关于矿田地质学的初步探讨

依据板块构造理论和构造-矿床组合规律,在数千-数万平方千米的范围内,基本掌握了不同级别的金属成矿区带.通过成矿模式和成矿系列研究,也在矿区周围不断发现一些新矿床.然而,如何开展矿田范围内地质找矿,国际上称为中尺度勘查的潜在矿产的识别标准、调查思路、勘查方法等问题,则成为国际成矿学发展所面临的严峻挑战.     

铁同位素体系及其在矿床学中的应用

本文报道了世界范围内不同含铁矿物的Fe同位素组成,进一步了解了铁同位素在不同含铁矿物中的基本分布特征;系统总结了铁同位素在不同储库和不同类型矿床中的分布特征,构筑了铁同位素体系的基本框架;结合最新的研究成果,较全面地总结了铁同位素在矿床学领域的应用,得出了铁同位素可以用来示踪流体出溶、流体演化、表生蚀变作用和成矿物质来源的基本认识。在流体出溶过程中,相对于岩体,出溶的流体富集铁的轻同位素;成矿流体体系的演化过程中,矿物的结晶沉淀会导致铁同位素发生分馏,随着Fe(III)矿物的结晶沉淀,流体逐渐富集铁的轻同位素,随着Fe(II)矿物的结晶沉淀,流体逐渐富集铁的重同位素,随着矿物的结晶沉淀,流体的Fe同位素组成随时间发生演化;在成矿后的表生蚀变作用过程,高温蚀变作用形成的产物相对于原矿物富集铁重同位素,低温蚀变作用形成的产物基本保留了原矿物的铁同位素组成;Fe同位素在示踪成矿物质来源具有应用潜力,流体出溶、流体演化等重要成矿作用过程中Fe同位素组成的变化规律是利用Fe同位素示踪Fe来源的关键所在。     

西藏多龙矿集区典型矿床(点)矿化特征与成矿作用对比研究

西藏多龙矿集区是近年来中国新发现的具有世界级潜力的铜金矿集区。该矿集区现已查明多不杂、波龙、拿若和铁格隆南4个大型-超大型矿床,并新发现地堡那木岗和拿顿矿点。文章对上述矿床(点)脉体、蚀变、矿化和流体特征开展了系统研究和对比。结果表明,多不杂、波龙和拿若矿床矿化类型以斑岩型为主,同时钾硅酸盐化、绢英岩化、青磐岩化等蚀变广泛发育,而铁格隆南矿床除上述蚀变类型外,还叠加有高级泥化蚀变,并发育与之相关的浅成低温热液型矿化。根据脉体特征对比和流体包裹体温压计算推测,上述4个矿床矿化类型的差异可能由剥蚀深度的差异所引起(前三者剥蚀深度约为2～3 km,后者约为1～1.5 km)。此外,地堡那木岗矿点蚀变类型以绢英岩化、泥化为主,该矿点发育与斑岩型金矿中类似的深色条带状石英脉,指示该地区可能存在斑岩型金矿。拿顿矿点为典型的高硫型浅成低温热液型矿化,铜金矿体赋存于角砾岩筒中。野外地质调查表明,上述矿点地表蚀变岩盖(Lithocaps)发育,并且蚀变岩盖空间分布位置与下伏铜金矿体表现出良好的匹配关系,可有效地指导找矿勘查工作。流体包裹体实验进一步表明,铜金元素在斑岩型矿化中的沉淀可能与温度降低和氧逸度的变化有关,而在浅成低温热液型矿化中的沉淀则受控于温度的降低和流体的不混溶作用。最后,在前人年代学研究基础上,结合本次实验结果构建了该地区与成矿作用有关的时空演化模型。     

Typological factor analysis: A new classification method applied to geology

The purpose of typological factor analysis is to detect, within a multidimensional sample, the existence of subsets characterized by different maximal elongation directions. The method which has been successfully applied in the field of pattern recognition can be considered from two points of view: (1) an automatic classification or dynamic clustering technique: and (2) a form of factor analysis. Using this form of analysis nuclei of affine varieties (points, axes, planes, etc) are identified. Different case studies were analyzed in order to establish the advantages of the method compared to other methods. Geochemical analyses of rock samples; that is, rhyolites, mafic, and intermediate rocks of the Normetal (Abitibi) area were subjected to typological factor analysis for the purpose of classification of geological deposits and detection of geochemical anomalies. The method was also applied to the classification of sediments from the Barataria Bay area in Louisiana.     

金属矿床地质的发展——纪念《矿床地质》创刊十周年

矿床知识来自矿业。有关矿石成因的争论曾引导到野外现场实际观察的良好趋向。20世纪中叶以来,先后应用先进的设备仪器以及如同位素和流体包裹体等对矿床进行研究;这不仅扩大了成矿作用的视野,而且更加深入洞察矿石的习性。然而,有关矿石成因与来源问题的争论仍在继续;不过进入了更深的层次。欲探索矿石形成的客观规律,最合理的方法是结合野外的现场观察进行室内的仔细研究。     

矿田地质分类研究

矿田地质学是研究矿田建造、矿田构造和矿田成矿的学科领域。本文提出矿田的构造岩相分类建议。矿田第一层次的构造岩相分类以成矿地质作用和成矿地质环境为基础,概分为4大类,即沉积矿田或沉积岩相矿田、岩浆矿田或岩浆岩相矿田、变质矿田或变质岩相矿田以及复成型构造蚀变矿田或构造蚀变岩相矿田。考虑矿田成矿构造环境的规模、可识别性和可观测性,本研究以次级岩相建造划分矿田类型：比如在火山岩矿田类型之中,应该具体细分为火山角砾岩相矿田、火山熔结凝灰岩相矿田等类型。初步划分了31类构造岩相矿田：例如,山东淄博湖泊相铝土矿田、德兴陆相次火山热液相斑岩铜矿田、攀枝花基性辉长岩相钒钛磁铁矿田、美国上湖绿片岩相铁矿田、胶东玲珑焦家式黄铁绢英岩相金矿田等。矿田成矿作用和环境及其构造岩相分类,将会推动矿田尺度的地质调查和勘探,推进构造结合建造研究,为矿田地质研究紧密结合找矿预测提供了一个基础分类和研究思路。     

Scanning electron microscopy cathodoluminescence of quartz: Principles,techniques and applications in ore geology

Scanning electron microscopy cathodoluminescence (SEM-CL) of quartz has been a prevalent research technique in porphyry and epithermal systems for the past two decades. Quartz from specific geological environments reveals unique textures in SEM-CL, which can be used to constrain the evolution of these ore-bearing systems when complemented by fluid inclusion, hyperspectral mapping, and trace element studies. We review SEM-CL principles and instrumentation, sample preparation and handling, and experimental conditions of quartz SEM-CL imaging that result in the high quality CL images. The effects of sample polishing, accelerating voltage, beam spot size, working distance, vacuum conditions, image acquisition, and post-processing were examined through experimental trial. For the XL 30 ESEM and the attached Gatan PanaCL detector used, the optimum experimental conditions to obtain high quality panochromatic SEM-CL images of quartz at high vacuum mode for carbon-coated conductive samples are as follows: 15 kV accelerating voltage, relative beam spot size 6 (approximately 500 nm in diameter), HT − 570 V to − 580 V photomultiplier tube (PMT) voltage. Low vacuum mode (with chamber H₂O vapor pressure from 0.1 to 1.0 Torr) working conditions are similar to the conditions at high vacuum mode except the PMT voltage should be reduced to − 550 V to − 560 V. Working distances vary based on the position of user's retractable CL detector. The sample surface should be as close as possible to the CL detector, but a 1 mm clearance between the detector and the sample surface is recommended to prevent detector from possible damage by the sample. Several minutes of beam exposure prior to image acquisition at 320 second scan speeds at 50×–1500× magnifications is recommended to generate the greatest CL emission. Monochromatic CL imaging requires three scans over the same area using red, green, and blue optical filters that can be merged to produce a “true color” image. The red and green filters require stronger PMT voltages to produce sufficient CL emissions by an increase of − 200 V to − 300 V and − 150 V to − 200 V, respectively, from the PMT voltage used for panochromatic imaging. Special attention is given to the challenges associated with imaging hydrothermal quartz veining in ore deposits and the value of CL data as a foundation for geochemical studies. SEM-CL imaging of vein quartz is explored through case studies of the Red Hills Porphyry Cu –Mo Deposit, Texas, USA, and the Ertsberg–Grasberg Cu–Au District, Papua, Indonesia to aid in vein paragenesis. The most common application of quartz SEM-CL in ore geology is to reveal the relative timing of mineral precipitation, mineral dissolution, and inherited structural features. Understanding of temporal relations among these events makes it possible to select specific generations of quartz within a vein for further studies such as the TitaniQ thermometry and fluid inclusion microthermometry in order to establish T–P–X fluctuations throughout the development of a hydrothermal system.     

紫金山高硫型金铜矿的矿床地质研究进展

随着紫金山金铜矿露天采矿规模的不断扩大,许多与矿床成因密切相关的地质现象被剥露出来,露采场成为进行矿床地质研究的最佳场所。本文对紫金山金铜矿露采场的构造、矿化及蚀变分带特征进行了详细研究,研究表明:在自北向南靠近火山机构的过程中,蚀变带依次为绢云母+地开石化带、地开石+明矾石化带、地开石+褐铁矿化带和强硅化带,各个蚀变带内的主要金属矿物组合变化依次为黄铁矿+斑铜矿±硫砷铜矿±蓝辉铜矿,黄铁矿+蓝辉铜矿+铜蓝+硫砷铜矿±斑铜矿,褐铁矿+针铁矿+自然金+次生铜蓝+孔雀石,黄铁矿+斑铜矿+硫砷铜矿+蓝辉铜矿。在空间分布上,主要的矿石矿物在水平方向上从斑铜矿渐变为蓝辉铜矿,垂直方向上从上部的自然金+褐铁矿向下变为蓝辉铜矿+斑铜矿,深部变为铜蓝±蓝辉铜矿。蚀变分带与金属矿物组合的空间分布都体现出在靠近火山机构及深度增加的过程中成矿热液的硫逸度和氧逸度越来越高。矿石中还出现了具有指示意义的含锡矿物。这些特征都表明紫金山金铜矿是含矿热液多期次叠加的结果。金的富集成矿和金铜的矿化分带受北西向与北东向密集节理交汇带的控制。     

现代遥感技术在地质找矿中的应用

文章论述了现代遥感技术在地质找矿中的应用,包括遥感岩性识别、矿化蚀变信息提取、地质构造信息提取和植被波谱特征的找矿应用等;总结了遥感地质找矿技术的若干新发展,即多光谱遥感蚀变信息提取技术、高光谱遥感技术、遥感生物地球化学技术,以及它们在地质找矿应用中的新发展;对遥感技术在地质找矿中的应用提出了几点认识及展望.     

锡同位素研究进展及其在矿床学中的应用展望

锡同位素是一种新兴的非传统稳定同位素,其在考古学及天体化学中的运用显示出非常大的示踪潜力和价值,然而目前其在地质学(尤其是矿床学)中的研究和应用前景缺乏系统介绍。本文总结分析了世界上目前所发表的主要天然及人工样品的锡同位素数据,发现天然样品中锡同位素组成有较大差异,其中玻璃陨石最富重锡(其δ^122/118Sn值可达2.53‰),而黝锡矿(黄锡矿)最富轻锡(其δ^120/116Sn值可达-1.71‰)。其中,含锡矿物(如锡石和黝锡矿)中的锡同位素组成变化范围要远远大于全岩样品。地幔及地壳来源的不同岩性或地质体的全岩锡同位素组成有明显差别;锡同位素在一定条件下可以发生分馏,且分馏程度可能远远大于锡同位素的初始值差异。锡石锡同位素对成矿环境非常敏感,其形成时的流体成分、化学反应速率以及物化条件(如温度、盐度、氧逸度、pH值等)等因素均能影响其锡同位素的组成。深部流体(如岩浆来源)结晶的锡石富重锡,而浅部流体(如地层流体)的加入将使锡石富轻锡,因此锡石的锡同位素具有判别不同矿床成因类型的潜力。展望未来,锡同位素的研究有望在以下三方面取得突破:(1)各地...     

Microplaty hematite ore in the Yilgarn Province of Western Australia: The geology and genesis of the Wiluna West iron ore deposits

The Wiluna West small (~ 130 Mt) high-grade bedded hematite ore deposits, consisting of anhedral hematite mesobands interbedded with porous layers of acicular hematite, show similar textural and mineralogical properties to the premium high-grade low-phosphorous direct-shipping ore from Pilbara sites such as Mt Tom Price, Mt Whaleback, etc., in the Hamersley Province and Goldsworthy, Shay Gap and Yarrie on the northern margin of the Pilbara craton. Both margins of the Pilbara Craton and the northern margin of the Yilgarn craton were subjected to sub-aerial erosion in the Paleoproterozoic era followed by marine transgressions but unlike the Hamersley Basin, the JFGB was covered by comparatively thin epeirogenic sediments and not subjected to Proterozoic deformation or burial metamorphism. The Joyner's Find greenstone belt (JFGB) in the Yilgarn region of Western Australia was exhumed by middle to late Cenozoic erosion of a cover of unmetamorphosed and relatively undeformed Paleoproterozoic epeirogenic sedimentary rocks that preserved the JFGB unaltered for nearly 2 Ga; thus providing a unique snapshot of the early Proterozoic environment.Acicular hematite, pseudomorphous after acicular iron silicate, is only found in iron ore and BIF that was exposed to subaerial deep-weathering in early Paleoproterozoic times (pre 2.2 Ga) and in the overlying unconformable Paleoproterozoic conglomerate derived from these rocks and is absent from unweathered rocks (Lascelles, 2002). High-grade ore and BIF weathered during later subaerial erosion cycles contain anhedral hematite and acicular pseudomorphous goethite. The acicular hematite was formed from goethite pseudomorphs of silicate minerals by dehydration in the vadose zone under extreme aridity during early Paleoproterozoic subaerial weathering.The principal high-grade hematite deposits at Wiluna West are interpreted as bedded ore bodies that formed from BIF by loss of chert bands during diagenesis and have been locally enriched to massive hematite by the introduction of hydrothermal specular hematite. No trace of chert bands are present in the deep saprolitic hematite and hematite–goethite ore in direct contrast to shallow supergene ore in which the trace of chert bands is clearly defined by goethite replacement, voids and detrital fill. Abundant hydrothermal microplaty hematite at Wiluna West is readily distinguished by its crystallinity.The genesis of the premium ore from the Pilbara Region has been much discussed in the literature and the discovery at Wiluna West provides a unique opportunity to compare the features that are common to both districts and to test genetic models.     

豫西南湍源银多金属矿集区典型矿床(点) ——来自地质、流体特征及锆石U-Pb年龄的证据

豫西南湍源银多金属矿集区位于秦岭造山带中部,分布有板厂铜多金属矿床、银洞沟银多金属矿床、许窑沟金矿床、银虎曼铅锌矿,以及万人洞沟、铁罗沟、万沟等金银矿点。流体包裹体研究表明,与含矿有关的石英脉流体包裹体组成复杂,特别是富气包裹体十分发育,而不含矿的石英包裹体类型简单,多为水盐包裹体。获得研究区内与成矿关系比较密切的卢家坪岩体和五龙潭岩体的锆石206Pb/238U年龄分别为446Ma±7Ma和424.6Ma±4.9Ma,据此认为该区成矿时间最早可延伸至加里东期。系统总结了矿集区矿床矿点的成矿作用过程,认为湍源银多金属异常区典型矿床可以分为以下几类：①与地层有关的火山喷流沉积及后期热液叠加改造的块状硫化物矿床(VMS-SEDEX),火山作用提供成矿物质,后期热液改造形成矿床,代表性矿床为银虎曼铅-锌矿床; ②与构造有关的蚀变岩-石英脉型金、银多金属矿床,成矿物质来源于深部和围岩,朱-夏断裂带次级构造提供容矿空间,代表性矿床为银洞沟银多金属矿床、许窑沟金矿; ③与中酸性侵入岩有关的斑岩型-矽卡岩型矿床,成矿物质来源于深部和围岩,朱阳关-夏馆断裂带提供容矿空间,代表性矿床为板厂铜多金属矿床 。     

桂东北茅安塘伟晶岩中石榴子石的特征及对岩浆演化的指示意义

为了解桂东北伟晶岩岩浆的形成环境及演化过程,对桂东北茅安塘Nb-Ta-Be-Rb稀有金属矿床周围伟晶岩中的石榴子石进行了镜下观察、电子探针（EPMA）和LA-ICP-MS原位微区主微量元素研究,探讨石榴子石的成因及其对成岩及成矿作用的指示.结果表明,桂东北茅安塘地区伟晶岩中的石榴子石为岩浆成因石榴子石,属于铁铝榴石-锰铝榴石（平均Alm_49.28-Sps_47.09）固溶体系列,可分为早期形成的Ⅰ型石榴子石（GrtⅠ）和晚期形成的Ⅱ型子石（GrtⅡ）.两期石榴子石均以富集重稀土（HREE）、高场强元素（HFSE）,亏损轻稀土（LREE）和缺乏大离子亲石元素（LILE）为特征,∑REE配分模式呈明显左倾趋势,显著的Eu负异常.石榴子石生长过程中的界面反应速率小于物质迁移速率,水岩作用较弱,∑REE主要以表面吸附或吸收的形式进入石榴子石中,是导致其重稀土（HREE）元素富集,轻稀土元素亏损的主要原因.随着岩浆分异演化程度的不断提高,∑REE逐渐进入并赋存于石榴子石中,促进岩浆从早期的低分馏（未分馏）的岩浆熔体逐渐向晚期的高分馏的岩浆熔体演化.石榴子石中HREE含量随岩浆演化程度逐渐增加表明,晚期分异演化的岩浆-热液中逐渐富集稀土及稀有金属元素.这些晚期富含成矿元素的热液流体交代原生矿物,导致外侧带及核部花岗伟晶岩中发育大量交代成因的稀土和稀有金属矿物.      

相山矿田铀矿地质研究进展与趋势

相山铀矿是华南最大的产于火山一侵入杂岩体中的热液脉型铀矿田。文章对相山铀矿地质研究的历史进行了简略回顾,重点阐述了铀矿地质研究的新进展,主要有:火山杂岩时代为早白垩世、火山岩浆具有反方向演化特点,成矿作用是一个相对连续的演化过程,铀矿类型归属斑岩型,属于与燕山晚期火山一斑岩作用有关的铀或铀一多金属矿床成矿系列。最后,文章展望了未来的研究方向。     

Selective flocculation applied to Barsuan iron ore tailings

Experiments have shown that it is possible to obtain a concentrate containing 65% iron, 1.8% alumina and 1.4% silica with an iron recovery of 80% from the tailings of Barsuan iron ore plant containing 52.5% iron, 7.4% alumina and 7.8% silica through selective flocculation employing starch. Key to such success lies in the manner in which the flocculant is desired from the parent starch. Barsuan deposit being a limiting case of typical fine-grained high-alumina iron ores, the results open up technical possibilities of better utilization of such deposits.     

Annual status of the profession: 1999: Encompassing hydrogeology, environmental geology and the applied geosciences

All professions began the countdown to the new world, considering the year 2000 to be the first year of the new millennium. Most of the actual impacts are already in place, including multinational businesses and the Euro as the first regional multinational currency. Most of the impacts have been harsh, and relief to individual consumers and professional people will be minor and felt mainly in enhanced ease of communication and media offerings. On the side of the conduct of the profession, the advantages will be far more narrow, as individual practitioners will be facing far stronger forms of competition for their services. Truly, the only way to survive will be for all of us to become more aware of the forces that impact engineering geology and the opportunities that engineering geologists have to provide their services, so basic to all forms of engineering, environmental protection and resource utilization.