PGE distribution in massive sulfide deposits of the Iberian Pyrite Belt     

Jan Pašava  Anna Vymazalová  Fernando Tornos 《Mineralium Deposita》2007,42(3):309-314

We present the first platinum group elements (PGE) data on seven massive sulfide deposits in the Iberian Pyrite Belt (IPB), one of the world largest massive sulfide provinces. Some of these deposits can contain significant PGE values. The highest PGE values were identified in the Cu-rich stockwork ores of the Aguas Teñidas Este (Σ PGE 350 ppb) and the Neves Corvo (Σ PGE 203 ppb) deposits. Chondrite normalized PGE patterns and Pd/Pt and Pd/Ir ratios in the IPB massive, and stockwork ores are consistent with the leaching of the PGE from the underlying rock sequence.  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   

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   

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   

Coupled trace element and SIMS sulfur isotope geochemistry of sedimentary pyrite:Implications on pyrite growth of Caixiashan Pb-Zn deposit     

《地学前缘(英文版)》2019,10(6):2177-2188

Colloform pyrite with core-rim texture is commonly deposited in carbonate platforms associated with the sulfide ores such as the Caixiashan Pb-Zn deposit.However,the genesis of colloform pyrite in Pb-Zn deposits,its growth controls and their geological implication are insufficiently understood.Integration of in-situ trace element and SIMS sulfur isotopes has revealed geochemical variations among these pyrite layers.These colloform pyrite occur as residual phases of core-rim aggregates,the cores are made up of very fine-grained anhedral pyrite particles,with some rims being made up of fine-grained and poorlycrystallized pyrite,while the other rims were featured with euhedral cubic pyrite.which are cemented by fine-grained calcite and/or dolomite with minor quartz.Sulfur isotope analysis shows that some wellpreserved rims have negative δ~(34)S values(-28.12‰to-0.49‰),whereas most of the cores and rims have positive δ~(34)S values(0 to+44.28‰;peak at+14.91‰).Integrating with the methane and sulfate were observed in previous fluid inclusion study,we suggest that the ~(34)S depleted rims were initially formed by bacteria sulfate reduction(BSR),whereas the positive δ~(34)S values were resulted from the sulfate reduction driven by anaerobic methane oxidation(AOM).The well-developed authigenic pyrite and calcite may also support the reaction of AOM.Combined with petrographic observations,trace element composition of the colloform pyrite reveals the incorporation and precipitation behavior of those high abundance elements in the pyrite:Pb and Zn were present as mineral inclusion and likely precipitated before Fe,as supported by the time-resolved Pb-Zn signal spikes in most of the analyzed pyrite grains.Other metals,such as Hg,Co and Ni,may have migrated as chloride complexes and entered the pyrite lattice.Arsenic and Sb,generally influenced by complex-forming reactions rather than substitution ones,could also enter the pyrite lattice,or slightly predate the precipitation of colloform pyrite as mineral inclusions,which are controlled by their hydrolysis constant in the ore fluids.The colloform pyrite may have grown inward from the rims.The successive BSR reaction process would enrich H_2~(32)S in the overlying water column but reduce the metal content,the nucleation of these pyrite rims was featured by strongly negative sulfur isotopes.The following AOM process should be activated by deformation like the turbidity sediment of the mudstone as the sulfide deposition are associated with fault activities that caused the emission of methane migration upward and simultaneously replenishing the metal in the column.The higher AOM reaction rate and the higher metal supply(not only Fe.but with minor other metals such as Pb and Zn) caused by sediment movement enhanced the metal concentration within the pyrite lattice.  相似文献   

草莓状黄铁矿形成机制及其研究意义   总被引：2，自引：0，他引：2       下载免费PDF全文

周 杰 邱 振 王红岩 卢 斌拜文华  刘德勋谈 昕 江增光 《地质科学》2017,(1):242-253

黄铁矿是沉积物中较为常见的矿物之一,而草莓状黄铁矿是由等粒度的亚微米级黄铁矿晶体或微晶体紧密堆积而成。基于已有的草莓状黄铁矿相关研究成果,本文综述了草莓状黄铁矿的形成机制,阐述了其对古环境恢复的意义。目前普遍认为草莓状黄铁矿的成因主要有两种,即有机成因和无机成因,前者认为有机质或细菌参与草莓状黄铁矿形成;而后者主要认为过饱和的黄铁矿浓度是微球粒草莓状黄铁矿形成的必备条件。草莓状黄铁矿粒径的大小是其古沉积环境的直接反映,被作为比较可靠的古氧化还原条件判别指标,已被广泛应用于古代及现代海洋沉积物的古环境恢复。目前,虽然草莓状黄铁矿粒径判别古环境的大小及分布范围还不统一,但普遍认为封闭的水体环境（硫化环境）草莓状黄铁矿粒径较小且变化不大,且随着含氧程度增加,草莓状黄铁矿的粒径大小增大且分布范围趋于加宽。  相似文献   

淮北宿临矿区构造煤中黄铁矿赋存特征及其地质控制          下载免费PDF全文

李云波  姜  波屈争辉 《地质科学》2017,(3):855-870

通过淮北宿临矿区不同类型构造煤中黄铁矿形态和分布的显微观测,结合常量及伴生元素分布特征分析,探讨了构造煤中黄铁矿的分布规律、形成机制及其地质控制作用。黄铁矿是典型的多期成因矿物,其分布受沉积环境和应力-应变环境共同作用,可划分为4 个形成阶段12 种类型;构造煤中的Co、Sb、Mn 等元素与黄铁矿关系密切,其分布反映应力-应变环境;进一步发现构造煤中的Hg 与硫化铁硫（Sp.d）呈良好相关性,随构造煤变形程度的增加呈“高-低-高”的演变趋势,受构造煤形成的动力学机制影响;构造煤中的黄铁矿可分为同生和后生两种模式,前者受控于沉积环境和古构造条件,而后者与构造改造和构造煤变形相关。分析认为,脆性变形阶段煤体结构的物理变化及过程为黄铁矿发育提供了赋存空间和条件,而韧性变形阶段中的动力变质和力化学作用为元素的迁移、散失及富集提供了动力,从而影响了黄铁矿的形成类型和分布。  相似文献   

胶东乳山金矿床成矿过程:周期性压力波动诱发的流体不混溶     

赛盛勋  邱昆峰 《岩石学报》2020,36(5):1547-1566

位于胶东东部苏鲁地体内的乳山金矿曾是我国单脉金储量最大的矿床,其主矿脉为一具有复杂内部结构的富金石英脉,形成于包含周期性流体活动的增量增长过程。该矿床成矿流体演化、精细成矿过程和金沉淀机制仍缺乏有效制约。本研究在详细结构构造观察基础上,在代表单次成矿流体活动的同一石英层内识别出分别代表三个连续成矿阶段的三类黄铁矿,开展激光剥蚀-电感耦合等离子质谱原位微量元素测试。结果显示不同阶段黄铁矿微量元素成分基本一致,Co、Ni、As等元素因成矿流体间歇性压力波动而周期性地以不同含量进入黄铁矿,形成这些元素的韵律成分环带。Au等其他微量元素在不同阶段黄铁矿内均匀分布,其分布行为受压力波动影响较小。间歇性压力波动和由此引发的周期性流体不混溶使乳白色粗粒石英和黄铁矿、烟灰色中细粒他形石英和黄铁矿依次大规模沉淀,金银碲化物、银金矿、自然金和方铅矿、闪锌矿、黄铜矿等硫化物随后在愈加富Au、Ag、Te、Pb、Zn和Cu等的流体中近于同时沉淀。在此过程中成矿流体虽整体表现为还原性,但其还原性随着压力波动而不断递减氧化性持续增加;流体碲逸度早期保持稳定,后期则大幅上升。金以可见金形式充填先成黄铁矿裂隙或沿黄铁矿边缘分布,周期性流体压力波动引发的间歇性流体不混溶导致H_2S、CO_2和CH_4等气体大规模逸出,金硫络合物失稳分解,金被吸附至黄铁矿内水力致裂形成的裂隙面发生沉淀。排除了先成黄铁矿内不可见金再活化为可见金的可能性,认为周期性流体压力波动引起的流体不混溶是引发乳山金矿床可见金高效沉淀的关键机制。  相似文献   

山东后大雪金矿床黄铁矿的成因矿物学研究     

魏明秀 《矿产与地质》2000,14(2):103-108

对山东后大雪金矿床黄铁矿的成因矿物学研究 ,指出成矿早期黄铁矿富 As、Sb、Au,晶胞大 ,结晶度指数低 ,相对贫 Ti、Mn、Co、Ni,Ag,中期贫 As、Sb,富多金属 ,矿化与早、中期关系密切。据黄铁矿的热电性和微量元素判别指数 ,判断后大雪金矿床 3号脉剥蚀最浅 ,深部矿化较好 ,是本区找矿的重点 ,2号脉剥蚀较深 ,9号脉剥蚀最深  相似文献   

东天山康古尔塔格金矿床黄铁矿的标型特征及找矿意义   总被引：5，自引：0，他引：5  

杨前进  丰成友  姬金生 《地质与勘探》1999,35(3):21-23

通过对黄铁矿的化学组成、晶体特征及热电性的研究,发现含金高的黄铁矿的Ａｇ、Ｃｕ、Ｔｅ 含量及晶胞参数ａ０ 均高于含金低的黄铁矿。而且,含金高的黄铁矿热电场为ｐ － ｎ 型,热电系数代数值高,而含金低的黄铁矿热电场为ｎ 型,热电系数代数值低  相似文献