 4.34–7.45 wt% Na Cl equivalent. δ~(18)Ofluid(3.98‰–7.18‰) and low δDV-SMOW(-90‰ to-44‰) for auriferous quartz veins suggest ore-forming fluids were mainly metamorphic in origin, with some addition of organic matter. Quartz vein pyrite has δ~(34)SV-CDT values of 1.2‰–3.6‰(an average of 2.2‰), whereas pyrite from phyllite has δ~(34)SV-CDT 5.7‰–9.9‰(an average of 7.4‰). Quartz vein pyrites yield 206Pb/204 Pb ratios of 18.662–18.764, 207Pb/204 Pb 15.650–15.683, and ~(208)Pb/204 Pb 38.901–39.079. These isotopic data indicate Bangbu ore-forming materials were probably derived from the Langjiexue accretionary wedge. 40Ar/39 Ar ages for sericite from auriferous sulfide-quartz veins yield a plateau age of 49.52 ± 0.52 Ma, an isochron age of 50.3 ± 0.31 Ma, suggesting that auriferous veins were formed during the main collisional period of the Tibet-Himalayan orogen(~65–41 Ma).     

甘肃北山公婆泉斑岩型铜矿地质特征及成矿流体包裹体研究

公婆泉铜矿位于甘肃-蒙古-北山斑岩铜矿成矿带公婆泉岛弧区,为典型的斑岩型铜矿,赋矿围岩主要为英安斑岩、花岗闪长斑岩和石英闪长玢岩.矿石矿物主要有黄铜矿和斑铜矿,其次有少量的黄铁矿、闪锌矿、方铅矿以及蓝辉铜矿等.对含矿石英脉中流体包裹体研究表明,公婆泉铜矿主要有4类流体包裹体:纯气相包裹体(I型)、纯液相包裹体(II型)、原生富液相气液两相包裹体(IIIa型)以及次生富液相气液两相包裹体(IIIb型).其中与成矿密切相关的为原生富液相气液两相包裹体(IIIa型).该类包裹体的均一温度集中在100~260 ℃,盐度在0.18%~9.98%(NaCleq),密度为0.75~1.0 g/cm3;激光拉曼探针分析表明,液相成分以H2O为主,气相成分以H2、N2以及CH4为主.成矿流体具有中低温、低盐度以及低密度的流体特征.斑岩的上升侵位为矿床的形成奠定了物质基础——Cu、S.斑岩分异出成矿流体沿早期断裂系统向上运移发生减压沸腾导致相态分离,从而造成Cu发生沉淀.因此,减压沸腾可能是导致流体中金属卸载的主要原因.     

内蒙古浩布高铅锌矿床小罕山岩体年代学、Hf同位素及地球化学特征

内蒙古赤峰浩布高铅锌矿床大地构造位置位于大兴安岭地区南段,属黄岗梁—甘珠尔庙褶皱成矿带.对浩布高铅锌矿床小罕山岩体进行了详细的岩石学、年代学、岩石地球化学和Hf同位素研究.结果显示:小罕山岩体主要岩石类型为二长花岗岩,形成于(143.9±1.1)Ma,属于早白垩世;地球化学组成上表现出高硅(SiO2=66.96％ ～6...     

甘肃合作早子沟金矿床流体包裹体及硫铅同位素特征

早子沟金矿床是西秦岭西段近年来发现的大型金矿床之一。矿床产于中三叠世古浪堤组中,矿体产出与中酸性岩脉关系密切;矿体受断裂控制,呈脉状、条带状,少数似层状产出。含金石英脉可分为两个成矿期次,分别为含金粗粒石英脉期和多金属硫化物-金石英期;金属硫化物主要为辉锑矿、黄铁矿、毒砂等。辉锑矿石英脉型金矿石中流体包裹体主要为富液相的气液两相流体包裹体,均一温度为129.8 ~324.3 ℃,平均为203.2 ℃,盐度（w（NaCl））为1.22%~10.73%,平均为6.04%,成矿流体的密度平均为0.90 g/cm³,矿床的成矿平均深度约为2.00 km;阴阳离子分析结果表明,流体包裹体液相成分主要为Na⁺-SO₄^2--Cl^-,单个流体包裹体激光拉曼显示流体包裹体中的气相成分主要为H₂O、CO₂和SO₂,个别样品显示有CO和CH₄,成矿流体为NaCl-H₂O-CO₂体系。流体包裹体研究揭示了早子沟金矿床辉锑矿-金成矿阶段的成矿流体为浅成中低温低盐度低密度流体,主要为岩浆水与地下水的混合热液,不同性质流体的混合作用和它们的沸腾作用是使金沉淀的重要因素。矿石中辉锑矿硫同位素组成很稳定,δ³⁴S_V-CDT值为-10.30‰~-8.10‰,平均为-9.33‰,表明硫主要为岩浆热液来源,并混有地层硫。矿石铅同位素组成显示²⁰⁶Pb/²⁰⁴Pb为18.166~19.027,²⁰⁷Pb/²⁰⁴Pb为15.608~15.741,²⁰⁸Pb/²⁰⁴Pb为38.249~39.275,矿石铅同位素组成为壳幔混合成因铅。根据早子沟金矿床特征,结合成矿流体性质及来源、成矿物质来源研究成果,推测甘肃早子沟金矿床应为岩浆期后低温热液金矿床。     

Fluid Inclusions and Hydrogen,Oxygen, Sulfur Isotopes of Nuri Cu‐W‐Mo Deposit in the Southern Gangdese,Tibet

The Nuri Cu‐W‐Mo deposit is located in the southern subzone of the Cenozoic Gangdese Cu‐Mo metallogenic belt. The intrusive rocks exposed in the Nuri ore district consist of quartz diorite, granodiorite, monzogranite, granite porphyry, quartz diorite porphyrite and granodiorite porphyry, all of which intrude in the Cretaceous strata of the Bima Group. Owing to the intense metasomatism and hydrothermal alteration, carbonate rocks of the Bima Group form stratiform skarn and hornfels. The mineralization at the Nuri deposit is dominated by skarn, quartz vein and porphyry type. Ore minerals are chalcopyrite, pyrite, molybdenite, scheelite, bornite and tetrahedrite, etc. The oxidized orebodies contain malachite and covellite on the surface. The mineralization of the Nuri deposit is divided into skarn stage, retrograde stage, oxide stage, quartz‐polymetallic sulfide stage and quartz‐carbonate stage. Detailed petrographic observation on the fluid inclusions in garnet, scheelite and quartz from the different stages shows that there are four types of primary fluid inclusions: two‐phase aqueous inclusions, daughter mineral‐bearing multiphase inclusions, CO₂‐rich inclusions and single‐phase inclusions. The homogenization temperature of the fluid inclusions are 280°C–386°C (skarn stage), 200°C–340°C (oxide stage), 140°C–375°C (quartz‐polymetallic sulfide stage) and 160°C–280°C (quartz‐carbonate stage), showing a temperature decreasing trend from the skarn stage to the quartz‐carbonate stage. The salinity of the corresponding stages are 2.9%–49.7 wt% (NaCl) equiv., 2.1%–7.2 wt% (NaCl) equiv._, 2.6%–55.8 wt% (NaCl) equiv. and 1.2%–15.3 wt% (NaCl) equiv., respectively. The analyses of CO₂‐rich inclusions suggest that the ore‐forming pressures are 22.1 M Pa–50.4 M Pa, corresponding to the depth of 0.9 km–2.2 km. The Laser Raman spectrum of the inclusions shows the fluid compositions are dominated in H₂O, with some CO₂ and very little CH₄, N₂, etc. δD values of garnet are between ?114.4‰ and ?108.7‰ and δ¹⁸O_H2O between 5.9‰ and 6.7‰; δD of scheelite range from ?103.2‰ to ?101.29‰ and δ¹⁸O_H2O values between 2.17‰ and 4.09‰; δD of quartz between ?110.2‰ and ?92.5‰ and δ¹⁸O_H2O between ?3.5‰ and 4.3‰. The results indicate that the fluid came from a deep magmatic hydrothermal system, and the proportion of meteoric water increased during the migration of original fluid. The δ³⁴S values of sulfides, concentrated in a rage between ?0.32‰ to 2.5‰, show that the sulfur has a homogeneous source with characteristics of magmatic sulfur. The characters of fluid inclusions, combined with hydrogen‐oxygen and sulfur isotopes data, show that the ore‐forming fluids of the Nuri deposit formed by a relatively high temperature, high salinity fluid originated from magma, which mixed with low temperature, low salinity meteoric water during the evolution. The fluid flow through wall carbonate rocks resulted in the formation of layered skarn and generated CO₂ or other gases. During the reaction, the ore‐forming fluid boiled and produced fractures when the pressure exceeded the overburden pressure. Themeteoric water mixed with the ore‐forming fluid along the fractures. The boiling changed the pressure and temperature, oxygen fugacity, physical and chemical conditions of the whole mineralization system. The escape of CO₂ from the fluid by boiling resulted in scheelite precipitation. The fluid mixing and boiling reduced the solubility of metal sulfides and led the precipitation of chalcopyrite, molybdenite, pyrite and other sulfide.     

Metallogeny of the Baiyangping Lead‐Zinc Polymetallic Ore Concentration Area,Northern Lanping Basin of Yunnan Province,China

The Lanping Basin in the Nujiang‐Lancangjiang‐Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of large unique sediment‐hosted Pb‐Zn polymetallic deposits or ore districts, such as the Baiyangping ore concentration area which is one of the representative ore district. The Baiyangping ore concentration area can be divided into the east and west ore belts, which were formed in a folded tectogene of the India‐Asia continental collisional setting and was controlled by a large reverse fault. Field observations reveal that the Mesozoic and Cenozoic sedimentary strata were outcropped in the mining area, and that the orebodies are obviously controlled by faults and hosted in sandstone and carbonate rocks. However, the ore‐forming elements in the east ore belt are mainly Pb‐Zn‐Sr‐Ag, while Pb‐Zn‐Ag‐Cu‐Co elements are dominant in the west ore belt. Comparative analysis of the C‐O‐Sr‐S‐Pb isotopic compositions suggest that both ore belts had a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata; the ore‐forming fluids were originated from formation water and precipitate water, which belonged to basin brine fluid system; sulfur was from organic thermal chemical sulfate reduction and biological sulfate reduction; the metal mineralization material was from sedimentary strata and basement, but the difference of the material source of the basement and the strata and the superimposed mineralization of the west ore belt resulted in the difference of metallogenic elements between the eastern and western metallogenic belts. The Pb‐Zn mineralization age of both ore belts was contemporary and formed in the same metallogenetic event. Both thrust formed at the same time and occurred at the Early Oligocene, which is consistent with the age constrained by field geological relationship.     

蒙古国图木尔廷敖包大型锌矿床地质特征及成因

蒙古国图木尔廷敖包锌矿床是二十世纪七十年代发现的一处夕卡岩型大型富锌矿床,锌矿体主要产于矽卡岩中.锆石SHRIMP铀-铅测年结果显示,与锌矿床有关的黑云母花岗岩的侵位年龄为240.9±3.4Ma,属于早三叠世.元素地球化学和钕-锶同位素研究表明,黑云母花岗岩形成于火山弧环境,其成岩物质主要来源于年轻的下地壳,成岩过程受部分熔融作用控制.矿石硫和铅同位素分析结果表明,成矿物质主要来自于黑云母花岗岩,部分来自围岩地层.     

Oxygen Isotopic Characteristics of Granitic Intrusions Related to Haobugao Zn-Pb-Cu-Sn Skarn Deposit, East Inner Mongolia, China

Abstract. Granitic rocks related to the formation of Haobugao Zn-Pb-Cu-Sn skarn deposit, Inner Mongolia, China, show unusual low whole-rock δ¹⁸O values down to -8.8 % (V-SMOW), whereas separated quartz crystals from those rocks give positive δ¹⁸O values of+4.1 to +9.9 %. Chemical analyses and microscopic observation of those granitic rocks confirm that they suffered hydrothermal alteration. Some skarn specimens and quartz from the Haobugao deposit also show negative δ¹⁸O values. The isotopic evidence indicates that intensive meteoric water circulation occurred at the time of granitic intrusion, and caused the pervasive hydrothermal alteration of granitic rocks and the precipitation of skarn deposit in this area.     

内蒙古花敖包特铅锌银多金属矿床成因探讨:流体包裹体及硫、铅、氢、氧同位素证据

内蒙古花敖包特铅锌银多金属热液型脉状矿床位于大兴安岭成矿带中南段。结合其蚀变矿化特征,依据矿石矿物与脉石矿物的生成顺序,矿化阶段可划分为自形石英-黄铁矿阶段、闪锌矿-方铅矿阶段及他形黄铁矿-毒砂阶段。流体包裹体研究表明:该矿床的成矿流体具有中—低温(146.7~274.3℃)、低盐度(w(NaCl)为0.54%~8.52%)及低密度(0.790~0.943g/cm3)的特点;流体成矿压力及成矿深度估算结果表明,该矿床形成于中深—浅成的环境。矿石中金属硫化物的硫、铅同位素分析结果显示,该矿床的成矿物质来源具有壳幔混合来源的特征。成矿流体氢、氧同位素组成:δ18 OSMOW为-11.78‰~-6.01‰,δD为-110.90‰~-70.30‰,表明该矿床的成矿流体主要由岩浆水与下渗的大气降水混合组成。结合区域地质特征及构造演化,认为该矿床是在大兴安岭南段中生代伸展造山构造背景下形成的受深断裂、早白垩世构造岩浆活动及寿山沟组多重地质因素控制的中—低温热液型脉状铅锌银多金属矿床。     

内蒙古白乃庙铜-金-钼矿床成矿机制——来自流体包裹体和He-Ar同位素的证据

白乃庙铜-金-钼矿是华北板块北缘中段一个重要矿床,其矿化特征既显示斑岩型蚀变特征,同时又表现出明显的后期造山作用改造的特点。本次研究通过系统的流体包裹体显微测温、激光拉曼和气液相色谱分析揭示其成矿流体为中—低温、中低盐度的CO_2(CO)-H_2O-CH_4(C_2H_2+C_2H_4)-NaCl-CaCl_2体系,流体混合作用和CO_2逃逸为成矿主要因素。富还原性流体的存在可能促使气相流体携带大量的Cu、Au等成矿元素迁移至较远点的白乃庙群地层,沿着片理或裂隙沉淀成矿。对不同成矿阶段矿石中黄铁矿的He-Ar同位素组成测试结果显示白乃庙矿床黄铁矿流体包裹体的~3He/~4He比值在0.06~0.71Ra之间,~(40)Ar/~(36)Ar比值为375.5~1436.3,指示成矿体系由不同性质和组成的两个端元流体混合而成,即混入了类似于MORB型地幔端元的高温高盐度流体和富含地壳放射成因氦但具有空气氩同位素组成特征的低温大气降水。白乃庙矿床属受后期造山作用改造的斑岩型铜-金-钼矿床,形成于古亚洲洋板块持续向南俯冲背景。     

乌兹别克斯坦Uchkulach铅锌矿流体包裹体特征及矿床成因分析

Uchkulach大型铅锌矿床位于乌兹别克斯坦南天山造山带北缘,矿体主要顺层产出于中泥盆统至上泥盆统碳酸盐岩地层中。由于赋矿地层下伏酸性火山岩,该矿床是否和岩浆活动有关仍存在争议。本次在对该矿床地质特征研究的基础上,对矿石样品中重晶石和闪锌矿的流体包裹体以及主要矿物的矿物化学进行分析。结果表明,其均一温度为71～153 ℃,峰值为93～133 ℃,冰点温度在-74～-169 ℃之间,盐度为110%～202%,属于低温中盐度流体,暗示其流体来源为盆地卤水或浓缩的海水。对矿石样品中的方铅矿、闪锌矿和重晶石的电子探针分析结果表明,闪锌矿中铁含量较低(＜6%),指示其形成温度较低。由此推测该矿床属于与盆地流体有关的MVT型铅锌矿床,而非前苏联学者认为的与下伏火山岩有关的火山-沉积型铅锌矿床。     

Genesis of the Zhaokalong Fe-Cu Polymetallic Deposit at Yushu, China:Evidence from Ore Geochemistry and Fluid Inclusions

The ore types of the Zhaokalong Fe-Cu deposit are divided into two categories: sulfide-type and oxide-type. The sulfide-type ore include siderite ore, galena-sphalerite ore and chalcopyrite ore, whereas the oxide-type ore include magnetite ore and hematite ore. The ore textures and structures indicate that the Zhaokalong deposit is of the sedimentary-exhalative mineralization type. Geochemical analyses show that the two ore types have a high As, Sb, Mn, Co and Ni content. The REE patterns reveal an enrichment of the LREE compared to the HREE. Isotopic analysis of siderite ore reveal that the δ13CPDB ranges from 2.01 to 3.34 (‰) whereas the δ18O SMOW ranges from 6.96 to 18.95 (‰). The fluid inclusion microthermometry results indicate that homogenization temperatures of fluid inclusions in quartz range from 131 to 181℃, with salinity values of 1.06 to 8.04 wt% NaCl eq. The mineralizing fluid therefore belongs to the low temperature - low salinity system, with a mineralizing solution of a CO2-Ca2+(Na+, K+)-SO42-(F-, Cl-)-H2O system. The geochemical results and fluid inclusion data provide additional evidence that the Zhaokalong deposit is a sedex-type deposit that experienced two stages of mineralization. The sulfide mineralization probably occurred first, during the sedimentary exhalative process, as exhibited by the abundance of marine materials associated with the sulfide ores, indicating a higher temperature and relatively deoxidized oceanic depositional environment. After the main exhalative stage, hydrothermal activity was superimposed to the sulfide mineralization. The later stage oxide mineralization occurred in a low temperature and relatively oxidized environment, in which magmatic fluid circulation was dominant.     

Genesis of the Jianbeigou Gold Deposit on the Southern Margin of the North China Craton: Insights from Fluid Inclusions, H-O-S Isotopes, and Pyrite in situ Trace Element Analyses

The Jianbeigou gold deposit is a typical lode gold deposit in the Qinling metallogenic belt, located on the southern margin of the North China Craton. Three stages of the hydrothermal process can be distinguished, including the quartz ± pyrite, quartz-polymetallic sulfide, and quartz-carbonate ± pyrite stages. From the early to late stages, the homogenization temperatures of primary fluid inclusions are 281–362°C, 227–331°C, and 149–261°C, respectively. The corresponding salinities estimated for these fluids are 3.9–9.9 wt%, 0.4–9.4 wt%, and 0.7–7.2 wt% NaCl equiv. Combined with laser Raman spectroscopy data, the ore-forming fluid belongs to a H2O-CO2-NaCl ± CH4 system with medium–low temperature and salinity. The δ18Ofluid and δD values for the quartz veins are ?1.0‰ to 6.0‰ and ?105‰ to ?84‰, respectively, which indicates that the ore-forming fluid is of mixed source, mainly derived from magma, with a contribution from meteoric water. Pyrite has been identified into three generations based on mineral paragenetic sequencing, including Py1, Py2, and Py3. The pyrites have δ34S sulfur isotopic compositions from three stages between 3.7‰ and 8.4‰, indicating that sulfur mainly originated from magma. Te, Bi, Sb, and Cu contents in pyrite were all high and showed a strong correlation with Au concentrations. Native gold and the Au-Ag-Bi telluride minerals were formed concurrently, and the As concentration was low and decoupled from the Au content. Therefore, Te, Bi, Sb and other low-melting point chalcophile elements play an important role for gold mineralization in arsenic-deficient ore-forming fluid. Combined with the geological setting, evolution of pyrite, and ore-fluids geochemistry, we propose that the Jianbeigou deposit can be classified as a magmatic–hydrothermal lode gold deposit. Gold mineralization on the southern margin of the North China Craton is related to Early Cretaceous magmatism and formed in an extensional setting.     

滇西北安乐铅锌矿床流体包裹体研究

安乐铅锌矿床位于三江地区的中甸断凹,是滇西北地区一处重要的铅锌矿。本文通过对该矿床与矿石密切共生的石英中流体包裹体的类型、特征、均一温度、盐度、密度、成矿压力以及流体包裹体中气液相成分的分析,探讨了流体性质、演化及矿床成因。结果表明,该区流体主要属于CO2一H20一NaCl体系,均一温度范围在130～370℃之间,盐度在3．00％～12．75％NaCl之间,由成矿压力推算的成矿深度为1．37～3．77km^2矿床特征及包裹体特征与造山型矿床相似,推测该矿床属于“同造山”构造体制下发育的成矿系统。     

黑龙江省东宁县金厂矿区两期成矿作用:地质、流体包裹体、稀土元素和同位素证据

[摘要]金厂金矿床产于岩浆岩内部,根据矿脉特征、容矿构造特征、矿石特征、矿化特征和蚀变特征、控制因素等方面,重新将矿区矿(化)体类型划分为角砾岩型和岩浆穹隆裂控型两种类型矿体;矿体地质、流体包裹体、稀土元素和同位素等研究表明两种类型矿体在地质特征、流体包裹体、稀土元素和同位素方面存在显著差异;结合矿区内岩浆岩测年数据和成矿年龄测试数据,初步确定矿区主要有两期成矿作用,第一期是与闪长玢岩侵入有关的角砾岩型矿体,第二期是与花岗斑岩侵入有关的岩浆穹隆裂控型矿体。     

蒙其古尔铀矿床流体包裹体研究

为探讨蒙其古尔铀矿床成矿流体的性质,为矿床成因提供新的依据,本文对该矿床开展了系统的流体包裹体研究。结果表明,石英裂隙中存在的包裹体主要是次生的富液盐水包裹体和含烃水溶液包裹体。包裹体均一温度为51~77℃,平均66.2℃;盐度1.4%~14.04%Na Cleq,平均4.49%Na Cleq;成矿流体密度0.98~1.04g/cm3,平均1.01g/cm3,说明成矿流体为低温低盐度中密度流体,具有大气降水成因的性质。计算得出成矿压力为(38.74~80.48)×105Pa,平均53.31×105Pa,成矿深度为0.13~0.26km,平均0.18km。从而推断蒙其古尔铀矿床属于低温浅成后生表生铀矿床。     

Ore Genesis of the Lunwei Granite‐Related Scheelite Deposit in the Wuyi Metallogenic Belt,Southeast China: Constraints from Geochronology,Fluid Inclusions,and H–O–S Isotopes

A granite‐related scheelite deposit has been recently discovered in the Wuyi metallogenic belt of southeast China. The veinlet–disseminated scheelite occurs mainly in the inner and outer contact zones of the porphyritic biotite granite, spatially associated with potassic feldspathization and silicification. Re–Os dating of molybdenite intergrowths with scheelite yield a well‐constrained isochron age of 170.4 ± 1.2 Ma, coeval with the LA–MC–ICP–MS concordant zircon age of porphyritic biotite granite (167.6 ± 2.2 Ma), indicating that the Lunwei W deposit was formed in the Middle Jurassic (~170 Ma). We identify three stages of ore formation (from early to late): (I) the quartz–K‐feldspar–scheelite stage; (II) the quartz–polymetallic sulfide stage; and (III) the quartz–carbonate stage. Based on petrographic observations and microthermometric criteria, the fluid inclusions in the scheelite and quartz are determined to be mainly aqueous two‐phase (liquid‐rich and gas‐rich) fluid inclusions, with minor gas‐pure and CO₂‐bearing fluid inclusions. Ore‐forming fluids in the Lunwei W deposit show a successive decrease in temperature and salinity from Stage I to Stage III. The homogenization temperature decreases from an average of 299 °C in Stage I, through 251 °C in Stage II, to 212 °C in Stage III, with a corresponding change in salinity from an average of 5.8 wt.%, through 5.2 wt.%, to 3.4 wt.%. The ore‐forming fluids have intermediate to low temperatures and low salinities, belonging to the H₂O–NaCl ± CO₂ system. The δ¹⁸O_H2O values vary from 1.8‰ to 3.3‰, and the δD_V‐SMOW values vary from –66‰ to –76‰, suggesting that the ore‐forming fluid was primarily of magmatic water mixed with various amounts of meteoric water. Sulfur isotope compositions of sulfides (δ³⁴S ranging from –1.1‰ to +2.4‰) and Re contents in molybdenite (1.45–19.25 µg/g, mean of 8.97 µg/g) indicate that the ore‐forming materials originated mainly in the crust. The primary mechanism for mineral deposition in the Lunwei W deposit was a decrease in temperature and the mixing of magmatic and meteoric water. The Lunwei deposit can be classified as a porphyry‐type scheelite deposit and is a product of widespread tungsten mineralization in South China. We summarize the geological characteristics of typical W deposits (the Xingluokeng, Shangfang, and Lunwei deposits) in the Wuyi metallogenic belt and suggest that porphyry and skarn scheelite deposits should be considered the principal exploration targets in this area.     

Fluid Inclusions and Hydrogen,Oxygen, and Lead Isotopes of the Antuoling Molybdenum Deposit,Northern Taihang Mountains,China

The Antuoling Mo deposit is a major porphyry‐type deposit in the polymetallic metallogenic belt of the northern Taihang Mountains, China. The processes of mineralization in this deposit can be divided into three stages: an early quartz–pyrite stage, a middle quartz–polymetallic sulfide stage, and a late quartz–carbonate stage. Four types of primary fluid inclusions are found in the deposit: two‐phase aqueous inclusions, daughter‐mineral‐bearing multiphase inclusions, CO₂–H₂O inclusions, and pure CO₂ inclusions. From the early to the late ore‐forming stages, the homogenization temperatures of the fluid inclusions are 300 to >500°C, 270–425°C, and 195–330°C, respectively, with salinities of up to 50.2 wt%, 5.3–47.3 wt%, and 2.2–10.4 wt% NaCl equivalent, revealing that the ore‐forming fluids changed from high temperature and high salinity to lower temperature and lower salinity. Moreover, based on the laser Raman spectra, the compositions of the fluid inclusions evolved from the NaCl–CO₂–H₂O to the NaCl–H₂O system. The δ¹⁸O_H2O and δD values of quartz in the deposit range from +3.9‰ to +7.0‰ and ?117.5‰ to ?134.2‰, respectively, reflecting the δD of local meteoric water after oxygen isotopic exchange with host rocks. The Pb isotope values of the sulfides (²⁰⁸Pb/²⁰⁴Pb, 36.320–37.428; ²⁰⁷Pb/²⁰⁴Pb, 15.210–15.495; ²⁰⁶Pb/²⁰⁴Pb, 16.366–17.822) indicate that the ore‐forming materials originated from a mixed upper mantle–lower crust source.