The first discovery of Xinlong epithermal gold deposit in southern margin of the Bangonghu-Nujiang metallogenic belt: A new expansion of gold prospecting in Northern Tibet

The Xinlong gold deposit is located in Niyma County,Naqu area of Tibet and was discovered by the Institute of Mineral Resources,Chinese Academy of Geological Sciences through the 1∶50000 mineral geological survey.The ore bodies occur in the Zenong Group volcanic rocks in the middle section of the central Lhasa subterrane and are structurally controlled by the NNW-striking faults.Four ore bodies have been found,exhibiting cloddy,dense-sparse,disseminated,and breccia structures.The ore minerals are mainly tetrahedrite group minerals,and other ore minerals include pyrite,chalcopyrite,nevskite,bornite,anglesite,native gold,and silver-gold bearing selenide,etc.The types of alteration are dominated by silicification,as well as middle-and high-graded argillization.The alteration mineral assemblages contain quzrtz,pyrophyllite,and kaolinite.The Zaliela Formation volcanic rocks of Zenong Group are silicified by later hydrothermal fluid with vuggy quartz in some fractured zones.The middle-and high-graded argillization are characterized by pyrophyllitization and kaolinization.The Xinlong gold deposit shows great metallogenetic potentiality and has been revealed by 1∶10000 geological mapping,IP sounding,and trial trenching in the mining area.Combined with the regional metallogenic geological setting,we suppose that a potential epithermal gold belt probably exists in the middle of the Lhasa terrane.The discovery of the Xinlong gold deposit opens a new chapter for the gold prospecting in Northern Tibet.

Laumontitization as an Exploration Indicator of Epithermal Gold Deposits: A Case Study of the Axi and Other Epithermal Systems in West Tianshan, China

In the light of field investigation, microscopic study, X\|ray phase analysis and mineral infrared spectral analysis, it is considered that laumontitization is of extensive occurrence in the Axi gold orefield. The development of laumontitization and its relationship to mineralization show that the laumontitization appeared mainly at the top of and in the periphery of orebodies, and occurred at the edge of the epithermal system or at the late stage of epithermal system evolution. Therefore, laumontitization can be used as an exploration indicator of epithermal gold deposits. The fluids responsible for laumontitization in the Axi gold orefield are similar to those producing hot spring\|type gold deposits or those from modern geothermal fields. Epithermal mineralization of the Axi gold deposit was dated at Carboniferous, indicating that the West Tianshan of China is a region favorable to epithermal\|type gold mineralization and preservation. Hence the West Tianshan of China is a target area for exploring epithermal gold deposits.

Geological Characteristics of Epithermal Ore Concentrated Areas and Epithermal Ore Deposits in China

The epithermal ore concentrated area is located in Southwestern China. We systematically study the regional geological characteristics such as the basement of Proterozoic, the capping bed, Moho, geothermal feature and tectonics, and discuss the relationship between distributed characteristics of the epithermal ore deposits and ore control factors in this paper. It is concluded that the conditions, under which the epithermal ore deposits form, are huge thick basement of Proterozoic, long time and wide scope developed capping bed and weak magmatic activity. The basement of Proterozoic that enriches volcanic matters and carbon and the carbonaceous bearing and paleo pool bearing capping bed provides main ore source. The large and deep faults and paleopool accordance with gravity anomaly gradient control the distribution of epithermal ore deposits. The lithologic assembles of microclastic rocks and carbonate rocks in the capping bed provide spaces of ore precipitation and create conditions of ore precipitation. The coincidence of many geological factors above forms the epithermal ore concentrated area.

A New Genetic Type of Gold Deposits-Meso-Epithermal Carbonate-Type Gold Deposits as Exemplified by the Baguamiao Superlarge Gold Deposit

Gold deposits of the meso-epithermal carbonate type were first proposed based on the study of the Baguamiao gold deposit.This new type of gold deposits has many unique characteristics as follows:(1)Obviously strata-bound.The gold deposits are hosted in Middle Devonian turbidite formations;(2)Structrually controlled.Struc-ture is an important factor leading to metallogenesis of this type of gold deposits.The shape and distribution of orebodies are controlled by byittle-ductile shear zones;(3)Multi-stage wall-rock alteration.According to the characteristics of mineral assemblage,gold mineralization can be classified into three stages in association with various wall-rock al-terations.Wall-rock alterations closely genetically related to the gold mineralization are ankerization ,silicification,pyrrhotization and pyritization ;(4)Mineral compositions of the orebodies are mainly pyrrhotite,pyrite,marcasitolite,chalcopyrite,quartz,ankerite,and sericite.Gold mineralization is associated closely in space and time with iron sulfides;(5)Rare elements and REE in ores are low in contents relative to those of the crust.Au content varies from 1.91g/t to 11.15g/t ,averaging 5.5g/t;(6)Studies of sulfur,hydrogen,oxygen and carbon isotopes in main gangue minerals (quartz and ankerite)indicate that fluids and ore-forming materials came from deep-seated sources;(7)Three types of inclusions are recognized in terms of their composition and the vapor amounts of inclusions.The homogenization temperatures of inclusions range from 210℃to 310℃,averaging 230℃,showing that this type of gold deposits belongs to the meso-epithermal type;(8)Metallogenic age of this type of gold deposits is similar to that of the collision between the Yangtze Plate and the North China Plate,indicating that gold deposits of this type are genetically related to continental-margin plate activity.

Characterization of Arroyo Verde Epithermal Deposit:Paragenesis,Mineral Geochemistry,Geochronology and Fluid Inclusions in Lower Chon Aike Volcanism,Argentina

Arroyo Verde epithermal deposit,in the North Patagonia region of Argentina,is located within the Lower Chon Aike volcanism and is developed between 192.6±2.5 Ma(mineralization host rock)and 189.5±2.6 Ma(overlying lava).Marifil volcanic complex is the host rock for these veins,veinlets and breccias.This particular small deposit has developed low to intermediate sulphidation characteristics,with gangue mineral textures associated with several ore minerals.Electron probe microanalysis determines electrum,silver minerals such as acanthite,and tetrahedrite,related Ag-Cu minerals like jalpaite,mckinstryite,stromeyerite,and base metals like chalcopyrite,sphalerite,galena and pyrite.Fluid inclusions in quartz of two out of five events indicate that these Low Jurassic veins were formed due to subtle boiling and dilution mechanisms and by low-salinity(3.4 wt.%to 6.7 wt.%NaCl Eq)magmatic-hydrothermal fluid at 225 to 310℃.The fluid inclusion measurements that indicate boiling(Event 3)were plotted,and based on this data,we interpret that the Arroyo Verde deposit has been eroded between 550 and 700 m.This particular character has not been previously recorded for other sectors of the eastern north Patagonian region.

Geology of Gold Ore Deposits in Western Linyi of Shandong Province,China

Western Linyi of Shandong Province is one of the most important gold ore mineralization concentration areas. Mesozoic gold ore deposits in this area can be subdivided into two types: magmatic hydrothermal and epithermal gold deposits. The occurrences of gold ore bodies are controlled by structures. Related subvolcanic rocks can be subdivided into high potassium calc-alkali series and alkaline series. These two types of subvolcanic rocks are of different geochemical features and different sources. The high potassium calc-alkali rocks are derived from enriched mantle and contribute to the formation of magmatic hydrothermal gold ore deposits including skarn gold-copper ore deposit and porphyry gold ore deposit. Alkaline rocks are derived from lower crust and they host epithermal gold deposits. Comprehensive studies show that there is no evolutionary or transitional relationship temporally and genetically between the epithermal gold deposit and the high temperature magma hydrothermal gold deposit in the western Linyi.

西秦岭洛大式菱铁矿矿床的基本成矿要素

洛大式菱铁矿分布于甘肃南秦岭成矿带,由翠古山铁矿、绿坝铁矿、洛大铁矿、查居铁矿和柴马山铁矿等小型矿床组成;主要矿石矿物为菱铁矿,其次为黄铁矿和赤铁矿;矿床成因类型一直被认为是沉积型或沉积改造型(1)。考虑大型矿床的发现往往源于对中小型矿床的研究(Richards,2013).

西藏多龙斑岩-浅成低温热液型铜(金)矿集区地质特征及找矿潜力分析

本文在总结多龙矿集区地质特征的基础上,开展了矿山深边部的潜力分析,以期为下一步的找矿预测提供勘查思路。多龙斑岩-浅成低温热液型铜(金)矿集区位于西藏班公湖-怒江成矿带的北西侧,主要由铁格隆南超大型斑岩-浅成低温热液型铜(金)矿床,拿若大型斑岩-隐爆角砾岩筒型铜(金)矿床,多不杂、波龙、多不杂西大型斑岩型铜(金)矿床,尕尔勤、地堡那木岗高硫化浅成低温热液型铜(金)矿点组成,共探获铜资源量超过1500万t,伴生金超250 t,伴生银3900 t。多龙矿集区形成于早白垩世(120 Ma)班公湖-怒江洋盆北向俯冲的陆缘弧环境,物质源区为壳幔混合源,成矿岩浆岩主要为中酸性的闪长玢岩-花岗闪长斑岩-花岗斑岩系列,具有弧岩浆特征。俯冲板片的折返是多龙矿集区深部岩浆形成和侵位的主要动力学机制,成矿后安山质火山岩(110 Ma)的覆盖对矿床起到重要的保存作用。多不杂矿区F2逆断层将矿体分割成上、下两部分,下部分矿体是找矿的重点方向。铁格隆南矿区深钻揭露了由南向北的逆冲断层,该逆冲断层将矿体错断并推覆到“红层”沉积之上,其下盘是寻找另一半隐伏矿体的方向。尕尔勤矿区大面积发育指示浅成低温热液成矿系统的“硅帽”,明显富集Au、Ag、As、Sb、Bi、Cu等元素,Au、As、Sb、Hg等呈现较好的元素组合异常,具有寻找浅成低温热液型矿床的潜力。地堡那木岗矿区发育高硫化浅成低温热液型蚀变(高岭石化、地开石化、明矾石化等)和矿物组合(铜蓝、蓝辉铜矿、斑铜矿等),且物探、化探、遥感异常套合良好,是未来矿产勘查的重点。区内逆冲断层对矿床的改造作用是未来研究的重点,对进一步的勘查评价具有重要的指导意义。

塞尔维亚蒂莫克铜金矿集区典型矿床地质特征

特提斯成矿带是全球三大成矿带之一,阿普塞尼(Apuseni)-巴纳特(Banat)-蒂莫克(Timok)-斯雷德诺戈里斯基(Srednogorie)岩浆成矿带(ABTS多金属成矿带)位于特提斯成矿带西缘,由阿普塞尼–巴纳特铁铜铅锌矿集区、蒂莫克铜金矿集区和斯雷德诺戈里斯基铜金矿集区组成,成矿作用主要与晚白垩世钙碱性岩浆活动有关。塞尔维亚蒂莫克铜金矿集区作为ABTS多金属成矿带经济意义巨大的矿集区之一,总结该地区矿床地质特征及成矿规律对下一步的找矿勘查具有重要指导意义。综述了蒂莫克铜金矿集区及其典型矿床的地质特征,总结了矿集区成矿规律与动力学背景。蒂莫克铜金矿集区典型矿床形成时代集中在88~78 Ma之间,成矿作用历时10 Ma左右,矿集区内成矿作用时代呈现出由东向西逐渐年轻的趋势。矿集区中典型矿床类型主要为斑岩型(如马伊丹佩克矿床、克里韦利矿床和瓦利亚斯特尔茨矿床)和高硫化浅成低温热液-斑岩型(如博尔矿床和丘卡卢佩吉矿床),这些矿床以铜金矿化为主。矿床类型、矿化特征及矿体埋深存在的差异可能与区域上新生代右旋构造在矿集区形成的逆冲推覆构造及成矿后不均匀剥蚀有关。根据矿集区典型矿床的矿化类型及矿体埋深海拔标高的变化趋势,认为矿集区北部—西北部和丘卡卢佩吉矿床东南部仍具有一定的找矿潜力。

福建紫金山矿田悦洋银多金属矿床银的赋存状态和沉淀机制

浅成低温热液矿床是世界上银矿的重要矿床类型,伴生有金铜铅锌等多种金属。银的赋存状态研究可以为矿床资源禀赋、选冶成本以及经济价值的综合评价提供重要的依据。近年来,矿物自动定量分析系统越来越多地应用到贵金属的赋存状态研究中,相比传统方法而言其能提供精确定量的矿物学信息。悦洋银多金属矿床位于福建省紫金山矿田,是典型的浅成低温热液矿床,是研究银赋存状态的理想选区。通过野外地质调查研究发现,矿体主要受控于岩性边界和断裂构造,主要矿石类型为热液角砾岩型和石英脉型。成矿作用可以分为石英-黄铁矿、石英-黄铁矿-黄铜矿、石英-银多金属、石英-碳酸盐等四个阶段,其中银在石英-银多金属阶段沉淀,可以进一步划分为石英伊利石硫化物亚阶段和石英冰长石硫化物亚阶段。本文在野外地质调查的基础上,针对不同的矿石类型使用TIMA(TESCAN Integrated Mineral Analyzer)自动矿物分析系统,结合显微镜下观察、扫描电镜和电子探针分析手段,对银的赋存形式和分布情况进行了定量化研究,根据矿物共生组合对银沉淀机制及成矿过程进行了探讨。研究结果显示,悦洋矿床中的银90%以上以独立矿物的形式存在,主要是硫化银和自然银,且粒径大多在10~50μm之间;少部分银以次显微包裹体形式存在于黄铜矿中,或以显微包裹体和类质同相形式存在于黄铁矿和闪锌矿中。成矿热液中银主要以硫氢络合物形式运移,主成矿期大量的冰长石与银矿物共生表明沸腾作用是主要的沉淀机制。

山西省吕梁山黄圈塔铅锌矿地质特征及找矿方向

黄圈塔铅锌矿位于吕梁碳酸盐台地的柳林背斜北翼,铅锌矿体主要赋存于下奥陶统三山子组和中奥陶统马家沟组碳酸盐岩中,蚀变和铅锌矿化产于NW向断裂破碎带中。通过对该矿床地质特征、地球物理特征、地球化学特征、矿化蚀变特征的综合研究表明,铅锌矿体主要赋存于NW走向的F1断层破碎带中,矿化以裂隙交代充填型为主,次为蚀变岩型;目前控制有2条铅锌矿体,其中以2号矿体为主,激电测深剖面显示极化率异常向下未封闭,指示深部(埋深150 m)存在极化地质体;勘查区地表未发现与成矿有关的火成岩;矿化成分较为简单,金属矿物主要是方铅矿、闪锌矿,脉石矿物为方解石、白云石,围岩蚀变为中低温矿物组合;矿床成因类型应属中低温热液型铅锌矿床。基于激电测深剖面资料,有必要进一步开展矿区深部找矿工作。

试论中亚造山带东部多宝山矿田斑岩铜浅成低温金系统成矿特征与矿床模型

多宝山矿田位于中亚造山带东段,是目前我国东北地区规模最大、成矿时代最老(477~470 Ma)的斑岩铜钼浅成低温热液金成矿系统,已探明铜、钼、金储量分别可达5 Mt、0.16 Mt和130 t。从成矿系统角度,其成矿特征和矿床模型尚不清晰。本文系统分析了矿床的地质地球化学特征和成矿时代,发现该成矿系统存在两期成矿事件,以第一期为主,发生在早奥陶世;第二期为叠加成矿,发生在晚三叠世。成矿作用具有下部为隐爆角砾状铜矿化、中部为脉状铜矿化、上部为金矿化的空间结构特征,围岩蚀变从中心向两侧依次为钾化黑云母化带、青磐岩化带、黏土化带、碳酸盐化带、绢英岩化带和硅化带。成矿流体主要来源于岩浆水,从多宝山斑岩铜矿到争光浅成热液金矿床呈现大气水加入比例增大的趋势。根据第一期成矿斑岩具有高Ce^(4+)/Ce^(3+)(174~461;均值约290)、高f_(O2)埃达克质岩浆特征,进一步得出主成矿期与古生代古亚洲洋俯冲作用相关的壳幔混源岩浆作用有关。成矿受古火山机构所制约,其北西到南东成矿深度增大与剥蚀程度相关,受铜山逆断层作用效应,暗示铜山断层以南为较好的找矿靶区。最后,本文建立了该区古生代斑岩铜浅成低温热液金成矿系统的矿床模型,以期为该区进一步矿产勘探提供借鉴。

内蒙古额仁陶勒盖大型银矿床地质及地球化学特征

内蒙古额仁陶勒盖银矿是得尔布干成矿带南西段的大型银矿床,位于蒙古-鄂霍茨克造山带和得尔布干断裂之间。该矿床热液成矿过程划分为石英-黄铁矿、石英-硫化物及石英-锰碳酸盐3个阶段。文章对不同成矿阶段的流体包裹体测温及采用氢氧同位素和硫同位素示踪成矿流体特征和来源,结果显示:前两阶段包裹体均一温度为200~423℃,盐度w(NaCl_(eq))可分为2组,一组盐度w(NaCl_(eq))为13.82%~16.05%,另一组盐度w(NaCl_(eq))为0.18%~8.14%;石英-锰碳酸盐阶段均一温度范围为124~245℃,盐度w(NaCl_(eq))为0.18%~15.42%,从早到晚阶段总体显示随温度降低、盐度降低的趋势;主成矿阶段对应成矿深度0.48~1.41 km,平均值为0.76 km;成矿流体氢、氧同位素组成(δ^(18)O_(H2O)值为-11.6‰~-3.3‰)位于原生岩浆水的左下方靠近雨水线位置,表明成矿流体可能是岩浆水与大气降水的混合流体,且成矿的中晚期以大气降水为主。硫同位素测试结果显示,δ^(34)S值皆分布于-4.0‰~+4.5‰之间,呈塔式分布,反映了硫主要来自幔源。铅同位素组成反映了成矿物质主要来自地壳深部或上地幔。综合分析认为,该矿床是一个与火山-次火山活动有关的浅成低温热液型银矿床。通过矿床地质及矿床地球化学研究,笔者进一步完善了额仁陶勒盖式浅成低温热液型矿床成矿模式,用该模式指导矿床外围新发现多个金、银、钼多金属矿(化)点。

新疆塔乌尔别克金矿矿床地质及稳定同位素地球化学特征

新疆塔乌尔别克金矿位于西天山吐拉苏断陷盆地,与阿希金矿相邻。金矿体主要赋存于下石炭统大哈拉军山组第五岩性段的火山岩类中,受4个环形构造及伴生的线性构造控制。本文在阐述塔乌尔别克金矿床地质特征的基础上,论述了金矿石的碳、氢、氧、硫、铅等稳定同位素地球化学特征。认为成矿流体中的碳的主要为岩浆来源,但是较为复杂,部分受到深部碳酸盐岩同位素交换的影响;成矿流体中的水源来自岩浆热液和大气降水的混合;矿石中的硫来自于深部岩浆;铅则显示造山带的特征,主要来自上地壳。分析稳定同位素特征,结合矿床地质特征,塔乌尔别克金矿的矿床类型确定为低硫型浅成低温热液斑岩型金矿。矿床稳定同位素的研究不仅能深化矿床地质的研究,还可对进一步的找矿工作提供珍贵信息。

Regional Metallogenesis of the Chang'an Gold Ore Deposit in Western Yunnan:Evidences from Fluid Inclusions and Stable Isotopes

The Chang＇an gold ore deposit in western Yunnan is located at the southern segment of the Ailaoshan metallogenic belt.The ore bodies are preserved in fractured Ordovician sedimentary clastic rocks.The gold-bearing minerals occur dominantly in sulfide-quartz veins.Fluid inclusion analysis shows that the Chang＇an gold ore deposit is characterized by epithermal gold mineralization at temperatures between 200℃and 280℃at a shallow crustal level.The mineralizing fluids have intermediate to low salinity（6%-18%） and low densities（0.72-1.27 g/cm^3）.The ore minerals haveδ^（34）S in a range from -13‰to 3.57‰,concentrated from -2.06‰to 3.57‰with an average of 1.55‰.The ^（206）Pb/^（204）Pb,^（207）Pb/^（204）Pb and ^（208）Pb/^（204）Pb values are 18.9977-19.5748,15.7093-15.784,39.3814-40.2004 respectively.These isotope data suggest that the ore-forming elements were mainly derived from mixed crustal and mantle sources.The Chang＇an gold ore deposit and Tongchang Cu-Mo deposit are closely related to each other in their spatial distribution and age of formation.They have similar sources of mineralizing elements and identical ore-forming metal elements,and show a close relationship in physical and chemical conditions of mineralization.The two deposits constitute an epithermal-porphyry -skarn type Cu-Mo-Au mineralization system in the Tongchang-Chang＇an area,which is related to the Cenozoic high-K alkaline magmatism.

Epithermal gold deposits in China and potential assessment

THE epithermal gold deposit (epi-gold) is one of the most important types in various gold deposits all overthe world. The discovery of several superlarge deposits of this type around the circum-Pacific Rim duringthe 1980s, greatly stimulated the interest in searching for epi-golds in the world as well as in China. Theepi-gold has become a major target in gold exploration in China during last two-decade "Golden Rush.The discovery of the Zijinshan Cu (Au) deposit in SE China and the Axi and other Au deposits in NWChina is the significant success in gold prospecting in this field. The author suggested that it is the timeto do an overview and the potential assessment of epi-golds in China Some people are holding an optimistic idea on this topic mainly based on the following considerations: (i) as a host rock, the subaerial volcanic rocks of Mesozoic are widespread in East China; (ii)

Metallogenesis and ore-forming time of the Changtuxili Mn-Ag-Pb-Zn deposit in Inner Mongolia:Evidence from C-O-S isotopes and U-Pb geochronology

This paper reports new geochronological(U-Pb) and isotope(C,O,and S) data to investigate the timing of mineralization and mode of ore genesis for the recently discovered Changtuxili Mn-Ag-Pb-Zn deposit,located on the western slopes of the southern Great Hinggan Range in NE China.The mineralization is hosted by intermediate-acidic lavas and pyroclastic rocks of the Baiyingaolao Formation.Three stages of mineralization are identified:quartz-pyrite(Stage I),galena-sphalerite-tetrahedrite-rhodochrosite(Stage II),and quartz-pyrite(Stage Ⅲ).δ13C and δ18O values for carbonate from the ore vary from-8.51‰ to-4.96‰ and 3.97‰ to 15.90‰,respectively,which are indicative of a low-temperature alteration environment.δ34SV-CDT values of sulfides range from-1.77‰ to 4.16‰ and show a trend of equilibrium fractionation(δ34SPy>δ34SSp>δ34SGn).These features indicate that pyrite,sphalerite,and galena precipitated during the period of mineralization.The alteration mineral assemblage and isotope data indicate that the weakly acidic to weakly alkaline ore-forming fluid was derived largely from meteoric water and the ore-forming elements C and S originated from magma.During the mineralization,a geochemical barrier was formed by changes in the pH of the ore-forming fluid,leading to the precipitation of rhodochrosite.On the basis of the mineralization characteristics,new isotope data,and comparison with adjacent deposits,we propose that the Changtuxili Mn-Ag-Pb-Zn deposit is an intermediate-to lowsulfidation epithermal deposit whose formation was controlled by fractures and variability in the pH of the oreforming fluid.The surrounding volcanic rocks yield zircon U-Pb ages of 160-146 Ma(Late Jurassic),indicating that the mineralization is younger than 146 Ma.

Tracer system on halogen mineralizer from the epithermal deposits in Guizhou Province

HALOGENS are typical mineralizer elements and play a very important role in remobilization and resettlement of the ore-forming mental elements in the hydrothermal deposits. Studies of tracer system on halogens mineralizer include the following aspects: (i) halogens’ role as mineralizer in ore-forming action;(ii) halogens importance as tracer elements in formation and evolution of the epithermal ore deposit;(iii) halogens’ significance as guidance in looking for the buried orebodies. Guizhou is a concentrated area of epithermal Hg, Sb and Au deposits, where are distributed famousepithermal deposits such as the Wanshan Hg deposit, the Banpo Sb deposit, the Danzhai Hg-Au depositand the Lannigou Au deposit. Many researches into geological and geochemical characteristics of thesedeposits have been done, but few study on halogen mineralizer.

Characteristics and metallogenesis of epithermal gold (copper)deposits in the middle-south parts of Tancheng-Lujiang deep fault zone and its vicinity, eastern China

EPITHERMAL gold (copper) deposits distributed in the middle-south parts of Tancheng-Lujiang deep faultzone and its vicinity have close relation to Mesozoic shoshonitic magmatism. According to their metallogenic features and ore-forming conditions, these deposits can be divided into three types; tellurium-goldtype Au deposit, quartz-adularia type Au deposit and quartz-manganoansiderite type Au-Cu deposit. Therepresentative deposits of them are Guilaizhuang, Dongxi and Tiantoushan. In this note, the general features of the three typical epithermal gold (copper) deposits are outlined and the relationship between mineralization and types of volcanic basins is discussed preliminarily.

Comparison of two end-member styles of epithermal Au-(Cu)deposits

EPITHERMA Au-(Cu) deposits occur largely in volcano-plutonic arcs (island arcs as well as continentalarcs) associated with subduction zones, with ages similar to those of volcanism. These deposits form atshallow depth,【1 km, and are hosted mainly by volcanic rocks. Modern volcanic-hydrothermal systems provide an analogue to the environment for the ancient intrusion-related and volcanic epithermal deposits. Recent studies also indicate that the volcanic epithennalore deposits are formed from magmatic fluids, although the magmatic signatures have been largely erasedby meteoric water. At depth (fig. 1), the magmatic fluid from the high-level intrusive magma will result in the formation of intrusion-related deposits (e.g. porphyry Cu, Au, Mo deposits). Detailed studies of fluid inclusions and stable isotopes indicate that the hydrothermal system that form these deposits are initially