Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay, Xinjiang: A Case Study on the Aketishikan Gold Deposit

Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.     

Analysis of the Ore-Controlling Structure of Ductile Shear Zone Type Gold Deposit in Southern Beishan Area, Gansu, Northwest China

The ductile shear zone-type gold deposit is a kind that both the ore-forming mechanism and ore-controlling factors are closely related to the ductile shear zone and its evolution. Ductile shear zone develops in Beishan area, Gansu of Northwest China, and develops especially well in the south belt. The controls of the ductile shear zone on gold deposits are as follows. (1) The regional distribution of gold deposits (and gold spots) is controlled by the ductile shear zone. (2) The ductile-brittle shear zone is formed in the evolution process of ductile shear zone and both are only ore-bearing structures and con- trol the shape, attitude, scale, and distribution of mineralization zones and ore-bodies. (3) Com- presso-shear ductile deformation results in that the main kind of gold mineralization is altered mylonite type and the main alteralization is metasomatic. (4) Ore-bearing fracture systems are mainly P-type ones, some D-type and R-type ones, but only individual R’-type and T-type ones. (5) Dynamic differen- tiation and dynamic metamorphic hydrothermal solution resulting from ductile deformation is one of the sources of ore-forming fluid of gold mineralization, and this is identical with that ore-forming ma- terials are mainly from metamorphic rocks, and ore-forming fluid is mainly composed of metamorphic water, and with the fluid inclusion and geo-chemical characteristics of the deposit. (6) There is a nega- tive correlation between the gold abundance and susceptibility anisotropy (P) of the altered mylonite samples from the deposit, which shows that the gold mineralization is slightly later than the structural deformation. All above further expound the ore-forming model of the ductile shear zone type of gold deposits.     

Geology and Geochemistry of Reworking Gold Deposits in Intrusive Rocks of China—Ⅱ Gold Deposits and Their Genesis

Gold deposits in intrusive masses include the veinlet dissemination,quartz vein and veinlet dissemination vein types,They are distributed in fracture zones along the endocontact zone of a batholith or in the centre and edge of a stock.The metallogenic epochs are Yenshanian,Hercynian,Archean,Proterozoic and Himalayan,The gold deposits are characterized by a big difference in time span between gold mineralization and the formation of host masses Ore-forming materials were derived from the masses and auriferous strata and ore-forming fluids came from meteoric and formation waters.When circulating water was heated by ascending heat flow,gold would be extracted,concentrated and transported from auriferous rocks and then precipitated in the masses during the late tectonic movement,Finally gold deposits were formed in the intrusive masses.     

Deep－Source Ore－Forming Materials and Prospecting of Gold Deposits in Eastern Hebei,China

Eastern Hebei Province is one of the important gold mineralization areas in North China,and detailed investigations have been made in this area.Different mineralization models and different ore-formng surces have been proposed for the gold deposits in this area.As more detailed work was made and more information has been accumulated,it is necessary to make a new investigation on gold metallogenesis and its source.This paper presents the data about 13 gold deposits(occurrences.)It is concluded that the element gold came from the deep mantle.Different models of metallogenesis substantially describe such processes that ore-forming fluids were involved in metallogenesis in different favorable loci.Gold ore prospecting should be focused on fluid channel ways and favorable structures.     

Geological Characteristics of Copper Mineralization,Jiujiang—Ruichang Area,Jiangxi Province,China

The Jiujiang-Ruichang area in northwestern Jiangxi extends along the western part of the minerogenic belt of the middle-lower Yangtze Valley in a terrain of sediments ranging from Ordovician to Triassic in age with NEE-folda,and NW-compressive,NNW-tensile and NEE-compressive-shearing faults as the major structures .Igneous rocks are mostly intermediate-acid epizonal intrusive bodies.Typical copper mineralizations in this area include the skarn-type and stratiform Cu-bearing pyrite-type deposits at Wushan and the porphyry and breccia-pipe type copper-molybdenum deposits at Chengmenshan.Silurian strata,with a great thickness and an average copper content of 51 ppm,are considered to be the source bed of copper mineralization,as is evidenced,among other things,by the presence of an envelope which is notably impoverished in Cu aroud most of the deposits.Magmatic rocks which intruded into the Silurian strata often have relatively high alkali contents and K2O/Na2O ratios ,with extensive potash alteration.Magmatic rocks in the area are of co-melting type or mixed type.The magma assimilated a large quanity of country rocks while ascending.They are characterized by high REE contents,absence of Eu anomalies and high LREE/HREE ratios.Ancient lead and strontium isotopes were detected in feldspar megaphenocrysts from the granodiorite porphyry.Hydrothermal convective circulation systems of magmatic water of magmatic water and supergenic water was extensively developed in the magmatic and country rocks,in which copper,potassium and other ore-forming components were extracted from the country rocks and concentrated through heating,boiling and evaporating.When the ore-forming fluids found their way into the skarn zone or the unconformity between the Wutong Formation and the Huanglong Formation,ore precipitation would have occurred as a result of changing media,If the concentration of KCl exceeded 9%,copper and other ore-forming components might have been deposited in magmatic rocks,forming the porphyry-type ore deposits.     

Temporo-Spatial Distribution of Rare Metal and REE Deposits in Xinjiang, Northwest China

Many rare metal and REE deposits have been found in the Altay orogenic belt, on the northern margin of the Tarim massif and in the Kunlun-Altun orogenic belt, constituting three very important rare metal-REE mineralization belts in western China. These deposits belong to various genetic types with complex ore-forming mechanism, and were formed in certain mineralization epochs. On the basis of a systematic sum-up of geologic and geochemical achievements and 40Ar-39Ar ages of potassium-rich minerals as well as whole-rock Rb-Sr dating results, the authors systematically analyzed the spatial distribution and mineralization epochs of rare metal-REE deposits in Xinjiang, northwestern China, and concluded that although the Hercynian rare metal-REE mineralizations in this area are very important, pre- and post-Hercynian (especially Indosinian and early Yanshanian) rare metal-REE mineralizations also have important theoretical and economic significance.     

Ore—Search Perspective for Superlarge Gold Deposits in the Jiaolai Basin of the Jiaodong Gold Metallogenetic Domain

There are three types of gold deposits in the Jiaodong gold metallogenetic domain.The strata-bound gold deposits are a new type,which occur in a hydrocarbon-dled double-source bed enriched in gold(Au 174ng/g) and organic carbon(0.007-4.225%),At diagenetic a d hydrotherrmal stages water and oil were simultaneously activated and the stratabound gold deposits were formed from interactions between water ,oil and rocks.In the late Yanshanian period,gold oreboides were enriched and enlarged in response to tectonmoagmatism and action of complex ore-forming hydrothermal solutions.As a results,it is highly expected to find suparlarge gold deposits and the Yanzi area is expected to be a perspective target area.     

Isotope Geochemistry of the Xinchang -Yongjia Silver (Lead-Zinc)Ore Belt in Eastern Zhejiang Province

In the Xinchang-Yongjia silver (lead-zinc) ore belt, there mainly occur the large to medium-sized Haoshi, Bamao, Dalingkou and Wubu silver deposits or silver-bearing lead-zinc deposits. On the basis of researches on these typical deposits, the mechanism of leaching-drawing mineralization of Mesozoic geothermal water and the related model are put forward in this paper in the light of the time interval between rock and formation ages as well as hydrogen, oxygen, sulphur and lead isotope geochemical characteristics. The major metallogenic process occurred in volcanic rock layers. The ore-forming fluids are geothermal water coming from meteoric water and circulating at shallow layers. This geothermal water leached and absorbed ore-forming materials from its country rocks during its flowing (such metallogenic elements as silver, lead-zinc and sulphur mainly came from consolidated volcanic rocks), leading to the formation of meso - epithermal silver deposits.     

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

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 modem 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.     

新疆阿尔泰诺尔特地区金矿成因

阿尔泰诺尔特地区的金矿床(点)主要赋存于下石炭统红山嘴组.区内断裂发育,加里东晚期、华力西中晚期及燕山期花岗岩分布广泛.该区的地壳演化经历了基底陆壳、拉张型过渡壳、汇聚型过渡壳、新陆壳及新陆壳在中生代的发展等阶段.对地层含矿性、元素地球化学特征、成矿流体性质、微量元素及同位素特征等的研究表明,区内金成矿物质主要来源于下石炭统.金成矿为燕山期南北向挤压、构造活化动力学背景下的产物,属于与岩浆活动有关的中低温热液成矿.     

新疆阿尔泰诺尔特地区石炭纪火山作用

诺尔特地区位于阿尔泰北部地区，西伯利亚板块西南缘。区内石炭纪火山岩主要沿红山嘴断裂带分布，赋存于下石炭统红山嘴组中，岩性主要为晶屑凝灰岩、碎斑熔岩、凝灰岩、火山角砾岩、流纹岩等。火山作用中爆发、喷溢、侵出3种喷发形式均存在，产生了爆发－喷溢相、降落相、侵出相及火山喷发沉积相等火山岩相。诺尔特地区石炭纪火山构造为裂隙－中心式，断裂导致岩浆上升喷发，火山活动的中心位于西部的托格尔托别、阔科依达拉斯等地，而东部的塔斯比格、阿克提什坎、库马苏等地则位于远火山活动中心地区，火山活动从西向东逐渐减弱，西部以爆发－喷溢为主，东部则以侵出为主。     

~(40)Ar-~(39)Ar Age and Geological Significance of the Sawur Gold Belt in Northern Xinjiang, China

1 IntroductionThe Sawur gold belt is an eastward extending section ofthe Zarma-Sawur gold-copper belt in Kazakhstan, locatedin the Sawur Mountain, northern Xinjiang, and mainlycomprises two large- to medium-sized gold deposits,accompanied by five small gold deposits and a series ofgold ore spots (Yin et al., 1996, 2003; Wang et al., 1999; Liet al., 2000; Liu et al., 2003; Shen et al., 2004a). TheKuo'erzhenkuola and Bu'erkesidai gold deposits are thebiggest and most important ones in this …     

蒙古国巴彦洪戈尔地区金矿床地质特征及成因

巴彦洪戈尔地区位于蒙古中央地块南侧, 构造活动复杂, 发育有多期构造岩浆活动。区内发育有与花岗岩类有关金、铜等矿床。金矿床类型有石英脉型和斑岩型、矽卡岩型, 主要金和铜矿化与二叠纪磁铁矿系列花岗岩类密切相关, 与钛铁矿系列花岗岩类有关的矿化较少。成矿年代学研究显示, 金矿床的形成应早于三叠纪, 主要发生于石炭纪和二叠纪, 形成于微大陆碰撞期构造转换过程中的岩浆活动期间, 区内金矿床(点)构成蒙古国最具潜力的金成矿带。     

河南桐柏围山城金银成矿系统矿床地球化学特征

河南桐柏围山城的金银矿床形成于印支—燕山期碰撞造山的动力学背景。对矿床地球化学的研究表明 ,各矿床围岩均发生大规模的成矿元素活化迁移 ,稀土元素和硫同位素资料均指示矿化主要源自早期的矿源层 ;Pb同位素资料指示俯冲下插的南秦岭构造岩片部分融熔形成的花岗岩浆和深源流体提供了部分成矿物质 ;H、O同位素资料指示成矿流体主要由大气降水、部分岩浆热液和变质热液混合演化而成。工业矿体的形成与后期的构造及热流体的叠加改造有关。矿化带内金银矿床具有共同的成矿地质背景和成矿地质特征 ,构成了一个完整的以沉积初始富集、构造及岩浆热液改造的成矿系统     

Gold Deposits in Beishan Mountain, Northwestern China

Abstract. The Beishan Mountain spans three provinces ‐ Gansu, Xinjiang and Inner Mongolia, having an area of 120,000 km² Tectonically, it transverses three different tectonic units, i.e. Siberia, Kazakhstan and Tarim plates, and is composed of nine ter‐rains with widely exposed Precambrian and Paleozoic strata, complex structures, intensive magmatic activities and widespread ore deposits. It is not only a main part of Tianshan‐Yinshan‐Great Hinggan metallogenic belt in China, but also a key to under‐stand the evolution of central‐Asian orogenic system. At present, more than 100 gold deposits and prospects have been discovered, explored and mined, among which Nanjinshan, Mazhuangshan, Liushashan, Jinwozi, Zhaobishan and Xiaoxigong are the most important ones. Based on the host rocks and the geological features, all these gold occurrences can be subdivided into three groups (or types): (1) hosted by Carboniferous or Permian volcanic or subvolcanic rocks; (2) hosted by or related to plutonic intrusions; and (3) hosted by Precambrian metamorphic rocks. The first group includes the Mazhuangshan gold deposit, which occurs in Hercynian quartz por‐phyry and rhyolite porphyry as gold‐bearing quartz veins. The second group is composed of the Liushashan, Nanjinshan Zhaobishan and Jinwozi gold deposits. Gold mineralization at these four deposits occurs within Hercynian granitoids intrusion: or late Paleozoic sedimentary rocks as quartz veins, veinlets and altered rocks. The Xiaoxigong gold deposit belongs to the third group, and is hosted by Precambrian schist, amphibolite and migmatite as quartz veins and altered rocks. Isotopic age dating data, geological and geochemical evidence suggest that most of the groups 1 and 2 gold deposits were generated during the emplacement of the Hercynian or partly Indosinian intrusions. These intrusions may provide both heat and metals for groups 1 and 2 deposits. In contrast, although the formation is closely related to the Hercynian magma‐tism, the ore‐forming materials of the group 3 deposits may not only come from the intrusions, but also from the Precambrian metamorphic rocks.     

长坑矿田金,银矿床地球化学特征及形成差异分析

长坑矿田金、银矿体主要产于下石炭统与上三叠统不整合面之下的硅质岩中,金、银矿体分离。金矿体主要为浸染状,富集As、Sb、Hg;银矿体主要为脉状,富集Cu、Pb、Zn。金矿体铅同位素组成与寒武纪—石炭纪地层及硅质岩的相同,银矿体铅同位素组成与金矿体的不同。金、银矿体的氢、氧、碳同位素组成也明显不同。银矿体Rb-Sr等时线年龄为70.4Ma。据上述特征,笔者认为长坑金、银矿床是不同成矿作用形成的,金矿主要是热水沉积形成,银矿主要是燕山期晚期改造形成。     

Intrusion-Related Gold Deposits of North China Craton, People's Republic of China

Abstract. Intrusion‐related gold deposits are widely distributed within the North China craton or along its marginal fold belts. Presently, about 200 individual intrusion‐related gold deposits (prospects) have been discovered, among which Yuerya, Anjia‐yingzi, Linglong, Jiaojia, Chenjiazhangzi, Qiyugou, Jinjiazhuang, Dongping, Hougou, Huangtuliang, Guilaizhuang, Wulashan and Donghuofang are the most important ones. In general, the intrusion‐related gold deposits can be classified into three major groups according to their host rocks: (1) hosted by or related to felsic intrusions, including (la) calc‐alkaline granitoid intrusions and (lb) cryptoexplosion breccia pipes; (2) related to ultramafic intrusions, and (3) hosted by or related to alkaline intrusions. The first group contains the Yuerya, Anjiayingzi, Linglong, Jiaojia, Chenjiazhangzi and Qiyugou gold deposits. Gold mineralization at these deposits occurs within Mesozoic Yanshanian calc‐alkaline granitoid intrusions or cryptoexplosion breccia pipes as gold‐bearing quartz veins and replacement bodies. Pyrite, galena, sphalerite, chalcopyrite, native gold and electrum are major metallic minerals. The Jinjiazhuang deposit belongs to the second group, and occurs within Hercynian diopsidite and peridotite as quartz veins and replacement bodies. Pyrite, marcasite, arsenopyrite, native gold and electrum are identified. The third group includes the Dongping, Hougou, Huangtuliang, Guilaizhuang, Wulashan and Donghuofang deposits. Gold mineralization at these deposits occurs predominantly within the Hercynian alkaline intrusive complexes as K‐feldspar‐quartz veins and replacement bodies. Major metal minerals are pyrite, galena, chalcopyrite, tellurides, native gold and electrum. All these pyrite separates from Hercynian and Yanshanian intrusions or cryptoexplosion pipes associated with the gold deposits show a broad range in δ³⁴S value, which is overall higher than those Precambrian rocks and their hosted gold deposits. For the alkaline intrusion‐related gold deposits, the δ³⁴S values of the sulfides (pyrite, galena and chalcopyrite) from the deposits increase systematically from orebodies to the alkaline intrusions. All of these intrusion‐related gold deposits show relatively radiogenic lead isotopic compositions compared to mantle or lower crust curves. Most lead isotope data of sulfides from the gold ores plot in between the fields of the intrusions and Precambrian metamorphic rocks. Data are interpreted as indicative of a mixing of sulfur and lead from magma with those from Precambrian metamorphic rocks. Isotopic age data, geological and geochemical evidences suggest that the ore‐forming materials for the intrusion‐related gold deposits were generated during the emplacement of the Hercynian or Yanshanian intrusion. The calc‐alkaline or alkaline magma may provide heat, volatiles and metals for the intrusion‐related gold deposits. Evolved meteoric water, which circulated the wall rocks, was also progressively involved in the magmatic hydrothermal system, and may have dominated the ore fluids during late stage of ore‐forming processes. Therefore, the ore fluid may have resulted from the mixing of calc‐alkaline or alkaline magmatic fluids and evolved meteoric water. All these intrusion‐related gold deposits are believed to be products of Hercynian or Yanshanian calc‐alkaline and alkaline igneous processes along deep‐seated fault zones within the North China craton or along its marginal belts.     

西藏甲玛铜多金属矿床金矿地质特征及成矿作用

甲玛铜多金属矿床按照赋矿岩石不同,共包含产于矽卡岩中的与铜共生的金矿(化)体、产于板岩-角岩中的脉状金矿(化)体、产于大理岩中的脉状金矿(化)体以及产于玢(斑)岩脉中的独立金矿(化)体4种金矿化类型。矽卡岩中的金矿化较强,全矿区金品位×厚度基本都大于1 m.g/t,存在多个富金块段;板岩中金矿化主要分布在矿区外围破碎细粒黄铁矿化硅化板岩中,角岩中金矿(化)体以富含雄黄、雌黄为特征;大理岩中金矿化较弱,矿(化)体通常呈透镜状产出;玢(斑)岩中金矿化主要产于岩脉中的石英脉内。矿石中金的赋存状态主要以独立矿物和类质同像形式存在。独立矿物形式的金以自然金、银金矿存在于铜矿物、石英、黄铁矿等载金矿物内;类质同像形式的金主要存在于以斑铜矿、黄铜矿为代表的铜矿物中。金矿物赋存状态以粒间金、包裹金为主,其次为连生金和裂隙金。笔者以甲玛铜多金属矿床金的地质特征、分布规律及赋存状态为研究基础,推测甲玛金成矿作用与幔源C-H-O流体有关,并初步建立了甲玛铜多金属矿床金成矿模型。此外,提出了运用模型开展区域及矿区下一步找矿工作的建议。