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1.
Gold deposits hosted in the Gezhen shear zone at Qingxi, Hainan Island occur in the Preeambrian metamorphic rock series and are regionally developed in the N-E direction along the tectonic zone. From northeast to southwest are distributed the Tuwaishan-Baoban gold mining district, the Erjia gold mining district and the Bumo gold mining district, making up the most industrially important gold metallogenesis zone on the Hainan Island. Isotope geochemical studies of the typical gold deposits in this metallogenesis zone indicate that their ore-forming materials stemmed largely from the Baoban Group migmatite series, though the involvement of some plutonic materials could not be ruled out. The ore fluids are the mixture of migrnatitized hydrothermal solutions and meteoric waters in addition to the involvement of local magmatic hydrothermal solutions. The superimposition of plutonie materials and magmatic hydrothermal solutions is controlled by the deformation environment of the shear zone and later magrnatic activities. Obvious variations are noticed in isotopic composition in the region studied, probably related to tectonic deformation, metamorphism and other evolutionary characteristics. This study is of great significance in understanding the relationship between the shear zone and gold metallogenesis,the rules of gold metallogenesis and gold ore prognosis.  相似文献   

2.
Based on comprehensive petrological, geochronological, and geochemical studies, this study analyzed the relationships between the Beiya gold-polymetallic skarn deposit and quartz syenite porphyries, and discussed the source(s) and evolution of magmas. Our results suggest that syenite porphyries (i.e. the Wandongshan, the Dashadi, and the Hongnitang porphyries), which formed between the Eocene and the early Oligocene epochs, are the sources for the gold-polymetallic ores at the Beiya deposit. Carbonate rocks (T2b) of the Triassic Beiya Formation in the ore district provide favorable host space for deposit formation. Fold and fault structures collectively play an important role in ore formation. The contact zone between the porphyries and carbonates, the structurally fractured zone of carbonate and clastic rocks, and the zone with well-developed fractures are the ideal locations for ore bodies. Four types of mineralization have been recognized: 1) porphyry-style stockwork gold–iron (copper) ore, 2) skarn-style gold-iron (copper and lead) ore in the near contact zone, 3) strata-bound, lense-type lead–silver–gold ore in the outer contact zone, and 4) distal vein-type gold–lead–silver ore. Supergene processes led to the formation of oxide ore, such as the weathered and accumulated gold–iron ore, the strata-bound fracture oxide ore, and the structure-controlled vein-type ore. Most of these ore deposits are distributed along the axis of the depressed basin, with the hypogene ore controlling the shape and characteristics of the oxide ore. This study provides critical geology understanding for mineral prospecting scenarios.  相似文献   

3.
The formation of the Tongyu gold deposit, controlled by regional polyphase deformation-metamorphism.is closely related to the regional composite antiform-shear slip fracture zone. Late-stage reworking of theTaihua Group accounts for the enrichment of ore substances. It is a typical syntectonic gold deposit. The formation and evolution of the deposit involved four stages: (Ⅰ) the state of preparation of ore sub-stances, in which primary source beds originated: (Ⅱ) the stage of remobilization of ore substances, in whichregional progressive metamorphism and migmatization and thermodynamic-chemical differentiation led toremobilization of gold and its initial local concentration: (Ⅲ) the stage of gold deposit formation, in which re-gional folding produced concordant and cross shear-slip fractures and under the dynamic action gold was sepa-rated and migrated in a certain direction and concentrated to form a gold deposit: (Ⅳ) the stage ofsuperpositon, reworking and exposure of orebodies, in which the block uplifted and the deposit againunderwent reworking through faulting and mechanical differentiation.Thermodynamic mineralization played adominant role in the formation of the deposit.  相似文献   

4.
Lead isotopes have been widely applied in geochemical exploration and evaluation of ore deposits, as well as in ascertaining the age of mineralization and the source of ore fluids.Long-term practice showed that the method of lead isotope targeting is somewhat efficient for macroscopic evaluation of forecasting areas, but not powerful enough for for ecasting concealed orebodies. As the contents of U and the variation of U/Pb ratio sharply decrease with depth in the lithosphere, U-Th-Pb isotopic differentiation must have occurred during the crust-mantle e-volution. Lead isotopic ratios show a wide variation range, varying in the front of mineralizationand shallow-derived ores, but maintaining very stable in the major orebody and being usuallyclose to the average isotopic composition of the crust and mantle of the continent block fromwhich the ores were derived. Therefore, the lead isotopic composition can serve as a measure for identifying the position of mineralization. The lead isotope geochemistry was applied to the ex-ploration and evaluation of the Baoban gold deposits of Hainan Province, China. The an alyticalresults of ore veins and adjacent rocks showed that there is a correlation between the lead isotopedata and the position of orebody. Based on the experience from the Baoban gold deposits and other ore deposits in Yunnan Province, an exploration principle has been established, that is,positive anomalies of lead isotope eigenvectors for prospecting deep-seated orebodies and nega-tive anomalies of eigenvectors for enlarging lateral exploration surrounding the known deposit.The ore beds in the Erjia and Beiniu mining districts should be as signed to the deep part of the orebody and those in the Tuwaishan mining district should be the shallow part, so ore beds cor-responding to those in the Erjia and Beiniu mining districts may be found in the Tuwaishan min-ing district.  相似文献   

5.
The Huangtuliang gold deposit is characterized by its wide and large ore belt, stable extension and closely spaced orebodies. Unfortunately, no orebody was found by deep drilling. As a result, ore prospecting in this region was once put into dilemma. Detailed analysis of ore-forming and ore-controlling structures in the mining district by the authors has revealed that the ore-forming and ore-controlling structure in this mining district is a steeply dipping (85°-110°/∠70°-85° N-NNE), spade-shaped ductile shear zone, and the ore-controlling structures are a series of nearly erected second-ordered faults which are developed in the upper part of the ductile shear zone, inter-secting with the ductile shear zone. Deep cutting of the ductile shear zone made it possible the ascending of ore fluids from the mantle plume at depth and these ore fluids would migrate upwards along the ductile shear zone under certain temperature and pressure conditions. Along their ascending path, the ore fluids would extract ore-forming elements from the country rocks and the extracted ore-forming elements would be deposited as ores in the hang- ing-wall second-ordered faults. The reason why no orebody was found in early prospecting at depth is that north- ward-dipping drilling in the southern part of the shear zone extended so deeply as to be beneath the shear zone. Only shallow-level orebodies could be found by southward-dipping drilling practice in the northern part of the shear zone. The location where deep-seated orebodies occurred shifted northwards and the orebodies occurred at greater depth. Therefore, it is natural that no orebody could be found when drill core passed through the shear zone. After the ore-forming and ore-controlling structures were well understood, the focus of ore prospecting was placed on the deep-level, northward-penetrating veins. In this way a number of new blind orebodies of great thickness have been found. On the basis of research development in the mining district, a prospecting plan has been made  相似文献   

6.
The Xishimen gold deposit is located in the tectonic zone southeast to the Shihu gold deposit, both of which belong to the same orefield. Then, how is the prospecting potential for the Xishimen gold deposit? A com-parison was made between the Xishimen gold deposit and the Shihu gold deposit on the basis of their geological background of metallogenesis, geological characteristics of the ore deposits, the sources of ore-forming materials, etc. The results showed that both the deposits possess many similarities in the respects mentioned above. And their met-allogeneses can be compared. Therefore, there is great potential for ore prospection in the periphery or at the deep levels of the Xishimen gold deposit. Ore exploration should be well programmed on the basis of a better dissection of the tectonic setting of the orefield. A breakthrough in ore prospection of the Xishimen gold deposit will be of great instructive significance in regionally geological prospecting.  相似文献   

7.
The Linglong-Jiaojia district is one of the most important regions containing gold deposits in China. These gold deposits can be divided into: a) the pyrite-gold-quartz vein type (Linglong type), which is controlled by brittle-ductile to ductile deformation structures, and b) the alteration-zone type (Jiaojia type), characterized by small veinlets, or the disseminated type recognized in brittle shear zones. Lode gold deposits in the Jiaojia area occur in NE brittle fracture zones, formed in a dominantly simple shear deformation regime, mainly in thrust attitude with a minor sinistral strike slip component. In the Linglong area, the lode gold deposits are located at the intersection of three types of structures: NNE and NE brittle-ductile fault zones and the ENE ductile reverse shear zone in the south of the area. The structural characteristics of these brittle shear zones are consistent with a tectonic NNW-SSE principal stress field orientation. Similar stresses explain the ENE Qixia fold axes, the Potouqing and several other ENE reverse ductile shear zones elsewhere in the region, the Tancheng-Lujiang fault zone and its subsidiaries in the vicinity of the Linglong-Jiaojia district, as well as the southern ENE suture zone north of Qingdao. Therefore these structural systems occurred as part of different major tectonic events under NNW-SSE compression principal stress fields in the area. Gold deposits are hosted in smaller-scale structures within the brittle fault zones and brittle-ductile shear zones. Although ore bodies and, on a smaller scale, quartz ore veins often seem to be randomly oriented, it is possible to explain their distribution and orientation in terms of the simple shear deformation process under which they were developed. The progressive simple shear failure is characterized by various fracture modes (tension and shear) that intervene in sequence. The tension and shear fractures are influenced by the stress level (depth of burial beneath the paleosurface) in their structural behavior, show variable dilatancy (void openings) and extend on all scales. By making use of these characteristics, a progressive failure analysis can be applied to predicting the shape and extent of ore bodies as well as the styles of mineralization at any given location.  相似文献   

8.
The Tongling ore district is one of the most economically important ore areas in the Middle–Lower Yangtze River Metallogenic Belt, eastern China. It contains hundreds of polymetallic copper–gold deposits and occurrences. Those deposits are mainly clustered(from west to east) within the Tongguanshan, Shizishan, Xinqiao, Fenghuangshan, and Shatanjiao orefields. Until recently, the majority of these deposits were thought to be skarn-or porphyry–skarn-type deposits; however there have been recent discoveries of numerous vein-type Au, Ag, and Pb-Zn deposits that do not fall into either of these categories. This indicates that there is some uncertainty over this classification. Here, we present the results of several systematic geological studies of representative deposits in the Tongling ore district. From investigation of the ore-controlling structures, lithology of the host rock, mineral assemblages, and the characteristics of the mineralization and alteration within these deposits, three genetic types of deposits(skarn-, porphyry-, and vein-type deposits) have been identified. The spatial and temporal relationships between the orebodies and Yanshanian intrusions combined with the sources of the ore-forming fluids and metals, as well as the geodynamic setting of this ore district, indicate that all three deposit types are genetically related each other and constitute a magmatic–hydrothermal system. This study outlines a model that relates the polymetallic copper–gold porphyry-, skarn-, and vein-type deposits within the Tongling ore district. This model provides a theoretical basis to guide exploration for deep-seated and concealed porphyry-type Cu(–Mo, –Au) deposits as well as shallow vein-type Au, Ag, and Pb–Zn deposits in this area and elsewhere.  相似文献   

9.
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.  相似文献   

10.
Shear zone-hosted gold deposits in China can be divided into four types:ductile,brittle-ductile,ductile-brittle and brittle,of which the ductile and brittle types are the basic ones.All these types of gold deposits have their own geochemical characteristics.The Hetai gold deposit in Guangdong Province,for example,is a mylonite-type gold deposit in a ductile shear zone.With increasing mylonitization,obvious changes took place in trace elements in minerals and rocks,enriching gold and mineralizing elements.The S and Pb isotope data indicated that the ore-forming materials were derived from the strata.Hydrogen and oxygen isotopic and fluid inclusion studies also implied that the ore-forming fluid was much closer to meteoric water from the early to the late ore-forming stage.The Linglong gold deposit,Shangdong Province,is a quartz-type gold deposit in a brittle shear zone.Changes in rocks,minerals and trace elements occurred in the process of f ormation of gold quartz veins,and the analytical results of S,Pb ,Hand O isotopes showed that ore deposition is connected not only with the Jiaodong Group,but also with anatexic granites.  相似文献   

11.
通过对江西银山矿区外围225km^2范围内213个双桥山群地层样品的金含量分析,获得了明显的围绕矿区展布的金地球化学降低及其含量梯度变化,从而证实双桥山群为银山矿床的金矿化提供了成矿物质。作者根据这一降低场的性质,对银山的蚀变矿化特征、NE向断裂构造的控矿作用以及找矿方向等进行了讨论。  相似文献   

12.
银山金铜多金属矿床位于赣东北深断裂的北西侧。矿区大面积出露前震旦系双桥山群浅变质岩,其上有零星不整合产出的上侏罗统鹅湖岭组火山碎屑岩—熔岩。矿区褶皱构造主体为双桥山群浅变质岩构成的银山背斜,沿背斜轴部发育一条斜贯全区的剪切带。区内主要发育燕山早期的火山碎屑岩、熔岩、次火山岩及隐爆角砾岩。大量事实表明,该矿床经历了构造动力热液成矿和火山-岩浆热液成矿,两种成矿作用在时间上具同期性,在空间上两者密切相关,构成了构造动力—火山岩浆同步一体的成矿体系。  相似文献   

13.
Based on previous studies and detailed field investigations of the Dexing porphyry copper deposit, the Yinshan Ag-Pb-Zn deposit and the Jinshan shear zone – hosted gold deposit in the Dele Jurassic volcanic basin, in the northeastern Jiangxi province, East China, we propose that the three deposits share spatial, temporal and genetic relationships and belong to the same metallogenic system. Dexing is a typical porphyry Cu–Au–Mo deposit in which both ore-forming fluid and metals are derived from the granite porphyry. The Yinshan deposit consists of a porphyry copper ore located in the cupola of a quartz porphyry stock, in the lower part, and Ag–Pb–Zn ore veins in the upper part. The hydrothermal fluids were mainly derived from the magma in the early stages of the mineralizing event and became mixed with meteoric waters in the late stages. Its ore metals are magma-derived. Both the Jinshan base metal veins and the Hamashi, Dongjie and Naikeng quartz vein-type gold deposit are hosted by brittle–ductile structures, which are distal in relation to the porphyry intrusions and were formed by mixed magmatic fluids and meteoric water, whereas the gold was mainly leached from the country rocks (Mesoproterozoic Shuangqiaoshan Group phyllite and schist). The deposits show a distinct spatial arrangement from porphyry Cu, to epithermal Ag–Pb–Zn and distal Au. We suggest a porphyry–epithermal–distal vein ore system model for this group of genetically related mineral deposits. They were formed in a back-arc setting in a Middle Jurassic active continental margin, with magmas derived from the subducted slab.  相似文献   

14.
江西金山金矿床成矿物质来源的铅和硫同位素示踪   总被引:10,自引:3,他引:10  
江西金山金矿床赋存于浅变质的中元古界双桥山群上亚群 ,该建造明显富Au ,Au平均丰度达 2 5 5× 10 -9。矿石铅同位素组成出现明显的线性关系表明 ,区域构造活动 成矿作用中存在着铅同位素的混合机制。大部分矿石铅Doe单阶段模式年龄与该矿床的Rb Sr年龄值十分接近 ,可能反映了区域变质的成矿意义。矿石铅 μ值介于 9 2 9~ 9 86之间 ,2 3 2 Th/ 2 3 8U比值变化于 3 88~ 4 0 9,揭示了成矿物质的壳源特征。Zartman图解和△γ △ β图解表明 ,双桥山群是矿石铅的主要源区。该矿床硫同位素组成特征与外围双桥山群上亚群中硫化物的硫同位素极为相似 ,成矿流体的硫主要来源于双桥山群含矿建造。对比研究表明 ,虽然不同金矿床的硫同位素组成特征不尽相同 ,但金山金矿床的层控特征与江南金成矿带中其他金矿极为相似。金山金矿床的铅、硫同位素地球化学特征揭示 ,该矿床的成矿物质主要来自浅变质的中元古界双桥山群含金建造 ,燕山期岩浆热液活动为该矿床的后期富集提供了部分成矿物质。  相似文献   

15.
在前人研究的基础上,通过系统的野外考察,论证了位于赣东北德兴地区德乐中生代火山盆地中的德兴铜矿、银山银铜铅锌矿和金山金矿及蛤蟆石金矿属于同一成矿系统。德兴铜矿是典型的斑岩铜矿,成矿流体和金属元素主要来自岩浆;银山银铜铅锌矿是一个下部为斑岩铜矿、上部为浅成低温热液型银铅锌矿,成矿流体早期以岩浆为主,晚期有较多的大气降水参与,成矿物质主要来自岩浆;金山和蛤蟆石金矿是远接触带热液矿床,成矿流体为岩浆热液与大气降水的混合产物,金主要来自围岩——双桥山群浅变质岩。这3套矿床以中酸性花岗斑岩或石英斑岩(高钾钙碱质花岗岩)为核心具有明显的分带性,自中心向外或深部向浅部为:斑岩铜金钼矿、浅成低温热液型银铅锌矿和远接触带热液型金矿。这种矿床组合关系不同于已知的经典斑岩铜矿模型和斑岩铜矿一浅成低温热液金银矿床模型,因而,有必要提出一个新的模型:斑岩铜矿一浅成低温热液银铅锌矿一远接触带热液金矿模型。这套矿『末形成于中侏罗世,抑或是古太平洋俯冲板片局部重熔或撕裂重熔的产物,抑或是在活动大陆边缘岩浆弧后伸展带由地幔底侵的结果。  相似文献   

16.
德兴大型铜金矿集区的研究进展和成矿模式   总被引:3,自引:1,他引:2  
王国光  倪培  赵超  姚静  李利  赵丹蕾  朱安冬  胡金山 《岩石学报》2019,35(12):3644-3658
德兴大型铜金矿集区是我国最重要的铜金产地之一。多年来,德兴矿集区的成矿过程和成因模式一直引起广大地质学家的广泛关注。在前期大量的野外工作观察和多年研究基础上,结合前人的研究成果,本文提出德兴矿集区由两套成矿系统组成:新元古代金山-水石坞-西蒋-渔塘-蛤蟆石-上洛造山型金成矿系统和燕山期德兴和银山斑岩-浅成低温热液型铜金多金属成矿系统。德兴矿集区的造山型金矿可进一步划分为两个亚系统,分别为对应于区域NW向推覆构造的NWW走向、缓倾斜的金山金矿田超糜棱岩型亚系统(约为840Ma),和对应于区域上NE向走滑剪切运动的NE走向、陡倾斜的蛤蟆石金矿田和金山金矿阳山矿段的石英脉型亚系统(约为750~710Ma)。造山型金矿的成矿物质来自富金的新元古代双桥山群基底地层,成矿流体主要为富CO_2的变质流体。燕山期斑岩-浅成低温热液系统的形成时代为约170Ma,此时古太平洋板块开始向华南大陆俯冲,导致赣东北深大断裂活化,引发新元古代形成的富铜金的初生地壳重熔再造,形成德兴Cu-Au-Mo矿和银山Cu-Au-Pb-Zn-Ag矿,成矿热液主要来自于岩浆流体来源的贫CO_2的NaCl-H_2O体系。  相似文献   

17.
The Yinshan deposit in the Jiangnan tectonic belt in South China consists of Pb‐Zn‐Ag and Cu‐Au ore bodies. This deposit contains approximately 83 Mt of the Cu‐Au ores at 0.52% Cu and 0.8 g/t Au, and 84 Mt of the Pb‐Zn‐Ag ores at 1.25% Pb, 1.02% Zn and 33.3 g/t Ag. It is hosted by low‐grade metamorphosed sedimentary rocks and mafic volcanic rocks of the lower Mesoproterozoic Shuangqiaoshan Group, and continental volcanic rocks of the Jurassic Erhuling Group and dacitic subvolcanic rocks. The ore bodies mainly consist of veinlets of sulfide minerals and sulfide‐disseminated rocks, which are divided into Cu‐Au and Pb‐Zn‐Ag ore bodies. The Cu‐Au ore bodies occur in the area close to a dacite porphyry stock (No. 3 stock), whereas Pb‐Zn‐Ag bodies occur in areas distal from the No. 3 stock. Muscovite is the main alteration mineral associated with the Cu‐Au ore bodies, and muscovite and chlorite are associated with the Pb‐Zn‐Ag ores. A zircon sensitive high‐resolution ion microprobe U‐Pb age from the No. 3 dacite stock suggests it was emplaced in Early Jurassic. Three 40Ar‐39Ar incremental‐heating mineral ages from muscovite, which are related to Cu‐Au and Pb‐Zn‐Ag mineralization, yielded 179–175 Ma. These muscovite ages indicate that Cu‐Au mineralization occurred at 178.2±1.4 Ma (2σ), and Pb‐Zn‐Ag mineralization at 175.4±1.2 Ma (2σ) and 175.3±1.1 Ma (2σ), which supports a restricted period for the mineralization. The Early Jurassic ages for the mineralization at Yinshan are similar to that of the porphyry Cu mineralization at Dexing in Jiangnan tectonic belt, and suggest that the polymetallic mineralization occurred in a regional transcompressional tectonic regime.  相似文献   

18.
吉林夹皮沟金矿床含金石英的40Ar/39Ar快中子活化年龄测定   总被引:16,自引:0,他引:16  
吴尚全 《矿床地质》1991,10(4):349-358
该文对夹皮沟金矿区有代表性的两个矿床及一个矿点的含金石英脉,用快中子活化法测定了40Ar/39Ar年龄。其年龄谱都以马鞍形为特征,年龄谱的最低坪年龄可作为石英脉的生成时代。3个数据分别为(1824±24)Ma、(1253±17)Ma和(203±60)Ma。由此认为夹皮沟矿区,金的成矿作用是多阶段的,吕梁期、晋宁期和燕山早期。而金矿的成因主要与吕梁期和晋宁期的变质作用有关,因此夹皮沟金矿可划为变质热液型金矿床。  相似文献   

19.
赣东北地区是我国重要的铜铅锌金银多金属矿集区,银山铅锌(银)铜(金)多金属矿床是赣东北地区一个重要的大型次火山热液型多金属矿床。银山铅锌矿发育有闪锌矿-方铅矿-石英脉,前人研究认为金属矿物与脉石矿物为伴生关系,但是没有强调它们的成因上的联系。本次研究开展了矿石矿物中闪锌矿和伴生脉石矿物中石英的流体包裹体对比研究。通过详细的岩相学观察、显微测温、显微激光拉曼探针工作,对伴生石英脉和闪锌矿内原生包裹体,伴生石英脉中的晚期微细石英脉和闪锌矿内部次生包裹体进行流体特征的对比研究。研究结果显示,伴生石英脉原生流体包裹体比闪锌矿的原生包裹体的平均均一温度高约30℃,明显富集CH4、N2、CH4、CO2等挥发份,伴生石英脉中的晚期微细石英脉流体包裹体比闪锌矿次生包裹体的平均均一温度高23℃。闪锌矿原生包裹体与想伴生的早期石英脉在平均均一温度有所差别,气相成分差异明显,均表明矿石矿物与伴生脉石矿物可能形成于不同的地质环境,具有不同的温度和流体成分。  相似文献   

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