Pyrite framboids and their development: a new conceptual mechanism     

Z. Sawlowicz 《International Journal of Earth Sciences》1993,82(1):148-156

It has been suggested that the two morphologies of sedimentary pyrite, framboids and euhedra, may reflect two distinct pathways of pyrite formation. Framboids form indirectly via iron monosulphides, whereas euhedra form from direct precipitation from solution. A third pathway which is bridging these two forms is proposed here, namely the continuous growth from a monosulphide globule through framboids to a euhedral single crystal. It is also suggested that framboids probably occur over a range of three orders of magnitude, from the least complex microframboids through framboids to polyframboids.Dedicated to Professors G. C. Amstutz and L. G. Love for their unrivalled contribution to the knowledge of pyrite framboids  相似文献   

湘西金矿黄铁矿的谱学研究及其意义探讨   总被引：3，自引：0，他引：3  

王学明  陈梦熊 《湖南地质》1990,9(4):51-56

对含金性不同之黄铁矿进行了电子顺磁共振谱(EPR谱)及远红外吸收光谱的研究表明:含金性不同的黄铁矿,它们的谱学特征也各异。黄铁矿的含金量与其EPR谱的峰数及强度有关,与其远红外吸收光谱的光密度值(D)成密切的负相关关系,据此可评价黄铁矿的含金性,以指导金矿床的找寻。  相似文献   

湖南省黄铁矿床地质地球化学特征初步探讨   总被引：1，自引：0，他引：1  

周雪昌 《湖南地质》1992,11(2):110-116

湖南省黄铁矿资源颇为丰富,已探明工业矿床50多处。矿床成因类型,可划分为岩浆热液型、层控型和沉积型3类6个亚类,以前两类最重要。岩浆热液型黄铁矿床,主要分布在湘东和湘南地区,与燕山期酸性小岩体密切有关,矿体形态复杂,矿石品位较富,矿物成分繁多,围岩蚀变发育,矿床规模较大;黄铁矿中Co/Ni>1、S/Se比值较低,矿石硫同位素组成具塔式分布效应,矿床硫源以岩浆硫为主,亦有部分地层沉积硫。层控型黄铁矿床,集中分布在湘西北和湘中地区,矿床的产出与岩浆岩无成因联系,受上震旦统陡山沱组和中泥盆统棋梓桥组等特定层位、岩相和岩性组合严格控制,矿体多呈似层状、透镜状等整合矿体,矿石品位一般较贫,矿物成分与围岩蚀变简单:黄铁矿中Co/Ni<1,S/Se比值较高,矿石δS~(34)‰离差大,在较大正、负值范围具多峰式分布,均一化程度低;矿床硫源,为古海水硫酸盐硫和生物成因硫等的混合硫。  相似文献   

吉林省放牛沟多金属矿床两种类型地球化学异常的成因研究与判别     

朴寿成  连长云 《吉林地质》1994,13(4):1-7

本文通过对黄铁矿的地球化学成因研究，查明吉林省放牛沟多金属矿床的围岩中存在同生沉积成因（无找矿意义）与后生热液矿化成因（具有找矿意义）地球化学异常，两者有明显区别。根据异常的元素相关性、指示元素组合、异常强度和判别分析等特征，建立了判别两种不同成因异常的标志，并利用这些标志评价了未知异常的含矿潜力。  相似文献   

焦家深部金矿床成矿流体来源:来自黄铁矿微量元素及S-He-Ar同位素的约束   总被引：1，自引：2，他引：1  

李杰  宋明春  梁金龙  姜梦瑶  李世勇  丁正江  苏菲 《岩石学报》2020,36(1):297-313

焦家金矿是胶东蚀变岩型金矿的典型代表，金储量超过200t。矿体受焦家主干断裂控制，呈脉状产出，发育钾化、绢英岩化、硅化和碳酸盐化等蚀变，矿石中主要载金矿物为黄铁矿。热液成矿期主要可分为四个阶段：黄铁矿-石英阶段（i）、金-石英-黄铁矿阶段（ii）、金-石英-多金属硫化物阶段（iii）和石英-碳酸盐阶段（iv）。本文选取焦家金矿床深部I号主矿体为研究对象，采集了不同标高（-600~-1100m）的钻孔岩心样品，分析了黄铁矿的微量元素和S-He-Ar同位素组成，以此讨论成矿流体的组成、性质及来源。研究发现：焦家深部I号矿体黄铁矿呈浅黄色，强金属光泽，自形-半自形粒状结构，粒度50~1000μm，呈浸染状-细脉状分布于黄铁绢英岩化碎裂岩中，为第ii成矿阶段的产物。黄铁矿的稀土元素含量较低，ΣREE为3.27×10^-6~38.5×10^-6，富集轻稀土元素，δCe值为0.81~1.05，δEu值为0.67~1.43，Th/La、Nb/La比值均小于1，指示成矿流体为富Cl的还原性流体。Co/Ni比值介于0.54~1.57之间，平均值为0.99，与变质流体相近；Y/Ho比值在21.9~35.5之间，与地幔值（25~30）和中国东部大陆地壳值（20~35）接近，指示成矿流体与壳-幔相互作用有关。Y/Ho值、Zr/Hf值和Nb/Ta值变化范围较大，表明成矿热液体系发生了交代作用或有外来热液加入。与大陆地壳相比，黄铁矿富集Cu、Pb、Zn、Cd、Co、Ni等亲硫、铁族元素，亏损高场强元素。焦家深部金矿床黄铁矿的δ³⁴S值介于7.5‰~9.8‰之间，平均值为8.7‰，低于浅部矿床δ³⁴S值，呈现出由浅到深δ³⁴S值逐渐降低的特点。胶东金矿硫同位素组成整体一致，绝大多数矿床δ³⁴S值均为正值，变化范围主要集中在6‰~12‰，其来源与古老的变质基底岩系、中生代花岗岩以及幔源流体具有继承演化关系。δ³⁴S值整体呈现出：石英脉型 < 硫化物石英脉型 < 蚀变岩型的变化规律，说明矿化类型的差异是造成硫同位素组成差别的最主要因素。黄铁矿的³He/⁴He值为1.6±0.1Ra~1.8±0.1Ra，⁴⁰Ar/³⁶Ar值为750~3106，均显示混合来源特征。幔源He所占比例为20%~22%，表明幔源流体可能参与了成矿过程。焦家金矿成矿与燕山晚期中国东部强烈的壳幔相互作用密切相关。  相似文献   

A quantitative evaluation of pyrite weathering     

Alwyn Vear  Charles Curtis 《地球表面变化过程与地形》1981,6(2):191-198

Namurian sediments at Mam Tor, Derbyshire are cut by a major landslide and a geological fault. Both channel oxygenated waters into fragmented pyritic shales. Pyrite is rapidly oxidized to sulphuric acid, 1.5 g being destroyed by each litre of water passing through the fault-crush. More than 99 per cent of the acid, however, is immediately consumed in clay-mineral transformation and carbonate dissolution reactions. The typical acid-sulphate ‘ochre’ springs thus retain less than 1 per cent of the acid generated in the crush zone. These very rapid and large scale chemical transformations probably contribute to the slide's continuing activity.  相似文献   

Potential environmental impact at São Domingos mining district (Iberian Pyrite Belt,SW Iberian Peninsula): evidence from a chemical and mineralogical characterization   总被引：2，自引：0，他引：2  

A. M. Álvarez-Valero  R. Pérez-López  J. Matos  M. A. Capitán  J. M. Nieto  R. Sáez  J. Delgado  M. Caraballo 《Environmental Geology》2008,55(8):1797-1809

São Domingos like other long-term activity mines of the Iberian Pyrite Belt (IPB) dating back to pre-Roman times, is supposed to produce considerable amounts of mining wastes which cause significant downstream negative environment impact related to the acid mine drainage (AMD) production and high content of potentially toxic metals and metalloids in Chanza and Guadiana Rivers. The AMD production of a given mining waste depends on the ratio of its acid production to neutralizing phases. In this work, a chemical and mineralogical characterization of the sulphide-rich wastes from São Domingos has been developed to discriminate which residues are the main sources of AMD generation. A total of 47 representative samples of the different residue types were collected to estimate their possible contamination hazards through detailed studies of (1) for a mineralogical characterization: reflected-light optical microscope, scanning electron microscope (SEM) and XRD analysis; and (2) for a chemical characterization: bulk-rock analysis. AMD prediction by the standard acid-base accounting method (ABA) was used in order to determine the acidification potential of each residue type. This study also offers an estimation of the contribution of toxic elements to the environment, being thus, a base for future remediation actions at São Domingos and other abandoned massive sulphide mines within the IPB.  相似文献   

巍山扎村金矿黄铁矿标形特征与含金性研究     

赵志瑜  刘宏伦 《云南地质》2008,27(3):320-324

扎村金矿为中-低温热液型金矿床。黄铁矿是最主要的载金矿物,其含金性与成矿期次有着密切连系。分粗粒、中细、细粒、微细粒四种类型,其含金性随着黄铁矿的粒径变细而降低。粗粒黄铁矿含金性最好（10～25．5）g／t;其次中细粒为（3—7．35）g／t;微细粒基本不含金。  相似文献   

山东旧店金矿成因矿物学研究及其意义          下载免费PDF全文

李洪奎  李军  禚传源  耿科  梁太涛 《山东国土资源》2016,32(3)

平度旧店金矿床位于华北板块之胶北隆起区内,其赋矿围岩为晚侏罗世玲珑花岗岩,矿床成因为岩浆期后热液裂隙充填石英脉型金矿。据成矿物质沉淀时序可分为Ⅰ黄铁矿化-绢英岩化、Ⅱ石英-磁黄铁矿-中粗粒黄铁矿、Ⅲ石英-黄铁矿-微细粒黄铁矿、Ⅳ石英-多金属硫化物和Ⅴ石英-碳酸盐岩等5个成矿阶段,其中Ⅱ,Ⅲ,Ⅳ阶段为金的主要富集成矿阶段。该文在对山东平度旧店金矿床中黄铁矿和石英矿物标型特征研究的基础上,根据成矿阶段,划分出5个时代的黄铁矿,即形成于黄铁绢英岩中的Ⅰ阶段黄铁矿、黄铁矿石英脉中的Ⅱ阶段黄铁矿、石英黄铁矿矿石中的Ⅲ阶段黄铁矿、多金属硫化物矿石中的Ⅳ阶段黄铁矿和产于石英碳酸岩细脉中的Ⅴ阶段黄铁矿。黄铁矿晶形主要为{100},{210},{111}单晶形态,{100}+{210},{100}+{111}和{100}+{210}+{111}的聚形晶态,随着成矿阶段的变化,立方体出现率逐渐减小,五角十二面体、立方体+五角十二面体的聚形晶出现率则逐渐增加,直至晚期成矿阶段又有出现率高的立方体黄铁矿。旧店金矿在石英黄铁矿成矿阶段(Ⅲ阶段)中黄铁矿晶形以{100}+{210}为主,在多金属硫化物成矿阶段(Ⅳ阶段)中,黄铁矿晶形以{100}+{111}和{100}+{210}+{111}聚形为主,而在早期阶段和晚期阶段,黄铁矿晶形简单,以{100},{210},{111}单晶为主。对黄铁矿主成分的研究表明,成矿阶段黄铁矿表现为早期亏S、富Fe的特点,在主成矿阶段Ⅲ,Ⅳ阶段中,黄铁矿则表现富S、亏Fe的特点,反映了在多金属硫化物成矿阶段,不仅是金大量沉淀形成的时期,也是载金矿物黄铁矿快速富集沉淀的时期,说明富S、亏Fe的地球化学环境有利于金的沉淀。黄铁矿物理特征及石英标型亦佐证了在多金属硫化物阶段的黄铁矿、石英晶胞参数稍高,说明同波谱段反射率和晶胞参数的变化与金含量有对应关系。  相似文献   

Synchronous deposition of massive sulphide deposits in the Iberian Pyrite Belt: New data from Las Herrerías and La Torerera ore-bodies     

Reinaldo Sez  Carmen Moreno  Felipe Gonzlez 《Comptes Rendus Geoscience》2008,340(12):829-839

Two small to medium sized massive sulphide deposits, Las Herrerías and La Torerera, located in the Iberian Pyrite Belt (IPB) are examined from a geological and palynostratigraphic perspective. The palynological assemblages are assignable to the Retispora lepidophyta–Verrucosisporites nitidus (LN) miospore Biozone (Latest Devonian: Latest Famennian/Strunian) of Western Europe. This age permits correlation with some of the main massive sulphide deposits dated so far in the region (viz., Tharsis, Aznalcóllar, Sotiel-Coronada or Neves-Corvo), and validates once again the hypothesis that a single mineralizing event was responsible for the genesis of most of the IPB’s massive sulphide deposits. The present study confirms that palynostratigraphy is an invaluable high-resolution biostratigraphic tool in the IPB, applicable to dating, correlation and ore-exploration.  相似文献