钒钛磁铁矿床的透岩浆流体成矿模型——来自马达加斯加扎卡岩体的证据

发布时间：2018-05-23 08:24

本文选题：钒钛磁铁矿床 + 镁铁-超镁铁岩　；参考：《中国地质》2017年04期

【摘要】：目前,国内外学术界对赋存于镁铁-超镁铁杂岩体中的钒钛磁铁矿床的成因存在多种不同的解释,在一定程度上对这类矿床的资源勘查造成了困惑。因此,阐明镁铁-超镁铁侵入体中成矿物质大规模聚集的机理依然是矿床学界和勘查学界面临的重要科学前缘问题。马达加斯加中北部Alaotra湖地区的扎卡岩体是一个赋存有超大型钒钛磁铁矿床的典型镁铁质层状侵入体,已探明铁矿石远景资源量8亿t(含333),伴生钛6000万t,伴生钒230万t,为阐明钒钛磁铁矿床的成因提供了良好的条件。本文报道了扎卡岩体的地质学、矿体地质学、岩相学、矿相学和岩石地球化学特征,主要得出以下认识:(1)扎卡岩体发育韵律性火成层理,为一个典型的镁铁质层状岩体,但伟晶岩可构成独立的侵入单元;(2)矿体主要赋存在层状岩体中,可划分为整合型、不整合型和伟晶岩型等3种不同的类型;(3)辉长岩具有橄榄石→斜长石→单斜辉石或橄榄石→斜长石+单斜辉石的结晶顺序,暗示扎卡岩体为一浅成层状岩体,岩浆侵位深度约3 km;(4)矿石矿物与硅酸盐矿物呈热力学不平衡关系,且与含水暗色矿物平衡共生,暗示成矿作用发生在岩浆演化晚期的富含挥发分环境;(5)致密块状铁矿石的REE四分组效应也表明成矿过程伴随着富F、Cl等组分的流体活动。据此,本文提出扎卡岩体中钒钛磁铁矿床的形成与透岩浆流体过程有关。
[Abstract]:At present, there are many different explanations for the genesis of vanadium titanomagnetite deposit in the magnesite-ultramafic complex, which to some extent cause confusion to the exploration of the mineral resources of this kind of deposit. Therefore, elucidating the mechanism of mass accumulation of ore-forming materials in magnesite-ultramafic intrusions is still an important scientific front problem in ore deposit and exploration fields. The Zaka rock body in Lake Alaotra, central and northern Madagascar, is a typical magnesite layered intrusion with a very large vanadium titanomagnetite deposit. It has been proved that the potential resource amount of iron ore is 800 million tons (containing 333n, 60 million tons of associated titanium and 2.3 million tons of associated vanadium), which provides a good condition for elucidating the genesis of vanadium-titanomagnetite deposit. In this paper, the geological, orebody geology, lithofacies, mineralogy and petrogeochemical characteristics of the Zaka rock mass are reported. The main conclusions are as follows: (1) the rhythmic igneous stratification of the Zaka rock mass is a typical magnesite layered rock mass. However, pegmatite can form an independent intrusive unit, Guanzao 2) orebody mainly occurs in layered rock mass and can be divided into integrated type. There are three different types of gabbro, I. e., irregular type and pegmatite type.) gabbro has the order of crystallization of olivine plagioclase or olivine plagioclase, suggesting that the Zaka rock body is a shallow layered rock mass. The magmatic emplacement depth is about 3 km / m ~ (4) the ore minerals and silicate minerals are thermodynamically disequilibrium and symbiotic with the water-bearing dark minerals. It is suggested that the REE four-group effect of dense block iron ore occurred in the late magmatic evolution of the rich volatile environment, indicating that the ore-forming process was accompanied by fluid activity rich in FCI-rich components. Therefore, the formation of vanadium titanomagnetite deposit in Zaka rock mass is related to the permeable magmatic fluid process.
【作者单位】：中国地质大学(北京);中国地质调查局沈阳地质调查中心;中国科学院地质与地球物理研究所;
【基金】：中国地质调查局项目(DD20160104、KE2010D2-3、1212011220921、2009DFA20840)资助~~
【分类号】：P612

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