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1.
The REE (Ln), Y, Sc, and Th distribution in the unique complex rare-metal ores of the Tomtor deposit is considered. Significant variability of these components and REE composition is revealed. Ore blocks with elevated Y and HREE contents are identified among prevailing LREE-enriched ores. It is established that the REE variations in the ores are correlated with evolution of REE carriers during epigenetic transformations of the carbonatite weathering products, in particular, with a replacement of Ce-bearing minerals (monazite and florencite) by Y-bearing mineral, xenotime. It is found that LREE and HREE exhibit different behavior during formation of the Tomtor ores, which is expressed in the inert behavior and residual accumulation of Ce-group REE at essential introduction of Y, HREE, Sc, and Th during epigenetic transformation of weathering products of carbonatites, which represent one of the main factors of the formation of the unique rare-metal ores of the Tomtor deposit. 相似文献
2.
Jessica Bonhoure Philippe Kister Michel Cuney Etienne Deloule 《Geostandards and Geoanalytical Research》2007,31(3):209-225
A methodology for the determination of the rare earth elements in uranium oxides by ion microprobe has been set up on a Cameca ims-3f instrument. An uranium oxide reference material from a syn-metamorphic uranium deposit related to albitisation has also been developed for this type of analysis. Applications of the methodology are presented for a series of uranium oxides selected from some major uranium deposit types: from the world's highest grade unconformity-related uranium deposit from the Athabasca Basin (Saskatchewan, Canada; the Shea Creek and the McArthur River examples), a perigranitic vein-type deposit (Pen Ar Ran, Vendée, France) and a volcanic caldera-related deposit (Streltsovkoye, Transbaikalia, Russia). Each type of uranium deposit appears to have a specific REE signature. All REE patterns from the Shea Creek and the McArthur deposits are characterised by bell-shaped patterns centred on Tb-Dy and similar to those already published for uranium oxides from unconformity-related deposits from Australia. Such bell-shaped REE patterns centred on Tb-Dy may therefore be considered as a typical signature of uranium oxides from Mesoproterozoic unconformity-related deposits. A smoother bell shape pattern centred on Eu characterises the syn-metamorphic albitisation related deposit of Mistamisk selected for the reference material. The REE patterns from the Pen Ar Ran deposit show a fractionation from LREE to HREE with anomalously high abundances of Sm, Eu and Gd with respect to the other REEs, similar to the REE patterns of uranium oxides from the volcanic-related deposits of Streltsovkoye. 相似文献
3.
<正>Carbonatites are commonly related to the accumulation of economically valuable substances such as REE.Cu,and P.The debate over the origin of carbonatites and their relationship to associated silicate rocks has been ongoing for about 45 years.Worldwide,the rocks characteristically display more geochemical enrichments in Ba,Sr and REE than sedimentary carbonate rocks.However,carbonatite's geochemical features are disputed because of secondary mineral effects.Rock-forming carbonates from carbonatites at Qinling.Panxi region,and Bayan Obo in China show REE distribution patterns ranging from LREE enrichment to flat patterns.They are characterized by a Sr content more than 10 times higher than that of secondary carbonates.The coarse- and fine-grained dolomites from Bayan Obo H8 dolomite marbles also show similar high Sr abundance,indicating that they are of igneous origin.Some carbonates in Chinese carbonatites show REE(especially HREE) contents and distribution patterns similar to those of the whole rocks.These intrusive carbonatites display lower platinum group elements and stronger fractionation between Pt and Ir relative to high-Si extrusive carbonatite.This indicates that most intrusive carbonatites may be carbonate cumulates.Maoniuping and Daluxiang in Panxi region are large REE deposits.Hydrothermal fluorite ore veins occur outside of the carbonatite bodies and are emplaced in wallrock syenite.The fiuorite in Maoniuping has Sr and Nd isotopes similar to carbonatite.The Daluxiang fiuorite shows Sr and REE compositions different from those in Maoniuping.The difference is reflected by both the carbonatites and rock-forming carbonates,indicating that REE mineralization is related to carbonatites.The cumulate processes of carbonate minerals make fractionated fluids rich in volatiles and LREE as a result of low partition coefficients for REE between carbonate and carbonatite melt and an increase from LREE to HREE.The carbonatite-derived fluid has interacted with wallrock to form REE ore veins.The amount of carbonatite dykes occurring near the Bayan Obo orebodies may support the same mineralization model,i.e.that fluids evolved from the carbonatite dykes reacted with H8 dolomite marble,and thus the different REE and isotope compositions of coarse- and fine-grained dolomite may be related to reaction processes. 相似文献
4.
Flat rare earth element patterns as an indicator of cumulate processes in the Lesser Qinling carbonatites, China 总被引：1，自引：0，他引：1
Cheng Xu Ian H. Campbell Charlotte M. Allen Zhilong Huang Liang Qi Huan Zhang Guishan Zhang 《Lithos》2007,95(3-4):267-278
The Lesser Qinling carbonatite dykes are mainly composed of calcites. They are characterized by unusually high heavy rare earth element concentrations (HREE; e.g. Yb > 30 ppm) and flat to weakly light rare earth element (LREE) enriched chondrite-normalized patterns (La/Ybn = 1.0–5.5), which is in marked contrast with all other published carbonatite data. The trace element contents of calcite crystals were measured in situ by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Some crystals show reduced LREE from core to rim, whereas their HREE compositions are relatively constant. The total REE contents and chondrite-normalized REE patterns from the cores of carbonate crystals are similar to those of the whole rock. The carbon and oxygen isotopic compositions of calcites fall within the range of primary, mantle-derived carbonatites. The initial Sr isotopic compositions (0.70480–0.70557) of calcites are consistent with an EM1 source or mixing between HIMU and EM1 mantle sources. However these sources cannot produce carbonatite parental magmas with a flat or slightly LREE enrichment pattern by low degrees of partial melting. Analyses of carbonates from other carbonatites show that carbonates have nearly flat REE pattern if they crystallize from a LREE enriched carbonatite melt. This implies that when carbonates crystallize from a carbonatite melt the calcite/melt partition coefficients (D) for HREE are much greater than the D for the LREE. The nearly flat REE patterns of the Lesser Qinling carbonatites can be explained if they are carbonate cumulates that contain little trapped carbonatite melt. Strong enrichment of HREE in the carbonatites may require their derivation by small degrees of melting from a garnet-poor source. 相似文献
5.
围绕国家战略性产业发展对稀土资源的需求, 特别是紧缺的重稀土资源, 如何快速有效地发现富含重稀土矿床找矿靶区是勘查地球化学急需解决的问题。“化学地球”大科学计划获得全国地球化学基准数据, 圈定稀土异常超常富集区9处, 其中新发现的滇南红河州蒙自—中越边境地区稀土富集区轻重稀土比值(LREE/HREE)为3.5, 与华南富含重稀土的离子吸附型稀土矿异常LREE/HREE比值一致。结合地质背景、成矿母岩、气候和地形地貌特点等初步判断具有寻找类似华南富含重稀土的离子吸附型稀土矿资源潜力。因此, 对这一异常的核心区, 开展了1:25万、1:5万地球化学调查和风化剖面测量, 并经29个钻孔验证, 初步发现马鞍底潜在超大型富含重稀土离子吸附型稀土矿。富矿区分布于坡度较缓的坡脚处, 风化母岩为印支期和燕山期花岗岩、元古界斜长片麻岩和变粒岩。风化剖面厚度最深可达25 m左右, 富矿层位位于全风化层, 一般在2~13 m深度, 矿体平均厚度6~13 m, 最厚可达21 m, 平均品位0.14%。根据29个钻孔和84个风化壳剖面测量, 初步估算稀土潜在矿石量约9.46亿吨、稀土氧化物潜在资源约100万吨。这是我国首次在滇南地区发现潜在超大型离子吸附型稀土矿。该离子吸附型稀土矿同时富含轻稀土(镧、铈、镨、钕)和重稀土(钆、铽、镝、钇), 具有重大经济价值和科学意义。这一发现表明开展从极低密度、低密度到高密度地球化学调查, 获得全部16个稀土元素高质量数据是发现离子吸附型稀土矿的快速有效方法。 相似文献
6.
与碱性火成岩相关的典型轻稀土矿床研究 总被引：1，自引：0，他引：1
轻稀土矿床和火成碱性岩系密切相关,典型轻稀土矿床以白云鄂博、四川冕宁以及北美西海岸科迪勒拉(Cordillera)矿带的芒廷帕斯、加里诺斯稀土矿(Gallinas Mountains)等为代表,这些矿床表现出一定的相似性,但是也有本质的区别.文章着重对以上矿床在产出环境、含矿岩性、成矿流体和物质来源、地球化学等方面做了对比,分析了它们之间的共性和特殊性,并对目前研究所存在的问题加以总结,这将有助于对轻稀土矿床成矿机制的理解,并对轻稀土找矿工作有一定指导意义. 相似文献
7.
邹家山铀矿床伴生重稀土元素的赋存特征 总被引：1，自引：0，他引：1
初步研究发现,相山矿田邹家山矿床中伴生有较高的重稀土元素,回收这些珍稀的资源和探索其成因具有重要的意义,而查明这些伴生稀土在铀矿床中的赋存特征是前期基础性工作。为此本文采用电子探针和激光剥蚀电感耦合等离子体质谱分析了邹家山铀矿床中稀土元素的赋存状态。结果显示：该矿床稀土矿物主要为独居石、氟碳钙铈矿和磷钇矿;独居石、氟碳钙铈矿的LREE/HREE>1,为轻稀土富集型;而磷钇矿的LREE/HREE<1,为重稀土富集型。沥青铀矿、钛铀矿、铀钍石、铀石、钍石、锆石等铀钍矿物的稀土特征为重稀土富集型;铀钍矿物稀土总量（∑REE+Y）较高,为（3 805.78~65 307.00）×10-6,LREE/HREE<1,为0.01~0.80,平均为0.29。其他伴生矿物磷灰石、钾长石为轻稀土富集型,萤石为轻、重稀土富集型两类都有,而伊利石、黄铁矿的轻重稀土无明显相对富集。重稀土在磷钇矿和铀钍矿物中以类质同象形式存在,少量赋存于伴生矿物。 相似文献
8.
贵州务川瓦厂坪铝土矿床地球化学特征 总被引：8，自引：0，他引：8
务川瓦厂坪铝土矿床是近年探明的大型矿床,332+333资源量4397万吨.地球化学研究显示,矿床中Al_2O_3与TiO_2含量成正相关关系,与SiO_2含量成负相关关系;硫同位素组成属于沉积岩范畴,总体显示出变化范围大(-29.20‰～+12.40‰),反映出复杂的成矿环境和轻重硫同位素的多次分离;不同岩、矿石的稀土总量(∑REE)含量变化大,LREE/HREE均大于1,显示轻稀土较富集;铝土矿层中,土状铝土矿稀土元素含量相对高,致密块状铝土矿含量相对低,稀土元素含量与矿石质量总体呈正相关关系.铝土矿层及志留系韩家店组的稀土总量含量较接近.矿床成因属古风化壳沉积型. 相似文献
9.
白云鄂博铁、铌、稀土矿床:研究进展、存在问题和新认识 总被引：2，自引：1，他引：1
白云鄂博是世界第一大稀土元素矿床,其稀土元素资源量占世界目前已知稀土元素资源总量的三分之二以上,具有重要的经济和战略地位。白云鄂博自1927年发现至今已有92年,对其的开发和研究历史悠久,在赋矿碳酸岩的成因、成矿年代、稀土矿物学等方面取得了一系列重要进展,为碳酸岩型稀土元素成矿理论发展做出了突出贡献。由于矿床经历了成矿后复杂的构造变形和热液蚀变,致使其地质、地球化学特征复杂,学界对其成因和成矿过程一直存在不同认识,对成矿碳酸岩的岩浆演化、稀土元素迁移与富集机理等方面的研究也相对薄弱。笔者最新研究表明,矿区过去被认为是下白云鄂博群的H1、H2、H9岩石单元并非沉积变质岩或变质火山岩,而应为岩浆侵入成因,矿区其他岩石单元(H3～H7)的成因也值得商榷。H9岩石单元中的黑云母岩(前人称为黑云母板岩)和富含黑云母的碳酸岩(前人称为暗色板岩)为成矿碳酸岩的一部分,是碳酸岩不同岩相带的表现。黑云母岩和富黑云母碳酸岩相对于含矿碳酸岩具有相对低的稀土元素含量和轻、重稀土元素比值,表明岩浆演化可能对稀土元素的富集和分异具有重要贡献。矿区主要岩石单元成因的新认识不仅为矿床成因、成矿背景研究提供了新的依据,同时也为研究区域构造演化、正确厘定矿区构造式样和指导矿区深部和外围找矿提供了新的思路。 相似文献
10.
“寨背式”离子吸附型稀土矿床多类型稀土矿化及其成因 总被引：1，自引：0，他引：1
赣南寨背离子吸附型稀土矿床产于寨背复式花岗岩体的风化壳中,自20世纪80年代发现以来一直以轻稀土型开采,近年在轻稀土型花岗岩风化壳中发现了重稀土矿。为了探讨轻稀土型花岗岩风化过程中重稀土元素的迁移、分馏和富集机制,本文选择了区内三个具有代表性的风化壳钻孔(ZK1、ZK2和ZK4)对其进行了全相和离子交换相稀土元素地球化学研究。结果显示：钻孔ZK4中离子交换相稀土含量介于14.90×10-6～835.8×10-6之间,并富集轻稀土(LREE/HREE=2.28～10.78);钻孔ZK1中离子交换相稀土含量达1470×10-6(9件样品均值),具有从轻稀土型向重稀土型过渡的配分特征(LREE/HREE=1.30～1.65),并且剖面自上而下显示轻、重稀土逐渐富集的趋势;钻孔ZK2中离子交换相稀土含量为492.4×10-6(8件样品均值),自上而下稀土配分类型从轻稀土型过渡至重稀土型(LREE/HREE=0.43～2.25),且轻稀土富集在全风化层上部而重稀土则富集在下部。三个钻孔的Nb/Ta和Zr/Hf... 相似文献
11.
《地学前缘(英文版)》2019,10(2):769-785
The Weishan REE deposit is located at the eastern part of North China Craton (NCC), western Shandong Province. The REE-bearing carbonatite occur as veins associated with aegirine syenite. LA-ICP-MS bastnaesite Th-Pb ages (129 Ma) of the Weishan carbonatite show that the carbonatite formed contemporary with the aegirine syenite. Based on the petrographic and geochemical characteristics of calcite, the REE-bearing carbonatite mainly consists of Generation-1 igneous calcite (G-1 calcite) with a small amount of Generation-2 hydrothermal calcite (G-2 calcite). Furthermore, the Weishan apatite is characterized by high Sr, LREE and low Y contents, and the carbonatite is rich in Sr, Ba and LREE contents. The δ13CV-PDB (−6.5‰ to −7.9‰) and δ13OV-SMOW (8.48‰–9.67‰) values are similar to those of primary, mantle-derived carbonatites. The above research supports that the carbonatite of the Weishan REE deposit is igneous carbonatite. Besides, the high Sr/Y, Th/U, Sr and Ba of the apatite indicate that the magma source of the Weishan REE deposit was enriched lithospheric mantle, which have suffered the fluid metasomatism. Taken together with the Mesozoic tectono-magmatic activities, the NW and NWW subduction of Izanagi plate along with lithosphere delamination and thinning of the North China plate support the formation of the Weishan REE deposit. Accordingly, the mineralization model of the Weishan REE deposit was concluded: The spatial-temporal relationships coupled with rare and trace element characteristics for both carbonatite and syenite suggest that the carbonatite melt was separated from the CO2-rich silicate melt by liquid immiscibility. The G-1 calcites were crystallized from the carbonatite melt, which made the residual melt rich in rare earth elements. Due to the common origin of G-1 and G-2 calcites, the REE-rich magmatic hydrothermal was subsequently separated from the melt. After that, large numbers of rare earth minerals were produced from the magmatic hydrothermal stage. 相似文献
12.
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
13.
湖南沃溪金-锑-钨矿床成因的稀土元素地球化学证据 总被引：11，自引：0，他引：11
沃溪金-锑-钨矿床的稀土元素地球化学组成良好地反映了成矿作用的条件和过程,并为示踪矿床成因提供了有用的信息.以流体包裹体为代表的成矿溶液,以较高的稀土总量、显著的轻稀土富集和缺乏明显的铕异常为特征,代表了一种通过在碎屑沉积物柱中循环而萃取矿质的演化的海水热液.矿石相对于成矿流体(母液)富集重稀土而轻微亏损铕,反映了矿石沉淀过程中来自于海水的稀土元素掺合.同一矿层内由下往上,重稀土相对富集的程度逐渐增大而稀土总量则逐渐降低,表明随着热液化学沉淀作用的进行,海水掺合的影响逐渐增强.矿石的稀土元素组成,无论在分布模式还是在轻重稀土之间的分馏程度上,均与其他许多 Sedex型多金属矿床十分相似,暗示了这些矿床具有相似的成因机制.稀土元素地球化学特征支持矿床同生沉积成因的观点. 相似文献
14.
在湘江及其支流采集了44件悬浮物样品进行稀土元素 ICP—MS分析。研究表明,湘江悬浮物中稀土总量(∑REE)、轻稀土(LREE) 和重稀土(HREE)含量分别为63～387 μg/g,58.2～353 μg/g和4.8～34μg/g。尽管湘江悬浮物中稀土分布不均匀,稀土含量相差很大,所有样品的球粒陨石标准化曲线均呈向右倾斜的富LREE的模式,北美页岩标准化模式为LREE稍富集的平坦型。湘江中下游河心与两岸水体悬浮物中稀土发生了明显分异。湘江悬浮颗粒物中REE受多方面因素控制,其源区控制了REE分配模式,而其稀土元素含量与颗粒中粘土矿物及重矿物有关。支流捞刀河悬浮物稀土的分布模式为Eu正异常型,与北美页岩有显著差别,捞刀河的悬浮物物源及成因有待进一步研究。 相似文献
15.
白云鄂博矿床成因——矿体内霓长岩化成矿作用与赋矿白云岩的联系 总被引：1，自引：0，他引：1
通过对组成赋矿白云岩的白云石矿物系统的显微结构和化学成分的研究表明,赋矿白云岩是碳酸岩质次火山岩,因此白云鄂博矿床是与火成碳酸岩有关的矿床。赋矿白云岩属于镁质碳酸岩(MgOFeO+MnO)和铁质碳酸岩(MgOFeO+MnO)系列,FeO、MnO和SrO含量高,这与FeO、MnO和SrO含量很低的沉积碳酸岩完全不同。赋矿白云岩的这一特点还表明它来自经历过分异结晶后的白云质碳酸岩浆而不是初始白云质碳酸岩浆。赋矿白云岩复杂的矿物组合表明,其母岩浆是富含F、Cl、P和S这些挥发分以及REE,Na、K和Fe这些元素的。在碳酸岩浆上升和侵位的过程中由于温度压力的降低,碳酸岩浆释放的含上述组分的流体会向上部地壳集中并对其接触的围岩进行交代,这就形成了矿体内呈不对称带状分布的霓长岩化矿石带。在大量的萤石和稀土氟碳酸盐矿物形成以后(其对应于萤石-稀土条带状矿石),流体的成分仍相对富钠和CO_2,钠可以和围岩中的硅结合形成钠辉石,流体较高的比值,有利于稀土的富集,此时形成的钠辉石型矿石的稀土含量是相当高的,仅次于条带状矿石。随着流体继续迁移和交代,流体中CO_2浓度下降而H_2O含量增加,温度也有所下降,但是流体中的钠依然活跃,所以出现了含有结构水的钠闪石,形成了钠闪石型矿石。流体中H_2O的增加,比值的下降,不利于稀土的大量富集,因此,钠闪石型矿石的稀土含量明显低于钠辉石型矿石。这说明,从碳酸岩浆中外逸的流体,在迁移交代围岩的过程中其成分、温度和氧逸度都是有变化的。从初期富CO_2,温度和氧逸度较高,到后期富H_2O,温度和氧逸度都有所降低。不同矿石类型的形成与这种变化有直接的关系。不同矿石类型中的磁铁矿的生成方式虽然不同于白云岩中的磁铁矿,但前者的氧同位素继承了后者的特点,表明了它们的亲缘关系和成因上的联系。稀土分布型式表明,不同矿石类型的稀土分布型式与赋矿白云岩的大体一致,有明显的LREE富集和明显的HREE亏损,且总稀土含量越高,轻重稀土分离程度越高。但是,不同矿石类型在轻稀土含量上有一定程度的差别,表明在霓长岩化过程中轻稀土活动性更强。总之,氟、钠和铁的交代作用在主东矿最强,稀土、铌和铁资源也最为富集,这里的白云岩厚度也最大,表明白云鄂博矿的霓长岩化成矿作用与赋矿白云岩衍生的流体的大量聚集以及流体对围岩广泛强烈的交代作用直接相关。 相似文献
16.
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
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18.
Based on geological mapping and grid channel geochemical sampling, a carbonatite plug hosted REE deposit has been discovered at Kamthai, Barmer district, Rajasthan. The main REE minerals hosted by carbonatite plug are bastanesite (La), basnaesite (Ce), synchysite (Ce), carbocernaite (Ce), cerianite (Ce), ancylite and parisite. The highest value of LREE is 17.31%, whereas, mean works out 3.33% and weighted average is 2.97%. The carbonatite plug covers 19475 sq. meters and the resources have been estimated upto 84 m depth under Proved, Probable and Possible categories. The total resource estimation for carbonatite plug and other carbonate sills, dykes and veins is 4.91 million tons, making this as truly world class deposit. The TMC of individual LREO (lower rare earth oxide) calculated for carbonatite plug only are La=52196 tonnes, Ce =66026 tonnes, Nd = 13663 tonnes, Pr = 5415 tonnes, Sm = 920 tonnes and Eu = 207 tonnes. Besides these REE, the Kamthai resource will produce 551 tonnes of Ga, 44 tonnes of Ge and 1,12,830 tonnes of SrO during its mining life. 相似文献
19.
白云鄂博含矿碱性火山岩建造及其地球化学 总被引：3，自引：1，他引：2
白云鄂博矿床历经几十年的研究,主要集中在矿区H8岩性段矿化白云岩成因的认识,许多研究显示含矿白云岩是岩浆碳酸岩,本文主要从岩石学和地球化学方面进一步分析其属于火山喷发环境形成的火山碳酸熔岩。H8含矿白云岩段和H9板岩段作为一套含矿岩系主要由含矿白云岩、霓闪钠长岩、钾长板岩3类岩石组成,白云岩和霓闪钠长岩都具有的碎屑结构及角砾状构造、条带构造,显示为火山熔岩和火山碎屑岩特征,而钾长板岩则主要显示致密微晶火山熔岩特征。工业矿物主要是磁铁矿、赤铁矿、稀土矿物和铌铁矿物,其重要特征是出现大量原生赤铁矿,反映岩石氧化系数高,与火山喷发环境一致。霓闪钠长岩、钾长板岩岩石化学显示碱性特征,稀土元素与CaO、F相关系数在0.7以上,并与Fe2O3高氧化物相关,而与硅酸盐矿物组分反相关,表示碳酸岩与稀土成矿密切相关,并显示为表生氧化环境形成。稀土地球化学特征显示白云岩∑REE最高,钾长板岩∑REE最低,相应的岩脉∑REE低于喷发岩。各种岩石均表现为明显的轻重稀土分异,但是以白云岩LREE/HREE比值最大,霓闪钠长岩LREE/HREE比值最小,而纯钠长石岩脉和含稀土磁铁矿LREE/HREE明显高于其他岩石。白云岩和霓闪钠长岩均表现出不同的铕、铈负异常,但是碳酸岩脉和钾长板岩则显示弱正铈异常,霓闪钠长岩和钾长板岩铕异常不明显。矿化白云岩和碳酸岩脉的δ18O、δ13C值介于沉积灰岩与已知碳酸岩的δ18O、δ13C值之间,碳酸岩中白云石的δ18O低于方解石的δ18O,而δ13C高于方解石的δ13C,稀土矿物的δ13C、δ18O与碳酸岩脉δ13C、δ18O接近。归纳这些特征,含矿白云岩与霓闪钠长岩、钾长板岩是碱性火山岩组合,与一系列同期的碳酸岩、霓闪钠长岩碱性岩脉一起,构成一套完整碱性火山岩系。 相似文献
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浙江八面山萤石矿床稀土元素地球化学特征及成因探讨 总被引：4，自引：2，他引：2
对浙江八面山萤石矿床中不同类型萤石矿石和围岩样品的稀土元素的系统分析表明,细粒萤石矿石的ΣREE〈39×10-6,LREE为14.36×10-6～34.24×10-6,HREE0.96×10-6～2.04×10-6,Y〈3×10-6;巨晶萤石矿石中的ΣREE3.62×10-6～20.81×10-6,LREE2.71×10-6～17.67×10-6,HREE0.24×10-6～1.49×10-6;而围岩花岗岩的ΣREE460.29×10-6,LREE225.97×10-6,HREE91.32×10-6,Y＆gt;140×10-6;沉积岩中的ΣREE20.22×10-6、LREE16.11×10-6、HREE1.61×10-6。矿石与围岩中沉积岩的稀土总量、轻稀土、重稀土和Y的含量接近,与花岗岩的稀土总量、轻稀土、重稀土和Y元素含量相差悬殊。萤石矿石的稀土分布型式主要为轻稀土富集型,（La/Yb）N通常多数大于8,在8.07～17.26间,δEu值在0.45～1.30,δCe在0.89～1.14间,Ce、Eu基本不显异常。矿石与围岩的稀土地球化学研究显示,八面山萤石矿床为受地层、岩体与断裂共同控制＂三位一体＂的低温热液型矿床。 相似文献