GENERAL CHARACTER OF MULTISTAGES OFMETALLOGENESIS FOR MICRO-MESOTHERMAL GOLD DEPOSITS:EXAMPLES FROM ZHANG-BALING TECTONIC BELT,ANHUI,CHINA

In Zhangbaling Tectonic Belt,two types of mineralization,auriferous quartz veins and alter- ation halos,can observed within many deposits.The pressure of metallogenesis of auriferous al- teration halos ismuch higher than thatof quartz vein,thetemperatures ofmetallogeneses ofthese two types of orebodies are don’tthe same Geochemistry study indicates thatboth ofthem are mi- cro- mesothermal deposits related to Yanshanian granites.The results of proton microprobe analy- sis of sulphides from the gold deposits in the area show that the“invisible” gold existed in sul- phides is in the form ofmicro inclusions,and the concentration of“invisible” gold in sulphidemin- erals within quartz vein is poorerthan thatfrom alteration halos.Field observation shows thatthe structural modality of the fractures controlling the orebodies of auriferous quartz vein is different from thatof the auriferous alteration zones.The fracture controlling the orebodies of auriferous alteration halos is compress- shearfracture,auriferous quartzvein is controlled by extensive fault. The alteration halos crosscut by auriferous quartz vein.The wallrocks of the former altered strongly and developed alteration zones well.The wallrocks of auriferous quartz vein altered slightly.The results of tectonogeochemical study shows that the concentration of associated met- allogenesis elements and intensity of alteration are positively correlated with tectonic deformation strength for auriferous alteration halos.Itindicates that it is probably a general character for mi- cro- mesothermal gold deposits due to the multistages of metallogeneses took place.The tectonic environmentis the most important fact determining the mechanism of fluid flow and precipitationof gold,and then the types of mineralization and modes of gold.

Isotopic Chronological Study of the Huangsha-Tieshanlong Quartz Vein-Type Tungsten Deposit and Timescale of Molybdenum Mineralization in Southern Jiangxi Province,China

The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma （n=11, MSWD-1.3）. Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153-3 Ma and model ages of 150.22.1 Ma - 155.4-2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Hnangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150-170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2-6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1-4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133-135 Ma, 150-162 Ma, and 166-170 Ma, respectively. The 150-162 Ma-stage is in accordance with ages of large-scale WoSn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.

Geochronology,Fluid Inclusions and Isotopic Characteristics of the Dongjun Pb-Zn-Ag Deposit,Inner Mongolia,NE China

The Dongjun Pb-Zn-Ag deposit in the northern part of the Great Xing’an Range(NE China)consists of quartzsulfide vein-type and breccia-type mineralization,related to granite porphyry.Hydrothermal alteration is well-developed and includes potassic-silicic-sericitic alteration,phyllic alteration and propylitic alteration.Three stages of mineralization are recognized on the basis of field evidence and petrographic observation,demarcated by assemblages of quartz-pyritearsenopyrite(early stage),quartz-polymetallic sulfide(intermediate stage)and quartz-carbonate-pyrite(late stage).Zircon LA-ICP-MS U-Pb dating indicates that the granite porphyry was emplaced at 146.7±1.2 Ma(Late Jurassic).Microthermometry and laser Raman spectroscopy shows that ore minerals were deposited in conditions of intermediate temperatures(175-359℃),low salinity(0.5-9.3 wt% Na Cl eqv.)and low density(0.60-0.91 g/cm^(3)).Ore-forming fluids were derived largely from magmatic hydrothermal processes,with late-stage addition of meteoric water,belonging to a H_(2)O-NaCl-CO_(2)±CH_(4) system.The δ^(34)SV-CDT values range from 0.75‰ to 4.70‰.The ^(206)Pb/^(204)Pb,^(207)Pb/^(204)Pb,and ^(208)Pb/^(204)Pb values of the ore minerals are in the ranges of 18.240-18.371,15.542-15.570,and 38.100-38.178,respectively.Data for the S and Pb isotopic systems indicate that the ore-forming metals and sulfur were derived from Mesozoic magma.Based on the geological characteristics and geochemical signatures documented in this study,we conclude that the Dongjun deposit is a mesothermal magmatic hydrothermal vein-type Pb-Zn-Ag deposit controlled by fractures and related to granite porphyry,in response to Late Jurassic tectonic-magmatic-hydrothermal activity.We further conclude that fluid immiscibility,fluid mixing and fluid-rock interactions were the dominant mechanisms for deposition of the ore-forming materials.

Geochronology and Petrogeochemistry of Metallogenic Intrusions in the Shanmen Large-scale Silver Deposit in the Siping Area of Jilin Province, NE China

The Shanmen deposit, located in the Siping area of Jilin Province, is one of large-scale silver deposits in Northeast(NE) China. Due to its high Ag grade, associated gold resources and special tectonic location, this deposit has important theoretical and ore-prospecting significance. To present new data on the ore genesis, mineralization time and tectonic settings, the relationship between silver mineralization and intrusions in this deposit has been studied and some analyses have been carried out, including LA-ICP-MS zircon U-Pb dating, whole-rock major and trace element analysis and Sr-Nd-Pb isotope analysis of the granitoids associated with silver mineralization. Studies on deposit geology indicate that the ore-hosting granodiorite and monzogranite have intimate genetic relationships with silver mineralization. LA-ICP-MS zircon U-Pb dating results of the both intrusions are 167.6 ± 1.9 Ma and 167.0 ± 1.5 Ma, respectively, implying that the two intrusions and associated silver mineralization in the Shanmen deposit formed during the Middle Jurassic. Major element analytical data suggest that the two intrusions are high-K calc–alkaline series I-type granites and belong to metaluminous and peraluminous rocks. Both intrusions have similar REE characteristics with regard to the relative enrichment of LREEs, depletion of HREEs, obvious fractionation of LREEs and HREEs(ΣLREE/ΣHREE = 8.68–14.09,(La/Yb)_N = 12.51–21.96), moderately negative Eu anomalies as well as weakly negative Ce anomalies(δEu = 0.56–0.71, δCe = 0.93–1.09). Moreover, the samples are generally enriched in LILEs and depleted in HFSEs. The rock assemblages and geochemical characteristics of granitoids in the Shanmen deposit suggest that they formed in an active continental margin associated with the Paleo-Pacific plate subduction. The Sr-Nd-Pb isotope compositions show that both the granodiorite and monzogranite have low Sr initial ratios and high Sm/Nd initial ratios. The ε_(Nd)(t) values and young Nd-model ages are-3.2 to-1.7 and 990 Ma to 1110 Ma, respectively. Considering the Sr-Nd isotope compositions, in conjunction with the relatively high ~(206)Pb, ~(207)Pb and ~(208)Pb, alongside the relatively low ~(204)Pb, it can be concluded that the Middle Jurassic intermediate-acidic magma represented by the studied monzogranite and granodiorite in the Shanmen deposit, was derived from the partial melting of juvenile lower crust enriched in mantle-derived materials and affected by the mixing of ancient crustal materials during the ascension and intrusion processes.

西秦岭鄂尔嘎斯地区金矿地球化学特征及找矿潜力分析

鄂尔嘎斯地区位于西秦岭造山带南亚带之西倾山隆起带,成矿区划属于西倾山汞锑金成矿带西段。该成矿带不仅发现了赫格楞汞锑矿床,还发现了大水、贡北、忠曲、辛曲、格尔托等一大批金矿床和矿点。本文对鄂尔嘎斯地区金矿的地质特征进行分析,结合该区地球化学特征,类比相邻金矿床和矿点,认为区内具有寻找浅成中低温热液型金矿的潜力。

试论主要类型矿床的形成深度与最大延深垂幅

在大量典型矿床实地调查和国内外综合对比研究的基础上,基于深部找矿的现实需要和存在问题,本文首先回顾评述了主要矿床类型的原始成矿深度,按受控于中下地壳尺度大规模岩浆堆积体的超深成岩浆矿床与受控于流体渗透率制约的中上地壳深成、中成和浅成岩浆热液矿床序列展开。在此基础上尝试探讨主要类型矿床的最大延深垂幅,探讨分析了以Bushveld层状岩体和Voisey s Bay小岩体为代表的铜镍矿床、驱龙为代表的斑岩铜矿床、Muruntau为代表的造山型金矿、胶东金矿省的已控制延深垂幅、剥蚀程度以及深部可能的延深空间。内生矿床系统具有很宽的成矿深度范围,大型层状岩体的成矿深度可逾20 km,最大矿化垂直延深幅度可达6~8 km。岩浆热液矿床的最大成矿深度以地壳尺度流体渗透的下限为底界,其中造山型金矿床成矿深度最大(约12~15 km),伟晶岩和花岗岩型矿床次之,斑岩型矿床居中(约2~6 km),浅成低温金银矿床深度最浅(1 km至近地表);相应的最大延深垂幅则依次可达4~7 km、2~3 km和1 km。评述了高渗透性的聚矿构造空间、成矿作用顶峰、合适的矿床保存条件等控制因素及部分标志。并对如何确定合理统一的成岩成矿深度(压力)的估算方法以及确定最大成矿深度与矿化体系最大延深幅度的理论依据、判断标志、综合辨识方法体系等未来研究方向进行了展望。

桐柏──大别地区中温热液金矿床成矿流体性质与沉淀机理

通过对桐柏─大别地区１０个中温热液金矿床（点）的流体包裹体研究，确定成矿流体属于低盐度（６ｗｔ％ＮａＣｌ）、富ＣＯ＿２（１０ｍｏｌ％）的Ｎａｃｌ－ＣＯ＿２－Ｈ＿２Ｏ体系。这种以演化的大气降水为主的流体在４～１０ｋｍ深度范围内，由于压力由静岩压力状态向静水压力状态的突变而发生的复杂三阶段不混溶过程中沉淀，在该过程的中晚期出现金矿化。压力状态的突变是柏桐─大别造山带在中生代碰撞造山晚期，由挤压体制向伸展体制转换抬升隆起作用的结果。

黑龙江省黑河市北大沟金矿床流体包裹体研究

黑龙江省黑河市北大沟金矿床是近年来在大兴安岭燕山期成矿带发现的小型金矿床。对石英脉中流体包裹体岩相学研究、显微测温和气液相成分分析表明：（1）主成矿阶段石英脉中发育纯液相、气液两相、富气相和纯气相4类包裹体。（2）流体包裹体均-温度在160—380℃之间，主要集中在260～300℃；成矿流体为NaCl-H2O体系；流体包裹体盐度估计在0．2％～2．0％（NaCleq）之间；成矿流体密度估计在0．550～0．912g／cm^3之间；成矿压力估计在6×10^5～210×10^5Pa之间；估算成矿深度为0．06～2．10km。（3）从流体包裹体成分分析获得的pH值为6．6～6．7之间，还原参数n（CH4＋CO＋H2）／n（CO2）（摩尔数比值）在0．027～0．271之间，表明具有浅成中偏酸性和弱还原环境成矿的特点。该矿床是与火山热液有关的浅成中-低温热液金矿床。

内蒙古额尔古纳地区431铀矿床地质特征与流体包裹体研究

为确定额尔古纳地区铀矿特征及成因类型,选择431铀矿床,在矿床地质特征研究基础上,对与铀矿化成因关系密切的硅化石英脉进行了流体包裹体显微测温.研究结果表明,431矿床产于印支期花岗岩与新元古代额尔古纳群变质岩接触带部位,受断裂构造控制明显,围岩普遍发育硅化、绿泥石化、水云母化、高岭土化、碳酸盐化等蚀变现象,地表矿石中铀矿物主要为钙铀云母.硅化石英脉中含气液两相和含CO2三相两种类型包裹体,对应的均一温度分别为132.2～301.5℃和322.5～408.9℃,平均值为247℃;盐度分别为12.65%～2.73%和4.04%～16.94%,平均值为8.18%;流体密度分别为0.76～0.94 g/cm3和0.60～0.78g/cm3;成矿流体属中温、中低盐度、低密度的NaCl-H2O-CO2流体体系.利用相关公式估算该区铀矿的成矿深度介于0.4～1.7km.431铀矿床属浅成中温热液矿床,成因上与花岗质岩浆作用有关.

胶东金矿床的矿石地球化学研究

胶东半岛存在不同地质环境和不同地质特征的两类金矿床——中深成热液金矿和浅成热液金矿。本文利用５个中深成热液金矿和５个浅成金矿的３２８件矿石地球化学样品，查明前者以相对富含Ｂｉ和Ａｕ／Ａｇ比值高为特征，后者以富含Ａｇ、Ｃｕ、Ｐｂ、Ｚｎ、Ａｓ、Ｓｂ和Ａｕ／Ａｇ比值低为特征，建立了判别两类不同成因金矿床的函数式。模式与矿床地质的研究结论一致，深化了对区内金矿床的认识。

高压流体与中、低温石英脉型金矿床

在中低温石英脉型金矿床成矿过程中，断裂带起着一个阀门作用，它引起了成矿流体压力的周期性变化。当流任满足矿液压裂的条件（σ3a-P≤－t）时，裂隙产生破裂、扩展。破裂后应力的突然释放，在断层带内产生了矿液的涌入、成矿物质的沉淀富集等作用，随后断层带的自我封闭，又导致了流压的重新积累而产生了周期性重复。矿脉就是在这种周期性的高压流体作用方式下形成的。

鄂西东岳中低温热液充填型大理石矿床的地质特征

通过对东岳大理石矿的地质特征、矿石化学成分、微量元素、矿物包裹体及同位素地球化学研究，认为该矿属于中低温热液充填矿床，成矿温度１４０～２２０℃，成矿溶液来源于大气降水。这类矿床是我国大理石矿新类型，对鄂西、河南。

新疆北山地区金矿床(点)成矿特征

新疆北山地区金矿床（点）为中低温浅成矿床，其矿化类型有准绿片岩型、破碎蚀变岩型、基性侵入体边缘含金石英脉型、浅变质含碳碎屑岩型，并具多期次矿化特征；同时，金矿床（点）受控于逆冲推覆前缘叠瓦断层带。

吉木乃地区金矿床地质特征及成因

吉木乃地区位于乌伦古——斋桑泊构造岩浆带。近年在此发现并勘查了两种不同围岩类型的金矿床。锶氧和铝同位素证据表明,这些金矿是海西期形成的岩浆热液金矿床。该区是一个新的金矿勘查重要靶区。

辽宁王家崴子金矿床矿石特征与金的赋存状态

王家崴子金矿主要的矿石类型为含金石英脉型.矿石中富含黄铁矿,作为主要的载金矿物,与金矿化具有密切的时空及成因联系,是金矿化的重要指示矿物.矿石呈不等粒粒状、交代溶蚀结构,块状、致密块状、细脉浸染状构造.金矿物以形态复杂的中、细粒状银金矿、金银矿为主,赋存形式有裂隙金、晶隙金、包裹体金.载金矿物有黄铁矿、方铅矿、闪锌矿、黄铜矿、石英等.综合分析认为,该矿床具有变质热液型金矿床的特点,多源性的中温-中低温热液为主要成矿因素.

河北茅山金矿地质特征及成矿条件探讨

茅山金矿位于华北板块北缘中段,是遵化—青龙矿集区内赋存于二长花岗岩岩株内的金矿床。茅山金矿的金矿化主要产于茅山二长花岗岩岩株内的蚀变黄铁绢英岩内。文章对矿床的区域地质特征、矿化带及矿体分布、矿石结构构造、围岩蚀变、矿床成因诸方面进行了分析研究,认为该矿床的矿物成分和化学成分较复杂,矿床经历了多期次热液活动的叠加作用。成矿热液沿构造裂隙充填交代了围岩,使其发生了热液蚀变作用。矿床成因属中温热液裂隙充填交代矿床。

山东莱西北泊金矿床本质特征

胶东地区存在两种不同地质特征的脉型金矿———中深成热液脉型金矿与浅成热液脉型金矿。本文用矿床模型思维 ,描述北泊金矿床的矿脉与矿体地质、矿石特征、矿石地球化学特征、近矿围岩蚀变、金矿与脉岩、成矿深度和成矿时代等矿床本质特征 。

与火山-次火山-侵入-热液作用有关的金矿床分类探讨

讨论近年来在陆相火山－次火山－侵入－热液作用有关的金矿床分类中的一些争论问题。从具体资料出发，认为扩大浅成低温热液作用的范围，摒弃中温热液和高温热液矿床，以及否定它们与斑岩矿床的关系是不妥当的；认为斑岩成矿系列是建立成矿模式、划分有关矿床的基础。

河北丰宁头道沟萤石矿地质特征及找矿方向

丰宁头道沟一带萤石矿赋存于下白垩统张家口组火山碎屑岩中,共发现2个矿体,呈脉状产出。矿石类型属石英萤石型,矿石结构为粒状结构,块状构造,少量皮壳状构造及条带状构造。属于岩浆期后中—低温热液充填型脉状矿床,为构造—岩浆活动的产物。

热液型金矿伴生脉岩系研究及其意义

本文总结了近年来国外有关煌斑岩与热液型金矿化关系研究的最新成果,分析了现状,提出了问题.根据我国辽东、胶东、冀东和秦岭十一个大(中)型金矿伴生脉岩资料,作者论证了把金矿伴生脉岩作为一个整体岩系来研究的重要性和必要性,同时将脉岩系成员划分为“共存型”和“随机型”两类,提出煌斑岩的出现,脉岩系成员基、中、酸、碱种类繁多,并以闪长(玢)岩为主可能是我国华北陆台大型金矿床的重要标志之一.文中罗列了金矿伴生脉岩系系统研究项目,强调了把(含金)石英脉作为一种“脉岩”置于脉岩系几何形态和排列组合系统之中研究的意义,指出大离子亲石元素(LILE)、高场强元素(HFSE)、铂族元素(PGE)以及幔/壳地球化学指纹元素Cr、Ni/Nb、Ta是研究脉岩系形成、演化、含金性和物质来源的重要地球化学工具.