Ironstones in the Upper Oxfordian of southern England

The Upper Calcareous Grit, the last of the four upward shallowing cycles that comprise the Corallian Beds of southern England, is relatively enriched in iron minerals, having local developments of chamosite oolite mudstone and much more widespread deposits of sand and mud containing variable amounts of siderite and disseminated chamosite. The chamosite oolite mudstones have a restricted fauna dominated by oysters and probably accumulated in slightly hyposaline lagoons where the ooids formed from mixed iron-, alumina- and silica-bearing gels. Siderite was produced during diagenesis from iron carried on the surface of clay minerals. This intimate association with the terrigenous clay fraction means that siderite occurs in sediments deposited in a variety of environments ranging from offshore shelf to lagoonal. The most important factor responsible for ironstone development was a very low rate of clastic supply throughout Upper Calcareous Grit times. The iron was probably derived by normal processes of weathering and erosion of sedimentary rocks exposed around the basin margin, but this cannot be conclusively proved and quite different iron sources may have been involved.     

中国重要金属矿产资源现状、供需、进出口数据集

金属矿产是经济社会发展的物质基础。本数据集采集了16种对国民经济发展有重要影响的大宗紧缺矿产（铁、锰、铜、铝、金、铅、锌、镍、铬）、优势矿产（钨、钼、锡、锑）及战略新兴矿产（锂、钴、钛）2006—2017年的世界及中国资源储量、原矿产量、消费量、贸易量及贸易金额等数据。数据集为Excel表格型数据,包含6个sheet表（世界资源量、中国查明资源储量、中国基础储量、中国原矿产量、中国原矿消费量、中国进出口量）,旨在分析研究我国在工业化进程中后期阶段所需重要金属矿产的资源现状和供需趋势。数据集显示：①我国大宗紧缺矿产如铁、锰、铜、金等查明资源储量虽稳步增长,但开采消耗量大,使得基础储量增速缓慢;未来需求总量仍将维持高位,国内保障程度不足,进口量持续攀升。优势矿产资源钨、锑储采比低,后备资源接替不足,优势程度下降;②战略新兴矿产锂、钴、钛资源量、基础储量增长缓慢或呈下降态势,国内资源品质较差,难利用资源多;产量、消费量近十年快速增长,且未来将持续高增长,国内资源储量增长缓慢,供需矛盾凸显。该数据集对已有金属矿产供需数据的收集和总结,为今后金属矿产勘查及战略部署提供参考。     

Iron and Manganese Minerals in Suspended Matter from the Barents Sea

The mineralogy of suspended matter from surface and bottom waters is studied at two sites in the Barents Sea. Along with terrigenous minerals, the suspended matter samples contain authigenic mineral phases of iron and manganese oxyhydroxides. Mn-feroxyhite, Fe-vernadite, goethite, and proto-ferrihydrite were identified in samples from surface waters, whereas birnessite and nonferruginous vernadite were registered in samples from bottom waters. The formation of suspended manganese minerals in bottom waters is explained by an additional Mn supply from underlying reduced sediments during their early diagenesis and oxygen depletion in the near-bottom nepheloid layer. Bacteria are supposed to take part in the authigenic mineral formation.     

Mapping the distribution of iron ore minerals and spatial correlation with environmental variables in hilltop mining areas

The prime contribution of this assignment was to examine the hyperspectral remote sensing, based on iron ore minerals identification using spectral angle mapper (SAM) technique. Correlation analyses between field iron contents and environmental variables (soil, water, and vegetation) have been performed. Spectral feature fitting (SFF) and multi-range spectral feature fitting (MRSFF) methods were used for accuracy assessment in extracting iron ore minerals from Hyperion EO-1 data. Spectral inspections as a reference were used in SAM technique for image classification for iron ore minerals: Hematite (24.26%), Goethite (32.98%) and Desert (42.76). Iron ore minerals classification is justified by the United States Geological Survey (USGS) spectral library and field sample points. The regression analysis of USGS and Hyperion reflectance spectra has shown the moderate positive correlation. The regression analyses between iron ore contents and environmental parameters (soil, water, and vegetation) have shown the moderate negative correlation. The examination was significantly effectual in extracting iron ore minerals: Hematite (SFF RMSE?≤?0.51 MRSFF RMSE?≤?0.48), Goethite (SFF RMSE?≤?0.047 MRSFF RMSE?≤?0.438) and Desert (SFF RMSE?≤?0.63 and MRSFF RMSE?≤?0.50); and the MRSFF RMSE histograms indicate the above result likened to a conventional SFF RMSE. MRSFF RMS error result is best because multiple absorption features typically characterize spectral signatures. This analysis demonstrates the potential applicability of the methodology for iron minerals identification framework and iron minerals impact on environmental parameters.     

Carbon–sulfur–iron relationships in sedimentary rocks from southwestern Taiwan: influence of geochemical environment on greigite and pyrrhotite formation

The importance of the magnetic iron sulfide minerals, greigite (Fe₃S₄) and pyrrhotite (Fe₇S₈), is often underappreciated in geochemical studies because they are metastable with respect to pyrite (FeS₂). Based on magnetic properties and X-ray diffraction analysis, previous studies have reported widespread occurrences of these magnetic minerals along with magnetite (Fe₃O₄) in two thick Plio-Pleistocene marine sedimentary sequences from southwestern Taiwan. Different stratigraphic zones were classified according to the dominant magnetic mineral assemblages (greigite-, pyrrhotite-, and magnetite-dominated zones). Greigite and pyrrhotite are intimately associated with fine-grained sediments, whereas magnetite is more abundant in coarse-grained sediments. We measured total organic carbon (TOC), total sulfur (TS), total iron (Fe_T), 1N HCl extractable iron (Fe_A), and bulk sediment grain size for different stratigraphic zones in order to understand the factors governing the formation and preservation of the two magnetic iron sulfide minerals. The studied sediments have low TS/Fe_A weight ratios (0.03–0.2), far below that of pyrite (1.15), which indicates that an excess of reactive iron was available for pyritization. Observed low TS (0.05–0.27%) is attributed to the low organic carbon contents (TOC=0.25–0.55%), which resulted from dilution by rapid terrigenous sedimentation. The fine-grained sediments also have the highest Fe_T and Fe_A values. We suggest that under conditions of low organic carbon provision, the high iron activity in the fine-grained sediments may have removed reduced sulfur so effectively that pyritization was arrested or retarded, which, in turn, favored preservation of the intermediate magnetic iron sulfides. The relative abundances of reactive iron and labile organic carbon appear to have controlled the transformation pathway of amorphous FeS into greigite or into pyrrhotite. Compared to pyrrhotite-dominated sediments, greigite-dominated sediments are finer-grained and have higher Fe_A but lower TS. We suggest that diagenetic environments with higher supply of reactive iron, lower supply of labile organic matter, and, consequently, lower sulfide concentration result in relatively high Eh conditions, which favor formation of greigite relative to pyrrhotite.     

Mineralogy,geochemistry and origin of Mn in the high-Mn iron ores,Bahariya Oasis,Egypt

Although Mn is one of the major impurities in the economic iron ores from the Bahariya Oasis, information on its modes of occurrence and origin is lacking in previous studies. High-Mn iron ores from El Gedida and Ghorabi–Nasser iron mines were subjected to detailed mineralogical, geochemical, and petrographic investigations using X-ray diffraction (XRD), infrared absorption spectrometry (IR), Raman spectroscopy, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA) to clarify the modes of occurrence of Mn in these deposits and its origin. The results showed that the MnO₂ contents range between 0.03 and 13.9 wt.%. Three mineralogical types have been identified for the Mn in the high-Mn iron ores, including: (1) inclusions within the hematite and goethite and/or Mn accumulated on their active surfaces, (2) coarse-grained and crystalline pyrolusite, and (3) fine-grained cement-like Mn oxide and hydroxide minerals (bixbyite, cryptomelane, aurorite, romanechite, manjiroite, and pyrochroite) between the Fe-bearing minerals. The Mn carbonate mineral (rhodochrosite) was detected only in the Ghorabi–Nasser high-Mn iron ores. Since IR patterns of low-Mn and high-Mn samples are almost the same, a combination of XRD analysis using non-filtered Fe-Kα radiations and Raman spectroscopy could be the best way to identify and distinguish between different Mn minerals.Assuming that both Fe and Mn were derived from the same source, the occurrence of high-Mn iron ores at the base of the stratigraphic section of the deposits overlain by the low-Mn iron ores indicated a supergene origin of the studied ores by descending solutions. The predominance of Mn oxide and hydroxide minerals in botryoidal shapes supports this interpretation. The small grain size of Mn-bearing minerals as well as the features of microbial fossils such as spherical, elliptical, and filamentous shapes of the Fe-bearing minerals suggested a microbial origin of studied iron ores.Variations in the distribution and mineralogy types of Mn in the iron ores of the Bahariya Oasis demanded detailed mineralogical and petrographic characterizations of the deposits before the beneficiation of high-Mn iron ores from the Bahariya Oasis as feedstock for the ironmaking industries in Egypt by magnetizing reduction. High Mn contents, especially in the Ghorabi–Nasser iron ore and occurrence of Mn as inclusions and/or accumulated on the surface of the Fe-bearing minerals would suggest a possible utilization of the high-Mn iron ores to produce ferromanganese alloys.     

Goethite-enhanced anaerobic bio-decomposition of sulfate minerals

The effects of goethite on the anaerobic bio-decomposition of sulfate minerals were investigated by using the beef extract as a carbon source and the activated sludge as the source of mixed bacteria. Solution pH, sulfate concentration, total iron ion concentration and the solid products of four different batch tests were monitored and analyzed. Experimental results showed that the presence of iron oxide can improve the alkalinity of the reaction system which results in the increase of pH value. Moreover, the added goethite consumed a large amount of H₂S generated from the sulfate minerals by SRB, thereby significantly enhancing the decomposition of gypsum and anhydrite compared with the control batch tests. In addition, the SEM observation and the EDS spectra showed that there were some rod-shaped microorganisms and new generated minerals, such as iron sulfide, calcium carbonate crystals, and elemental sulfur. Both of the proliferation of new minerals (iron sulfide and calcium carbonate crystals) and the complete disappearance of sulfate minerals indicated that iron oxide can play the role in fixing the S element through the metabolism of SRB and hence improve the bio-decomposition of sulfate minerals.     

胶州湾李村河口沉积物中硫化物形成的控制因素

在胶州湾李村河口,对多个短柱状岩芯沉积物中的有机质（有机碳和有机氮）、酸可挥发性硫化物（AVS）、黄铁矿及活性铁等进行了分析。结果表明,样品的有机质含量较高,有机碳含量为0．16％～3．21％,有机氮含量为0．002％-0．2％;6个短柱状样的AVS含量变化较大：198．4—0．4umol／g,平均35．6umol／g;活性铁含量为47．5～169．3umol／g,平均91．4umol／g;黄铁矿含量为14．8～41．0umol／g,平均28．7umol／g。通过计算沉积物中活性铁的黄铁矿化度（DOP）与硫化度（DOS）指标,及分析各参数间相关性,发现以下现象：（1）胶州湾李村河口沉积物中的活性铁被转化为硫化物的程度较高,被转化为黄铁矿的程度较低,沉积物中的黄铁矿得到了较好保存。DOP不适宜用作河口区氧化还原状态的判断指标,DOS对氧化还原状态的响应更加灵敏;（2）距河口较近的区域,受李村河河水的影响较大,易分解有机质供应充足,AVS大量形成,其向黄铁矿的转化并不充分,活性铁成为硫化物形成的控制因素。距河口较远的站位,活性铁含量相对充足,有机质含量相对不足,因此有机质含量成为硫化物形成的控制因素,AVS向黄铁矿的转化比较充分;（3）有机质尤其是易分解有机质含量是李村河口硫化物形成、活性铁富集及其黄铁矿化度的主要控制因素。AVS的形成主要受到有机氮的限制,而黄铁矿的形成主要受到有机碳的限制。因此,河流输入物质对河口区沉积物中C、S和Fe的循环具有显著的影响。     

郭山高岭土铁钛赋存状态的分析电子显微术研究

使用分析电子显微术对福建郭山高岭土中铁、钛元素的赋存状态进行了研究。结果表明,高岭土中铁钛的赋存状态分为两类,一类为参加到粘土矿物晶格中的铁和钛,简称为结构铁、结构钛;另一类为游离出现或吸附在高岭矿物(高岭石和埃洛石)颗粒表面的铁、钛矿物。查明了在全铁和全钛中,结构铁和结构钛仅占少数,大部分以铁、钛独立矿物形式出现。从而确定了可将高岭土粘粒级(<2μm)中铁、钛含量降低到的最低限度,这便为提高高岭土品级和经济价值提供了可靠的依据。     

一价阳离子和水溶性有机质对生物沥浸中次生铁矿物形成的影响

在嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)作用下,污泥生物沥浸体系中常会有次生铁矿物形成,这些矿物对污泥脱水和重金属溶出有重要影响。本研究模拟生物沥浸体系,考察了一价阳离子(K+、NH4+、Na+)和污泥DOM(dissolved organic matter)对次生铁矿物形成的影响。结果表明,一价阳离子生成次生黄铁矾类矿物的能力迥异,其中K+的成矾能力最强,120 mmol/L NH4+和80 mmol/L Na+会抑制体系中黄钾铁矾形成。在1.6 mmol/L K+-120 mmol/L NH4+-40 mmol/L Na+和1.6 mmol/L K+-80 mmol/L NH4+-80 mmol/L Na+两个处理所得矿物的结晶度均低于1.6 mmol/L K+-80 mmol/L NH4+-40 mmol/L Na+处理所得矿物的结晶度。另外,在50 mg/L DOM(以DOC计)存在的生物氧化体系,Fe2+最大氧化速率为4.96 h-1,比没有DOM存在时降低48.1%,矿物结晶度也明显低于后者。可见,过高的一价阳离子和DOM含量会影响A.ferrooxidans菌生理生化活性,降低Fe2+氧化速率,继而影响Fe3+供应,使微环境中的黄铁矾形成动力发生改变,最终在一定程度上影响了次生铁矿物的形成。     

基于光谱特征空间的苏必利尔湖型铁矿高光谱遥感蚀变信息提取方法

由于境外铁矿床位置偏远, 现场研究困难, 旨在探讨苏必利尔湖型铁矿的高光谱遥感蚀变信息提取方法, 为境外找矿提供依据.鉴于传统蚀变信息提取方法的局限性, 研究了在二维光谱特征空间中提取蚀变信息的方法.高光谱影像经主成分变换后, 包含较多地物信息的两个主成分的二维光谱特征空间体现了各向异性的特点, 不同地物的聚类常呈类似椭圆分布.在蚀变信息的聚类椭圆中圈定散点, 并应用波谱特征拟合, 将异常散点的平均光谱与美国地质调查局(United States Geological Survey, USGS)光谱库中的矿物光谱匹配, 确定蚀变矿物类型.以苏必利尔湖型铁矿——巴西Aguas Claras铁矿区为例, 提取了赤铁矿、绿泥石等蚀变矿物, 结果表明矿物的类型和分布与该区地质概况吻合.      

铁细菌胞外多聚物对铁矿物的调控形成及其环境意义

环境介质溶液中铁的水解作用和稳定化作用主要受铁细菌及其代谢有机物质的影响。铁细菌普遍存在于自然环境中,可利用低价铁源为自身生长所需能量。铁细菌胞外有机物的主要组分如多糖和蛋白质等可与铁结合,并通过氧化或沉淀作用使铁稳定、沉积而形成铁矿物;此外铁细菌胞外多聚物可催化铁的氧化或促进铁的聚集。这些生物成因铁矿物因具有良好的表面吸附与氧化还原等化学活性,及有效固定环境中的重金属、放射性核素和催化降解有机污染物的良好环境属性,在环境生物矿物材料和环境治理研究领域被日益重视。故本文基于铁细菌及其胞外多聚物对铁矿物矿化形成的重要调控作用,介绍了环境中存在的铁细菌及其生物矿化特征,重点阐述了铁细菌胞外多聚物(组分、结构及特性)及其在铁矿物矿化过程中的作用,同时对铁细菌胞外多聚物及生物成因铁矿物的环境意义进行了概述。     

Arsenic solubilization and redistribution under anoxic conditions in three aquifer sediments from a basin-fill aquifer in Northern Utah: The role of natural organic carbon and carbonate minerals

The basin-fill aquifers of the Western U.S. contain elevated concentrations of arsenic in the groundwater due to ancient volcanic deposits that host arsenic minerals. Microcosms were constructed using two oxidized sediments and, by contrast, a reduced sediment collected from a shallow basin-fill aquifer in the Cache Valley Basin, Northern Utah to evaluate the fate of geologic arsenic under anoxic conditions. Sequential extractions indicated the primary arsenic host mineral was amorphous iron oxides, but 13%–17% of the total arsenic was associated with carbonate minerals. Arsenic was solubilized from the sediments when incubated with groundwater in the presence of native organic carbon. Arsenic solubilization occurred prior to iron reduction rather than the commonly observed co-reactivity. Arsenic(V) associated with carbonate minerals was the main source of arsenic released to solution and redistributed onto less soluble minerals, including FeS and siderite as defined by chemical extraction. Arsenic reduction occurred only in the site-oxidized sediments. The addition of a carbon and energy source, glucose, resulted in enhanced arsenic solubilization, which was coupled with iron reduction from the site-oxidized sediments. Adding glucose promoted iron reduction that masked the role of carbonate minerals in arsenic solubilization and retention as observed with incubation with groundwater only.     

The Experimental Study of Iron Sulfide Mineral Evolution Under Thermal Sulfurization Condition

Iron sulfide minerals are widely distributed, of which characteristics had the identification significance of formation environment. Previously, there were more research on iron sulfide minerals under hydrothermal condition, and few studies under volcanism formation condition. To simulate volcanic mineralization, the study of different temperature from 250 to 410℃ , different iron sulfur ratio from Fe:S=2∶1 to 1∶8, and two different sources of iron, reduced iron powder (Fe) and ferrous sulfide (FeS), on iron sulfide mineral evolution was investigated under thermal sulfurization condition. By using scanning electron microscopy (SEM), X-ray diffraction (XRD) and other methods, the morphology, composition and structural characteristics of the products were observed and analyzed.     

Characterization of bauxite deposits from Kachchh Area,Gujarat

The bauxites deposits of Kachchh area in Gujarat are investigated to characterize them based on mineralogical and petrographic studies. The major bauxitic mineral in these occurrences is gibbsite, with minor concentration of boehmite and diaspore. Apart from the bauxitic minerals, the other associate minerals are kaolin, calcite, alunite and the iron ore minerals such as hematite and goethite and titanium rich anatase. The iron ore minerals (hematite and goethite) are 10-50microns in size and are disseminated throughout the oolitic and pisolitic bauxitic minerals. At places the goethite exhibits colloform texture. The preservation of basaltic texture in some of the samples indicate that the insitu nature of these bauxites, which are formed by the alteration of calcic plagioclase from the parent basalt. Although, the basalt occurs as the main parent rock for these bauxites, the presence of calcite in some of the samples represent the possibility of having a limestone parent rock at least in some of the bauxite occurrences.     

碳酸盐岩红色风化壳中的氧化铁矿物

氧化铁矿物是碳酸盐岩红色风化壳的主要矿物成分和重要结构单元。运用X射线衍射、透射电镜、扫描电镜、穆斯堡尔谱和电子探针等方法对碳酸盐岩红色风化壳中的氧化铁矿物进行了系统研究。碳酸盐岩红色风化壳中的氧化铁矿物主要有针铁矿、赤铁矿和磁赤铁矿。氧化铁矿物组合、含量和化学成分随成土环境和风化强度在剖面中呈明显的规律性变化,这为碳酸盐岩风化成土作用、红色风化壳成因与环境问题的深入研究提供了重要的矿物学依据。     

福建龙岩中甲铁矿床中铟、镉赋存状态及其综合回收经济评价

福建龙岩中甲铁矿是上世纪60年代探明的海相火山沉积-热液叠加改造型多金属硫化物磁铁矿矿床。随着该矿难选铁矿石选矿技术的突破,最近发现矿石中共(伴)生的分散元素铟、镉含量超过综合利用工业最低品位要求,铟、镉的储量估算均可达大型规模。通过研究铟、镉的赋存状态,认为矿石中尚无铟、镉的独立矿物存在,铟、镉主要与锌呈类质同象存在于闪锌矿的晶格中;铟、镉综合回收经济评价表明,铟、镉在选矿流程中主要走向锌精矿,可在锌的冶炼过程中综合回收,并会获得很好的经济效益。永安—梅县凹陷带内有众多与该矿床类似的铁多金属矿,该矿床共(伴)生铟、镉含量及赋存状态的考察,对区域同类矿床伴生元素的综合利用、提升经济价值有重大意义。     

热液脉型铅-锌-银矿床富铁闪锌矿中硫化物包裹体成因探讨

通过对热液脉型的铅－锌－银矿床（３个）和银矿床（１个）和闪锌矿中硫化物包囊体的特征研究表明,石英－硫化物阶段富铁闪锌矿（主矿物）的硫化物包裹体十分发育：沿生长带产出的乳滴状黄铜矿与主矿物为共同沉淀成因;沿穿切主矿物的黄铜矿或石英细脉两侧,和受粗粒黄铜矿溶蚀的富铁闪锌矿近接触部位发育的乳滴状黄铜矿为渗透－交代产物;沿解理（裂隙）或粒间、粒内产出的各种形态磁黄铁矿是充填－交代的结果;沿解理分布的脉状毒     

安庆夕卡岩型铁铜矿床地质地球化学特征及铁质来源研究

安庆夕卡岩型铁铜矿床是长江中下游地区铜、铁成矿带的一个重要组成部分，其成岩成矿特征与典型的夕卡岩矿床有明显差别。本文通过对与成矿密切相关的月山岩体的岩石学和地球化学研究，以及夕卡岩分带特征与夕卡岩矿物学研究，指出岩体具高碱低铁的特征，夕卡岩矿物(石榴子石和透辉石)具富铁的特征，并有明显的逆向分带规律。并据此提出了铁质来源与磁铁矿的成矿作用的新观点，指出Fe质源自于形成岩体的富钠高铁的玄武岩浆；由于AFC作用，使FeNa分离，形成了富铁的成矿流体。而夕卡岩矿物的逆向分带和富铁夕卡岩矿物的广泛存在则是富铁流体参与夕卡岩成岩作用的结果。     

我国显生宙鲕铁石

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