共查询到20条相似文献，搜索用时 93 毫秒
1.
雅鲁藏布江蛇绿岩带的康金拉铬铁矿中发现金刚石 总被引：16，自引：10，他引：6
前人在雅鲁藏布江蛇绿岩带的罗布莎铬铁矿石中发现许多异常矿物,包括金刚石和柯石英等典型压力指示矿物.蛇绿岩型铬铁矿石中为什么会产出金刚石等异常矿物,与其伴生的铬铁矿和蛇绿岩是什么成因,是一个新的重大科学问题.为此,开展了同一蛇绿岩带中康金拉矿区的铬铁矿的人工重砂研究.从1116kg的铬铁矿样品中发现了近千粒金刚石,以及自然元素、金属互化物、氧化物、硫化物、硅酸盐、钨酸盐和碳酸盐矿物等一批异常矿物.从一个新的矿区发现了大批金刚石,不仅是对罗布莎铬铁矿中存在金刚石的佐证,并且将金刚石的产出规模增加了几个数量级,由此引出蛇绿岩铬铁矿中金刚石是否成矿的新问题.尤其重要的是,从同一蛇绿岩带的不同铬铁矿床中再次发现金刚石,为探讨金刚石及其寄主的铬铁矿和蛇绿岩的成因,提供了新的重要依据. 相似文献
2.
近十余年来的研究,在西藏雅鲁藏布江缝合带中的罗布莎蛇绿岩型铬铁矿中,发现可能来自深部(>300km深度)异常地幔矿物群.该矿物群中具有深部成因指示意义的矿物有:①呈斯石英假象的柯石英;②微粒金刚石和产在锇铱矿中的原位金刚石;③铬铁矿和饿铱矿巾发现硅尖晶石;④铬铁矿中发现硅金红石;⑤呈八面体假象的蛇纹石和绿泥石,并具有清晰的爆炸结构;⑥方铁矿和自然铁矿物组合.此外,罗布莎铬铁矿中有4个新矿物获批准,并在极地乌拉尔蛇绿岩铬铁矿中也发现了大最微粒金刚石和碳硅石等地幔超高压矿物.蛇绿岩铬铁矿中发现来自地幔深部的超高压矿物,提供了铬铁矿可能深部成因的重要信息,该发现有可能改变传统的蛇绿岩铬铁矿的形成于俯冲带上的浅部环境(<50 km深度)的认识以及蛇绿岩成因的概念. 相似文献
3.
西藏雅鲁藏布江缝合带的普兰地幔橄榄岩中发现金刚石:蛇绿岩型金刚石分类的提出 总被引：15，自引：9，他引：6
西藏罗布莎蛇绿岩的地幔橄榄岩和铬铁矿中发现金刚石和特殊矿物群引发了新的问题,罗布莎地幔橄榄岩含特殊地幔矿物是不是一个孤立的特殊现象,或这是一个普遍存在的规律?显然,这是一个至关重要的问题.本文报道在雅鲁藏布江缝合带西段,距离罗布莎1000km以远的普兰蛇绿岩的地幔橄榄岩中发现与罗布莎类似的金刚石和特殊地幔矿物群.普兰的地幔橄榄岩体主体为方辉橄榄岩,含少量的纯橄岩和二辉橄榄岩,研究表明,属典型MOR型亏损地幔橄榄岩.通过分选,在657kg的地幔橄榄岩大样中发现了金刚石和碳硅石等30余种矿物的特殊矿物群,包括自然铬、自然铁和自然锌等强还原条件下形成的单质元素矿物.该矿物群与罗布莎地幔橄榄岩和铬铁矿中发现的特殊矿物群十分相似,表明罗布莎的地幔橄榄岩不是雅鲁藏布江缝合带中的一个特例.结合在俄罗斯乌拉尔Ray-Iz铬铁矿中发现类似的矿物群,以及世界其他地区的有关阿尔卑斯型地幔橄榄岩中金刚石的报道,认为蛇绿岩地幔橄榄岩中可能普遍含有金刚石,并将蛇绿岩地幔橄榄岩中产出的金刚石归为一种新的金刚石产出类型,即蛇绿岩型金刚石,不同于金伯利岩型金刚石和超高压变质带中产出的变质金刚石类型. 相似文献
4.
前人报道在西藏中生代和俄罗斯极地乌拉尔早古生代蛇绿岩地幔橄榄岩铬铁矿中发现了金刚石等深部地幔矿物,认为需重新考虑铬铁矿浅部成因的传统认识。为了查明不同造山带蛇绿岩的铬铁矿中金刚石等深部矿物的分布规律和豆荚状铬铁矿的成因,笔者开展了内蒙古贺根山晚古生代蛇绿岩中的铬铁矿床的人工重砂矿物学研究,本研究获得约2000 kg的内蒙古贺根山蛇绿岩铬铁矿石样品,对所采样品开展人工重砂选矿,表明该铬铁矿矿石样品中至少有金刚石、碳硅石及其他自然元素类、金属互化物类、氧化物类、硫化物类、硅酸盐类等30余种矿物。内蒙—大兴安岭造山带晚古生代的内蒙古贺根山蛇绿岩带铬铁矿石中,发现金刚石等深部地幔矿物表明,贺根山铬铁矿可能为深部成因。 相似文献
5.
西藏罗布莎铬铁矿体围岩方辉橄榄岩中的异常矿物 总被引：14，自引：8，他引：6
近些年,我们在西藏罗布莎蛇绿岩型铬铁矿中发现金刚石和柯石英等超高压矿物和异常地幔矿物,成果多次在美国AGU会议上做特邀报告,发表在2007年(Geology)和国内期刊上,并有4个新矿物获得国际新矿物委员会批准.这些成果在国内外引起广泛关注,也引发出一系列新的科学问题,例如,金刚石的赋存状态,物质来源和成因?与其伴随的铬铁矿的成因,与金刚石的关系?两者形成的地质背景、物理化学环境、保存和运移的规律、机制,等等.为了探讨这些问题,我们认为除了研究罗布莎铬铁矿之外,还应该开展铬铁矿的围岩地幔橄榄岩的研究,看看它们中都有什么矿物,与铬铁矿中的矿物究竟存在什么异同以及两者之间的成因联系?为此,我们从西藏罗布莎铬铁矿31号矿体不同高度取回两个各自为1吨重的方辉橄榄岩围岩样品,开展人工重砂矿物的分选.通过矿物成分、激光拉曼和X射线衍射光谱的研究,从中识别出金刚石等50余种矿物.经初步对,认为铬铁矿围岩方辉橄榄岩中发现的矿物组合与铬铁矿中相似,表明两者存在成因上的联系,并可能共同经历了从深部到浅部的地质过程. 相似文献
6.
西藏蛇绿岩地幔中的主要自然金属矿物 总被引：9，自引：0，他引：9
在西藏雅鲁藏布江蛇绿岩带的罗布莎蛇绿岩块的豆荚状铬铁矿床中 ,揭示出一个由 70～ 80种矿物组成的地幔矿物群 ,包括自然金属、合金、硫 (砷 )化物、氧化物和硅酸盐等。这些矿物呈包裹体或脉石产于铬铁矿石中 ,经人工重砂分析 ,自然元素矿物有自然硅、自然铁、自然锌、自然铅、自然铝、自然铬、自然锡、自然镍、自然钨、自然钛、自然锇、自然铱、自然钌、自然钯、石墨、金刚石、自然金和自然银等。文中选择一些自然元素矿物 ,探索这些地幔矿物特点以及蛇绿岩和铬铁矿的形成机制。根据共生矿物群以及罗布莎地幔橄榄岩为新鲜的未蛇纹石化的岩石 ,认为罗布莎自然元素矿物与蛇纹石化作用无关。它们可能是在地核形成时期滞留于地幔中的成核物质 ,抑或是核幔之间化学反应的产物 ,后来被铬铁矿矿浆捕获 ,并同铬铁矿一起由地幔柱作用和板块作用侵位于浅部并仰冲出露于地表。 相似文献
7.
西藏罗布莎橄榄岩与中国大陆科学钻探主孔(CCSD-MH)榴辉岩中金刚石的红外特征初探 总被引：5，自引：1，他引：4
大别苏鲁超高压变质带上的大陆科学钻探主孔(CCSD-MH)中榴辉岩中的金刚石形成于大陆深俯冲作用过程,西藏雅鲁藏布江缝合带罗布莎蛇绿岩铬铁矿中的金刚石来自深部地幔,两者的形成背景和机制可能不同.本文对两地的金刚石样品开展了傅立叶变换红外光谱(FT-IR)定性分析.结果表明,西藏罗布莎金刚石样品为ⅠaA型;而CCSD-MH金刚石为ⅠaAB型,既表明其杂质氮的聚集形式和演化路径上存在着差异.红外光谱特征不仅仅表明两者属天然金刚石常见类型,并且超高压变质带中的金刚石形成时间可能更久远. 相似文献
8.
蛇绿岩型金刚石产在地幔橄榄岩和铬铁矿中，是新建立的金刚石产出类型，不同于产在金伯利岩和超高压变质岩中的金刚石。全球已在21个蛇绿岩中发现了该类金刚石，含金刚石的蛇绿岩主要分布在特提斯造山带、乌拉尔- 中亚造山带、日高变质岩带和北美克拉马斯- 阿卡特兰造山带。本文梳理了含金刚石蛇绿岩的全球分布和地质背景以及蛇绿岩中超高压－强还原矿物与其它壳幔矿物组合的特征，讨论了已有的含金刚石铬铁矿和地幔橄榄岩的四种成因机制。金刚石和伴生的超高压－强还原矿物组合产在不同时代的造山带蛇绿岩中，不仅仅揭示了金刚石在蛇绿岩中普遍存在，需要重新思考蛇绿岩和铬铁矿的成因以及它们形成的地质构造背景，还证实了蛇绿岩地幔橄榄岩和铬铁矿是地球深部矿物重要的储存库，为认识地球深部的物质组成和物理化学环境，以及深部物质运移的轨迹和动力学过程等提供了天然样品。 相似文献
9.
蛇绿岩中铬铁矿床成因一直存在较大争议,其主要原因可归结为:寄主蛇绿岩存在成因争议、产出状态不清、矿石及围岩矿物组合单一以及主要矿物成分简单但矿物包裹体复杂多样.针对这些研究瓶颈,率先对西藏普兰和罗布莎、土耳其K?z?lda?和Kop蛇绿岩中的地幔橄榄岩和铬铁岩进行了全岩和单矿物Fe-Mg同位素的探索性研究工作.结果表明:（1）蛇绿岩中的地幔橄榄岩具有较均一的Fe-Mg同位素组成,与世界上其他地区的地幔橄榄岩相似;（2）铬铁岩中铬铁矿和橄榄石之间存在明显的Fe-Mg同位素分馏,铬铁矿多具有比共存橄榄石轻的Fe同位素组成,与地幔橄榄岩中的尖晶石和橄榄石相反,Mg同位素变化较大;（3）铬铁矿和橄榄石的Fe-Mg同位素主要受控于结晶分异和Fe-Mg交换,且这两个过程造成的同位素变化趋势明显不同.因此,Fe-Mg同位素在揭示铬铁矿母岩浆来源、性质及成矿过程方面具有较大的应用潜力. 相似文献
10.
西藏罗布莎豆荚状铬铁矿床深部找矿突破与成因模式讨论 总被引：2，自引：1，他引：1
中国铬铁矿资源的瓶颈状态已持续多年。最近,在西藏罗布莎蛇绿岩地幔橄榄岩的深部勘探发现200万t致密块状铬铁矿床,这是中国近50年来铬铁矿找矿的重大突破,对今后继续寻找同类型的铬铁矿床具有重要指导意义。蛇绿岩地幔橄榄岩中产出的豆荚状铬铁矿床是工业需求铬的重要来源。研究豆荚状铬铁矿的成矿作用和矿体围岩地幔橄榄岩地质特征,建立铬铁矿的成矿模型和找矿标志,是开展寻找同类型矿床的重要保证。随着近些年在豆荚状铬铁矿及围岩地幔橄榄岩中金刚石等深部矿物的不断发现和深入研究,人们对蛇绿岩型铬铁矿的物质来源和形成过程,有了新的认识,提出了铬铁矿的深部成因模式。研究认为深部成因铬铁矿床主要经历了4个阶段:(1)早期俯冲到地幔过渡带(410~660 km)的陆壳和洋壳物质被脱水和肢解,过渡带产生的热和流体促成了地幔的熔融和Cr的释放和汇聚;(2)铬铁矿浆在地幔柱驱动下,运移到过渡带顶部冷凝固结,并有强还原的流体进入,后者携带了深部形成的金刚石、斯石英等高压矿物,进入"塑性—半塑性地幔橄榄岩"中;(3)随着物质向上移动,深度降低,早期超高压相矿物发生相变,如斯石英转变成柯石英,高压相的铬铁矿中出溶成柯石英和单斜辉石;(4)在侵位过程和俯冲带环境下,含水熔体与方辉橄榄岩反应形成了不含超高压矿物的规模相对较小的浸染状铬铁矿及纯橄岩岩壳。进一步研究表明,同处雅鲁藏布江缝合带西段的几个大型地幔橄榄岩岩体与罗布莎岩体可以对比,经历了相同的构造背景和豆荚状铬铁矿的成矿作用,存在较大的找矿空间。 相似文献
11.
J. Proenza F. Gervilla J. Melgarejo O. Vera P. Alfonso A. Fallick 《Mineralium Deposita》2001,36(7):658-669
The Potosí Mine is located in the Moa-Baracoa massif in the easternmost part of the Cuban Ophiolitic Belt. Chromite mineralization occurs within the mantle-crust transition zone. Two events of magma intrusion overprint the chromitite bodies: one gave rise to the crystallization of pegmatitic olivine-norite dikes, and the other produced pegmatitic gabbro dikes. Sulfide-poor chromite ores, brecciated chromite ores, and sulfide-rich chromite ores can be distinguished in the different chromitite bodies. Sulfide-poor ores represent more than 80 vol% of the chromitites. This type occurs far from the zones intruded by pegmatitic gabbro dikes and shows petrographic and chemical features similar to other chromitite bodies described in the Moa-Baracoa massif. Brecciated chromite ores occur within pegmatitic gabbro dikes. In this type, chromite crystals occur included within chromian diopside and plagioclase. These silicates often contain droplet-like sulfide aggregates. Sulfide-rich ores are spatially associated to the contacts between sulfide-poor chromite and pegmatitic olivine-norite dikes. These ores mainly consist of recrystallized (coarse) chromite with interstitial pyrrhotite, pentlandite, cubanite, and chalcopyrite. Chromite from sulfide-rich ores exhibits TiO2, FeO, V2O3, MnO, and especially, Fe2O3 contents, higher than those of chromite from brecciated ores and much higher than those of chromite from sulfide-poor ores. The sulfide-rich ores are PGE-rich (up to 1,113 ppb of total PGE), and show nearly flat chondrite-normalized PGE patterns, slightly above 0.1 times chondritic values. Mineralogical and chemical data indicate that the chromite ores of the Potosí Mine were modified by the intrusions of olivine-norite and gabbro dikes. The interaction between pre-existing sulfide-poor chromite ores and the intruding volatile-rich silicate melts produced strong brecciation, partial dissolution, and recrystallization (coarsening) of chromite. The sulfide assemblage formed by fractionation of the immiscible sulfide melt segregated from the volatile-rich silicate melt that generated the pegmatitic olivine-norite. The segregation of the sulfide melt can be interpreted as the consequence of chemical interaction between intruding melts and the host chromite. The variable extent of this interaction produced chromite ores with variable sulfide ratios. The magmatic nature of the sulfide mineralization is supported by sulfur isotope data, which range from -0.4 to +0.9. Sulfide melt collected incompatible PGE (Rh, Pt, Pd) to produce the typical flat chondrite-normalized pattern of sulfide-rich chromite ores. 相似文献
12.
Sridhar D. IYER Elapavalooru V.S.S.K. BABU Premchand G. MISLANKAR Anup R. GUJAR Navso V. AMBRE Victor J. LOVESON 《《地质学报》英文版》2010,84(3):515-527
<正>In the present study,we present the occurrence and emplacement of chromite ore deposits from two abandoned mines(Kankavali[Janoli]and Wagda) in the Sindhudurg district of Maharashtra,India.These ores,that occurred as lenses and are associated with metamorphic and ultrabasic rocks,consist of octahedral grains of chromite,while clinochlore is present between the interstices of these grains.The Kankavali(Janoli) and Wagda ores revealed a dominance of Cr_2O_3 followed by FeO and variable proportions of A1_2O_3,MgO,and SiO_2.The former deposits have a slightly higher Cr_2O_3(average 52 wt%) and FeO(～18 wt%) than those from Wagda(Cr_2O_3～50 wt%,FeO～25 wt%).The similar Cr~# values(0.73 for Kankavali[Janoli],0.74 for Wagda) correspond to those reported for typical podiform-type chromite deposits.We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest-southeast trend.We postulate the continuation of the fold structure from Janoli to Wagda(～4.5 km apart) and the probable (sporadic) occurrence of chromite along this stretch.The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out. 相似文献
13.
On the basis of a representative collection of ultramafic rocks and chromite ores and a series of technological samples from the largest (Central and Western) deposits in the Rai-Iz massif of the Polar Urals and the Almaz-Zhemchuzhina and Poiskovy deposits in the Kempirsai massif of the southern Urals, the distribution and speciation of platinum-group elements (PGE) in various type sections of mafic-ultramafic massifs of the Main ophiolite belt of the Urals have been studied. Spectral-chemical and spectrophotometric analyses were carried out to estimate PGE in 700 samples of ultramafic rocks and chromite ores; 400 analyses of minerals from rocks, ores, and concentrates and 100 analyses of PGE minerals (PGM) in chromite ores and concentrates were performed using an electron microprobe. Near-chondritic and nonchondritic PGE patterns in chromitebearing sections have been identified. PGE mineralization has been established to occur in chromite ore from all parts of the mafic-ultramafic massifs in the Main ophiolite belt of the Urals. The PGE deposits and occurrences discovered therein are attributed to four types (Kraka, Kempirsai, Nurali-Upper Neiva, and Shandasha), which are different in mode of geological occurrence, geochemical specialization, and placer-forming capability. Fluid-bearing minerals of the pargasite-edenite series have been identified for the first time in the matrix of chromite ore of the Kempirsai massif (the Almaz-Zhemchuzhina deposit) and Voikar-Syn’ya massif (the Kershor deposit). The PGE grade in various types of chromite ore ranges from 0.1–0.2 to 1–2 g/t or higher. According to technological sampling, the average PGE grade in the largest deposits of the southeastern ore field of the Kempirsai massif is 0.5–0.7 g/t. Due to the occurrence of most PGE as PGM 10–100 mm in size and the proved feasibility of their recovery into nickel alloys, chromites of the Kempirsai massif can be considered a complex ore with elevated and locally high Os, Ir, and Ru contents. The Nurali-Upper Neiva type of ore is characterized by small-sized primary deposits, which nevertheless are the main source of large Os-Ir placers in the Miass and Nev’yansk districts of the southern and central Urals, respectively. 相似文献
14.
The Zambales ophiolite is the major source of chromite ore in the Philippines. The chromitites are concordant cumulates and are associated with distinct chromitite-bearing sequences within the mantle peridotites. Refractory and metallurgical chromite deposits are spatially separated and related to different lithologic associations, which crystallized from different parental magmas. — Refractory chromite ores (30–44 wt% Cr2O3; 20–30 wt% Al2O3) are linked with the peridotite-troctolite-olivine gabbro lineage. Two main types were found: (1) Al-rich refractory ores associated with harzburgites and feldspathic periodotites and (2) more Cr-rich varieties associated with lherzolites. — Metallurgical chromite ores (45–53 wt% Cr2O3; 12–18 wt% Al2O3) are linked with the peridotite-pyroxenite-norite lineage. Two main types were also found: (1) Cr-rich metallurgical ores associated with orthopyroxenites and (2) more Al-rich varieties related to clinopyroxenites. — The chemical composition of chromite within the deposits varies depending on the chromite/silicate ratios of the ore types and grades continuously into accessory chrome spinels in the wall-rock peridotites. — The geochemistry of accessory chrome spinels in various peridotites and mafic cumulates depends on the mineralogical composition and the stratigraphic position of their host rocks.New address: BEB Erdgas und Erdöl GmbH, Riethorst 12, D-3000 Hannover 51The terms chrome-spinels and chromite are used as follows: 1. Chrome-spinel is only used for those occuring as accessory minerals in various ultramafic and mafic rocks (= accessory chrome-spinels). Their chemical composition has been determined only by microprobe analysis. — 2. Chromite is used for ore and ore deposits (=chromitites); the chemical composition has been determined by wet chemistry (AAS) or by microprobe analysis 相似文献
15.
我国铬铁矿资源奇缺.长期以来我国冶炼合金钢所用的铬铁矿,基本上都是依赖于国外进口.长此下去将严重地影响我国钢铁工业的进一步发展.我国川滇地区,基性和超基性岩广布,具一定的产出铬铁矿的地质条件,而前人作一些工作后多持否定意见.本文作者试图用最新的成矿观点和最新的研究成果,对川滇地区的找铬前景进行一些讨论.铬铁矿的产出只与基性、超基性岩有关.目前国际上对于基性、超基性岩的分类方案繁多.但无论何种方案,都认为与铬铁矿有关的超基性岩主要是其中的两类,即人们所熟悉的 相似文献
16.
Gehad M. Saleh 《中国地球化学学报》2006,25(4):307-317
1 Introduction The association of massive Fe-Ni-Cu sulfides andchromite is a very unusual feature of podiformchromitites occurring in mantle tectonites of ophioliticcomplexes. It has only been described in theSoutheastern Desert, Egypt, where sulfides a… 相似文献
17.
Chromite ores formation is still a debated topic and, in this study, detailed analyses of major, minor elements by EMPA and Rare Earth Elements (REE) by SIMS, were performed on silicate inclusions detected in chromite grains of chromitite pods, enveloping dunites and on clinopyroxene of lherzolitic host rock of well known Trodoos chromite ores. Results show the complexity of relationships among lithologies that reflects the subtlety of genetic events and of chromite ore occurrence.Analyses of textural and chemical features have led to a better understanding of the chromite ore genetic process, that is related to a supra-subduction geodynamic setting where partial melting processes were overlapped by metasomatic events.Metasomatism, that marks the general genetic context, is characterized by the presence of a hydrated boninitic melt that favors the precipitation of chromite ores. Chromite ores, typical of ophiolite complexes and usually enveloped by dunite are, in this case, characterized by the presence of two different types of dunites whose geochemical differences are reflected by olivine mineral chemistry and by different REE patterns of analyzed clinopyroxenes. Such geochemical marks, related to different magmatic and metasomatic events, could be a main key for location of fertile or barren dunites in terms of chromite ore occurrence in the field. 相似文献
18.
Among the dominant species of chromium, the trivalent form widely occurs in nature in chromite ores or in silicate minerals and is extremely immobile. The higher oxidation state Cr(VI), is, however, rarely found in nature, is more mobile, and several times more toxic than Cr(III). Cr(VI) occurs in chromates and dichromates manufactured from chromite ores. The hexavalent state is stable in an oxidizing alkaline environment, whereas the trivalent state is stable in a reducing acidic environment. Serpentinization and Mg release during deuteric alteration of ultramafic rocks create alkaline pore water and lateritization is an intensive oxidation process. Chromite ore bodies in oxidized serpentinite therefore may generate hexavalent chromium from the inert chromites and cause hazardous chromium pollution of the water. With this end in view, a combined field and laboratory study has been made on chromite-bearing oxidized serpentinite rocks of Sukinda in Orissa, India. Laboratory leaching studies on mine overburden samples, chemical analyses of streamwater, and hydrolysate incrustation on detrital grains taken from stream beds have indicated the possibility of chromium mobilization from the chromite ores into the waterbodies. 相似文献
19.
辽西豆荚状铬铁矿的发现及其意义 总被引：14，自引：0，他引：14
在辽西建平新太古代变质基底构造混杂带内首次识别出豆荚状铬铁矿。铬铁矿石显示特征的豆荚状构造、褶皱条带、透镜构造、豆状构造、拉长网孔构造等，它们可以与蛇绿岩内典型的豆荚状铬铁矿进行对比。依据同位素年龄制约，辽西豆英状铬铁矿形成于2．50Ga前后。结合该区已报道的新太古变基性火山岩具有大洋拉斑玄武岩成分特点、并广泛发育新太古代高压麻粒岩，可以认为辽西地区新太古代期间曾发生大规模的板块俯冲及碰撞作用过程。 相似文献
20.
铬铁矿作为蛇绿岩中的重要矿产,其成矿母岩浆性质及演化一直存在较大争议.铬铁矿的矿物包裹体同时或先于铬铁矿结晶,其成分和类别能很好地记录成矿母岩浆性质和演化过程.土耳其Pozant?-Karsant?蛇绿岩不同类型铬铁岩的铬铁矿中发现了多种类型包裹体:不含水硅酸盐矿物（如橄榄石和单斜辉石）、含水硅酸盐矿物（如角闪石和金云母）、复合型矿物包裹体（如蛇纹石、硅灰石和单斜辉石的复合型包裹体）和不常见矿物（如磷灰石、铂族元素硫化物）.含水矿物包裹体的出现以及矿物的高Mg#特征（如橄榄石Fo=95.4~97.1;单斜辉石Mg#=92.0~99.9;角闪石Mg#=88.9~99.8）表明结晶铬铁矿的母岩浆具有富水、富Mg的特征.同时,除钙铬榴石和磷灰石的包裹体外,在铬铁矿中首次发现富Ca矿物方解石和硅灰石,其中方解石和菱镁矿以复合型包裹体形式产出,硅灰石则分布于蛇纹石矿物包裹体中.这些富Ca矿物的出现以及硅酸盐矿物的高CaO含量均揭示了铬铁岩母岩浆的富Ca特征.母岩浆中的Ca组分可能来源于俯冲板块中富Ca岩石/矿物的部分熔融,Ca离子的大量出现使得Cr3+在熔体中更加稳定,同时富Ca矿物的结晶促进了岩浆中Cr的进一步富集而利于铬铁矿的大量结晶沉淀. 相似文献