A new type of micro-disseminated gold deposits in association with diabase found in Yunnan and Guizhou provinces and Guangxi Zhuang Autonomous Region——Their geological characteristics and metallogenic conditions

With the continuous development of gold ore prospecting and exploration in recent years a new type of micro-disseminated gold deposits have been found in the regions of Southwest Guizhou Province and Northwest Guangxi Zhuang Autonomous Region,with the orebodies directly occurring in diabase or in the contact zone between diabase and strata.The orebodies are strictly controlled by fault structures.The discovery of this type of gold deposits has brought about new prospects for gold ore prospecting in the Yunnan-Guizhou-Guangxi Golden Triangle region.From the preliminary analysis of the geological characteristics of the Qiaoxiang gold deposit in Wangmo County,in combination with the results of research work in the adjacent areas in recent years,this paper roughly described the geological characteristics and metallogenic conditions of this type of gold ore deposits with an attempt to make more and more geologists pay enough attention to this type of gold ore deposits,so as to promote gold ore prospecting in Guizhou Province to develop toward a variety of types of gold deposits in all round way.

Geological and Geochemical Characteristics and Genesis of the Shaxi Porphyry Copper (Gold) Deposits, Anhui Province

The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± 1.6 Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ion lithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (Isr=0.7058); thus it is the product of differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similar to the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts of CO2, Ca2+, Na+ and ***CI?. The homogenization temperatures of fluid inclusions for the main mineralization stage range from 280 to 420°C, the δ18O values of the ore fluids vary from 3.51 to 5.52 %, the δD values are in the range between ?82.4 and ?59.8 %, the δ34S values of sulphides vary from ?0.3 to 2.49 %, and the δ13C values of CO2 in inclusions range between ?2.66 and ?6.53 %. Isotope data indicate that the hydrothermal ore fluids and ore substances of the Shaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.

Geological and geochemical characteristics and metallogenic model of the Wenquan molybdenum deposit

The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic model of this deposit was established.The Wenquan granitic batholith belongs to the K-rich(alkali-rich) calc-alkaline rock series,which is the mineralization parent rock.The rock massif shows the characteristics of both crust-remelting granite and mantle-source granite.At the same time,the data of REE contents,hydrogen and oxygen isotopes and inclusion temperatures showed that the metallogenic hydrothermal solution is a mixed mesothermal solution of magmato-hydrothermal fluid and meteoric water.Mineralization was dated at 214±7.1 Ma,basically identical with the parent rock's age(207-226 Ma).This reflects that molybdenum mineralization has a close relation to tectonic magmatism evoked by orogenic processes,and molybdenum mineralization occurred mainly at the petrogenesis stage at the late stage of magma emplacement.Mixing with meteoric water led to a decrease in the sa-linity of magmato-hydrothermal solution and changes in other physical and chemical properties.During the tectonic process,ore-bearing hydrothermal solution ascended along favorable fault structure channels.With physicochemical changes,it filled in the surrounding rock joints on both sides of faults,forming ore deposits.

Geological characteristics and the origin of ore-forming materials of(Laozhaiwan gold deposit, Yunnan Province

"Golden triangle"area bordered on Yunnan-Guizhou-Guangxi was one of the most important Carlin-type gold deposits concentration areas.Deep understanding of Carlin-type gold deposits in Guizhou and Guangxi Province had reached through several decades studies,but geological environment was very complex in the southeastern Yunnan,and Carlin-type gold deposits produced in the southeastern Yunnan were different from that of America,few studies were taken there.Based on a large number of field work,studies on the geological characteristics combining with geochemistry characteristics were taken,and analysis the genesis of Laozhaiwan gold deposit.The types of alteration in Laozhaiwan gold deposit were mainly silicification and pyritization,and Gold grade was high when silicification and pyritization were both occurred.It could be caculated that fluid density(g/cm3)varied from 0.7 to 4.9,salinity varied from 0.76%to 0.95%and ore-forming pressure(Pa)varied from 1.81×105 to 49.96×105 according to fluid inclusion test results,showed that Laozhaiwan gold deposit was hypabyssal hydrothermal deposit in low temperature and low salinity.According to composition of fluid inclusion analysis,combining with H-O isotope,made theδD-δ18O figure,showed that the fluid of the deposit rooted in formation water and mixed with meteoric waters later.

CHARACTERISTICS AND METALLOGENIC EVOLUTION OF AILAOSHAN GOLD METALLOGENIC BELTS IN YUNNAN, CHINA

Observations made in different superlarge\|large gold deposits in Ailaoshan gold metallogenic belts, Yunnan Province, China, on the eastern margin of the Qingzang (Himalayas—Karakoram—Tibet) were investigated. Geotectonically, the study area is situated in the conjoint between the Tethys and Himalayas tectonic domain, characterized by very complex geological structure, with strongly influenced by the Himalayas in late development.1\ Regional geology and gold deposits\;Ailaoshan gold metallogenic belts is localized between Ailaoshan super lithospheric faults and Jiujia—Anding brittle\|ductile shear zone, with NNW\|trending about 250km long. To southward, Zhenyuan supergiant gold deposits, Mojiang large gold deposits, and Daping giant gold deposits hosted in low metamorphic volcanic\|sedimentary rocks (D—C). Ore types include gold\|bearing quartz veins, gold\|bearing altered rocks, and the mixing of the two types. Most of gold orebodies took their positions in the substructures of the brittle\|ductile shear zone.

Metallogenic Features and Metalogenic Model of Laterite Gold Deposits in Southern China

The modern laterite gold deposits in southern China, which belong to reworked laterite deposits, can be further divided into three subclasses and seven types. Their geological features, ore-forming conditions and regularities are discussed. A geologic-geochemical metallogenic model for laterite gold deposits has been established.

Rock-forming mechanism of Qingshanjiao intrusion in Dongguashan copper(gold) deposit, Tongling area, Anhui province, China

Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magma origin, rock-forming dynamic background and rock-forming process were studied, and the rock-forming mechanism of Qingshanjiao intrusion was discussed, based on geological characteristics, detailed observation of petrography and systematic investigation of petrochemistry, trace elements and REE geochemistry characteristics of Qingshanjiao intrusion. The results show that Qingshanjiao rock body belongs to high-K calc-alkaline series with higher LREE elements, Th, Rb and Sr abundance, but depleted in HREE elements, Ba, Nb and Ta. The primary magma originated from the mantle-crust mixtures which were caused by basaltic magma of mantle mixing with syenite magma of partial melting of the lower crust, and the formation environment of Qingshanjiao intrusion was emplaced in the transitional environment from compression to extension. The Harker diagram and hybrid structures of plagioclase and potassium feldspar indicate that the fractional crystallization occurred in the process of magmatic evolution. The petrochemistry, trace elements and REE geochemistry characteristics indicate that the magma was contaminated by crustal material during the rock-forming. These results suggested that the Qingshanjiao intrusion was formed by fractional crystallization and assimilation and hybridization of mantle-crust magma in the transitional environment from compression to extensional.

Geology and mineralization of the Dayin’gezhuang supergiant gold deposit(180 t)in the Jiaodong Peninsula,China:A review

The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case of prospecting at a depth of 500-2000 m in recent years,with cumulative proven gold resources exceeding 180 t.The main orebodies(No.1 and No.2 orebody)generally have a pitch direction of NNE and a plunge direction of NEE.As the ore-controlling fault,the Zhaoping Fault is a shovel-shaped stepped fault,with its dip angle presenting stepped high-to-low transitions at the elevation of -2000-0 m.The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently,forming a stepped metallogenic pattern from shallow to deep.It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma.The ore-forming fluids were H_(2)O-CO_(2)-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity.The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage.The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components.The comprehensive analysis shows that the Dayin’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism.The strong crust-mantle interactions,large-scale magmatism,and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization.Moreover,the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.

Statistical Prediction of Endogenetic Gold Deposit in East Junggar,Xinjiang

The system of mineral deposit statistical prediction methods , based on the similarity - analogy theory , searching anomaly theory and the theory of ore - controlling by quantitative assemblage of metallotects , can be summarized into the following aspects : (1) concluding main ore - controlling conditions and ore - hunting indicators from typical deposits; (2)establishing geological concept model of deposits ; (3)selecting geological variable and dividing study units and granting specific value for each variable; (4) by the use of geological and mathematical geology method , building predication model , delineating prospective area for exploration and estimating the total resources; (5) evaluating the prospecting work . It is good practice to use this system for metallogenic prognosis and regional prospecting of gold deposit in East Junggar , Xinjiang and has achieved great success . As a result , we discovered the Kubusu gold mineralized belt . delineated prospective area - estimated total resources of gold in the belt and found out Kubusu gold deposit .

Metallogenic characteristics of epithermal gold deposits in Tianshan, Xinjiang, China

TIANSHAN in southern Xinjiang belongs to the Paleozoic island arc system in which volcanic rocks are extensively distributed. A series of epithermal gold deposits such as the Axi, Xitan, Cuiling andShuangfengshan gold deposits have been discovered. 1 Geological settings of epithermal gold deposits in Tianshan, southern Xinjiang Tianshan in southern Xinjiang belongs to the Paleozoic island arc system. To its north is the Kazakhstan plate, and to its north is the Tarim plate. From west to east, the tectonic units are characterizedby Yili island arc, southern Tianshan arc-basin, Jiaoluotage island arc and Xingxingxia island arc. TheEW-trending Tianshan ore belt is controlled by Kanggurtag geosuture. In its west part, it is controlled byShenglidaban geosuture. The linear structure is NNW-trending; from north to south, the faults

Metallogenic characteristics of epithermal gold deposits in China

VOLCANIC-SUBVOLCANIC rocks are extensively distributed in China, in which a series of epithermal golddeposits related to volcanism have been discovered. 1 Metallogenic tectonic settings of epithermal gold deposits The epithermal gold deposits are mainly formed under the following tectonic settings: (i) ancient island arc collision, such as Xingxingxia island arc, Armantai island arc, Beishan island arc and Jueluotage island arc, etc. in periphery of Gunggar, Altai, Baishan, etc. in ancient Europe domain; (ii) extension area of continental margin of back arc, such as Fujian, Zhejiang, Jiangsu and Henlongjiang, etc.in circum-Pacific metallogenic domain; (iii) Mesozoic-Cenozoic island arc, such as the Tethys-Himalayametallogenic domain and Taiwan; (iV) intracontinental faulting depression or intraplate deep-seatedfaults, such as northern Hebei, Liaoning, Inner Mongolia at the north margin of the North China platformand periphery of Taicheng-Loujiang fault.

胶东型金矿

胶东是全球唯一已知赋存于前寒武纪变质地体中的晚中生代巨型金矿省,其成矿系统独具特色,具体表现为:(1)位于陆内复合构造域,经历了多期重大构造-热事件,大规模金成矿作用受控于120±2Ma古太平洋板块俯冲方向变化及其诱发的软流圈上涌、岩石圈改造和伸展-挤压变形交替及控矿断裂剪压-剪张转换;(2)多重控矿构造和多样赋矿建造联合控制了不同规模和类型金矿的发育,形成了三山岛、焦家、招平、栖霞、郭即和牟乳六条NE向金矿带和三山岛-栖霞EW向富金廊带,导致了金矿化类型(焦家式/破碎带蚀变岩型、玲珑式/石英脉型、蓬家夼式/蚀变砾岩±角砾岩型、辽上式/黄铁矿-碳酸盐脉型)及其地质-地球化学特征的多样性;(3)主要矿化元素Au、Ag、Cu、Pb和Zn均达到工业利用要求,并有多种共/伴生关键金属超常富集;(4)不同金矿带中硫化物Pb同位素组成与探明金资源储量及到郯庐断裂带的距离线性相关,反映距离幔源流体主通道越近、金属硫化物中放射性成因Pb含量和幔源组分占比越多、金成矿强度越大;(5)区域总体相对均一的Δ199 Hg(平均~0.012‰)及Δ199 Hg/Δ201 Hg与金品位呈线性负相关,表明成矿物质来源于富集岩石圈地幔、且地幔被俯冲洋壳及其上覆沉积物交代的程度控制了金品位的高低;(6)区域恒定的Δ33 S同位素组成(~0‰)排除了巨量金源自太古宙变质基底及其重熔花岗岩的可能,重的δ34 S(平均9.0±3.7‰)来源于俯冲的古太平洋板片及其上覆沉积物的脱挥发份;不同金矿带Δ33 S/δ34 S与探明金资源储量及其到郯庐断裂带距离线性相关,反映成矿期地壳伸展程度控制了金成矿强度;(7)区域He-Ar和H-O同位素组成显示壳幔混合特征,焦家式金矿的成矿流体组成更靠近地幔、玲珑式金矿位于地幔与地壳过渡带;三山岛、焦家和招平金矿带的成矿流体相对接近幔源流体,而郭即金矿带具有相对开放的构造环境;不同金矿带氢-氧同位素组成和探明金资源储量正相关,可能表征了从西到东成矿流体通量和流体-岩石反应强度逐渐降低。基于对上述特征的总结,提出了胶东型金矿的成因模式,明确了其成矿地球动力学背景和深部驱动、巨量金属和流体及络合物来源、输运通道和方式、源→汇过程和机制、成矿后变化和保存等成矿系统形成的关键因素,确立了“拆离断裂系与基底活化带及幔源流体通道复合控矿”的勘查思路和“四步式”的勘查模型。综上,胶东金矿不同尺度的鉴别特征及其形成的关键因素明显不同于全球已知的其他金矿类型,难以被已有成矿模式所涵盖,属于一种新的金矿类型——胶东型,其成因模式对华北、华南、西伯利亚、西澳伊尔岗、北美怀俄明和南美圭亚那等陆内金矿床具有普适性;系列找矿突破则验证了该成因模式与勘查模型的合理性和适用性。因此,本文认为胶东型金矿是全球研究热点和重要的金矿勘查方向,而该地区找矿的主攻目标是资源量大且品位和产状稳定的破碎带蚀变岩型金矿。

基于地质大数据的中国金矿时空分布规律定量研究

在大数据科学成为新的科学范式的背景下,基于地质大数据理念,将传统的定性地质研究方法推向定量研究的高度。文章通过对5300余处金矿产地资料的系统梳理,定量分析了中国省(自治区)、市、县级及Ⅲ级成矿区带金矿成矿密度、成矿强度和各成矿时代金矿的成矿强度问题。研究表明,中国金矿具有明显的时空集中分布趋势。中国金矿空间分布具有区域性集中的明显趋势,以胶东、小秦岭等区域为金矿高密度、高强度成矿区;新疆矿床数量最多;山东省金矿成矿密度最大,成矿强度最强;在地级市统计中,山东烟台市和河北承德市是全国仅有的两处矿产地数量过百的地级市,山东烟台市的金矿无论是矿产地数量、成矿密度,还是成矿强度均居全国首位;在县级行政区统计中,新疆塔城地区托里县金矿矿产地数量最多(52处),安徽铜陵市区金矿成矿密度最大,山东烟台市莱州市的金资源储量最大(2341 t),成矿强度最强(1.35 t/km^(2));在成矿区带统计中,华北陆块北缘东段成矿带(Ⅲ-57)金矿矿产地数量最多(345处),胶东成矿带(Ⅲ-65)金矿成矿密度最大,成矿强度最强。中国金矿时间分布不平衡,具有成矿强度老弱新强、东西南北成矿有别、叠加成矿时间跨度大和新生代金矿资源潜力大的特点;燕山期是中国金矿最重要的成矿时期,成矿强度大,达到10.5个矿区/Ma,金资源储量93 t/Ma。今后中国金矿地质工作的核心依然是加强金矿找矿工作、保障国家金融安全。

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。

贵州水银洞金矿床成矿规律与找矿预测模型

水银洞金矿床是黔西南地区超大型金矿床之一,由于多年的开采和生产规模的扩大,保有资源量越来越少,亟须综合研究成矿规律和分析成矿潜力。在综合分析以往资料基础上,结合野外调查,认为水银洞金矿床成矿地质体为深部隐伏岩浆岩体,成矿构造为灰家堡背斜与其两侧的逆冲断裂,成矿结构面为浅部三叠系地层裂隙面、龙潭组地层层间裂隙面和切层裂隙面、龙潭组地层与茅口组地层不整合接触面,成矿具有明显垂向分带特征。结合地球物理和地球化学信息构建找矿预测模型,圈定5处找矿潜力区,即控制边界区(包括已知矿体或矿权边界的北部和南部)、新矿化样式/新矿种找矿区(簸箕田矿段以东地区)、新类型/新空间找矿区(水银洞矿权范围隆起区的深部)、新找矿方向区(矿区西南部背斜,如矮煤洞背斜)和探索找矿区(灰家堡背斜水银洞矿权边界以西至回龙断裂之间的区域),为进一步找矿预测提供了参考。

河南银洞坡金矿“三位一体”找矿预测地质模型及应用示范

河南银洞坡金矿位于河南省桐柏县朱庄镇,为一特大型金矿床,同体共生银、铅锌。运用勘查区找矿预测方法与理论,构建成矿地质体、成矿构造与成矿结构面和成矿作用特征标志为主的“三位一体”找矿预测地质模型。野外调查和矿床学研究认为,矿床成因为与早白垩世岩浆作用有关的中低温岩浆热液矿床,主成矿阶段温度介于200~350℃之间,碳、氢、氧、硫同位素研究表明,成矿物质和成矿流体主要来源于岩浆。确定成矿地质体为矿区深部隐伏早白垩世花岗岩体;成矿结构面为岩性界面(硅/钙面)、褶皱成矿构造系统结构面、沉积成岩结构面;成矿作用特征标志主要为矽卡岩化、钾化、黄铁绢英岩化、硅化、铁白云石化、萤石矿化、碳酸盐化。由此建立了银洞坡金矿找矿预测地质模型,圈定了找矿靶区,施工的钻孔见矿率达到85%,对该地区及邻区进一步找矿具有现实的指导意义。

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。

福建吉花金银矿床地质特征及含矿蚀变带元素迁移对区域成矿的启示

吉花金银矿床为中型浅成中低温热液型矿床,共圈定36个金银矿体,均赋存于北东向断裂蚀变带中。银物相分析表明,银以硫化物银、自然银为主,银、金总体上同体共生,且二者品位具有正相关性。主成矿阶段矿物组合以石英-黄铁矿-黄铜矿-金-辉银矿为特征。沿矿体横向(侧向)划分为4个蚀变分带。为了厘定热液蚀变过程中的物质迁移,对蚀变碎裂岩采用标准化Isocon图解法计算物质迁移特征,结果表明,蚀变过程中Fe、Si、Mg、Ti、Cu、As、Mo、Co、Cr、La、Li、Ni、V呈迁入特征;Na、Ca、Ba、Sr、Nb呈迁出特征,其中Ca、Ba、Sr的迁出表明成矿热液具有富硅、去钙化的特征。通过类比区域内邱村金矿床、东洋金矿床、大冬坑金矿床,四者均为闽中金银成矿系统形成的矿床系列,可能是在古太平洋板块俯冲、后撤动力背景下,含矿流体沿火山机构及酸性岩脉通道运移至到浅部断裂中沉淀成矿的区域成矿模式。该成果可为区域内寻找金银矿提供思路。

柴北缘青山造山型金-铅矿床成矿机制:矿石和黄铁矿组成约束

青山金铅矿床位于柴北缘滩间山矿集区内,是全球罕见的金-铅共/伴生的造山型矿床。矿体主要赋存于古元古代达肯大坂群片岩中,受到北西西向断裂控制,发育蚀变岩和石英脉两种矿石类型,矿石中硫化物较为发育,常见黄铁矿、褐铁矿、方铅矿、黄铜矿、闪锌矿等。黄铁矿作为该矿床的主要载金矿物,其地球化学特征可以指示金赋存状态,揭示成矿流体性质和矿床成因。为此,选取ZK2103和ZK3701钻孔中不同深度空间的矿石和围岩样品,分别进行成矿元素全岩测试和黄铁矿的电子探针分析工作。矿石和围岩稀土元素配分模式曲线都为右倾型,呈现明显的Eu负异常,未见Ce异常,说明成矿流体为变质流体且不含海水。矿石相对富集Au、Ag、Cu、Pb、Zn、As、Co、Bi、Sb、W、Ni、Sr、Cd、V元素,而Sn、Mo、Cr元素含量则相对偏低。矿石和围岩中黄铁矿的S/Fe值小于2.0,表现出亏S和富Fe的特征;黄铁矿的Au/Ag值均大于0.5,Co-Ni图解结果指示黄铁矿为热液成因。金主要以纳米粒子形式赋存,少量以固溶体形式存在。金在流体中以Au(HS)-2的形式运移,流体混合作用破坏了Au(HS)-2的稳定性,致使金的沉淀。高硫的成矿流体可以运移部分的铜、铅、锌。在金沉淀后,成矿流体温度和压力降低,致使铅开始沉淀。但由于该流体运移铅、锌的能力有限,青山金铅矿床铅矿体的规模较小。硫-铅同位素结果显示成矿物质来源于围岩,区域上金龙沟矿区和青龙沟矿区围岩中铅锌含量较低,所以未形成铅矿体。