共查询到18条相似文献，搜索用时 156 毫秒
1.
Sediment-hosted gold deposits are the major type of gold resources in china,Concen trated mostly in the two“Triangle Regios“,they are generally hosted in fine-clastic turbidite,hydrothermal chet and marl ranging from cambrian to Triassic in age,structurally controlled by domes,anticlines and second-ordered faults.They are similar to the Carlin-type gold deposits in mineral assemblage and geochemical marks,with an element association closely comparable to those of modern springs and submarine hydrothermal sediments.Organic matter may have played an important role in mineralization .The ore solution may be hydrothermally altered meteoric water developed i areas of local geothermal anomaly. 相似文献
2.
Geological-Geochemical Characteristics of Carlin-and Carlin-Like-Type Gold Deposits in south Qinling Mountains 总被引：2，自引：0，他引：2
In this paper an intergrated geological and geochemical comparison is made of Carlintype and Carlin-like-type gold depostis in the region of South Qinling with their associated hydrothermal sedimentary lead-zinc pdposits,the Carlin-type deposits in the Yunnan-Guizhou-Guangxi gold triangle,China,the Carlin gold deposits,Carlin,western United States,and the Muruntau-type gold deposits in Uzbekistan.The comparative study indicates that the formation of these deposits has an intimate coupling relation with the mechanism of the tectonic movement of modern plates.Therefore,these deposits belong to those that were formed in the orogenic stage. They have the following similar characteristics:they are all sediment-hosted.occur in a tectonic environment of extensional rifting nature and show the characteristics of syngenetically modified mineralization.On the other hand,they alsso have noticeable differences:they are different in respect to their tectonic settings.association and structure of orogenic belts and complexity and strength of the modified mineralization.The regional tectonic evolution and extensive mineralization in orogenic belts are different expressions of the same continental dynamic process. 相似文献
3.
Zhang Sheng Li Tongjin Wang LiankuiGuangzhou Institute of Geochemistry Chinese Academy of SciencesWushan Guangzhou 《《地质学报》英文版》1997,71(4):433-445
The Changkeng gold-silver deposits consist of a sediment-hosted, disseminated gold deposit and a replacement-type silver deposit. The mineralizations of gold and silver are zoned and closely related to the silicification of carbonate and clastic rocks, so that siliceous ores dominate in the deposit. The mineralizing temperature ranges mainly from 300 to 170℃, and K+, Na+, Ca2+, Mg2+, and Cl- are the major ions in the ore-forming fluid. Calculations of distribution of metal complexes show that gold is mainly transported by hydrosulphide complexes, but chloride complexes of silver, iron, lead, and zinc, which are transformed into hydroxyl and hydrosulphide complexes under neutral to weak-alkaline circumstances in the late stage, predominate in the ore-forming solutions. Water-rock interaction is confirmed to be the effective mechanism for the formation of silver ores by computer modelling of reaction of hydrothermal solution with carbonate rocks. The solubility analyses demonstrate that the precipitation 相似文献
4.
Platinum-group elements （PGE） in PGE-rich porphyry copper （gold） deposits are mainly Pt and Pd, whereas the concentrations of other PGE （Ru, Rh, Os, Ir） are significantly low. Moreover, Pt and Pd mainly exist in sulfides in the forms of crystal lattice or tiny platinum-group mineral （PGM） inclusions. The present data show that there is a positive relationship between Pt and Pd concentrations and Cu （Au） in porphyry copper （gold） deposits. The comparison of chondrite-normalized PGE distribution patterns between the ore-bearing porphyry intrusions and ore-barren porphyry intrusions in arc setting, 187^Os/188^Os, 87^Sr/86^Sr and S isotopes for porphyry copper （gold） deposits shows that PGEs were mainly derived from the mantle, and fluids from subduction zones devoted trivial PGE to the magma. The porphyry copper （gold） deposits associated with subducted events are most probably enriched in PGE, whereas those related to crustal thickening, lithospheric delamination or underplating rarely concentrate PGE. The osmium isotopic compositions in porphyry copper （gold） deposits reveal that （187^Os/188^Os）i values are highly variable and not lower than those of primitive upper mantle （PUM） and mantle peridotite, however, osmium concentrations are commonly lower than mantle peridotite, suggesting that parental magmas of some porphyry intrusions had experienced crustal contamination during magma evolution. Experimental investigations have proved that PGE exist in the forms of Cl^- and HS^- complexes during transportation and migration of the oreforming fluids. This paper summarizes previous studies including crucial controlling factors and mechanisms for PGE enrichment, and points out that the mantle-derived magmas parental to porphyry intrusions are the prerequisite for PGE enrichment in porphyry copper （gold） deposits. Favorable physical and chemical conditions （including salinity, temperature, pressure, pH, and oxygen fugacity） in hydrothermal fluids crucially control the 相似文献
5.
The sediment-hosted disseminated gold deposits in the Oinling region are of sedimentation-slight-metamorphic origin superimposed by hydrothermal reworking at moderate-low temperatures and are well comparable with the typical Carlin gold deposits in the United States.In view of the confusing concept concerning the “sediment-hosted”and “Carlin-type” gold deposits,the authors propose that the term“sediment-hosted gold deposit”should be used in a broad sense which encompasses at least the four subtypes,i.e.,the Carlin type,the metamorphic fine clastic type,the hydrothermal sedimentary type and the vein type.In oter words,the “Carlin-type”should not be used as a synonym for “sediment-hosted”but is recommended as a subtype under the general category of “sediment-hosted gold deposits” 相似文献
6.
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. 相似文献
7.
华仁民 《中国地球化学学报》1990,9(3):231-243
The Dongchuan-type copper deposits have long been studied and well reported because of their great economic significance.The present paper proposes a “sedimentation-reworking“ origin for this type of deposits to challenge the current “sedimentation-metamorphism“ model which has been widely asscpted since 1970s.According to the new idea,orebodies were not directly deposited in the Luoxue dolomite where they are hosted.Instead,copper was preliminarily concentrated in the Yinmin Formation.During or after diagenesis,copper in the Yinmin Formation was mobilized and leached by hydrothermal solutions derived from the interstitial water of sediments under the high geothermal gradient of rift environment,Thus,copper was transported from the source bed(the Yinmin Formation)upward to the Luoxue algal dolomite where sulfur was produced by the reduction of sulfates.The copper sulfides were formed through replacement of initial sulfides by Cu-bearing solutions. 相似文献
8.
Fine disseminated gold deposits occurring along the southeastern margin of the Yangtze Plate belong to the epithermal type resulting from different systems of ore-forming fluids.According to their sources, the ore-forming fluids can be divided into four systems: a)meteoric water system; b)oil-brine system; c)basin-brine system;and d)magmatic-formation water system.The four hydrothermal systems are responsible for four types of gold deposits, respectively.The meteoric water system produces hot spring gold deposits. The basin-brines,which are derived from fissure water, structural water and absorbed water sealed up in strata, are responsible for the absin-brine-type deposits.The oil-brine system, having the same source as the bain-brines ,is characterized by the involvement of organic matter and is responsible for the oil-brine-type deposits. Inclusion fluid data show that there are obvious differences in chemical composition and carbon, oxygen,hydrogen and sulfur isotopes for these hydrothermal systems.Different metallogenic provinces, in which one of the four systems is dominant, can be recognized in the region. 相似文献
9.
李文达 《中国地球化学学报》1990,9(4):304-318
The so-called“Yangtze-type”copper deposits include:（1）Cu-bearing massive pyrite bed ,(2)Cu-bearing skarn and magnetite-type ore deposits,with replacement Cu-vein-type deposits near the metasomatic zone,and (3)mineralized intrusive bodies and breccia pipes ,some of which are known as porphyry copper ores(e.g.Chengmenshan).This type of ore deposits is a typical example to verify the polygenesis of inost of the deposits in China,as has been promoted by Prof.Tu Guangchi in view of the polycyclic development of the geological history in China.This paper is con-cemed with one sub-type of such deposits. 相似文献
10.
《地学前缘(英文版)》2020,11(5):1477-1494
The gold deposits in the Youjiang basin,totaling 25 Moz gold,have traditionally been thought to be of Carlintype,particularly those with extensional structural geometries in the northern basin dominated by platform sedimentary sequences.However,the structural geometries,mineralization styles and alteration types for the Jinya,Gaolong and Nakuang gold deposits in the south-central part of the basin are remarkably similar to those of unequivocal orogenic gold deposits.Structural studies show that gold mineralization in the three gold deposits was controlled by tight "locked-up"anticlines with NW—SE-to E-W-trending and/or concomitant thrusts and/or shear zones,which resulted from NE-SW-to N-S-trending compression or transpression following the Early Triassic closure of the Paleo-Tethyan Ocean.Alteration zones in these deposits are dominated by silicification(quartz),sericitization,sulfidation and carbonation.Zoned pyrites in these deposits comprise Au-poor cores and invisible Au-bearing rims with minor external free gold.Euhedral to subhedral auriferous arsenopyrites also contribute to the gold budget.These features indicate that the three gold deposits are sediment-hosted orogenic gold deposits that contrast markedly with the Carlin-type gold deposits in the northern part of the Youjiang basin in terms of structural geometry and timing,mineralization style and nature of associated alteration.Although additional reliable ages using robust methodologies are still required,the older isotopic ages of the gold deposits in the south-central Youjiang basin are also consistent with earlier formation during transpression that predated extension during orogenic collapse,the period of formation of the Carlin-type gold deposits in the northern Youjiang basin. 相似文献
11.
微细浸染型金矿床的一种新的亚类--硅质岩型金矿 总被引：3，自引：0，他引：3
根据广东和广西 3个金矿床 (长坑 ,高龙和果提 )的资料认为 ,微细浸染型金矿 (卡林型金矿 )中存在一种亚类 ,叫做硅质岩型金矿。它以碳质硅质岩为含矿主岩 ,该岩石宏观上呈层状 ,主要由细小的石英和碳质物组成 ,金呈微细浸染状存在。该类矿床具有一般微细浸染型金矿床的主要特征 ,但不属于后生热液蚀变交代成因 ,而是主要通过热水沉积作用形成 ,同时可以混入一定量的生物沉积和冷水沉积的物质。由此认为 ,微细浸染型金矿有多种成因 ,包括后生热液成因 ,热水沉积成因以及其他成因 ,应该从“热水沉积同生成矿”的角度考虑硅质岩型金矿的找矿思路。建议对一些金矿区的“硅化岩”重新研究 ,查明其真正属性。中国南方是寻找硅质岩型金矿床极有远景的区域 相似文献
12.
沉积岩型铅锌矿床的成矿系统研究 总被引：9，自引：0，他引：9
沉积岩型铅锌矿床是铅锌矿床中重要类型之一。在系统论述沉积岩型铅锌矿床成矿背景、地球化学和矿床类型的基础上,分别阐明了沉积喷流型(SEDEX)、密西西比型(MVT)和砂岩型(SST)3个成矿系统的成矿要素、作用过程、矿床和异常组合以及成矿模式。对3个铅锌成矿系统作了全面对比,获得一些认识:(1)SST矿床的矿化表现为对构造和高孔隙度有利岩性而不是地层层位的依赖性;(2)云南会泽碳酸盐型铅锌矿(MVT)成矿物质除热卤水沉淀来源外,还有火山岩系的提供,属后生混合流体成矿作用;(3)沿古陆边缘同生断裂构造发生的海底热水喷流沉积作用为SEDEX型铅锌成矿奠定了物质基础;裂谷伸展期常有“双峰式”火山活动,提供部分矿源、热源、水源;同生断层长期活动提供热水循环通道和矿质沉积场所;(4)风化剥蚀的变质基底为三者提供了成矿物质,成矿热卤水在盆地中经过了演化过程。 相似文献
13.
文章对与沉积岩容矿有关的热液广西高龙微细浸染型金矿、新疆霍什布拉克铅锌矿、广西盘龙铅锌矿和下雷锰矿等矿床硫化物进行硫同位素测定,硫同位素组成分别为-15.3‰~+15.6‰,-18.8‰~+24.2‰,-21.0‰~+26.4‰,-32.6‰~+32.2‰。硫同位素可以达到平衡(高龙、霍什布拉克、下雷),也可以没达到平衡(盘龙)。δ34SΣS值在+13‰~+28‰之间,表明与沉积岩容矿热液矿床中硫来源于海水硫酸盐还原硫,但不排除有岩浆硫的加入。 相似文献
14.
Genesis of sediment-hosted stratiform copper–cobalt deposits, central African Copperbelt 总被引：3，自引：0，他引：3
J.L.H. Cailteux A.B. Kampunzu C. Lerouge A.K. Kaputo J.P. Milesi 《Journal of African Earth Sciences》2005,42(1-5):134
The Neoproterozoic central African Copperbelt is one of the greatest sediment-hosted stratiform Cu–Co provinces in the world, totalling 140 Mt copper and 6 Mt cobalt and including several world-class deposits (10 Mt copper). The origin of Cu–Co mineralisation in this province remains speculative, with the debate centred around syngenetic–diagenetic and hydrothermal-diagenetic hypotheses.The regional distribution of metals indicates that most of the cobalt-rich copper deposits are hosted in dolomites and dolomitic shales forming allochthonous units exposed in Congo and known as Congolese facies of the Katangan sedimentary succession (average Co:Cu = 1:13). The highest Co:Cu ratio (up to 3:1) occurs in ore deposits located along the southern structural block of the Lufilian Arc. The predominantly siliciclastic Zambian facies, exposed in Zambia and in SE Congo, forms para-autochthonous sedimentary units hosting ore deposits characterized by lower a Co:Cu ratio (average 1:57). Transitional lithofacies in Zambia (e.g. Baluba, Mindola) and in Congo (e.g. Lubembe) indicate a gradual transition in the Katangan basin during the deposition of laterally correlative clastic and carbonate sedimentary rocks exposed in Zambia and in Congo, and are marked by Co:Cu ratios in the range 1:15.The main Cu–Co orebodies occur at the base of the Mines/Musoshi Subgroup, which is characterized by evaporitic intertidal–supratidal sedimentary rocks. All additional lenticular orebodies known in the upper part of the Mines/Musoshi Subgroup are hosted in similar sedimentary rocks, suggesting highly favourable conditions for the ore genesis in particular sedimentary environments. Pre-lithification sedimentary structures affecting disseminated sulphides indicate that metals were deposited before compaction and consolidation of the host sediment.The ore parageneses indicate several generations of sulphides marking syngenetic, early diagenetic and late diagenetic processes. Sulphur isotopic data on sulphides suggest the derivation of sulphur essentially from the bacterial reduction of seawater sulphates. The mineralizing brines were generated from sea water in sabkhas or hypersaline lagoons during the deposition of the host rocks. Changes of Eh–pH and salinity probably were critical for concentrating copper–cobalt and nickel mineralisation. Compressional tectonic and related metamorphic processes and supergene enrichment have played variable roles in the remobilisation and upgrading of the primary mineralisation.There is no evidence to support models assuming that metals originated from: (1) Katangan igneous rocks and related hydrothermal processes or; (2) leaching of red beds underlying the orebodies. The metal sources are pre-Katangan continental rocks, especially the Palaeoproterozoic low-grade porphyry copper deposits known in the Bangweulu block and subsidiary Cu–Co–Ni deposits/occurrences in the Archaean rocks of the Zimbabwe craton. These two sources contain low grade ore deposits portraying the peculiar metal association (Cu, Co, Ni, U, Cr, Au, Ag, PGE) recorded in the Katangan sediment-hosted ore deposits. Metals were transported into the basin dissolved in water.The stratiform deposits of Congo and Zambia display features indicating that syngenetic and early diagenetic processes controlled the formation of the Neoproterozoic Copperbelt of central Africa. 相似文献
15.
Craig A. Johnson Poul Emsbo Forrest G. Poole Robert O. Rye 《Geochimica et cosmochimica acta》2009,73(1):133-99
Sulfur- and oxygen-isotope analyses have been obtained for sediment-hosted stratiform barite deposits in Alaska, Nevada, Mexico, and China to examine the environment of formation of this deposit type. The barite is contained in sedimentary sequences as old as Late Neoproterozoic and as young as Mississippian. If previously published data for other localities are considered, sulfur- and oxygen-isotope data are now available for deposits spanning a host-rock age range of Late Neoproterozoic to Triassic. On a δ34S versus δ18O diagram, many deposits show linear or concave-upward trends that project down toward the isotopic composition of seawater sulfate. The trends suggest that barite formed from seawater sulfate that had been isotopically modified to varying degrees. The δ34S versus δ18O patterns resemble patterns that have been observed in the modern oceans in pore water sulfate and water column sulfate in some anoxic basins. However, the closest isotopic analog is barite mineralization that occurs at fluid seeps on modern continental margins. Thus the data favor genetic models for the deposits in which barium was delivered by seafloor seeps over models in which barium was delivered by sedimentation of pelagic organisms. The isotopic variations within the deposits appear to reflect bacterial sulfate reduction operating at different rates and possibly with different electron donors, oxygen isotope exchange between reduction intermediates and H2O, and sulfate availability. Because they are isotopically heterogeneous, sediment-hosted stratiform barite deposits are of limited value in reconstructing the isotopic composition of ancient seawater sulfate. 相似文献
16.
秦岭造山带沉积岩容矿金矿床地质特征和矿床成因 总被引：5，自引：1，他引：4
讨论了秦岭造山带沉积岩容矿金矿床地质背景、地质特征和矿床成因。认为俯冲碰撞过程中形成的浊积岩系是金矿的主要矿源层,在金矿源层原始沉积时,热水沉积起了重要作用。在褶皱造山过程中,金元素发生了活化、再分配,在层间破碎带、构造片理化带、剪切带等处发生了富集。在印支－燕山期岩浆侵入作用的热驱动下,金矿最终在有利构造部位定位,富集成矿。 相似文献
17.
沉积型铜矿作为重要的铜矿类型之一,一直是工业界找矿和开发的重点。中非铜(-钴)矿带是世界著名的巨型沉积型铜矿带之一。赞比亚谦比希铜矿是我国企业在非洲矿业开发的成功典范项目,其矿体分布和产状严格受新元古代加丹加超群的下罗恩组地层控制,含矿岩石为下罗恩组下部的含矿泥质页岩、砂岩。本文通过对谦比希铜矿的矿床地质特征、成矿地质背景、成岩-成矿规律的详细研究,揭示了其含矿地层和矿体明显受古沉积环境、基底形态的控制;成岩-成矿过程经历了海侵-海退过程,沉积古地理环境为滨浅海蒸发背景。赞比亚铜带省和西北省拥有巨大的资源和找矿潜力,未来必将吸引更多投资。 相似文献