A STUDY ON THE GEOLOGICAL FEATURES AND GENESIS OF THE LONGSHAN Au-Sb DEPOSIT

The geological features of the Longshan Au Sb deposits are systematically described. Mineralization conditions, sources of ore materials and metallogenetic mechanism are also analysed according to sulfur,oxygen isotope composition, pyrite typomorphic features and fluid inclusion thermometry dating, The results show that it is a sedimentary metamophic hydrothermal deposit.

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 FEATURES AND ORE- FORMING MODEL OF THE SHIZHUYUAN W-SN-MO-BI ORE DEPOSIT,HUNAN PROVINCE,CHINA

The Shizhuyuan W,Sn,Mo and Bi polymetallic ore deposit is one of the world famous superlarge ore deposits.The paper briefly introduced the geological setting and features of the ore deposit.Further,an ore－ forming model was put forward at the end of the paper.

Geological Features,Mineralization Types and Metallogenic Setting of the Phlaythong Large Iron Deposit,Southern Laos

The Phlaythong large iron deposit in Shampasak of southern Laos,is located in the Kon Tum microblock （Fig.1A）,central-southern part of the Indo-China block,and the geographic coordinate of the central mining area is 14°43′04″ N and 106°07′02″ E.

Geological characteristics and genesis of subbottom pinnoite deposit of Da Qaidam salt lake in Qaidam Basin

Da Qaidam salt lake is known for its both liquid and solid boron resource.Data from previous investigation of the Da Qaidam salt lake provided a comparable framework for this study that focused on investigating the section beneath the bottom of the perennial salt lake,including the timing,

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.

GEOLOGICAL FEATURES AND FORMATIVE MECHANISM OF THE YULONG PORPHYRY COPPER BELT OF INTRACONTINENTAL REJUVENATED PLATFORM TYPE IN CHINA

Extending in a NNW-SSE direction. the Yulong porphyry copper belt is the largest and richest porphyry copper belt in China, originating in the Paleogene. Tectonically located on the eastern margin of the northern Tibet geodepression. and nearly 500 km of the Himalayan Yarlung Zangbo plate subduction zone of nearly E-W trend. it is a relatively typical intracontinental rejuvenated platform-type porphyry copper belt. Ore-bearing porphyry masses in the belt mainly represented by monzogranite-porphyry occurring as stocks in variegated sandshale of the lower Upper Triassic Jiapila Fromation and its overlying and underlying copper-bearing strata. They are characterized by enrichment in K. CI and LREE. abundant fluid inclusions and a distinct porphyroblastic texture. The oxygen. hydrogen. strotium. lead and sulfur isotopic values of the rock show the feature of crust-mantle mixing.The Orebodies are plpe-shaped stratoid; the mineralization is dominated by Cu and Mo, accompanied by Fe. Co. Au. Ag. Bi. W. Pb. Zn. and Pt-group elements. Alteration is strong. marked mainly by potassic alteration, silicification. skarnization and propylitization. The formation of this type of deposit largely progressed through two stages. The first stage was the stage of formation of Cu-bearing source beds. It occurred in the Triassic. when a transgressive copper-bearing formation was deposited on the western margin of the Qamdo Bay. which was represented by intermediate-acid volcanic rocks and variegated sandshale in the lower part. dolomitic carbonate rocks in the middle and black carbonaceous sandshale in the upper part. In the second stage. composite porphyry copper deposits were formed. This stage took place in the Paleogene. when this district was in a stage of platform rejuvenation. forming a series of NNW-trending deep faults. so that Na, K. Cl. H2O and CO2-rich hydrothermal fluids from the depths were injected into the upper crust and replaced and melted copper-bearing sialic rocks of the upper crust. e. g. the Triassic copper-bearing rock series in the Yulong area. to form porphyroblastic cooper-bearing intermediate-acid porphyry.

THE GEOLOGY AND GENESIS OF THE Q1YUGOU EXPLOSIVE BRECCIA TYPE GOLD DEPOSITS,HENAN PROVINCE

The Qiyugou explosive breccia type gold deposits of northwestern Songxian, Henan Province is situated at the East Qinling, on the southern margin of the North China Platform.The basement rocks are the Archean Taihua Group gneisses which were overlaid by the Proterozoic Xionger Group metaandesites. NW-and NE-trending folds and fractures are well developed. Nlagmatism of the Mid-Late Yanshan Epoch led to the formation of the Huashan granite batholith and a variety of acid/alkali dykes, meanwhile more than thirty explosive breccia bodies had been brought about. The most important deposit type is the explosive breccia type represented by the Qiyugou deposit, meanwhile there are structure fracture altered rock type,the goldbearing quartz vein type, as well as porphyry-breccia type. All these types are the terminal products of the evolution and differentiation of the syntectic magma originated from lower crust or upper mantle. They are controlled by a unified structural pattern occurred in the same

Geological Characteristics and Prospecting Criteria of Senji Molybdenum Ore Body in Urad Houqi, Inner Mongolia, China

Geological Characteristics and Prospecting Indicators of Senji Molybdenum Ore Body in Urad Houqi, Inner Mongolia Based on geological mapping, soil geochemical survey, surface trough exploration and deep drilling verification and control, the Senji Molybdenum deposit was discovered. Geological characteristics of the molybdenum ore body are described. The host lithology of molybdenum ore body is mainly in the cataclastic carbonated black plagioclase gneiss of the second rock member of the Paleoproterozoic Baoyintu Group, followed by Early Carboniferous monzogranite. The genetic type of the deposit is preliminarily deduced to be a hydrothermal filling vein-type molybdenum deposit. The significance of this paper is to summarize the prospecting marks of the molybdenum ore body in this area, so as to further guide the exploration work in this area, and at the same time provide a useful reference for the exploration work of similar deposits in other areas.

老挝川圹省BanDa锡多金属矿床地质特征及找矿标志

BanDa锡多金属矿床位于长山成矿带西北段,为近年来新发现的一处中型锡多金属矿床,随着勘查的深入有望突破为大型锡多金属矿床。现阶段矿体主要赋存于二叠系Khang Khai组泥质粉砂岩、粉砂质泥岩中的近SN向构造破碎带和层间破碎带中,矿体的产状、空间分布及形态特征严格受NE向断裂、近SN向断裂和层间破碎带的联合控制。矿体主要呈脉状、细网脉状、条带状、蜂窝状在断裂带和层间破碎带中产出,矿体沿走向和倾向变化较大,具分支复合、尖灭再现和尖灭侧现等现象。矿体中矿石矿物以锡石为主,其次为闪锌矿和黄铜矿,矿石结构以它形-半自形粒状结构为主,矿石构造以浸染状构造为主,认为该矿床为构造-热液充填交代型锡多金属矿床。厘定了五大找矿标志:露头标志、岩性标志、构造标志、围岩蚀变标志及地球物理-地球化学标志等,为下一步矿床深边部找矿勘查和长山成矿带西北段锡多金属矿找矿勘查起指导作用。

Structural Control of the Getang Carlin-Type Gold Deposit in Southwest China

The Getang is a representative Carlin-type gold deposit in Southwest China.It has a proven reserve of about 30 tonnes at an average grade of 5.1 g/t Au.The orebodies occur as strat-abound lenses,and are structurally controlled by shallow NWW-and NE-trending fold-fault systems and the unconformity between the Upper and Middle Permian.In this study,the regional-and deposit-scale structural investigations,joints and finite strain measurements,and stress and dynamic analysis were conducted with an aim to reveal the structural process of the Getang gold deposit and clarify the relationship between the gold mineralization and structures.Three phases of deformation were identified in the deposit:(1)paleokarst was generated by a crustal uplift when the Youjiang Basin experienced extension at the end of the Middle Permian,laying the foundation for the unconformity;(2)the NW-trending structures were formed under a NNE-SSW compression during the Indochina-South China collision(Indosinian orogeny)in Triassic;(3)the NE-trending structures were generated or reactivated under a NW-SE-oriented compression during the Yanshanian intracontinental orogeny.The unconformity recorded two episodes of tectonic evolution in the NNE-SSW and NW-SE directions.Structural analyses and geochronology data suggest that the Getang gold deposit was formed as a result of tectonic transition from compression to extension during the Yanshanian intracontinental orogeny.

A Research Review of Iron Oxide Copper-Gold Deposits

Iron oxide copper-gold （IOCG） deposits are a research focus of the current ore deposit geology, and have attracted much attention among the worldwide geologists and exploration experts due to their shallow depth, a wide variety of mineral species and large scale. This paper presents a review of the present IOCG deposits research, which includes the definition of IOCG deposits, temporal and spatial distribution, ore-forming environments, ore-forming magmatic rocks, their geological features, ore-controlling structures and ore-bearing rocks, mineralized alteration zoning, and their genesis and ore-forming process. This work also proposed the ore prospecting direction of IOCG deposits from a trinity model of metaUogenic geological bodies, metallogenic structure surface and metailogenic information signs, and discussed the existing problems of the IOCG deposits research.

Genesis of Xinzhai Sandstone-Type Copper Deposit in Northern Laos: Geological and Geochemical Evidences

Xinzhai sandstone-type copper deposit located in northern Laos lies in the Jiangcheng-Phongsaly-Phrae Mesozoic basin(JPMB), which is regarded as southern extension of the Lanping-Simao Mesozoic basin in China. The copper deposit belt is bounded by the AilaoshanHeishui River fault and the Dian Bien Phu-Luang Prabang fault at the east and Lancang RiverBannankan faults at the west. Two types of orebodies are identified in the Xinzhai area based on geological investigation. One is lamellar copper orebody hosted by the fine lithic feldspar sandstones and feldspar lithic sandstones; another is vein-type orebody. The sulfur isotopic compositions of the chalcopyrite and tetrahedrite are from -11.6‰ to -1.8‰, indicating that sulfur is derived from bacterial sulfate reduction(BSR). δD values of fluid inclusions in ore-bearing quartz samples are from -99‰ to -78‰. The calculated δ^(18)OH_2O values of ore-forming fluid vary from -2.3‰ to 0.4‰ using the quartz-water fractionation equations and the mineralization temperature. Oxygen and hydrogen isotopic compositions show that the ore-forming fluid was derived from basin fluid. Rock-mineral identifications show that both of the mineral grain maturity and the structural maturity are high in the Jurassic Huakaizuo Formation, reflecting a far-source accumulation and lake facies sedimentatary environment. Based on tectonic determination diagram of the Al_2O_3/SiO_2-TFe+MgO, the sandstone samples collected from the Huakaizuo Formation were plotted in the passive continental margin. The collision of the Indian and Eurasian blocks during the Cenozoic formed large-scale strikeslips and thrust nappe structures in margin of the basin. With the tectonic movement, Cu-rich basin fluid from the basement of basin migrated upward along the contemporaneous fault and into the high porosity strata. At the same time, in organic matter-riched condition, bacterial sulfate reduction(BSR) has been triggered, forming a large number of S^(2-) ions, and then precipitation of sulfide started. This mechanism describes the process of copper mineral deposition in the Xinzhai deposit.

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。

喜马拉雅琼嘉岗伟晶岩型锂矿成矿地质特征和形成机制

西藏喜马拉雅琼嘉岗伟晶岩型锂矿是喜马拉雅稀有金属成矿带标志性的伟晶岩型矿床。其成矿地质特征、成矿机理-机制和含矿性评价的研究对喜马拉雅稀有金属成矿带的形成机制和找矿勘查工作研究具有重要意义。中国科学院地质与地球物理研究所在2021~2023年期间对喜马拉雅琼嘉岗伟晶岩型锂矿形成机制研究中,获得如下认识:(1)琼嘉岗锂辉石伟晶岩的主矿体主要顺矽卡岩化大理岩和钙质千枚岩面理侵入,中部整体上呈板状近水平(10°~20°),主矿体两侧倾角相对较大(30°~50°);(2)琼嘉岗矿床的富锂矿物主要为锂辉石(包括3个期次),次为透锂长石、锂绿泥石、锂云母等,其他稀有金属矿物包括绿柱石、日光榴石、羟硅铍石、铌锰矿-铌铁矿、锡石等,围岩蚀变主要为矽卡岩化并含有少量锡矿化;(3)琼嘉岗锂矿中花岗岩-伟晶岩的演化和成矿受岩浆结晶分异过程控制,锂辉石伟晶岩矿体的形成与系统大量流体出溶有关,花岗质熔体演化的早期阶段稀有金属可能达到饱和;(4)钾长石Ti温度计和流体包裹体等容线相交法揭示出从电气石白云母花岗岩到锂辉石伟晶岩呈现降温趋势,锂辉石伟晶岩石英形成时流体的捕获温度为410~475℃,捕获压力为180~240MPa,结合含锂矿物相关系揭示出降压是锂辉石伟晶岩形成的重要机制;(5)建立了琼嘉岗锂矿的成矿模式,指出高度结晶分异、流体出溶和降压过程控制了琼嘉岗锂辉石伟晶岩的形成,流体交代作用形成了稀有金属矿化;(6)长石结构和化学成分(Rb、Cs、Sr、Ba、K/Rb和形成温度)、石榴子石组成(高水含量、高Mn/(Mn+Fe)的锰铝榴石)、副矿物组成及其包裹矿物类型是琼嘉岗及周边伟晶岩含矿性评价的有效指标。

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。

肯尼亚沃伊矿区高岭土矿床地质特征及成因探讨

本文在对肯尼亚沃伊矿区高岭土矿进行专项地质调查和综合研究的基础上,分析了高岭土矿床的地质特征和矿床成因,总结了找矿标志。研究认为:肯尼亚沃伊矿区高岭土矿床赋存于前寒武纪长英质变粒岩中,是优质的高岭土矿石,可满足各类工业应用要求;该矿床为风化残积型高岭土矿床;区内高岭土一般为白色高岭土,白色的黏土矿物为本区高岭土找矿直接标志,富含有长石的基岩为高岭土矿的间接找矿标志。研究结果为肯尼亚高岭土的找矿工作提供参考。

福建闽清前洋铁矿地质特征及成因分析

通过对前洋铁矿区域地质背景、矿区地质特征和矿床地质特征进行研究,分析了矿床成因。结果表明:铁矿体赋存于晚侏罗世南园组第二段火山岩中,壳幔混合源岩浆为铁矿成矿提供了物质来源,成矿母岩为中性次火山岩,次火山岩浆热液为成矿提供了巨大的动能和热能,断裂构造为矿床形成提供容矿空间及导矿通道。矿床成因属玢岩型铁矿床。

安徽省太湖县刘羊河金红石砂矿地质特征及找矿标志研究

在太湖县刘羊河金红石砂矿区开展的地质填图、重砂测量、钻探等地质工作基础上,总结了刘羊河金红石砂矿区域地质、矿区地质、矿床地质特征,确定了砂矿体赋存于第四系全新统的砂层及砂砾层中。认为:矿床成因类型为河谷冲积型,砂矿体形状受地貌控制,与河谷形状一致;大别山前剥蚀丘陵区内次级地貌单元-侵蚀堆积河谷区有利于砂矿的形成和保存;大别山岩群桥岭岩组和新元古代变质侵入岩及石英脉中的矿物为本区金红石重要的物质来源;地貌特征、物源母岩、重砂异常是金红石砂矿重要的找矿标志。以期为安徽省大别山南部潜山、太湖一带进一步开展金红石砂矿床找矿工作提供参考。

大横路铜钴矿含矿地层的物源区属性和沉积环境:对钴富集的制约

大横路铜钴矿床位于胶-辽-吉古元古代构造带北段,是我国目前探明的以钴为主的大型变沉积岩容矿型铜钴矿床。然而,关于该矿床的含矿地层物源属性及沉积时的氧化还原条件,以及二者与钴成矿之间的联系尚不清楚。本次研究以采自钻孔的贫Co和富Co变碎屑岩以及老岭群地表出露的变质碎屑岩和碳酸盐岩作为研究对象,开展了详细的全岩地球化学以及C-O-S同位素研究,对比含矿与不含矿地层的物源属性、风化程度以及沉积时水体氧化还原环境的差异,进而探讨它们对Co(富Co硫化物)富集的制约。钻孔及地表的大栗子组变碎屑岩的地球化学特征表明含矿的大栗子组样品相对老岭群其他组样品更加富集Fe_(2)O_(3)^(T)和Sc且具有更低的Zr/Sc比值,这表明含矿地层中具有更多的镁铁质岩石来源的碎屑物质的输入。这与大栗子组中Hf含量小于8300×10^(-6)以及ε_(Hf)(t)值大于+2.3的碎屑锆石的比例更高是一致的。富Co的绢云千枚岩(变质页岩)相比贫Co样品具有更高的校正后化学蚀变指数CIA(大于83)、化学风化指数CIW(大于89)和斜长石蚀变指数PIA(大于85),这表明前者的母岩区经历了较高程度的化学风化,导致了含矿岩石中具有更高的黏土矿物含量。此外,富Co样品显示了更低的Fe^(3+)/Fe^(2+)比值,表明了其形成于相对较为还原的沉积环境。综上所述,在大横路铜钴矿的赋矿岩石大栗子组绢云千枚岩的原岩沉积时,其更高的基性源区组份、母岩区较高的化学风化程度以及相对较为还原的沉积环境为Co的初始富集提供了有利条件。这一研究结果为深入探讨该类型矿床的成矿机制提供了重要依据。