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1.
Geochemistry of Apatite from the Apatite-rich Iron Deposits in the Ningwu Region, East Central China
YU Jinjie ZHANG Qi MAO Jingwen YAN Shenghao 《《地质学报》英文版》2007,81(4):637-648
Four types of apatite have been identified in the Ningwu region.The first type of apatite is widely distributed in the middle dark colored zones(i.e.iron ores) of individual deposits.The assemblage includes magnetite,apatite and actinolite(or diopside).The second type occurs within magnetite-apatite veins in the iron ores.The third type is seen in magnetite-apatite veins and (or) nodules in host rocks(i.e.gabbro-diorite porphyry or gabbro-diorite or pyroxene diorite).The fourth type occurs within apatite-pyrite-quartz veins filling fractures in the Xiangshan Group.Rare earth elements (REE) geochemistry of apatite of the four occurrences in porphyry iron deposits is presented.The REE distribution patterns of apatite are generally similar to those of apatites in the Kiruna-type iron ores,nelsonites.They are enriched in light REE,with pronounced negative Eu anomalies.The similarity of REE distribution patterns in apatites from various deposits in different locations in the world indicates a common process of formation for various ore types,e.g. immiscibility.Early magmatic apatites contain 3031.48-12080×10~(-6) REE.Later hydrothermal apatite contains 1958×10~(-6) REE,indicating that the later hydrothermal ore-forming solution contains lower REE.Although gabbro-diorite porphyry and apatite show similar REE patterns,gabbro-diorite porphyries have no europium anomalies or feeble positive or feeble negative europium anomalies, caused both by reduction environment of mantle source region and by fractionation and crystallization(immiscibility) under a high oxygen fugacity condition.Negative Eu anomalies of apatites were formed possibly due to acquisition of Eu~(2+) by earlier diopsite during ore magma cooling. The apatites in the Aoshan and Taishan iron deposits yield a narrow variation range of ~(87)Sr/~(86)Sr values from 0.7071 to 0.7073,similar to those of the volcanic and subvolcanic rocks,indicating that apatites were formed by liquid immiscibility and differentiation of intermediate and basic magmas. 相似文献
2.
Geochemistry and petrography of REE-bearing Fe-oxide assemblages in Choghart iron deposit,Yazd, Iran
Younes Shekarian Ardeshir Hezarkhani Nima Najafi Anaraki Arash Nikvar Hassani 《Arabian Journal of Geosciences》2017,10(12):273
The Choghart magnetite-apatite deposit situated in the Bafq district, Central Iran, has been scrutinized for rare earth elements (REEs) by precise geochemical investigation. The Central Iran is a susceptible area of rare earth elements. One of the Choghart’s prominent points is the existence of hydrothermal zones which made prediction of REEs occurrence within the deposit possible. Choghart is placed within felsic volcanic tuffs, rhyolitic rocks, and volcanic sedimentary sections belonging to the lower Cambrian. Abundance and distribution pattern of REEs in Choghart iron deposits reveal a part of deposit formation and its mineralogical modifications. Petrography and mineralogy of the ore body demonstrated two main types of alterations (sodic and calcic) associated with iron ore mineralization in Choghart deposit. The main ore includes a large quantity of massive magnetite in the lower part of Choghart deposit. The minor mineralization involves apatite, pyrite, alkaline amphibole, especially actinolite and tremolite, calcite, talc, quart, monazite, and bastnasite. Geochemical sampling from north–northeast (N-NE) side of the mine denotes the presence of these elements in hydrothermal zones. Statistical populations of the area were categorized by fractal geometry into four main differentiations: host rock type (albitofyre), iron, metasomatose, phosphate zones, and a subset of the phosphate zone which is named high iron high phosphate type. REEs like lanthanum, neodymium, yttrium, and niobium constitute the most quantity of Choghart. Deposit characteristics demonstrate its similarity to Kiruna type. The significant feature of iron oxide-apatite deposits of Kiruna ore type is the existence of monazite inclusions within apatite. These inclusions were also observed within apatite type I and II of Choghart mineralization. Moreover, REEs geochemistry in Choghart deposit was identified by investigation on geochemical data analyses. The analysis represents negative Eu anomaly and further enrichment of light REEs compared to the heavy ones. Chondrite normalized REEs patterns are defined by negative anomalies of Eu, which is the main characteristic of Kiruna ore type. The results showed that REEs concentration in phosphate zone, as a high absorption of REEs, is much higher than metsomatose, albitofyre, and iron zones. REEs distribution in N-NE side of the mine indicated that the contact of iron ore with tailings in N-NW side of the mine leads REEs to be enriched nearly 1% , as well as that of NE with high contents of REEs 1.5% ), which is very significant. 相似文献
3.
赞坎铁矿位于西昆仑造山带塔什库尔干地块西段,是近年新发现的一个大型沉积变质型磁铁矿床。铁矿体的顶一底板围岩分别为古元古代布伦阔勒群斜长角闪片岩和黑云母石英片岩;矿区南部出露早古生代花岗岩岩体;矿石类型以条带状及浸染状磁铁矿石为主,兼具少量块状磁铁矿石。在详细矿区地质观察的基础上,本文报道了矿石的地球化学特征与锆石U-Pb年代学分析结果。元素地球化学分析表明,条带状铁矿石具有较高的稀土总量,明显富集轻稀土,未呈现明显Ce和Y元素的异常(Ce/Ce~*=0.93~1.12、Y/Y~*=0.74~1.30);部分矿石显示Eu正异常(Eu/Eu~*=1.66~4.46),稀土配分形式与沉积变质型铁矿相似。矿体围岩变粒岩锆石U-Pb年龄为2 416±54 Ma,大致反映沉积铁矿的形成时代,而807±51 Ma的年龄反映变质作用时代。矿区一有铁矿捕虏体的花岗岩锆石U-Pb年龄为504±26 Ma。该期花岗岩的侵入对铁矿有明显的改造和叠加作用。 相似文献
4.
The Coniacian-Santonian high-phosphorus oolitic iron ore at Aswan area is one of the major iron ore deposits in Egypt. However, there are no reports on its geochemistry, which includes trace and rare earth elements evaluation. Texture, mineralogy and origin of phosphorus that represents the main impurity in these ore deposits have not been discussed in previous studies. In this investigation, iron ores from three localities were subjected to petrographic, mineralogical and geochemical analyses. The Aswan oolitic iron ores consist of uniform size ooids with snowball-like texture and tangentially arranged laminae of hematite and chamosite. The ores also possess detrital quartz, apatite and fine-grained ferruginous chamosite groundmass. In addition to Fe2O3, the studied iron ores show relatively high contents of SiO2 and Al2O3 due to the abundance of quartz and chamosite. P2O5 ranges from 0.3 to 3.4 wt.% showing strong positive correlation with CaO and suggesting the occurrence of P mainly as apatite. X-ray diffraction analysis confirmed the occurrence of this apatite as hydroxyapatite. Under the optical microscope and scanning electron microscope, hydroxyapatite occurred as massive and structureless grains of undefined outlines and variable size (5–150 μm) inside the ooids and/or in the ferruginous groundmass. Among trace elements, V, Ba, Sr, Co, Zr, Y, Ni, Zn, and Cu occurred in relatively high concentrations (62–240 ppm) in comparison to other trace elements. Most of these trace elements exhibit positive correlations with SiO2, Al2O3, and TiO2 suggesting their occurrence in the detrital fraction which includes the clay minerals. ΣREE ranges between 129.5 and 617 ppm with strong positive correlations with P2O5 indicating the occurrence of REE in the apatite. Chondrite-normalized REE patterns showed LREE enrichment over HREE ((La/Yb)N = 2.3–5.4) and negative Eu anomalies (Eu/Eu* = 0.75–0.89). The oolitic texture of the studied ores forms as direct precipitation of iron-rich minerals from sea water in open space near the sediment-water interface by accretion of FeO, SiO2, and Al2O3 around suspended solid particles such as quartz and parts of broken ooliths. The fairly uniform size of the ooids reflects sorting due to the current action. The geochemistry of major and trace elements in the ores reflects their hydrogenous origin. The oolitic iron ores of the Timsha Formation represent a transgressive phase of the Tethys into southern Egypt during the Coniacian-Santonian between the non-marine Turonian Abu Agag and Santonian-Campanian Um Barmil formations. The abundance of detrital quartz, positive correlations between trace elements and TiO2 and Al2O3, and the abundance mudstone intervals within the iron ores supports the detrital source of Fe. This prediction is due to the weathering of adjacent land masses from Cambrian to late Cretaceous. The texture of the apatite and the REE patterns, which occurs entirely in the apatite, exhibits a pattern similar to those in the granite, thus suggesting a detrital origin of the hydroxyapatite that was probably derived from the Precambrian igneous rocks. Determining the mode of occurrence and grain size of hydroxyapatite assists in the maximum utilization of both physical and biological separation of apatite from the Aswan iron ores, and hence encourages the use of these ores as raw materials in the iron making industry. 相似文献
5.
Chemical analysis for major and trace elements have been performed on 30 Swedish Precambrian iron ores and on some from Iran and Chile. The Swedish ores consist of apatite iron ores, quartz-banded iron ores, skarn and limestone iron ores from the two main ore districts of Sweden, the Bergslagen and the Norrbotten province. Some Swedish titaniferous iron ores were also included in the investigation. The trace element data show that the Swedish ores can be subdivided into two major groups: 1. orthomagmatic and exhalative, 2. sedimentary. Within group 1 the titaniferous iron ores are distinguished by their high Ti-contents. From the ferride contents of the Kiruna apatite iron ores, the ores are considered to be mobilization products of skarn iron ores from the Norbotten province. 相似文献
6.
Takeru Moriyama Mruganka K. Panigrahi Dinesh Pandit Yasushi Watanabe 《Resource Geology》2008,58(4):402-413
The major, trace and rare earth element (REE) composition of Late Archean manganese, ferromanganese and iron ores from the Iron Ore Group (IOG) in Orissa, east India, was examined. Manganese deposits, occurring above the iron formations of the IOG, display massive, rhythmically laminated or botryoidal textures. The ores are composed primarily of iron and manganese, and are low in other major and trace elements such as SiO2, Al2O3, P2O5 and Zr. The total REE concentration is as high as 975 ppm in manganese ores, whereas concentrations as high as 345 ppm and 211 ppm are found in ferromanganese and iron ores, respectively. Heavy REE (HREE) enrichments, negative Ce anomalies and positive Eu anomalies were observed in post‐Archean average shale (PAAS)‐normalized REE patterns of the IOG manganese and ferromanganese ores. The stratiform or stratabound shapes of ore bodies within the shale horizon, and REE geochemistry, suggest that the manganese and ferromanganese ores of the IOG were formed by iron and/or manganese precipitation from a submarine, hydrothermal solution under oxic conditions that occurred as a result of mixing with oxic seawater. While HREE concentrations in the Late Archean manganese and ferromanganese ores in the IOG are slightly less than those of the Phanerozoic ferromanganese ores in Japan, HREE resources in the IOG manganese deposits appear to be two orders of magnitude higher because of the large size of the deposits. Although a reliable, economic concentration technique for HREE from manganese and ferromanganese ores has not yet been developed, those ores could be an important future source of HREE. 相似文献
7.
辽宁齐大山铁矿元素地球化学特征 总被引：1，自引：0，他引：1
齐大山铁矿大地构造上属于华北地台辽东台背斜的西部.其铁矿层产于鞍山群樱桃园岩组,含矿建造为砂质泥岩-泥岩建造（阿尔戈马型）,变质相为绿片岩相.通过稀土元素地球化学研究,铁矿石表现为轻稀土富集,LREE/HREE比值平均为3.43.围岩表现为重稀土略富集,LREE/HREE比值平均为0.97.铁矿石和围岩稀土元素原始地幔标准化值显示铁矿石稀土元素整体具有弱的正铕异常（δEu为1.03~1.50）,Ce无明显的正负异常（δCe为0.54~1.15）,这与海底喷气沉积产物的特征一致.围岩中无明显Eu异常,平均为1.16.δCe的范围为0.18~1.01,相对比较稳定.这些特征显示属于早前寒武纪海洋化学沉积的产物,表明矿物大地构造背景为大洋岛弧,物源区类型为未切割的岩浆弧. 相似文献
8.
宁芜玢岩铁矿磷灰石的稀土元素特征 总被引：12，自引：2，他引：12
文章分析了宁芜玢岩铁矿 4种产状磷灰石的稀土元素组成 ,并与Kiruna型铁矿和斜长岩、苏长岩及钛铁霞辉岩中磷灰石的稀土元素组成进行了对比。结果表明产地和母岩不同的矿床中 ,它们的磷灰石稀土元素分布型式一致 ,以轻稀土富集和Eu负异常明显为特征 ,属陆相岩浆成因。前 3种产状磷灰石的ΣREE变化于 30 31.48×10 -6～ 12 0 80× 10 -6,第 4种产状磷灰石的ΣREE仅为 195 8× 10 -6,反映岩浆演化到热液的晚期阶段成矿溶液稀土元素含量较低。尽管辉长闪长玢岩与磷灰石的稀土元素分布型式一致 ,但辉长闪长玢岩无Eu异常或有弱Eu正异常 ,代表它们的地幔源区低氧逸度的还原环境 ,或反映氧逸度较高情况下的分离结晶作用。不混溶作用形成的矿浆在冷凝过程中 ,Eu2 + 优先被透辉石捕获 ,使得稍晚结晶的磷灰石产生负Eu异常 相似文献
9.
The accessory minerals apatite and sphene are the main carriers of REE in alkaline rocks.Their chondrite-normalized REE patterns decline sharply to the right as those of the host rocks,In the patterns an obvious negative Eu anomaly and a positive Ce anomaly can be seen in apatite and sphene,respectively.Zircon from alkaline rocks is different in REE pattern,I,e,. a nearly symmetric“V“-shaped pattern with a maximum negative Eu anomaly.Compared with the equivalents from granites,apatite,sphene and zircon from alkaline rocks are all characterized by higher (La/Yb)N ratio and less Eu depletion,As to the relative contents of REE in minerals,apatite,sphene and zircon are enriched in LREE,MREE and HREE respectively,depending on their crystallochemical properties. 相似文献
10.
文中主要选取大红山铜铁矿床典型穿脉进行构造-岩石地球化学编录,系统取样并对样品稀土元素进行化验分析。研究表明:(1)该矿区内各类岩(矿石)从矿化构造岩→矿石→未矿化构造岩的稀土总量呈现出逐渐降低的趋势,反映出成矿流体与不同构造岩的水岩反应程度上的差异。(2)从(La∕Yb)N看,该矿区内同类断裂构造岩的轻稀土分异程度较大,但不同断裂构造岩间的分异性却较为均一,从该区围岩、矿石、构造断裂岩的LREE∕HREE与(La∕Yb)N比值特征中可以看出,轻稀土元素与重稀土元素间的分异程度具有一定的相似性,反映出成矿流体对地层岩石存在着一定的继承性,却又具有一定的阶段演化性特征。(3)从地层岩石→未矿化断裂构造岩→矿化断裂构造岩→块状、条带状矿石,LREE∕HREE(5.66~13.27)有逐渐增大的趋势,反映出在断裂构造作用过程中,稀土元素发生了迁移;该矿区内各类岩(矿)石的δEu均大于1,δCe弱负异常,显示出大红山铜铁矿床的成矿作用主要是在相对氧化的环境下进行。 相似文献
11.
Enrichment iron ore of the Hamersley Province, currently estimated at a resource of over 40 billion tonnes (Gt), mainly consists of BIF (banded iron-formation)-hosted bedded iron deposits (BID) and channel iron deposits (CID), with only minor detrital iron deposits (DID). The Hamersley BID comprises two major ore types: the dominant supergene martite–goethite (M-G) ores (Mesozoic–Paleocene) and the premium martite–microplaty hematite ores (M-mplH; ca 2.0 Ga) with their various subtypes. The supergene M-G ores are not common outside Australia, whereas the M-mplH ores are the principal worldwide resource. There are two current dominant genetic models for the Hamersley BID. In the earlier 1980–1985 model, supergene M-G ores formed in the Paleoproterozoic well below normal atmospheric access, driven by seasonal oxidising electrochemical reactions in the vadose zone of the parent BIF (cathode) linked through conducting magnetite horizons to the deep reacting zone (anode). Proterozoic regional metamorphism/diagenesis at ～80–100°C of these M-G ores formed mplH from the matrix goethite in the local hydrothermal environment of its own exhaled water to produce M-mplH ores with residual goethite. Following general exposure by erosion in the Cretaceous–Paleocene when a major second phase of M-G ores formed, ground water leaching of residual goethite from the metamorphosed Proterozoic ores resulted in the mainly goethite-free M-mplH ores of Mt Whaleback and Mt Tom Price. Residual goethite is common in the Paraburdoo M-mplH-goethite ores where erratic remnants of Paleoproterozoic cover indicate more recent exposure. Deep unweathered BIF alteration residuals in two small areas of the Mt Tom Price M-mplH deposits have been used since 1999 for new hypogene–supergene modelling of the M-mplH ores. These models involve a major Paleoproterozoic hydrothermal stage in which alkaline solutions from the underlying Wittenoom Formation dolomite traversed the Southern Batter Fault to leach matrix silica from the BIF, adding siderite and apatite to produce a magnetite–siderite–apatite ‘protore.’ A later heated meteoric solution stage oxidised siderite to mplH + ankerite and magnetite to martite. Weathering finally removed residual carbonates and apatite leaving the high-grade porous M-mplH ore. Further concepts for the Mt Tom Price North and the Southern Ridge Deposits involving acid solutions followed, but these have been modified to return essentially to the earlier hypogene–supergene model. Textural data from erratic ‘metasomatic BIF’ zones associated with the above deposits are unlike those of the typical martite–microplaty hematite ore bodies. The destiny of the massive volumes of dissolved silica gangue and the absence of massive silica aureoles has not been explained. Petrographic and other evidence indicate the Mt Tom Price metasomatism is a localised post-ore phenomenon. Exothermic oxidation reactions in the associated pyrite-rich black shales during post-ore removal by groundwater of remnant goethite in the ores may have resulted in this very localised and erratic hydrothermal alteration of BIF and its immediately associated pre-existing ore. 相似文献
12.
针对北秦岭丹凤地区产铀花岗岩的区域地层、赋矿围岩、蚀变岩和铀矿石进行稀土元素地球化学研究,结果表明:各类样品具有大体类似的LREE富集及Eu负异常的稀土配分模式,表明它们之间稀土元素特征具有继承性;赋矿黑云母二长花岗岩与区域地层(丹凤岩群变质基性火山岩)稀土元素特征指示,二者均形成于岛弧环境;蚀变花岗岩和铀矿石主要继承了赋矿花岗岩的特征。各类样品Y/Ho值变化范围狭窄,为25.09~33.46,显示它们具有共同的源区。铀矿石具有最高的wB(∑HREE),且与铀矿石的品位存在正相关关系,暗示HREE与铀的迁移具有同步性。 相似文献
13.
新疆赞坎铁矿床位于西昆仑塔什库尔干地块西段,是近年新发现的一个大型沉积变质型磁铁矿床。赋矿岩系布伦阔勒群主要由黑云母石英片岩、斜长角闪片岩、变粒岩、硅质岩及磁铁石英岩等组成。目前探明工业矿体4条,单个矿体长度大于2.5km,矿体厚10~70m;局部见高品位铁矿段(mFe50%),长度达900m,厚度40m左右。矿石类型主要为2种,一种为原生的条纹-条带状磁铁矿(为主);另一种为热液改造形成的块状(高品位铁矿石)及浸染状磁铁矿。矿石稀土元素配分(PAAS)表明,原生条纹-条带状铁矿石Ce和Y元素异常不明显(~1.15、~0.94),Eu具正异常(~1.69),Y/Ho平均值为25,稀土配分模式与沉积变质型铁矿相似。而受改造的矿石中,浸染状矿石具有较高的稀土总量,明显富集轻稀土,La和Ce显示正异常(~1.46、~1.17),Y显示负异常(=0.66~0.72),Eu表现为强烈的正异常(~4.37),稀土配分模式明显不同于原生条纹-条带状铁矿石。矿体围岩斜长角闪片岩(变沉积岩)中的碎屑锆石U-Pb年龄为591±1Ma,结合前人对矿区内侵入体的年代学研究(霏细斑岩,533Ma),大致反映沉积铁矿的形成时代为新元古代至早寒武世。电子探针显示,条带状磁铁矿中的TiO_2、AL_2O_3、MgO、MnO含量较低,标型组分含量与沉积变质型磁铁矿颇为接近,在磁铁矿单矿物成因图解中,条带状磁铁矿整体显示磁铁矿为沉积变质型铁矿;浸染状矿石和块状矿石的组成与典型沉积变质型铁矿的偏离反映了后期岩浆-构造热事件对条带状铁矿石的改造;上述结果显示赞坎铁矿整体属于沉积变质型铁矿(BIF)。调查发现赞坎高品位铁矿体与早寒武世侵入的霏细斑岩联系密切,高品位矿石及其围岩发育一定程度的矽卡岩化,如阳起石化、碳酸盐化和黄铁矿化。本文推测高品位铁矿石的成因可能为霏细斑岩的岩浆热液溶解并运移早期沉积变质铁矿中的含铁物质,在构造发育处充填交代形成块状磁铁富矿石。在早寒武世侵入到矿区中部的霏细斑岩体中,同时发育有角砾状磁铁矿和脉状磁铁矿,因此,岩浆热液改造原生条带状铁矿石形成高品位铁矿石的时代应为早寒武世。 相似文献
14.
The Bhukia gold (+copper) deposit hosted by albitite and carbonates that occur within the Paleoproterozoic Aravalli-Delhi Fold Belt (ADFB) in western India consists of magnetite, graphite, apatite and tourmaline along with sulfide mineralization. Ubiquitous presence of magnetite and apatite in gold-sulfide association, alteration patterns and shear controlled mineralization suggest it to be IOCG (Iron-oxide copper gold) type deposits. The detailed mineral chemistry of magnetite and apatite are generated and interpreted in terms of their genetic significance, hydrothermal and magmatic origin vis-à-vis their affiliation with IOCG deposition. The data suggest that the magnetite has hydrothermal affiliation. The Ni/Cr ratio is greater than 1, which is explained by differences in solubility and mobility of Ni and Cr in hydrothermal fluids and is corroborated with other key evidences including that of wide ranging Mg concentration further supports a strong hydrothermal input that is envisaged for the deposition of magnetite. Concentration of vanadium in magnetite is generally <1000 ppm in case of barren hydrothermal occurrences while in the study area, it is relatively higher as it is attributed to the gold-sulfide-Cu mineralization. Ti vs Ni/Cr, Ni/(Cr+Mn) vs Ti+V, Ca+Al+Mn vs Ti+V and Al+Mn vs Ti+V variations are interpreted in terms of magnetite genesis. EPMA data suggests that apatite present in Bhukia is of fluorapatite variety with F content >1 wt% and F/Cl >1. Higher concentration of F and moderate Mn along with lower concentration of Cl attests their magmatic hydrothermal character and its derivation from meta-volcano sedimentary source. REE patterns obtained from LA-ICP-MS analysis suggest enrichment of LREE relative to MREE and HREE with negative Eu anomaly. Y/∑REE, La/Sm, Ce/Th and Eu/Eu1 vs Ce/Ce1 values of apatite is indicative of their origin in a highly oxidized environment. Presence of magnetite along with apatite is a common feature in IOCG-IOA (Iron-Oxide Apatite) association. Bhukia Gold Deposit has many similarities with Kiruna type Iron-Oxide Apatite (IOA) deposits particularly with respect to their similar tectonic setting, alteration patterns, mineral assemblages such as abundance of magnetite, apatite and presence of late stage sulfides based on EPMA and Laser ablation ICP-MS (LA-ICP-MS) studies. Lithological, petro-mineralogical and geochemical signatures of magnetite and apatite infer that the Bhukia is a possible IOCG-IOA type gold deposit typically associated with sulfides and graphite which may be used as petrogenetic indicators and pathfinders for exploration. 相似文献
15.
铁山河铁矿床赋存于古元古界银鱼沟群地层中,是华北陆块南缘一个重要的富铁矿床。文章对铁山河铁矿床进行了系统的野外地质调查和矿床地球化学研究,并与国内外典型的沉积变质型铁矿床进行了对比。结果显示:铁山河铁矿床保存有明显的化学沉积的特征,化学成分主要由Fe_2O_3、FeO和SiO_2组成,Al_2O_3和TiO_2含量较低;稀土元素总量较低,稀土元素配分模式呈轻稀土元素亏损、重稀土元素富集的特征,具有明显的Eu、Y、La正异常,弱的Ce异常,Y/Ho比值与海水的分布范围相近,Sr/Ba和Ni/Co比值分别与鞍山弓长岭铁矿和山西五台山、冀东迁安地区铁矿相似,但与基性岩浆活动相关的Co、Ni、Cr、V、Ti元素含量相对偏高。这些特征表明:该矿床的形成可能与海相火山沉积物有关,属于火山沉积变质型铁矿的范围,区内基性岩脉广泛发育,矿床可能遭受了后期热液的叠加改造作用;成矿物质来源于热液和海水的混合作用,矿床形成于相对缺氧的环境。 相似文献
16.
牦牛坪稀土矿床黑色土状风化物中富Eu、Y次生稀土的迁移富集及其经济价值 总被引：2，自引：0，他引：2
耗牛坪稀土矿床之氧化带，广泛分布泥化率为１４．３３％─２４．６０％的．黑色土状风化物，其次生ＲＥＯ含量在２．０６％─６．６７％；Ｅｕ＿２Ｏ＿３和Ｙ＿２Ｏ＿３的配分为０．４３％─０．６３％和１．１２％─５．１８％，是矿石、工业矿物氟碳铈矿的数倍到数十倍。次生稀土是在弱碱性介质条件下发生分馏而富集中重稀土的，黑色土状风化物中的Ｍｎ－Ｆｅ非晶质体是富Ｅｕ、Ｙ等次生稀土富集体，是选矿矿泥的主要部分，如能综合开发利用将产生巨大的经济和社会效益。 相似文献
17.
The Khanlogh deposit in the Cenozoic Quchan-Sabzevar magmatic belt, NE Iran, is hosted by Oligocene granodioritic rock. The Khanlogh intrusive body is I-type granitoid of the calc-alkaline series. The orebodies are vein, veinlet, massive, and breccia in shape and occur along the fault zones and fractures within the host rock. Ore minerals dominantly comprise magnetite and apatite associated with epidote, clinopyroxene, calcite, quartz, and chlorite. Apatites of the Khanlogh deposit have a high concentration of REE, and show a strong LREE/HREE ratio with a pronounced negative Eu anomaly. Magnetites have a high concentration of REE and show weak to moderate LREE/HREE fractionation. They are comparable to the REE patterns in Kiruna-type iron ores and show an affinity to calc-alkaline magmas. The Khanlogh deposit is similar in the aspects of host rock lithology, alteration, mineralogy, and mineral chemistry to the Kiruna-type deposits. Field observations, hydrothermal alteration halos, style of mineralization, and the geochemical characteristics of apatite, magnetite, and host rock indicate that these magnetite veins have hydrothermal origin similar to Cenozoic Kiruna-type deposits within the Tarom subzone, NW Iran, and are not related to silica-iron oxide immiscibility, as are the major Precambrian magnetite deposits in central Iran. 相似文献
18.
辽宁歪头山铁矿床两类矿石地球化学特征及其对成矿作用的制约 总被引：1，自引：0，他引：1
歪头山铁矿床是鞍山-本溪地区条带状铁建造（BIFs）的典型代表,并且有一定规模的富铁矿分布。本文主要报道了矿区内较贫铁矿石和较富铁矿石的地球化学特征,结果表明两类矿石既有一致性又存在差异性。一致性表现在：所有矿石主要由TFe2O3和SiO2组成,其他氧化物含量很少,结合微量元素和稀土元素特征,指示其为一种化学沉积岩,但受到了火山热液作用的影响;矿石的稀土元素总量很低,经太古界后平均澳大利亚页岩（PAAS）标准化后,呈现重稀土相对富集,轻稀土相对亏损的配分模式,都具有明显的Eu正异常,和比较高的Y/Ho比值,与热液相关的Cr、Co、Ni含量也相对较高,暗示其成矿物质来源于海底热液,同时具有海水的特征。差异性表现在：较富铁矿石具有明显的热液特征,并且K2O含量大于Na2O含量,某些微量元素组成也与混合花岗岩具有相似性,结合野外地质特征,暗示较富铁矿石可能是在较贫铁矿石的基础上受混合岩化热液作用形成的。 相似文献
19.
20.
Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis 总被引：1，自引：0，他引：1
The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling-Langalata iron ore deposits,
Singhbhum-North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the
geochemical evaluation of different iron ores. The geochemical and mineralogical characterization suggests that the massive,
hard laminated, soft laminated ore and blue dust had a genetic lineage from BIFs aided with certain input from hydrothermal
activity. The PAAS normalized REE pattern of Jilling BIF striking positive Eu anomaly, resembling those of modern hydrothermal
solutions from mid-oceanic ridge (MOR). Major part of the iron could have been added to the bottom sea water by hydrothermal
solutions derived from hydrothermally active anoxic marine environments. The ubiquitous presence of intercalated tuffaceous
shales indicates the volcanic signature in BIF.
Mineralogical studies reveal that magnetite was the principal iron oxide mineral, whose depositional history is preserved
in BHJ, where it remains in the form of martite and the platy hematite is mainly the product of martite. The different types
of iron ores are intricately related with the BHJ. Removal of silica from BIF and successive precipitation of iron by hydrothermal
fluids of possible meteoric origin resulted in the formation of martite-goethite ore. The hard laminated ore has been formed
in the second phase of supergene processes, where the deep burial upgrades the hydrous iron oxides to hematite. The massive
ore is syngenetic in origin with BHJ. Soft laminated ores and biscuity ores were formed where further precipitation of iron
was partial or absent. 相似文献