东天山二叠纪镁铁-超镁铁质成矿岩体造岩矿物特征及其成因意义

发布时间：2018-05-02 18:36

  本文选题：矿物学 + 镁铁-超镁铁质岩体　； 参考：《岩石矿物学杂志》2017年04期

【摘要】：东天山造山带与镁铁-超镁铁质岩体有关的铜镍硫化物矿床数量多,分布集中,是我国重要的铜镍成矿带之一。成矿岩体多以小岩体群形式产出,由西向东分布有白鑫滩、黄山和图拉尔根3个岩体群,大型矿床主要赋存在黄山岩体群内。本文对3个岩体群内成矿岩体的主要造岩矿物进行了系统的对比研究。成矿岩体的主要造岩矿物为贵橄榄石、古铜辉石、单斜辉石、斜长石和角闪石以及少量的铬尖晶石和金云母。橄榄石Al温度计计算结果表明,黄山岩体群内成矿岩体的母岩浆结晶温度介于1 143~1 257℃之间,略低于白鑫滩和图拉尔根岩体群(1 283~1 301℃)。单斜辉石压力计算表明成矿岩体的结晶压力相似,介于0.31~0.33 GPa之间。成矿岩体中均富含含水矿物,且单斜辉石结晶早于斜长石,指示成矿岩体的原始岩浆形成于富水环境。成矿岩体的单斜辉石具有较高的Al/Ti值,铬尖晶石和橄榄石具有与岛弧火山岩相似的矿物学特征,结合区域构造演化,认为东天山镁铁-超镁铁质成矿岩体的原始岩浆是被消减板片交代过的地幔部分熔融的产物。矿物学特征对比显示了黄山岩体群内成矿岩体更富斜方辉石和中性斜长石,且具有较低的铬尖晶石Cr~#值和橄榄石Ca含量。结合前人研究成果和相关地球化学数据,认为相对高的混染程度导致了黄山岩体群的母岩浆富SiO_2和Al_2O_3,同时降低了岩浆的结晶温度。
[Abstract]:The East Tianshan orogenic belt is one of the important copper-nickel metallogenic belts in China. The ore-forming rock mass is mostly in the form of small rock mass group, and from west to east there are three rock bodies groups: Baixintan, Huangshan and Tulargen. Large deposits mainly occur in Huangshan rock mass group. In this paper, the main rock-forming minerals of ore-forming rock bodies in three groups of rock masses are studied systematically and comparatively. The main rock-forming minerals of the ore-forming rock body are olivine, palaeopyroxene, clinopyroxene, plagioclase and hornblende, as well as a small amount of chromium spinel and phlogopite. The calculated results of olivine Al thermometer show that the crystallization temperature of the parent magma of the ore-forming rock body in Huangshan rock mass group is between 1 143 鈩，

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