吉林六批叶沟金矿床绢云母40Ar-39Ar 快中子活化法定年研究

在六批叶沟金矿石中,精选出与金矿物同期生成的绢云母作为样品,采用40Ar-39Ar快中子活化法测年,获得8个一致相连的平坦型绢云母年龄谱,tp=(190.28±0.30) Ma,氩同位素计算得等时线年龄为(189.98±0.58) Ma,两者完全吻合.等时线截距为(296.9±10.0) Ma,与大气氩的该值(295.5 Ma)相比较,两者完全吻合,表明该样品出自未受明显后期热力作用影响的非扰动体系.锁定六批叶沟金矿床主要成矿年龄为190 Ma左右,属早侏罗世的燕山早期.     

山东龙口大顶金矿地质特征及找矿方向

重点介绍大顶金矿区的地质特征及区内主要矿脉体(36号矿脉群)特征，同时，对控矿因素作了一定的分析，初步总结了36号矿脉群在双顶矿段北东缘的成矿规律，指明了本矿区的找矿标志及下一步的找矿方向。     

李坝金矿床金的赋存状态与选矿工艺学

李坝大型金矿床是产于西秦岭上古生代沉积岩系中类卡林型金矿床典型代表。通过显微镜及选矿实验查定了李坝金矿床金的赋存状态，矿床金矿物呈微细粒多种独立矿物出现，金的赋存形式多样，显示多期多阶段成矿特点，成为划分类卡林型金矿的重要参考。矿石工艺学的研究对工业选矿有指导意义。     

黑龙江东安金矿床成因探讨

东安金矿床是黑龙江省新近发现的大型浅成热液金矿床。受断裂和隐爆角砾岩带控制，赋存于中生代陆相火山-侵入岩及晚印支期碱长花岗岩强硅化带中。成矿与火山-侵入岩作用有密切成生关系。通过对矿区内矿化围岩和基底岩石的金丰度和稀土元素特征的研究，以及对石英中包裹体测温、盐度、液相成分、氢-氧同位素特征的研究，认为该矿床的成矿物质主要来源于基底变质岩；成矿温度为144℃～348℃；成矿深度约0．2km～1．0km；成矿时代为中燕山晚期，为一浅成热液低硫型金矿床。     

黑龙江东安金矿潜火山岩的控矿作用

东安金矿是黑龙江省发现的大型浅成低温热液低硫化物型金矿床。赋存于中生代潜流纹岩和晚印支期碱长花岗岩接触外带的断裂系统中，近矿围岩硅化强烈、冰长石化发育。通过对潜火山岩的控矿作用研究，认为该区钙碱性中酸性潜火山岩是成矿的重要条件。     

豫西金矿类型划分

豫西金矿矿床类型复杂，在前人的金矿床类型划分的基础上，根据豫西金矿床明显的野外地质特征，提出了豫西金矿类型划分方案，并对各金矿床类型的地质特征进行了简述，同时，对它们之间的共性作了总结。指出：豫西各类金矿类型之间既存明显的区别又具有密切的时间和空间上的成因联系，这一特点对用于拓宽该地区进一步的金矿找矿思路是十分必要的。     

我国主要金矿类型中黄铁矿"电子-空穴心"特征及影响因素

通过对我国主要金矿类型中黄铁矿导电类型的分析表明，黄铁矿“电子。空穴心”与金矿床的成因类型具有密切的联系，华北地台太古代变基性火山岩中的金矿床(绿岩带型)、热水淋滤型(卡林型)金矿床，黄铁矿多为单一的“电子心”型导电。大多数产于中生代岩体中的中深脉状金矿、火山次火山岩中的金矿床，黄铁矿为“电子心”、“空穴心”混合型导电，个别的为单一的“空穴心”导电。黄铁矿的“电子．空穴心”受杂质成分As、Co、Nl在成矿背景中的丰度，进入黄铁矿品格中的替代能力的差异、补偿类质同象现象、成矿时温度以及．f(S2)等多种因素的耦合制约。     

西秦岭三个典型金矿床稳定同位素地球化学特征

据八卦庙金矿、李坝金矿、小沟里金矿稳定同位素研究,金矿床δ34S比正常沉积岩变化范围窄,比岩浆-火山岩型矿床宽,硫源是海水硫酸盐还原硫与深部热液来源硫所组成的混合硫。石英包裹体流体氢、氧同位素分布于岩浆水、大气降水的重叠过渡区,更靠近岩浆水区,岩浆水的同位素特征更明显。八卦庙金矿石英脉3He/4He高于地壳3He/4He值(n×10-8),低于地幔3He/4He值(n×10-5),为壳-幔混合源。上述同位素地球化学证据表明,金成矿与岩浆岩有一定的成因关系。岩浆岩与金矿床空间关系密切,矿区内脉岩发育,脉岩为矿体的上下盘。含矿岩石中发育斑点构造,斑点为黄铁矿、磁黄铁矿、毒砂、绿泥石、石英、绢云母、黑云母、堇青石、红柱石、电气石、碳酸盐等热变质矿物和热液交代矿物,表明花岗岩为成矿提供热动力。据八卦庙金矿、李坝金矿、小沟里金矿稳定同位素地球化学研究,结合成矿地质背景分析和区域成矿地质特征对比,认为凤太、西成、礼岷地区金矿与微细浸染型(卡林型)金矿有明显的差别,该区金矿类似于岩浆热液矿床。     

Genesis of the Shear Zone-related Gold Vein Mineralization of the Lega Dembi Gold Deposit, Adola Gold Field, Southern Ethiopia

The Lega Dembi Primary Gold Deposit in southern Ethiopia is related to the shear zone-hosted vein in the Neoproterozoic metamorphosed volcano-sedimentary succession of greenschist- to amphibolite-facies metamorphism. The rocks consists of a sequence of biotite-feldspar-quartz schists, carbonaceous mica-schists, amphibolites and basic to ultrabasic rocks. This unit is separated from a foot wall biotite gneiss by a major shear zone. The ore bodies are hosted in the volcano-sedimentary sequence and consist of swarms of quartz veins, lenses, and stockworks that propagated along mesoscale ductile to brittle-ductile shear zones.The mineralization is defined by a complex paragenesis of gold in association with Cu-Pb-Zn-Fe sulphides, tellurides and sulphosalts. The presence of Ni-bearing minerals in amphibolites of the host sequence, together with the ore mineral association, suggests an origin related to mafic volcanism.     

Chemical Composition of Ores from the Takara Volcanogenic Massive Sulfide Deposit, Central Japan

Abstract. The Takara volcanogenic massive sulfide (VMS) deposit occurs in Miocene formation of the Misaka Mountain, the South Fossa Magna region, central Japan. The tectonic setting of the Misaka Mountain is reconstructed to be a part of the paleo Izu-Ogasawara arc which collided with the Honshu arc and to form accreted body in the present position. The Takara deposit, therefore, is considered to have formed in the paleo Izu-Ogasawara arc.
The ores from the Takara deposit are classified into pyrite-type ore, chalcopyrite-type ore, and sphalerite-type ore on the basis of chemical composition and their mineral assemblages. Some pyrite-type ores are characterized by their high Au content. The Au content is hardly recognized in the chalcopyrite-type and sphalerite-type ores.
The ores from the Takara deposit have intermediate bulk chemical composition between those from the Besshi-type deposits and the Kuroko-type deposits that are two representative VMS deposits. However, the bulk chemical composition is closer to that from the Kuroko-type deposits. And moreover, chemical composition of tetrahedrite-tennantite series minerals (tetrahedrite) is similar to that from the Kuroko-type deposits. The bulk chemical composition (Cu, Zn, Co, Pb, and As contents) of ores is affected by the chemical composition of volcanic rocks associated with VMS deposits.