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1.
黄铁矿是安徽铜陵包村金(铜)矿床中主要硫化物,对热液成因的显晶质黄铁矿已有大量研究,而胶状黄铁矿研究较少且成因存在争议.本文以粉晶X射线衍射、扫描电镜(SEM)、透射电镜(TEM)以及拉曼光谱(RS)为主要研究方法和手段,对包村金(铜)矿床中胶状黄铁矿的矿物组成和微结构进行研究.包村胶状黄铁矿主要由黄铁矿组成,含有白铁矿、菱铁矿、石英、含铁白云石、高岭石和有机质.黄铁矿主要以纳米-亚微米粒径的自形、半自形的立方体为主,少量微米级他形颗粒,显著不同于胶体或非晶态的无定型黄铁矿.由黄铁矿、白铁矿和有机质组成的胶状结构中,白铁矿和有机质富集在暗色环带,黄铁矿相对富集在浅色环带,浅色和暗色交替变化主要由三者含量变化所致,与矿物粒径无关.结合铜陵地区胶状黄铁矿研究成果,我们认为铜陵地区乃至长江中下游成矿带内铜-金-铁多金属硫化物矿床相关研究文献中记载的胶状黄铁矿为铁硫化物、碳酸盐矿物、黏土矿物、石英和有机质组成的矿物集合体,是在陆源物质输入受限的半封闭海盆环境下经生物化学作用直接沉淀的纳米-亚微米黄铁矿为主的矿物集合体.虽然胶状黄铁矿经历沉积成岩作用和中生代岩浆热液叠加改造作用,但是沉积微结构、矿物成因信息仍然被有效保存. 相似文献
2.
豫西南淅川上泥盆统王冠组地层中发育大量与层面平行且具有蹼纹的U形遗迹化石Rhizocorallium。利用环境扫描电镜对Rhizocorallium进行微观观察,发现在其边缘管和蹼纹内部发育大量不同形态的莓状黄铁矿及莓状铁氧化物（单晶为五角十二面体,八面体,立方体和近球形）,与之对应的围岩中仅见少量黄铁矿单晶颗粒。表面具有覆盖膜的莓状黄铁矿大多存在于潜穴内部,其中边缘管中莓状黄铁矿的单晶直径（0.672~1.603 μm,平均直径1.063 μm）较之蹼纹中部的（0.376~0.877 μm,平均直径0.5 μm）的大。上述特征显示出潜穴中莓状黄铁矿的存在可能与硫酸盐类还原菌有关。Rhizocorallium边缘管和蹼纹中高丰度莓状黄铁矿的发现表明:遗迹化石Rhizocorallium可能是造迹者精心构筑的觅食-花园。由于食物供应和氧化还原条件的不同,Rhizocorallium造迹者在其潜穴内部培植不同的微生物,形成一个互利共生的群落。 相似文献
3.
北大西洋Logatchev热液区产出的黄铁矿形貌丰富、成分各异,极具特殊性和代表性.运用扫描电镜和电子探针系统观测黄铁矿矿物学特征,发现粒状黄铁矿粒径不一,具高Fe、S,低微量元素的特点;草莓状黄铁矿见有松散莓体、球形-次球形莓体和自形结构莓体,其Cu含量总体较高,不同晶体特征的莓体成分存在差异;胶状黄铁矿见有多层环带,内核到环带由纳微米晶体聚合生成,由内到外成分具有S/Fe比、Zn含量减小,As含量增大的趋势.分析认为早期粒状黄铁矿是在较高温度下的热液体系中直接形成,随热液作用衰减,生成的粒状黄铁矿多呈纳-微米晶产出;草莓状黄铁矿是由松散纳-微米晶逐步聚集形成,受溶液过饱和度影响,莓体粒度和聚集程度存在差异;胶状黄铁矿多晶聚集环带生长方向是由内向外的,聚集程度差异指示沉积环境的反复交替.研究区多形貌黄铁矿具有由分散的微晶→多晶聚合体→自形单晶的完整演化系列特征,对于解读现代海底热液活动的方式和特点,揭示纳米晶体-宏观晶体的演化过程有积极意义. 相似文献
4.
南海北部西沙海槽S1站位的岩心柱沉积物中广泛发育自生矿物黄铁矿,其形态以管状为主,且具有内部中空的圈层结构。使用扫描电镜、电子探针、LA-ICP-MS、SIMS等测试方法研究了管状黄铁矿的形态及圈层结构,结果显示: (1)管状黄铁矿发育内部中空的圈层结构,其中内圈层(Ipy)由莓球状黄铁矿呈五角十二面体紧密堆积组成,外圈层(Opy)由晶形较好晶粒较大的八面体黄铁矿组成,并混有沉积碎屑及钙质生物壳体;(2)内圈层和外圈层分别呈现出贫S富Fe和富S贫Fe的特征,其成因是甲烷渗漏造成的局部还原环境使得As进入黄铁矿中导致晶格空缺或被扭曲,从而促进Ni、Co、Cu、Zn、Pb等微量元素的掺入;(3)内圈层、外圈层发生了明显的硫同位素分馏现象,内圈层中 δ34S 平均为-37.8‰,外圈层中 δ34S 平均为-29.3‰。研究认为,管状黄铁矿作为曾经甲烷渗漏的通道,其生长机制可分为3个阶段: (1)气水通道形成阶段: 向上运移的甲烷流体在沉积物孔隙中逐渐形成气水通道;(2)外圈层形成阶段: 当向上运移的甲烷与硫酸盐发生甲烷厌氧氧化时,逐渐形成晶体较大、晶形较好的八面体黄铁矿外圈层;(3)内圈层形成阶段: 随着甲烷浓度逐渐降低,在气水通道中的微生物作用下,剩余甲烷与向下运移的硫酸盐继续反应形成莓球状黄铁矿内圈层。因此,南海北部的泥岩中大量发育的管状黄铁矿常常与地层中甲烷水合物的存在有关。 相似文献
5.
Pyritization of tubes and burrows from Late Pleistocene continental shelf sediments off North Norway 总被引：1，自引：0，他引：1
Four different types of pyritized tubes and three types of pyritized burrow fillings are described from Pleistocene glaciomarine sediments in Andfjorden, northern Norway. The tubes and burrows probably originated from tubicolous and burrowing polychaetes respectively. The decomposition of the organic matter in the tubes and burrows created a reducing micro-environment favouring precipitation of pyrite. By comparison with Holocene tubes from marine sediments in Andfjorden and FugloSyfjorden, it is seen that pyritization commenced with isolated spherules. These spherules with incipient pyrite crystals and framboids were formed mainly on the inner wall of the tube. Presence of a monosulphide in the Holocene Fugløyfjorden material suggests that the pyritization process has reached a later phase; the final result would be a completely pyritized trace fossil. It is shown that single pyrite crystals (octahedra) generally attain greater size in the burrow fillings than in the tubes. The microstructure found in some of the pyritized tubes is interpreted as a reflection of the microstructure in the original wall. Finally, the implications for the depositional environment in Pleistocene in Andfjorden is investigated with reference to the benthic skeletal macrofaunal assemblage in the sequence. The pyritized trace fossils occur frequently in an opportunistic assemblage from a period (c. 14,000–13,000 yr BP) characterized by some oxygen deficiency. Later (13,000–10,000 yr BP) they play a minor role in an established assemblage under improved oxygen conditions. 相似文献
6.
Polished and thin section examinations of samples from Indiana Coal Bed V (Springfield) have shown three sulfides to be present; namely pyrite, marcasite and sphalerite. Pyrite and marcasite are dominant forms whereas sphalerite is very minor. These sulfides appear to have formed in four distinct stages as judged on the basis of mineralogy and mineral texture. Pyrite occurs as framboids throughout the coal seam, as fibrous crystals in two horizons of the coal and in massive form as cleat fillings and cell fillings in fusinite and semi-fusinite. Marcasite occurs in spherical polycrystalline and twinned grains, as polycrystalline overgrowths on framboids, as cementing material for clusters of framboids, as blocky polycrystalline grains and with pyrite as cell fillings in fusinite and semi-fusinite. Sphalerite occurs exclusively as cell fillings in semi-fusinite. The paragenetic sequence indicates fluctuations in the overall coal bed chemistry. Individual sections display evidence of chemical variation on the micro scale. 相似文献
7.
在湖北省京山县雁门口地区二叠世栖霞组上部的含泥灰岩中发现棘皮动物化石,其腔被不同形态微晶的草莓状黄铁矿充填,有正四面体、正六面体、五角十二面体和近球体。溶解氧与草莓状黄铁矿的形成过程有关,其浓度决定微晶的S/Fe。统计显示,黄铁矿的S/Fe平均值随微晶的边数增加而增加,所以,棘皮动物腔内草莓状黄铁矿形成由早及晚的次序为：近球体微晶,五角十二面体微晶,正六面体微晶,正四面体微晶的草莓状黄铁矿。同一环境中,黄铁矿微晶的S/Fe可用来指示形成次序。 相似文献
8.
沉积地层中草莓状黄铁矿分析方法及其在古海洋学上的应用 总被引：1，自引：1，他引：0
草莓状黄铁矿是黄铁矿的特殊形态,其定义为由相近大小、相似形态的黄铁矿微晶颗粒组成的球形、亚球形聚合体。草莓状黄铁矿粒径分析已广泛应用于各个地质历史时期的古海洋环境恢复研究中,但其形成机理、判别标准与实验方法仍存在分歧。因此对沉积地层中草莓状黄铁矿的形成机理、在古海洋环境恢复中的指示意义及判别标准、实验与数据分析方法等进行总结阐述,有助于理解草莓状黄铁矿的粒径大小与形态对氧化还原条件的指示意义。草莓状黄铁矿在不同氧化还原环境下的形成机理存在差异,其粒径大小、数量以及分布范围可综合反映沉积时水体的氧化还原条件;而草莓状黄铁矿微晶几何形态及整体形貌特征也与古海洋氧化还原环境密切相关。此外,虽然有学者指出该方法可能存在一些问题,但只要在分析过程中结合沉积特征、古生态特征、地球化学指标等多方面证据对环境进行综合判别,甄别特殊条件下沉积的草莓状黄铁矿,则可有效避免这些问题。最后,针对后期氧化作用对草莓状黄铁矿粒径分布的影响进行了评价,结果显示经过后期氧化作用的草莓状黄铁矿粒径变化很小,不会对其在恢复古海洋氧化还原环境的应用上产生影响。 相似文献
9.
Heavy mineral separates of peat from a mineralotrophic bog contain sulphide minerals with distinctive textures. Pyrite framboids, consisting of spherical aggregates of subhedral pyrite crystals, are surrounded by a thin rim of chalcopyrite or a layer of massive marcasite. Clusters of framboids are cemented by covellite which also occurs as small idiomorphic grains, with rectangular or hexagonal outlines, surrounded by chalcopyrite. The sulphides appear to have resulted from discharge of groundwaters, enriched in copper from weathering of primary sulphides in bedrock and in iron by reduction of the till underlying the peat, into the hydrogen sulphide charged bog. 相似文献
10.
Sulfide minerals in coal bed III at the Chinook Mine, Indiana, are pyrite, marcasite, and rarely sphalerite. Pyrite occurs as framboids concentrated mainly in exinite, as bands or lenses in vitrinite and clay partings, as cell fillings in fusinite, and in cleats. Marcasite normally occurs in association with clusters of pyrite framboids within micro-organic remains. Sphalerite occurs exclusively in fusinite associated with cleat pyrite. The iron sulfides, which are of authigenic origin, were formed during the biochemical stage of coalification during the accumulation and compaction of peat. The factor that limited their formation in such an environment was the availability and reactivity of iron. Chemical heterogeneity in the peat swamps where the sulfides formed existed even on a microscopic scale. The iron sulfides were commonly precipitated in localized micro-environments that were favorable for their formation. The metamorphic stage of coalification did not affect the iron sulfides significantly, although it may have been responsible for the recrystallization of pyrite framboids and minor deformation of pyrite in fusinite and its local mobilisation. 相似文献
11.
Hisanari Sugawara Masayuki Sakakibara David Belton Tetsuya Suzuki 《Environmental Earth Sciences》2013,69(3):811-819
Pyrite framboid in sedimentary rocks could be concerned with arsenic contamination in groundwater of acidic environment and has been studied for the formation process of its unique morphology. However, not much has been discussed about the formation process based on the heavy-metal distribution in pyrite framboids and their aggregates. To reveal the formation process of pyrite framboids and their aggregates, mudstone from the Late Cretaceous Hakobuchi Group, central Hokkaido, Japan, are investigated for mode, petrographical, mineralogical, and micro-PIXE (particle-induced X-ray emission) analysis in this study. Spherical and sub-spherical pyrite framboids observed in polyframboids can be divided into two types based on the diameter of framboids (D) and the average diameter of microcrystals (d) within framboids: type 1, ranging from 2 to 9 μm and from 0.4 to 0.9 μm, respectively, and type 2, ranging from 8 to 50 μm and from 0.5 to 1.8 μm, respectively. Based on the quantitative traverse analyses and 2-D elemental mapping results by micro-PIXE, heterogeneities in the concentrations of heavy metals within the analyzed aggregations of pyrite are exhibited. On the basis of the As and Pb zoning patterns, the time range and chronological stages of pyrite-aggregation growth are revealed. 相似文献
12.
沁水盆地晚古生代煤中硫的地球化学特征及其对有害微量元素富集的影响 总被引：1，自引：0，他引：1
煤中硫是多种有害微量元素的重要载体。基于形态硫分析、电感耦合等离子质谱及X射线衍射等方法分析沁水盆地晚古生代煤中硫和有害微量元素的分布规律,探讨了煤中硫对有害微量元素富集的影响,运用带能谱的扫描电镜和光学显微镜划分煤中硫化物的微观赋存特征。结果表明,沁水盆地煤中硫整体上以有机硫为主,平均占全硫的78%,只有在太原组个别高硫煤中以黄铁矿硫为占优势。显微镜和扫描电镜下可识别出煤中黄铁矿的微观赋存状态包括莓球状、薄膜状、晶粒状、结核状、团窝状黄铁矿和细粒黄铁矿集合体,白铁矿的微观赋存特征包括聚片状、板状和矛头状白铁矿,部分白铁矿与黄铁矿共生。沁水盆地煤中有害微量元素含量整体较低,黄铁矿是有害微量元素As、Se和Hg的重要载体,而有机硫决定了煤中U的富集。研究认为,成煤时期海水对泥炭沼泽的影响导致太原组煤中全硫和黄铁矿硫较高,太原组煤中硫的来源具有多样性,煤中黄铁矿具有多阶段演化的特点。 相似文献
13.
有孔虫壳体内草莓状黄铁矿成因及其地质意义——以湖北雁门口地区栖霞组有孔虫化石为例 总被引：1，自引：0，他引：1
在湖北省京山县雁门口地区栖霞组上部的含泥灰岩中存在丰富的节房虫科底栖有孔虫化石,主要有节房虫属、厚壁虫属和郎格虫属,壳体均被草莓状黄铁矿充填。对其系统的显微镜、扫描电镜观察和黄铁矿的能谱分析结果发现,黄铁矿草莓体直径最大为15 μm,平均约10 μm,硫铁原子比值（S/Fe）为1.90±0.10,表明在黄铁矿形成过程中,有孔虫壳体空腔内呈轻度- 中度贫氧的微环境。在分析该类黄铁矿成因的基础上,认为有孔虫壳体内的黄铁矿在指示沉积环境和保存环境方面具有局限性。 相似文献
14.
To characterize the hydrothermal processes of East Pacific rise at 9o-10oN, sulfide mineral compositions, textural, and geochemical features of chimney ores were studied using ore microscope, scanning electron microscope, X-ray diffraction analysis, and electron microprobe techniques. Results show that there are three mineral assemblages for the hydrothermal chimney ores, namely: (i) anhydrite marcasite pyrite, (ii) pyrite sphalerite chalcopyrite, and (iii) chalcopyrite bornite digenite covellite. Mineral assemblages, zonational features, and geochemical characteristics of the ore minerals indicate that ore fluid temperature changed from low to high then to low with a maximum temperature up to 400 ℃. The chimney is a typical black smoker. The initial structure of the chimney was formed by the precipitation of anhydrites, and later the sulfides began to precipitate in the inner wall. 相似文献
15.
《Chemical Geology》2006,225(3-4):278-290
The thermodynamic mixing properties of As into pyrite and marcasite have been investigated using first-principles and Monte Carlo calculations in order to understand the incorporation of this important metalloid into solid solution. Using quantum-mechanical methods to account for spin and electron transfer processes typical of sulfide minerals, the total energies of different As–S configurations were calculated at the atomic scale, and the resulting As–S interactions were incorporated into Monte Carlo simulations. Enthalpies, configurational entropies and Gibbs free energies of mixing show that two-phase mixtures of FeS2 (pyrite or marcasite) and FeAsS (arsenopyrite) are energetically more favorable than the solid solution Fe(S,As)2 (arsenian pyrite or marcasite) for a wide range of geologically relevant temperatures. Although miscibility gaps dominate both solid solution series, the solubility of As is favored for XAs < 0.05 in iron disulfides. Consequently, pyrite and marcasite can host up to ∼6 wt.% of As in solid solution before unmixing into (pyrite or marcasite) + arsenopyrite. This finding is in agreement with previously published HRTEM observations of As-rich pyrites (> 6 wt.% As) that document the presence of randomly distributed domains of pyrite + arsenopyrite at the nanoscale. According to the calculations, stable and metastable varieties of arsenian pyrite and marcasite are predicted to occur at low (XAs < 0.05) and high (XAs > 0.05) As bulk compositions, respectively. 相似文献
16.
N. D. MacRae M. E. Fleet A. J. Andrews 《Contributions to Mineralogy and Petrology》1977,63(3):309-317
Two types of secondary sulfides occur on the walls of a vesicle in slightly altered basalt recovered from site 332A of DSDP
Leg 37. The first consists of euhedral crystals of pure pyrite, with occasional small partial overgrowths of fibrous chalcopyrite,
embedded within smectite (altered glass) which lines the vesicle. The second type occurs as small composite sulfide spherules
lightly attached to the surface of the smectite. The spherules are composed of pyrite crystallites arranged in approximate
pyritohedral symmetry, with marcasite crystallites decorating the pyritohedron edges. Precession camera photographs and optical
studies suggest the marcasite and pyrite grew simultaneously from a pyrite nucleus, with marcasite adopting the pyrite growth
habit. These spherules differ sharply from the magmatic sulfide spherules previously described. 相似文献
17.
The bedded clastic ore widespread on the slopes and flanks of the deeply eroded sulfide mound at the Saf’yanovka volcanic-hosted
copper massive sulfide deposit consists of products of destruction of the Paleozoic black smoker along with diverse newly
formed sulfides. The size of ore clasts gradually decreases with distance from the massive ore mound, from more than tens
of centimeters to a few millimeters. The clastic sediments are characterized by good preservation of sulfide material composed
of hydrothermal sedimentary colloform pyrite, chalcopyrite with lamellae of relict isocubanite, and concentrically zoned sphalerite.
Numerous pyrite framboids, nodules, and euhedral crystals; chalcopyrite segregations; and twinned sphalerite are typical of
sulfide-bearing black shale. Enargite, tennantite, and galena were formed after pyrite, filling interstices between nodules
or partially replacing and corroding the previously formed minerals. The interrelations between minerals show that the fine-clastic
sulfide-bearing black shale underwent diagenesis in the presence of organic matter. 相似文献
18.
广西宁明组植物化石中黄铁矿及其沉积意义 总被引：1，自引：1，他引：0
对化石中的黄铁矿进行研究,有助于明确生物的化石化过程以及期间的沉积微环境。利用光学显微镜和扫描电镜,对广西宁明组植物化石中保存的黄铁矿进行了分析,发现离散型单晶和成群的莓状体共同保存。单晶绝大多数为无规则至球状体,晶棱不明显,表面可见凹点;少数为八面体,晶棱明显,表面光滑;单晶直径为0.79~1.58 μm;莓状体为圆球状,粒径为7.23~14.95 μm,S/Fe原子个数比的均值为1.54。莓状体的粒径大小和变化幅度均处于低值段,其S/Fe原子个数比值小于2,结果均说明当时植物体上、下表皮间为一种贫氧的水体环境,并在短时间内形成了莓状体。植物化石上、下表皮间由于未保存组织结构,而被大量的、近似层状分布的黄铁矿单晶和莓状体充填,结果支持了化石内莓状体形成与有机质降解之间存在着必然联系。 相似文献
19.
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
20.
铊(Tl)是一种战略性关键金属,在高科技领域具有重要用途。作为“稀散元素”之一,Tl主要富集于低温贱金属硫化物矿床中,黄铁矿和白铁矿是其主要载体矿物。滇东北火德红MVT铅锌矿床中黄铁矿和白铁矿显示Tl的富集,其中白铁矿中Tl含量显著高于黄铁矿,为探究Tl在不同矿物之间的差异性富集机制提供了理想对象。本文对火德红矿床共生黄铁矿-白铁矿开展系统的结晶学、矿物学和地球化学研究。电子背散射衍射(EBSD)结果表明,热液黄铁矿、白铁矿晶粒组构具有一定继承性,与闪锌矿紧密共生,暗示为同一成矿事件的产物。激光剥蚀耦合等离子体质谱(LA-ICPMS)原位微量元素含量分析结果显示,黄铁矿和白铁矿中的Tl含量分别为127×10^(-6)~516×10^(-6)和356×10^(-6)~1046×10^(-6),不同含量测点Tl的激光剥蚀时间分辨元素信号曲线均较为平滑,暗示Tl主要以类质同象形式进入黄铁矿和白铁矿晶格。透射电镜(TEM)进一步证实Tl类质同象直接替换Fe为主,即2Tl^(+)←→□(空位)+Fe^(2+)。结合黄铁矿和白铁矿中Tl与Zn含量的正相关关系,本文认为白铁矿中Tl的超常富集可能与偏酸性条件下富Tl、Zn和Fe等金属成矿流体有关。综合研究表明,火德红矿床黄铁矿与白铁矿中Tl的差异性富集与晶体结构、Tl赋存状态无关,而是流体成分、物化条件共同制约的结果,受到矿物和矿床等不同尺度苛刻成矿条件的影响。与闪锌矿共生的白铁矿是未来寻找铊资源的重要方向。 相似文献