新疆主要矿床的区域成矿件的初步探讨

1. The division of main tectonic regions and their minerogenetic belts. In quite a few fold zones of geosynclinal systems, such as Altay, Junggar, Tianshan, Kunlun and Beishan Mountains, there exist ore zones of rare metals, muscovite, Fe, Cr, Mn, Au, P, asbestos, nonferrous metals, etc., whereas in Tarim platform, Fe, Al, Zn, Cr, P, S, Cu and coal minerogenetic belts have already been found. 2. Minerogenetic relations between major types of ore deposits and magmatic series, sedimentary formation, or metamorphic facies. Cr, Cu, Ni, Co, Fe and rare metals of magmatic type are related to magnesian ultrabasic, ferruginous basic-ultrabasic or acid-alkaline rocks, nonferrous and noble metals, Fe and asbestos of hydrothermal type are found associated with acid, intermediate-acid intrusive rocks generally rich in alkali; rare metals and muscovite of pegmatitic type are genetically in connection with acid-alkaline rocks, Fe of volcanic type has to do with alkali-rich acid to basic eruptive rocks, coal, Fe, Mn, Al, Cu, Pb, Zn, P and S of sedimentary type occur mostly in clastic carbonate-rocks, siliceous carbonate rocks, detrital rocks, red beds, salt-bearing or coal-bearing formations, Fe, P of sedimentary-metamorphic type are preserrt: within such metamorphic facies as ferro-siliceous hornblendite, green schist-marble or siliceous-magnesian carbonatite. 3. Regularity of the formation and distribution of ore deposits. The formation and distribution of ore deposits are generally characterued by zoning, fault-controlling, polycycles, stratabinding, inheritance, regeneration, ore combination, equidistance, migration and superimposition, with individual ore deposit having its specific characteristics.     

Geology,geochemistry and sulphur isotopes of the Hat Han gold–antimony deposit,NE Vietnam

The Song Hien Rift basin is considered as one of the important regions for gold deposits in North East Vietnam. Host rocks of a number gold deposits in the Song Hien Rift basin are mainly in Lower Triassic sedimentary formations. However, there is the Hat Han gold deposit hosted in fined-grained mafic magmatic rocks with similar characteristics as gold deposit hosted in the Triassic sediments. Sulphur isotopic compositions of sulphide are similar to those in carbonaceous shale, suggesting that the sulphur was ‘borrowed’ from sedimentary rocks in filling the rift basin. Gold-bearing sulphides (pyrite and arsenopyrite) are the main form of Au presence in the ore. Gold in pyrite is present as Au^+ 1, and a minor amount of as nanoparticles of native Au (Au⁰); whereas in arsenopyrite, gold is chemically bound as the octahedral complex AuAs₂. Analysis of geology, as well as geochemical and isotopic studies show that the genesis of the Hat Han gold deposit is not related to the Cao Bang mafic magmatism; instead the latter only serves as (ore) host rock. The geochemical results presented above suggest that the gabbro host rock only supplies iron needed for sulphide formation. With regard to ore genesis, the Hat Han gold deposit in the Song Hien rift basin was generated in the similar way as sediment-hosted gold deposit. There are many similar typomorphic features between the Hat Han deposit and Carlin-like deposits in the Nanpanjang sedimentary basin in China.     

格陵兰地质矿产特征及主要金属矿产找矿方向

格陵兰为前寒武纪地盾区,出露的岩石以片麻岩和上壳岩为主,形成于太古代和元古代一系列碰撞造山环境;在地盾西部、东部和北部边缘广泛发育了元古代一中生代的沉积地层和盆地;岩浆活动贯穿于太占代至新乍代,形成了岩性多样、规模不一的岩浆岩。格陵兰矿产资源丰富,已发现铁、金、铅锌、稀有稀土、铂族、铜、镍等多种矿产资源。分析表明,格陵兰西南部、中西部和北部分布的条带状含铁建造是寻找BIF型铁矿的有利靶区;西南部太古代绿岩带、南部凯蒂利z也活动带具有寻找绿岩带型金矿和造山带型金矿的潜力;西南部碳酸岩、碱性岩岩体是寻找稀有稀土金属矿床的主要靶区;西北和东北部发育的沉积箍地和地层是寻找SEDEX型和MVT型铅锌矿以及砂页岩型铜矿的有利地区;西南和东南部分布的太古代一元占代丛性、超基性岩是寻找铂族元素和镍矿的有利靶区。     

对金矿成矿作用的重新认识

含金建造是富含C、S、Fe的沉积岩系或火山沉积岩系,根据形成环境和演化特点,将含金建造划分5种类型.认为金元素地球化学二重性决定其成矿作用具有二重性,含金建造是各种类型内生金矿床成矿物质的直接来源,成矿热液来源于建造水.对独立金矿床进行了类型划分,强调含金建造的存在是金矿成矿的基本条件,运用液态矿源说和二次迁移论探讨了成矿作用机制,并建立了金矿成矿模式.     

Physical and chemical characteristics of the host rocks in controlling the mineralization of the Chinkuashih high-sulfidation gold–copper deposits,northeastern Taiwan

Epithermal high-sulfidation gold–copper deposits at the Chinkuashih area in northeastern Taiwan occur both within Pleistocene andesite and Miocene sedimentary rocks. Spatially associated Penshan and Shumei deposits of a major gold–copper vein, the “Main Vein”, were both mineralized along an extended normal fault zone. These deposits appear to have formed from the same original hydrothermal fluids, but in different host rock types. However, the results of trace element analyses indicate that the andesite-hosted Penshan deposit has distinctly higher ore-metal and lower LREE contents than the sediment-hosted Shumei deposit. The development of higher grade ore at Penshan deposit resulted from the presence of ferrous Fe-rich minerals in andesite that caused the deposition of a larger amount of pyrite and gold during the sulfidation–reduction reactions of acidic fluid with host rocks. Moreover, the porous–permeable silicic alteration facies of the Penshan deposit provided conduits for the circulation of ore-metal bearing fluids and the trapping of metal-bearing magmatic volatile to precipitate ore minerals. On the other hand, the higher LREE contents of the Shumei open pit reflect the low pH and abundance of mainly SO₄^2? ion in the hydrothermal fluid perhaps because sedimentary host rocks were not able to neutralize and to reduce the acidic fluid effectively through the reactions of fluid and host rocks. Moreover, the Fe-poor host rocks have lower capacity to consume H₂S and precipitate pyrite and gold. In addition, the circulation of ore-metal bearing fluids and trapping of metal-bearing magmatic volatile to precipitate ore minerals could be handicapped by the low permeability and porosity of the silicified sedimentary rocks. It is apparent from these observations that physical and chemical characteristics of host rocks are important factors in controlling the ore grade of the Chinkuashih high-sulfidation gold–copper deposits.     

Wall-rock metasomatism of carbonaceous terrigenous rocks in the Lena gold district

The Lena gold district is situated in the fold-and-shear belt of the southern framework of the Siberian Platform. The gold deposits are hosted in the Riphean-Vendian Khomolkho and Aunakit formations, revealing the strict control of ore mineralization by folding and shearing. The microstructure of metasomatically altered ore-bearing carbonaceous sedimentary rocks at the Sukhoi Log, Golets Vysochaishy, and Verninsky deposits (the latter includes the Pervenets vein zone) testifies to parallelism in the development of shearing, foliation, and ore-forming metasomatism. The local pressure gradients are marked by removal of silica from pressured zones into opened cleavage fractures and pockets. Two metasomatic stages are recognized: (1) early sodic metasomatism, which is characterized by the assemblage of magnesian siderite and paragonite, and (2) late potassic metasomatism, with formation of muscovite in association with sideroplesite and ankerite. The rocks altered at the early stage are distinguished by elevated Ni, Cr, and probably PGE contents. The second stage, close in age to the emplacement of Hercynian granitic plutons, was accompanied by the gain of chalcophile metals and deposition of the bulk of gold. In mineral composition, the metasomatic rocks are close to beresites, but the alteration differed in somewhat elevated alkalinity, so that microveinlets of albite and potassium feldspar occur in the ore zone together with muscovite. The ratio of modal muscovite to paragonite contents in orebodies is substantially higher than in the surrounding metasomatized rocks. This ratio directly depends on the degree of rock permeability and the intensity of the flow of ore-forming solutions. Carbonaceous matter (CM) in the ore zone underwent reworking and redeposition. CM is graphitized to a lesser extent than in the rocks affected by regional metamorphism. The spatial distribution of CM containing nitro and amino groups indicates more oxidizing conditions in the zone of ore deposition than at a distance from this zone. The temperature of metasomatic processes estimated from the muscovite, muscovite-paragonite, and chlorite mineral thermometers and fluid inclusions in quartz was 300–350°C at a pressure of about 1 kbar. The S, O, and C isotopic compositions of ore-forming fluids that pertain to the second stage of metasomatism (δ³⁴S= +8.5‰, δ¹⁸O = +10‰, and δ¹³C= ?11 to ?18‰) indicate their crustal origin. The generally similar conditions and products of the ore-forming metasomatic process at the giant Sukhoi Log deposit and at the small Golets Vysochaishy deposit are combined with some differences. The formation of the described deposits was related to the deep convection of fluids along shear zones followed by more local flows of postmagmatic solutions derived from the emplaced granitic magma.     

新疆北部早石炭世沉积建造及其形成的大地构造环境

本文详细地研究了新疆北部早石炭世发育的三类沉积建造:碳酸盐建造、陆屑建造和火山-沉积建造,并进行了建造区的划分,据此论述了早石炭世新疆北部的大地构造环境及其分区。     

秦岭凤太地区金矿床成矿地质条件与时空分布特征

秦岭凤太地区金矿床产于商丹板块对接带和南秦岭边缘海盆区,含金建造为火山碎屑岩和细碎屑(热水)沉积建造,赋矿围岩以绿片岩相细碎屑岩为主。区内的金矿床主成矿年龄为220~170Ma,属晚印支期,主成矿期后叠加燕山期构造热液。空间上金矿带与铅锌矿带呈平行展布,金矿与韧性构造关系密切,显示了构造边界对金矿带的控制,具有继承性特征的脆韧性剪切带为含矿构造,北北东向与近东西向(北西西向)断裂的复合是金矿富集的主要构造特征。     

右江裂谷区三叠系岩石物性特征及其与金矿化的关系

本文阐述了右江裂谷区微细粒浸染型金矿床控矿层位三叠系百蓬组泥质粉砂岩及砂质泥岩的粒度，比表面、孔隙度及孔隙类型和渗透率等物性特征，讨论了与其成矿流体的循回、水岩反应及其有效浸取围岩矿物质的关系。在此基础邮成矿流体和矿矿物质主要来自于地层；由于热液躲避低势能方向迁移，造成断理解发的盆地边缘区和水下隆起周围的环状断裂带为金矿床沉淀的场所。并通过形成金矿所需热液量的估算得出，该区金矿床的形成，是由于热流     

陕西秦岭地区泥盆系同生断裂、岩相与海底喷流沉积铅锌矿床

秦岭泥盆系及其喷流沉积铅锌矿床，位于扬子板块北部边缘的线型裂谷环境中。裂谷系的扩张演化伴随三组同生断裂活动：近东西向、北东向和南北向，它们具有继承性活动特点，对本区地质演化起着重要的构造调整作用。泥盆纪岩相古地理特征，是研究区统一的构造沉积环境下出现的，岩相变化往往与同生断裂平行，直接控制了泥盆系的沉积。在该环境下形成的铅锌矿和铁白云石硅质岩，具有海底喷流沉积岩的地质地球化学特征。可作为恢复构造沉积环境和同生断裂的重要标志。本区同生断裂及岩相与赋存于泥盆系中的喷流铅锌矿床之间的相互关系，表现为东西向的构造一岩相带控制着铅锌成矿带的分布，北东向和南北向构造一岩相带制约着一系列单个矿床的线形分布。     

Nature and source of the ore-forming fluids associated with orogenic gold deposits in the Dharwar Craton

Neoarchean orogenic gold deposits, associated with the greenstone-granite milieus in the Dharwar Craton include(1) the famous Kolar mine and the world class Hutti deposit;(2) small mines at HiraBuddini, Uti, Ajjanahalli, and Guddadarangavanahalli;(3) prospects at Jonnagiri; and(4) old mining camps in the Gadag and Ramagiri-Penakacherla belts. The existing diametric views on the source of ore fluid for formation of these deposits include fluids exsolved from granitic melts and extracted by metamorphic devolatilization of the greenstone sequences. Lode gold mineralization occurs in structurally controlled higher order splays in variety of host rocks such as mafic/felsic greenstones, banded iron formations, volcaniclastic rocks and granitoids. Estimated metamorphic conditions of the greenstones vary from lower greenschist facies to mid-amphibolite facies and mineralizations in all the camps are associated with distinct hydrothermal alterations. Fluid inclusion microthermometric and Raman spectroscopic studies document low salinity aqueous-gaseous(H_2O + CO_2 ± CH_4 + NaCl) ore fluids,which precipitated gold and altered the host rocks in a narrow P-T window of 0.7-2.5 kbar and 215-320℃. While the calculated fluid O-and C-isotopic values are ambiguous, S-isotopic compositions of pyrite-precipitating fluid show distinct craton-scale uniformity in terms of its reduced nature and a suggested crustal sulfur source.Available ages on greenstone metamorphism, granitoid plutonism and mineralization in the Hutti Belt are tantamount, making a geochronology-based resolution of the existing debate on the metamorphic vs.magmatic fluid source impossible. In contrast, tourmaline geochemistry suggests involvement of single fluid in formation of gold mineralization, primarily derived by metamorphic devolatilization of mafic greenstones and interlayered sedimentary rocks, with minor magmatic contributions. Similarly, compositions of scheelite, pyrite and arsenopyrite point toward operation of fault-valves that caused pressure fluctuation-induced fluid phase separation, which acted as the dominant process of gold precipitation,apart from fluid-rock sulfidation reactions. Therefore, results from geochemistry of hydrothermal minerals and those from fluid inclusion microthermometry corroborate in constraining source of ore fluid,nature of gold transport(by Au-bisulfide complex) and mechanism of gold ore formation in the Dharwar Craton.     

Geochemical Features and Formation of the Auriferous Cherts in the Mojiang Gold Deposit,Yunnan

Auriferous cherts in the Middle Carboniferous Jinchang Formation are the dominant host rocks of auriferous quartz veins and mixed orebodies comprised of gold-bearing quartz veins and cherts in the Mojiang gold deposit.The rocks exhibit sedimentary texture and structure and are composed of hot-water deposited minerals.The FeO,Fe2O3,Au and Ag contents of the auriferous cherts are high;the Cr,Ni and Co contents are also high but significantly variable;MnO/TiO2 and TFe/TiO2 ratios are relatively higy.As viewed from a few diagrams that distinguish different chert formations,the auriferous cherts are in or near the range of hot-water deposited cherts.Because the correlation coefficients between Au contents and those of Cr, Ni of the rocks are negative,a great Au amount in the cherts might not be brought about by later hydrothermal alterations.The rare-earth elements,O and Si isotopic compositions of the auriferous cherts demonstrate that the cherts belong to hot-water deposited rocks.The later hydrothermal alterations made the petrochemical compositions of the cherts deviate from the characteristics of hot-water deposition.In general,the geological and geochemical features of the auriferous cherts demonstrate that the rocks were formed by hot water deposition.     

我国沉积建造的含金性

将我国的沉积建造划分为前地槽型、地槽型、地台型和地洼型４类，并均从（１）赋存金故体，（２）在沉积－成岩期成矿和（３）为沉积－成岩期后成矿提供矿质３个方面加以探讨。     

Lithological Features of Precambrian Gold-Bearing Rocks: Evidence from the Ukrainian Shield

Based on traditional petrochemical and nontraditional mineralogical methods (accessory zircon generation analysis), specific features of the primary composition of strongly metamorphosed rocks from some Early Precambrian Au-bearing rocks of the Ukrainian Shield (US) were studied. The confinement of several gold ore occurrences to primarily sedimentary Late Archean rocks of the Ukrainian Shield has been established and the possibility of their chemogenic origin is considered. The joint analysis of plicative tectonics and metamorphism facies in the study area demonstrated that Au-bearing primarily sedimentary (chemogenic) rocks of the Khashchevatoe–Zaval'ev Formation of the Bug Group (AR₂) are confined to amphibolite-facies domains within tectonic (high-order synform) structures with a significant gold potential.     

四川若尔盖阿西金矿岩石学及岩石地球化学特征

阿西金矿地处川甘陕“金三角”成矿集中区,中三叠统为本区内最重要的金矿源层和赋矿层。阿西金矿田的形成经历了一个从沉积－成岩－富集成矿的漫长复杂的由量的积累到质的飞跃过程,是多阶段、多层次、多因素作用有机结合的产物。赋矿岩系特征表明,阿西金矿田的主要成矿环境为半深海斜坡环境。区内岩石类型极为复杂,三大岩类均有产出。主要有细砂岩、杂砂岩、沉凝灰岩、碳酸盐岩、硅质岩;变粒岩、石英岩、角岩、大理岩、夕卡岩、角砾岩;岩浆岩类主要为英安斑岩（玢岩）、闪长岩等。其中最重要的赋矿岩石为石英岩,其主要特征为具块状、不规则条带状构造,呈褐黄色／浅灰色变余层状构造。由石英（75％－80％）、高龄石（10％－15％）、绢云母（2％－3％）、钛铁质（3％－4％）、玉髓（2％－3％）及少量碳质组成。其岩石化学成分与典型硅质岩相比,SiO2偏低,Al2O3总体偏高,出现较强的高岭土化。通过研究认为,该区主要赋矿岩石石英岩的原岩应属正常碎屑沉积岩。     

HISTORIC-DYNAMIC ANALYSIS OF GOLD METALLOGENY OF WEST SARAWAK,EAST MALAYSIS

West Sarawak,which located in the northwest of South Kalimantan Diwa Region,underwent geosynclinal period (An C-T),platform period (J1-J2) and diwa period (J3-).In geosynclinal evolution period,the crust was thickened and accreted by sedimentary accumulating,orogenic movement and metamorphism.In the different kinds of volcanic-sedimentary rocks,content of gold is general higher than the mean value of upper crust and its enrichment factor ranges from 0.94 to 4.7.The basement tectonics formed in geosynclinal fold inversionstage strike northeast,which controlled the distribution ofmagmatic activities and gold mineralization belts of the west part of west Sarawak.     

凤县八卦庙特大型金矿热水沉积岩的地质地球化学特征

八卦庙特大型金矿的成因引人注目 ,作者提出含矿地层中存在的一套条带状岩石属于热水沉积成因。此套岩石顺层产出 ,主要由富石英纹层、富钠长石 -石英纹层和富铁碳酸盐纹层互层 ,构成纹层条带构造 ,具有沉积韵律和沉积旋回 ;地层走向上 ,条带状岩石渐变过渡为千枚岩或板岩 ,显示局部凹陷的热水沉积盆地特点 ;条带岩的化学成分、微量元素特征与秦岭泥盆系铅锌矿床中的硅质 -钠质 -铁碳酸质热水沉积岩非常相似 ,具有热水沉积特点。热水沉积岩与金矿化空间关系密切 ,说明八卦庙金矿属于热水沉积 (改造 )型金矿床。矿床成因类型的正确认识有利于指导区域找矿工作。     

Genetic model of uranium mineralization in the Permo-Triassic sedimentary rocks of the Stara Planina eastern Serbia

One deposit and four occurrences of uranium minerals in the Permo-Triassic sedimentary rocks of the Stara Planina in eastern Serbia were ascertained using data from years of multidisciplinary geological research. The minerals are the fissure-filling type, and were assigned to the exogenic mineralization group, being mostly epigene in nature. Relevant geological information was used to derive a genetic model of uranium mineralization in the Permo-Triassic sedimentary rocks of the Stara Planina. The model explains the formation of Permo-Triassic rocks and three stages of the complex process of U mineralization. The genetic model treats: (1) the primary sources of the uranium; (2) the mobility of uranium; and (3) accessory metals from the parent rocks to their deposition in host rocks and the postmineral change in ore bodies. A geochemical barrier zone was identified in the sedimentary rocks that contained uranium mineral ore. This geochemical barrier area included crescent-shaped, flat-lens, or vein-like ore bodies. The U-containing mineral described is comparable with those from the relatively common fissure-filling uranium minerals found around the world.     

复合成矿与构造转换——以长江中下游成矿带为例

复合成因矿床分布广泛,把它们单独划分出来进行研究,对于深入认识成矿过程、发展成矿理论和指导找矿勘探,均有重要意义.鉴于中国大陆东部中生代岩浆作用强烈,对前期成矿作用的影响也很明显,因此本文以长江中下游成矿带为例,评介了复合成矿作用的几种主要机理,认同前人提出的叠加和改造是其基本类型,但预富集作用也应重视,同时也不能忽视继承成矿和再生成矿,特别是继承和预富集联合多次出现时,可以形成区域性成矿元素大规模富集.同时,本文还将它们放在区域构造体制和机制转化演化过程中加以考察,进一步明确它们在中生代构造体制转换以前主要以沉积(含热水沉积)成因的含矿建造、矿源层或矿(胚)层产出,而矿床的最终形成与就位则主要与新构造体制下由挤压向引张转化的过渡环境中构造-岩浆活动有关,呈现出“成矿大爆发”的现象.其中早期( 145～136Ma)构造机制是以走滑挤压作用为主,形成与高钾钙碱性岩系有关的铜金矿化.晚期(135 ～ 127Ma)以走滑引张作用为主,形成了与橄榄安粗岩系有关的铁硫矿化.但这两期都有广泛发育的以叠加改造为主的复合成因铜、金、铁、硫及铅锌矿床,从而在典型的岩浆热液矿床和沉积矿床之间形成了一套过渡性矿床序列(层控矽卡岩型→沉积热液叠加型→层控叠改型→迁移式改造型→原地式改造型),构建了一个矿床“家族”.末期( 126 ～ 123Ma)以引张作用为主,出现碱性火山岩和A型花岗岩类,伴随铁、金、钼、铀等矿化,成矿带的成矿活动随之进入尾声.     

新疆麦兹火山沉积盆地含矿建造及金矿找矿潜力分析

含有铅锌等贱金属矿床的火山沉积盆地内金矿找矿越来越为人们所关注,文章通过对麦兹泥盆纪火山沉积盆地含矿建造特征进行分析,总结6种含矿火山沉积岩性建造,其岩石的微量元素地球化学表明,除盆地两翼边缘的花岗岩外,本区岩石均富集Pb、Zn、As、Sb、Au、Ag等元素.根据海相火山沉积盆地演化与成矿分析,麦兹地区具有金矿找矿前景.