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1.
The greenstone belt and metamorphosed microclastic rock-type superlarge gold deposits in China are hosted in metamorphic rocks and later intrusive bodies.Sedimentation.regional metamorphism and mineralization contributed a lot to the formation of the deposits,so did remelting magmatic process to some deposits,but the deposits were finally formed by reworking processes.The key factor leading to the formation of superlarge gold deposits is the reworking intensity,which for superlarge gold deposits is reflected by the large-scale reworked source rocks and even ore materials of various sources,strongly oxidized ore-forming fluids with a long and repeated active history and stable geothermal heat current.The factor which decides the reworking intensity is the network consisting of structures of different classes. 相似文献
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The gold deposits,occurring in the south subzone of western Qinling,are the only typical and important strata-bound gold deposits,which are associated with submarine exhalative sedimentation.The gold deposits include the La‘erma ore deposit,the Qiongmo ore deposit and the Yaxiang ore occurrence.They are hosted i the Cambrian silicalite formation composed of black chert and slate.The presence of typical chert offers important evidence to evaluate the possible submarine exhalative system and its role in the formation of the gold deposits,which are closely associated with peroclation and diffusion in the horizontal,vertical and axial directions,Element-assemblage zonation is clearly seen due to differences in element concentrations in different directions,Such a zonation makes gold.selenium,uranium,copper,stibium,molybdenum,mercury,etc,precipitate in the form of simple or composite orebodies.The establishent of the element-assemblage zonation is highly helpful for evaluating directly the metallogenesis of gold deposits. 相似文献
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JIANG Sihong NIE Fengjun Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing 《《地质学报》英文版》2005,79(1):87-97
Located in Alxa Zuoqi (Left Banner) of Inner Mongolia, China, the Zhulazhaga gold deposit is the first largescale gold deposit that was found in the middle-upper Proterozoic strata along the north margin of the North China craton in recent years. It was discovered by the No. l Geophysical and Geochemical Exploration Party of Inner Mongolia as a result of prospecting a geochemical anomaly. By now, over 50 tonnes of gold has been defined, with an average Au grade of 4 g/t. The ore bodies occur in the first lithological unit of the Mesoproterozoic Zhulazhagamaodao Formation (MZF), which is composed mainly of epimetamorphic sandstone and siltstone and partly of volcanic rocks. With high concentration of gold,the first lithological unit of the MZF became the source bed for the late-stage ore formation. Controlled by the interstratal fracture zones, the ore bodies mostly appear along the bedding with occurrence similar to that of the strata. The primitiveore types are predominantly the altered rock type with minor ore belonging to the quartz veins type. There are also some oxidized ore near the surface. The metallic minerals are composed mainly of pyrite, pyrrhotite and arsenopyrite with minor chalcopyrite, galena and limonite. Most gold minerals appear as native gold and electrum. Hydrothermal alterations associated with the ore formation are actinolitization, silicatization, sulfidation and carbonation. A total of 100 two-phase H2O-rich and 7 three-phase daughter crystal-beating inclusions were measured in seven goldbearing quartz samples from the Zhulazhaga gold deposit. The homogenization temperatures of the two-phase H2O-rich inclusions range from 155 to 401℃, with an average temperature of 284℃ and bimodal distributions from 240 to 260℃ and 300 to 320℃ respectively. The salinities of the two-phase H2O-rich inclusions vary from 9.22wt% to 24.30wt% NaCl eqniv, with a mode between 23 wt% and 24wt% NaC1 equiv. Comparatively, the homogenization temperatures of the threephase daughter crystal-beating inclusions vary from 210 to 435℃ and the salinities from 29.13wt% to 32.62wt% NaCl equiv. It indicates that the ore-forming fluid is meso-hypothermal and characterized by high salinity, which is apparently different from the metamorphic origin with low salinity. It suggests a magmatic origin of the gold-bearing fluid. The δ^18O values of quartz from auriferous veins range from 11.9 to 16.3 per mil, and the calculated δ^18OH2O values in equilibrium with quartz vary from 1.06 to 9.60 per mil, which fall between the values of meteoric water and magmatic water. It reflects that the ore-forming fluid may be the product of mixing of meteoric water and magmatic water.Based on geological and geochemical studies of the Zhulazhaga gold deposit, it is supposed that the volcanism in the Mesoproterozoic might make gold pre-concentrate in the strata. The extensive and intensive Hercynian tectono-magmatic activity not only brought along a large number of ore-forming materials, but also made the gold from the strata rework. It can be concluded that the ore bodies were mainly formed in late hydrothermal reworking stage. Compared with typical gold deposits associated with epimetamorphic clastic rocks, the Zhulazhaga deposit has similar features in occurrence of ore bodies, ore-controlling structure, wall-rock alterations and mineral assemblages. Therefore, the Zhulazhaga gold deposit belongs to the epimetamorphic clastic rock type. 相似文献
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This paper presents a method of establishing a hydrothermal ore-forming reaction system.On the basis of the study of four typical hydrothermal deposits,the following conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been sions concerning geochemical dynaamic controlling during hydrothermal mineralization have been drawn:(1)The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system.(2)During hydrothermal mineralization the activites of ore-bearing faults can be divideb into two stages:the brittle splitting stage and the brittle-tough tensing stage,which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system.(3)The hydrothermal ore-forming reaaction system is an open dynamic system.At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids.And at the brittle-tough tensing stage,the ore-forming system was in a weak supersaturated state;with decreasing temperature and pressure the crystallization of oreforming material would show down,and it can be regarded as an equilibrated state.(4)In the lates stages of hydrothermal evolution,gold would be concentrated in the residual ore-forming solution.The pulsating fracture activite in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution,forming high-grage“fissure”gold ore.This ore-forming process could be called the coupling mechanism of ore formation. 相似文献
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The Zhaceqiao gold-polymetal deposit was discovered recently in the Jiangnan Transitional Zone. In order to obtain the ore-forming age, sericite was separated from the altered granite porphyry which hosts the gold deposit. 40Ar-39Ar analyses of sericite in gold ore yield spectrum age of 156.9±1.6 Ma with the isochron age of 152±28 Ma. The spectrum age of sericite in altered granodiorite porphyry is 142.1±1.3 Ma with the isochron age of 137±13 Ma. The homogenization temperature of fluid inclusions in quartz from the Niutougaojia and Chengtan ore sections is c.a. 160℃. The H-O isotopic compositions indicate that the ore-forming fluids mainly come from magmatic hydrothermal sources. Integrating with regional studies, the Zhaceqiao gold deposit is predominantly characterized by shallow, low temperature and epithermal, similar to Carlin-like type gold deposit. The Zhaceqiao gold deposit was formed in Yanshanian through multi-stage superimposition. The gold mineralization was related to the ductile-brittle compressional tectonic deformation and alteration in middle Jurassic to gold, while the polymetallic mineralization was related to the Late Jurassic-Early Cretaceous igneous activity, and the epithermal mineralization in the middle and late stage of the Early Cretaceous. © 2017, Science Press. All right reserved. 相似文献
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On the Genesis of the Super-large Baguamiao Gold Deposit in Fengxian County, Shaanxi Province 总被引：2，自引：0，他引：2
Zhong Jianhua Zhang Guowei Exploration Department Petroleum University of Chin Dongying Shandong Department of Geology Northwest University Xi''an Shaanxi 《《地质学报》英文版》1997,71(2):189-203
The Baguamiao gold deposit in Fengxian County, Shaanxi Province, is a recentlyexplored super-large gold ore deposit. A comprehensive and deep-going study has revealedthat it is a polygenetic deposit: early-stage mineralization due to shearing, middle-stagemineralization due to hydrothermal alteration, and late-stage mineralization due toweathering, leaching and concentration at shallow depths. Shearing played a dominant role inthe formation of gold orebodies. 相似文献
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Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone—Hosted Gold Deposit and Discovery of Melt Inclusions 总被引：1，自引：0，他引：1
The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated fault mylonite zone of the Sinian-Silurian metamorphic rock series. In this study there have been discovered melt inclusions, fluid-melt inclusions and organic inclusions in ore-bearing quartz veins of the ore deposit and mylonite for the first time. The homogenization temperatures of the various types of inclusions are 160℃, 180 - 350℃, 530℃ and 870℃ for organic inclusions, liquid inclusions, two-phase immiscible liquid inclusions and melt inclusions, respectively. Ore fluid is categorized as the neutral to basic K+ -Ca2+ -Mg2+ -Na+ - SO2- 4-HCO3-Cl- system. The contents of trace gases follow a descending order of H2O＞CO2＞CH4＞(or ＜ ) H2＞CO＞C2H2＞C2I-I6＞O2＞N2.The concentrations of K , Ca2 + ,SO2-4,HCO3-,Cl- H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in ores from different levels of the gold deposit. This is significant for deep ore prospecting in the region. Daughter minerals in melt inclusions were analyzed using SEM. Quartz, orthoclase, wollastonite and other silicate minerals were identified. They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins. Sedimentary metamorphic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism, which possess melt-solution characteristics. Ore formation is related to the multi-stage forming process of silicate melt and fluid. 相似文献
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Regional Metallogenesis of the Chang’an Gold Ore Deposit in Western Yunnan: Evidences from Fluid Inclusions and Stable Isotopes 总被引：2，自引：0，他引：2
<正>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. 相似文献
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Organic geochemistry and comparisons of characteristics of the organic matter in wall rocks of the ore-controlling strata and ores of the Lower Jurassic Songling black shale formation and the related Songxi silver-antimony deposit of northeastern Guangdong have been studied in this paper.The results show that the Lower Jurassic Songling shale formation is a suite of biologic-rich and organic-rich ore-bearing marine sedimentary rocks.Micro-components of the organic matter in the Songling black shale formation consists primarily of algae,amorphous marine kerogen,solid bitument,and pyrobitument.The thermal evolution of organic matter is at the over-maturity stage.There is a general positive correlation between total organic carbon(CO)and metallogenetic elements such as Ag and Sb in the black shale formation.Organic matter in the host rocks in the Songxi ore deposit played a role in controlling the silver-antimony depositing environment during the forming process of the black shale ore-bearing formation.In the absence of vitrinite,the relative level of thermal maturity calculated by solid bitument reflectance indicates that the ore-forming temperatute of the Songxi silver-antimony deposit was about 150-170℃,which was considered as an epithermally reworked ore deposit.The roles of organic matter in the formation of the Sonxi ore deposit are a primitive accumulation of the metallogenetic elements(Ag,Sb) in the sea-water cycle system for ore source and a concentration of metals by ion exchange of chelation as well as reductionn of the oxidzed metals. 相似文献
10.
A Three—Stage Metallogenic Model for Gold Deposits in Metamorphosed Microclastic Rocks 总被引：1，自引：0，他引：1
Gld deposits occurring in metamorphosed microcelastic rocks are distributed extensively at home and abroad.Some deposits of this type are of superlarge tonnage.The formation of gold deposits in metamorphosed microclastic rocks involves three stages:the sedimentary stage,the regionally metamorphic stage,and the ore-forming stage.At the first stage,microclastic sedimentary source rocks were developed in a relatively semi-enclosed reducing sea basin and were enriched in carbon,sulfur and gold.At the second stage,the gold adsorbed on organic matter and clay minerals was relesed and poorly concentrated during the destruction of organic matter and the depletion of clay minerals by regional metamorphism with increase temperature and pressure.At the third stage,a tectono-hydrothermal event took place.As a result,gold was leached from metamorphosed microclastic rocks,transported to ore depositional locus and/or mixed with gold of other sources in the course of migration,and finally precipitared as ores.Gold deposits of this type were eventually formed at the third stage,and they also can be classified as the orogenic belt type and the activation zone type.The gold deposits occurring in metamorphosed microcalastic rocks are the products of reworking processes and the influence of magmatism should be taken into consideration in some cases. 相似文献
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叠生成矿作用主要是指早期成矿作用被晚期成矿作用叠加、复合和改造。晚期成矿作用的性质常与早期成矿作用不同,也就是说,在早先己有矿床(或矿体、矿源层)的基础上,叠加复合了晚期成矿作用,即成矿时间上有先后、空间产出上有重叠、并对早先形成的矿床进行复杂的复合、叠加和改造,使成矿作用具有多样性、复杂性,并可形成大矿、富矿。铁矿床中叠生成矿作用广泛发育。按矿床或矿体产出和形成的地质特征,中国叠生型铁矿床可分为风化淋滤型、热液叠加改造型和热液叠加复合型3个亚类。风化淋滤型铁矿床在中国分布有限,规模不大,工业利用价值不大,因而中国的叠生型铁矿床主要是指热液叠加改造型和热液叠加复合型两个亚类。热液叠加改造型主要是指早期的铁矿床(或矿体、矿源层)经后期热液叠加改造,使早期的较贫铁矿床(或矿体、矿源层)成为较富铁矿床(或矿体),这是中国BIF型铁矿床中最重要的富铁矿类型,以鞍本地区弓长岭二矿区为典型代表。弓长岭二矿区铁矿,早期在新太古代形成条带状磁铁石英岩(2528 Ma,贫矿石),后期在古元古代,含矿热液交代改造贫铁矿形成富铁矿(1840 Ma)。热液叠加复合型主要是指后期脉型铁(或稀土元素等)矿床叠加在早期(沉积或其他成因)铁等矿床上而形成的矿床,如白云鄂博铁-铌-稀土元素矿床和黔西菱铁矿矿床。白云鄂博铁-铌-稀土元素矿床的形成与火成碳酸岩有关,在中元古代(1.3 Ga)左右,区内火成碳酸岩的侵位,在早期主要形成以岩浆熔离作用为主的铁-铌-稀土元素矿,晚期叠加了加里东期稀土-铌矿化热液脉。古陆边缘构造带或陆内活化带是形成叠生型铁矿床的有利构造空间,较大的地球化学块体,为形成多期、多成因的矿床提供物质来源,叠生型铁矿床的形成明显受构造的控制。叠生成矿是复杂地质过程的一种具体表现。热液叠加改造型和热液叠加复合型的叠生型铁矿床的形成是因中国独特的大地构造环境决定的。叠生成矿作用的研究,尚处在初步阶段。加强对叠生成矿作用的研究,了解其形成的地质背景、成矿机制、作用过程、控矿因素等,对发展矿床学研究,认识区域成矿特征和指导地质找矿具有重要的理论和实际意义。 相似文献
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Ar-Ar Dating on the Metallogenesis of the Dongchuang Gold Deposit in the Xiaoqinling Area 总被引：2，自引：0，他引：2
LI Qiangzhi CHEN Yanjing ZHONG Zengqiu LI Wenliang LI Shaoru GUO Xiaodong JIN BaoyiCollege of Earth Space Science Peking University Beijing Institute of Gold Geology Armed Police Force of Chin Langfang Hebei College of Earth Sciences China University of Geosciences Wuhan Hubei 《《地质学报》英文版》2002,76(4):488-493
The Dongchuang gold deposit in the Xiaoqinling area is an orogenic-type lode gold deposit. It is one of the few superlarge (>100 t Au) deposits in China. Although it has been argued that it was formed in the Mesozoic, related isotopic age data have not been reported in previous studies. Based on detailed geological study, the authors have carried out isotopic dating on various metallogenic generations. The ore-forming process of the Dongchuang gold deposit consists of four stages: coarse-grained pyrite-bearing quartz veins (stage Ⅰ), fine-grained pyrite-quartz veinlets (stage Ⅱ), multi-sulfides (stage Ⅲ) and carbonate-quartz veinlets (stage IV). Ar-Ar dating on mineral separates of stages Ⅰ, Ⅱ and Ⅲ yields plateau ages of 142.9±2.9 Ma, 132.2±2.6 Ma and 128.3±6.2 Ma, respectively. Sericite separates from stage Ⅱ assemblage also yield an Ar-Ar isochron age of 132.6±2.7 Ma, similar to the Ar-Ar plateau age. These results suggest that the Dongchuang gold deposit was mainly formed during 143-128 M 相似文献
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红花沟金矿矿区内已发现40余条金矿脉和含金石英脉,它们均产于在区域Ⅰ级和Ⅱ级断裂构造(龙头山断裂)控制下侵位的燕山期龙头山花岗岩岩体与太古宙古老变质岩的内、外接触带上.蚀变岩型矿体是2000年发现和圈定出的新类型金矿体,分布在走向NW305 °的龙头山断裂的下盘,受其次级弧形构造所控制.分析认为沿龙头山断裂向上迁移的含金流体在运移到碎裂状糜棱岩化花岗岩后,在其中交代、充填并产生硅化、绢云母化和黄铁绢英岩化,形成蚀变岩型金矿体.晚阶段含金流体则在已蚀变的碎裂状花岗岩中充填成矿,进一步提高了蚀变岩型矿体和矿石的工业品位. 相似文献
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小秦岭东闯金矿S507脉地质特征及构造控矿分析——S507单脉储量过半的启示 总被引：1，自引：0，他引：1
小秦岭矿集区东闯金矿为石英脉型矿化类型,其最突出的特点是矿脉延伸长、延深大,且矿体连续性好,仅S507一条矿脉在矿区走向延长超过3.2km,垂向延深超过1600m(深部尚未圈闭),单脉勘探提交黄金储量达47.2t,约占该矿黄金储量的70.35%。研究表明,该区从早到晚经历了四期褶皱-剪切作用,表现为从塑性流变到晚期构造隆升。其中五台期褶皱翼部的构造薄弱带发育成了压扭性脆韧性剪切带,又被燕山早期第三期褶皱作用改造成张扭性韧脆性剪切带,并为含矿流体的大规模贯入和成矿提供了有利的容矿空间。来自于深部的成矿流体,在较高温度、压力等物理化学条件控制下,快速贯入到区域性韧脆性剪切带中积聚、沉淀成矿。也正是由于含矿流体快速贯入区域性韧脆性剪切带,而导致含矿流体物理化学条件的快速改变,使得某条矿脉储量达到全矿黄金储量的50%以上。 相似文献
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太古宙绿岩建造中与韧性剪切带有关的动力变质热液金矿床(排山楼式),早-中元古代变质碎屑岩建造中的浊积岩金矿床(猎岭式或白云式)和与显生宙交代-深熔花岗岩类有关的钾质蚀变岩型金矿床(东坪-后沟式)是华北地台北缘近几年发现和探明的具有巨大资源潜力的新类型金矿床。区域潜在含金性和适宜的活化营力是这些矿床形成的基本条件。通过矿源层(岩)中成矿物质的二次活化再成矿是它们的主要成矿机制。稳定同位素研究成果可为此提供证据。 相似文献
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燕山-喜马拉雅旋回在中国内生金矿成矿作用中的重要意义及其原因探讨 总被引：4，自引：0，他引：4
中国内生金矿分布广，矿化产出层位多，矿床类型复杂。成矿物质主要来自四类含金地质建造。矿化与构造关系密切，与岩浆活动也有程度不同的联系。实际资料表明，燕山-喜马拉雅期是中国内生金矿的主要成矿期。中新生代中国大陆所处的特殊板块运动环境所导致的构造-岩浆事件及随之出现的前所未有的热效应和扩容空间效应，是中国内生金矿集中形成于这一时期的根本原因。本文最后对中国内生金矿成矿的演化过程作了归纳。 相似文献