共查询到19条相似文献，搜索用时 125 毫秒
1.
水库析出物中显微针铁矿的成因差异——以湖北省富水水库及南河水库为例 总被引：2，自引：0，他引：2
通过对湖北省富水、南河水库坝基渗漏水及其析出物的研究 ,探讨了不同水库沉积环境中显微针铁矿的成因差异及微生物在铁的生物矿化中的作用和意义。采用化学分析、X射线衍射、红外光谱、穆斯堡尔谱、透射电镜和扫描电镜分析等手段 ,研究了两个水库坝基渗漏水析出物的组成、物相和形貌特征。两个水库坝基渗漏水的成分相似 ,阳离子均以Ca2 + 、Mg2 + 、K+ 、Na+ 为主 ,Fe2 + 和Fe3 + 含量极少 ,阴离子以HCO-3 为主。渗漏水析出物的化学成分以铁的氧化物为主 ,析出物的主要矿物相为针铁矿、石英、伊利石、蒙脱石及微量方解石 ,呈弱结晶状态。穆斯堡尔谱图和SEM显微形貌特征证实了南河水库中针铁矿以化学成因为主 ,系菱铁矿风化而成 ;富水水库中针铁矿的形成受铁细菌的影响 ,以生物成因为主。 相似文献
2.
通过对湖北省富水水库坝基渗漏水及其析出物的研究，探讨了现代沉积环境（水库）中显微铁矿物形成的机理及微生物在铁的生物矿化中的作用和意义。对析出物中微量元素的富集特征也进行了初步研究。用化学分析方法测试出坝基渗漏水中阳离子以Ca^2 、Mg^2 、K^ 、Na^ 为主，Fe^2 和Fe^3 含量极少，阴离子以HCO3^-为主。析出物的化学成分以铁的氧化物为主。采用X射线衍射、差热分析、红外光谱和穆斯堡尔谱，以及透射电镜和扫描电镜等测试手段，分析研究了析出物的物相和形貌特征。析出物的主要矿物相为针铁矿、石英、伊利石、蒙脱石和微量方解石，呈弱结晶状态。由析出物中显微针铁矿特殊的形貌特征及其特征的穆斯堡尔谱图推测出富水水库沉积环境中显微针铁矿是由铁细菌形成。ICP－MS测试测试结果表明，析出物中不仅富集了铁，还富集了Yb、Pb、Dy、Zn、Co、Be、Eu、Sm和Tb等微量元素。微量元素的富集是微生物与显微针铁矿共同作用的结果。 相似文献
3.
针铁矿-四方纤铁矿-水体系氧同位素分馏的实验研究 总被引：3，自引：0，他引：3
针铁矿是非常重要的三价铁氧化物之一,其氧同位素组成对于古环境再造具有很大的价值。以4种不同的铁化合物作为Fe3+离子的源物质,于30～120℃范围内,采用强迫水解方法,在不同同位素组成的水中分别实验合成针铁矿和四方纤铁矿。结果表明,以Fe(NO3)3·9H2O、NH4Fe(SO4)2·12H2O、Fe(SO4)3·7H2O为Fe3+源物质合成的是纯针铁矿,而以FeCl3·6H2O为Fe3+源物质合成的是四方纤铁矿。氧同位素分析显示,在30～120℃范围内实验测定的针铁矿-水体系和四方纤铁矿-水体系氧同位素分馏几乎不可区分,并且满足下列分馏关系:103lnα针铁矿-水=9.59×103/T-26.39103lnα四方纤铁矿-水=8.85×103/T-24.44实验测定的针铁矿-水体系氧同位素分馏不仅与前人实验结果一致,而且与增量方法理论计算相近。由于实验采用不同反应途径得到了一致的分馏结果,因此所测定的针铁矿-水体系氧同位素分馏代表了热力学平衡。 相似文献
4.
碳酸盐岩地区红土针铁矿中铝对铁的置换作用及其环境意义 总被引：6，自引：0，他引：6
针铁矿是地表分布最广的氢氧化铁矿物，针铁矿的结构、成分和形态等特片，在一定程度上反映了某形成环境特征及其变化。根据作者提出和设计的红土中氧化铁矿物分离和分析程序，运用Ｘ射线衍射分析，红外光谱和电子探针等方法研究了贵州碳酸盐岩红土中针铁矿的铝类质同像置换作用。 相似文献
5.
本文以智博铁矿区内的安山岩为研究对象,通过详细的野外地质调查,并利用电子显微镜和电子探针,对安山岩中的主要矿物进行了系统的岩相学观察和矿物学研究。研究表明,智博安山岩中斜长石主要为Na-高钠长石,具低TiO2,高Na2O和Al2O3的特点;辉石主要为普通辉石,具高TiO2,高Al2O3的特点;角闪石主要为镁角闪石和阳起石,具低TiO2和Al2O3,高MgO的特点;副矿物磁铁矿具高TiO2,低MgO和Al2O3的特点。辉石、角闪石矿物化学特征表明,智博铁矿安山岩的母岩浆属于壳幔混源的玄武质岩浆,构造环境为火山岛弧环境。智博安山岩中单斜辉石结晶温度为1225℃左右,结晶压力约0.795GPa,结晶深度约26km。智博铁矿后期的热液作用也参与了磁铁矿成矿,对智博铁矿的成矿有一定的贡献。 相似文献
6.
新疆西天山式可布台铁矿发育于伊犁裂谷内,赋存于上石炭统中酸性火山碎屑岩、浅变质片岩、千枚岩中,矿体呈层状、似层状以及透镜状顺层产出。金属矿物以赤铁矿、镜铁矿为主,含少量黄铁矿、菱铁矿;脉石矿物主要为碧玉、重晶石、石英以及少量方解石。矿石构造以条带状、纹层状和块状为主,矿物结构多为隐晶质结构、半自形结构以及充填结构。矿床分为4个成矿阶段,即黄铁矿-赤铁矿-铁碧玉-重晶石阶段、菱铁矿-软锰矿阶段、石英-镜铁矿阶段、氧化物阶段。矿体顺层产出和发育纹层状矿石构造指示矿床为沉积成因。电子探针分析显示:(1)块状赤铁矿Al2O3、Na2O、MgO、SiO2含量相对分散,推测这可能与块状矿石快速沉淀结晶有关,暗示了剧烈的流体喷流活动,而纹层状和条带状赤铁矿Al2O3、Na2O、MgO、Si O2含量相对集中则反映平静的沉积环境以及微弱的喷流活动,两者的比较可能暗示了成矿过程中流体喷溢速率以及沉积环境都不断改变;(2)黄铁矿中含有较高的Co、Ni比,显示其形成与火山作用关系密切;(3)菱铁矿的FeOT与Mn O+MgO含量呈负相关关系,并形成两个聚集区,与镜下其具有不同特征相吻合,可能暗示了成矿后期菱铁矿随热液析出时候发生了分异作用。黄铁矿(δ34S=-6.1‰~6.5‰)和重晶石(δ34S=12.9‰)硫同位素组成显示曾发生过硫酸盐和硫化物之间的硫同位素分馏作用,成矿热液的硫可能来源于岩浆硫。综合分析认为,式可布台铁矿可能为海相火山喷流沉积型铁矿床。 相似文献
7.
利用工艺矿物学研究手段,对氧化铝生产高压溶出过程硅质结疤物的形貌结构进行深入研究,从而为预防和治理硅结疤提供了理论依据。研究结果表明:单套管预热器中硅质结疤物为钠硅质渣,呈微细粒状,与铝针铁矿一起填充在晶形规整、晶体粗大的赤铁矿晶体间的空隙里;压煮器中硅质结疤物为少量的微细粒钠硅质渣,与氢氧化镁基体共同沉积于钛的第一沉积旋回的层间局部;停留罐中硅质结疤物以水化石榴子石和橄榄石为主,它们以微细粒状填充于针铁矿晶体间隙中,有少量针状碳酸钠及钠硅渣;闪蒸器中硅质结疤物主要是铁石榴子石和Na2Ca3Si3O10相,前者与Al2O3(Al2O3·3H2O)共生成为球粒状结构中填隙物的主要成分,后者以微细粒状与氢氧化铝相混合成为纹层状结构中的主要成分。 相似文献
8.
天然半导体矿物由于成分、缺陷复杂,传统测试方法如紫外可见漫反射等难以准确测定其禁带宽度.本文以针铁矿为例,通过第一性原理计算得到纯针铁矿及掺Al针铁矿的电子结构.计算结果显示,纯针铁矿导带底与价带顶均由Fe3d与O2p轨道组成,而当含杂质Al时,Al2p与O2p发生杂化参与了价带组成.在此基础上,利用同步辐射X射线氧的K边吸收谱与发射谱对纯针铁矿及天然针铁矿的能带结构进行了测定.结果表明,天然含Al的针铁矿禁带宽度为2.30eV,小于纯针铁矿(2.57eV).本研究提供了一种测定天然氧化物矿物禁带宽度的新方法,为深入研究天然半导体可见光催化活性产生机制提供了理论依据. 相似文献
9.
采用矿物自动检测仪(MLA)、扫描电镜能谱仪(EDS)、X射线荧光光谱仪(AxiosmAX)等分析技术和光学显微镜(OM)观察,对国外某钒钛铁矿进行了系统的工艺矿物学研究.结果 表明,本矿石为深度蚀变氧化矿,包含了从原生到氧化带的一系列矿物,铁矿物为主要赤铁矿,少量磁铁矿和磁赤铁矿,钒主要赋存于铁矿物中;钛矿物主要为钛铁矿和蚀变钛铁矿.铁矿物与钛矿物嵌布关系十分紧密,难以磨矿解离.在工艺矿物学研究基础上,采用磁选回收工艺,原矿经弱磁选得到了Fe、V2O5、TiO2品位分别为60.28％、1.06％、9.85％,回收率分别为7.98％、8.32％、4.05％的含钒铁精矿;弱磁选尾矿经强磁选得到较高品位的钛铁精矿,Fe、V2O5、TiO2品位分别为49.42％、0.82％、16.46％,回收率分别为78.52％、77.23％、81.19％,该精矿可作为进一步提取钒、钛、铁的原料. 相似文献
10.
铁(氢)氧化物矿物对有机污染物的光催化氧化作用 总被引：22，自引：3，他引：19
对水溶液中(氢)氧化铁的光催化氧化反应的发展与机理研究进行了总结,着重对近十年来应用针铁矿／过氧化氢进行光催化氧化环境中有机物的研究进展及其环境矿物学意义作了概述和探讨。采用天然生物矿化的纳米针铁矿／过氧化氢以偶氮染料甲基橙为光解模型物进行了光催化氧化的初步研究,结果表明铁细菌形成的针铁矿具有降解生物难降解的有机污染物的能力。在甲基橙溶液初始浓度为30mg／L,铁细菌矿化的针铁矿用量2．5g／L,反应体系H2O2的初始浓度97mmol／L,pH值为6．92,15W紫外灯照射2h后,甲基橙浓度可降低33％。 相似文献
11.
K. A. Novoselov E. V. Belogub V. A. Kotlyarov K. A. Filippova S. A. Sadykov 《Geology of Ore Deposits》2018,60(3):265-276
The paper discusses the mineralogical and geochemical features of oolitic ironstones from the Sinara–Techa deposit, Transural region, Kurgan district. The ore unit is localized in the lower part of a thick Mesozoic–Cenozoic sequence of sedimentary rocks that fill the West Siberian Basin beneath calcareous clay and overlying beds enriched in glauconite and clinoptilolite. The ironstone consists of goethite ooids in smectite–opal cement. Accessory minerals are pyrite, galena, sphalerite, and monazite. The texture and structure make it possible to suggest the formation of sediments enriched in iron as a result of colloid coagulation. The most probable source of iron is related to inland drift. Deposition of iron took place in the estuaries of subtropical rivers due to mixing of colloidal solution of river water with seawater electrolyte. The chemical features of rocks are controlled by the composition of the adsorbed iron oxi/hydroxide complex. 相似文献
12.
13.
《International Geology Review》2012,54(7):766-772
Ferrihydrite (2.5 Fe2O2-4.5 H2O) is an unstable colloidal mineral. It dissolves in highly alkaline solutions and is precipitated from them in the form of goethite. Jarosite is stable at very low pH but is decomposed at higher values of pH with separation of iron oxides. Experiments show that in rapid decomposition of jarosite a protohematite substance, ferrihydrite, is formed. This transformation occurs at moderate pH values when solutions percolate through the aggregates of jarosite. Ferrihydrite, an unstable colloidal hydrated oxide of ferric iron, changes spontaneously to stable hematite with time. Very slow decomposition of jarosite results in its replacement by iron hydroxide, goethite. Under laboratory conditions in alkaline solutions lepidocrocite may be obtained from jarosite. The synthesis of this iron hydroxide passes through a stage of intermediate products: ferrihydrite and hydrated ferric oxide - ferriprotolepidocrocite, formed by solution of ferrihydrite in strongly alkaline solutions. The transformation of ferriprotolepidocrocite into lepidocrocite may be regarded as a topotactic reaction. —Authors. 相似文献
14.
通过在滇池开展原位实验,研究探讨了湖泊沉积物中磷灰石制约水铁矿分解和转化的机制,以及二者共存时的环境效应。结果表明:将水铁矿放置到沉积物中1个月,矿物保持稳定;放置时间达到3个月时,添加磷灰石实验中水铁矿发生了显著物相转变。冬天(12—2月)实验中,转化产物随深度的变化趋势为针铁矿+磁(赤)铁矿→针铁矿+纤铁矿→针铁矿;夏天(6—9月)实验中,转化产物随深度的变化趋势为针铁矿+纤铁矿+磁(赤)铁矿→针铁矿+纤铁矿→未转化。透射电镜分析结果显示冬天实验中生成的磁性铁氧化物为纳米磁铁矿和磁赤铁矿,夏天实验中产生的则主要为纳米磁铁矿。X射线光电子能谱分析结果显示冬天表层实验样品具有较高P含量。分析表明的湖泊沉积物中磷灰石促进水铁矿转化的过程为:(1)微生物促进磷灰石溶解;(2)磷灰石溶解释放的P促进铁还原菌生长;(3)铁还原菌促进水铁矿还原;(4)水铁矿还原产生的溶解态Fe2+催化水铁矿向针铁矿、纤铁矿和磁铁矿转化。冬天及沉积氧化-还原界面最适宜磷灰石分解菌和铁还原菌生长,水铁矿的转化和P释放能力也更强,相应地内源磷释放的风险也更大。 相似文献
15.
Quartz and iron (hydr)oxide are reactive surface phases that are often associated with one another in soils and sediments. Despite the several studies on the coating of quartz with iron oxides, the reactivity of dissolved species (Si) leached from quartz with iron (hydr)oxides has received limited attention. In this study, goethite synthesized on quartz substrates were characterized using field emission scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, and Fourier-transform infrared (FT-IR) spectroscopy. The SEM characterization revealed that bundles of thin parallel aligned goethite rods were formed at pH?>?10, while large pseudohexagonal crystals of twinned goethite needles were synthesized at pH?≤?10 after dehydration and hydration in the alkaline media. TEM analysis showed expanded and distorted lattice spacing of the crystal structure of iron (hydr)oxide due to silica incorporation. The characterization showed that silica increased the crystallite size of the goethite and transformed its acicular texture to a larger, twinned needle structure. FT-IR and XRD analyses revealed band shifts in crystal bonds as well as new bond formations, which indicate the presence of changes in the chemical environment of Fe–O and Si–O bonds. Thus, the presence of sorbed silicates modifies the crystal and lattice structure of goethite. 相似文献
16.
A.E.KELEPERTSIS 《中国地球化学学报》2002,21(3):193-205
A nickel laterite deposit occurs in the Vatera area of Lesvos Island,Greece ,and is transgressively developed on serpentinized basic rock (norite).The overlying sedimentary rocks include marls and marly limestones with sandstone intercalations and belong to the Pliocene sed-iments.The following alteritic zones are defined from the bottom to top layers:a)bedrock (norite);b)serpentinized zone;c)goethitic zone.The bedrock consists of the following pri-mary minerals:basic plagioclase,orthopyroxenes and clinopyroxenes.The serpentinized zone includes clinochrysotile,lizardite,antigorite clinoenstatite,calcite and dolomite while in the goethic zone there are goethite,quartz,pyrite,chromite,dolomite.Al2O3 ,Fe2O3,CaO,Na2O,K2O,Ba,Sr,Ni,C and S are enriched in the goethitic zone .Nickel enrichment is re-lated to the formation of nickeliferons minerals substituting for Mg or/and Fe in the goethite and pyrite.Enrichment of Ni in the matrix may be due to the presence of amorphous Ni-sili-cates(pimelite).There is a significant change(decrease)in the concentration of Ni from the top to bottom parts of the laterite formation,indicating that there was no tendency to migrate downwards(immature laterite).A second support of the immaturity of the Vatera laterite is the incomplete oxidation of ferrous iron to form ferric iron hydroxides.Under tropical/subtropical conditions,which dominated from the end of Miocene to the Pliocene the norite rocks of the Vatera area altered in response to reaction with acid solutions enriched in CO2.Due to hydrolysis and oxidation of pyroxenes,Mg^2 ,H4SiO4 and Ni^2 were removed in the continental acid solutions. 相似文献
17.
对分布于赤道东太平洋克拉里昂和克里帕顿断裂带之间 (C-C区 )的硅质沉积物所作的环境磁学研究表明,沉积物的磁性特征由亚铁磁性矿物主导,亚铁磁性矿物颗粒以单畴 (SD)和超顺磁 (SP)为主。磁性参数和透射电镜(TEM )分析表明,该区沉积物中存在着细菌合成的磁铁矿,并观察到磁铁矿存在不同程度的溶解。这一发现是微生物参与C-C区铁元素循环的直接证据。不完整反铁磁性矿物在氧化性较强的西区沉积物中含量较高,且随着纬度升高而增加,显示随着远离赤道,沉积物氧化性趋强. 相似文献
18.
The iron mineralization is hosted in carbonate beds of the Garagu Formation (Early Cretaceous) at Gara Mountain, Duhok Governorate, Kurdistan Region, NE Iraq. The Garagu Formation is composed of a series of limestone and siltstone beds with iron-rich beds in the middle part. The iron-rich limestones are iron-rich oolitic grainstone and bioclastic wackestone with hematite and goethite minerals. Geochemical results drawn from this study indicate that the percentage of iron in these beds reaches 19.73 %. Moreover, petrographical investigation of thin and polished sections reveals the presence of different types of fossils, indicating an open marine interior platform depositional environment. Different iron minerals, including hematite, goethite, siderite, pyrite and magnetite, were identified in the sections, and their geneses were related to syngenetic and diagenetic processes. The geochemical distribution of major and trace elements, as well as the V/Ni, V/(V+Ni), V/Cr and Sr/Ba ratios, indicates a reducing environment during the precipitation of carbonate sediments and a subsequent oxidizing condition during the concentration of iron minerals via diagenesis. 相似文献
19.
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. 相似文献