东天山香山中镁铁-超镁铁质岩体岩石学与矿物学特征:对成岩成矿过程的约束

发布时间：2018-03-04 22:04

本文选题：东天山　切入点：香山　出处：《中国地质》2017年06期 　论文类型：期刊论文

【摘要】：香山中镁铁-超镁铁岩体产出于新疆东天山地区的黄山—镜儿泉镁铁-超镁铁岩带。主要的岩石类型为二辉橄榄岩、(含长)单辉橄榄岩、橄榄辉石岩及角闪辉长岩。矿物学特征显示,岩体造岩矿物的结晶顺序为铬尖晶石→橄榄石→斜方辉石→单斜辉石→斜长石→角闪石。电子探针分析显示,同一侵入期次中各岩相具有良好的过渡渐变关系,钻孔剖面上橄榄石含量与颗粒大小、单斜辉石的成分有随深度连续变化的特征,铬尖晶石则具有良好的Cr→Fe3+、Ti的演化趋势,由此反映岩体的形成主要受结晶分异作用的控制;含长单辉橄榄岩中橄榄石和单斜辉石成分的突然变化显示岩浆结晶过程中受到了地壳物质阶段性的混染;模拟计算表明,橄榄石分离结晶伴随着硫化物的熔离;钻孔ZK3693深度为295~325 m,含长单辉橄榄岩中橄榄石、斜长石、单颗粒单斜辉石成分突然性的变化指示在区间内有新鲜的基性程度更高的岩浆注入,而此区间内矿石的Cu、Ni品位明显高于区间外同一岩相岩体,说明新鲜岩浆的注入是香山中岩体硫化物富集的重要原因。
[Abstract]:Magnesium-ultramafic intrusions occurred in the Huangshan-Jingerquan Magnesium-ultramafic rock belt in the eastern Tianshan area of Xinjiang. Olivine pyroxenites and hornblende gabbro. Mineralogical characteristics show that the order of crystallization of rock-forming minerals in the rock mass is chromium spinel. 鈫扥livine. 鈫扥rthopyroxene. 鈫扖linopyroxene. 鈫扨lagioclase. 鈫扐mphibole. Electron probe analysis showed that the lithofacies had a good transition gradient relationship in the same intrusive period, the olivine content and particle size in the borehole profile, and the composition of clinopyroxene varied continuously with depth. Chromium spinel has good Cr. 鈫扵he evolution trend of Fe3 and Ti shows that the formation of the rock mass is mainly controlled by crystallization differentiation, and the sudden changes of the composition of olivine and clinopyroxene in the peridotite indicate that the magma is mixed with crustal materials in the process of crystallization. The simulation results show that the separation and crystallization of olivine is accompanied by the melting of sulfides, the depth of borehole ZK3693 is 295 ~ 325m, and the peridotite contains olivine and plagioclase. The sudden change of single particle clinopyroxene composition indicates that there is a higher degree of fresh magma injection in the region, and the copper nickel grade of the ore in this zone is obviously higher than that of the same lithofacies rock body outside the interval. It shows that the injection of fresh magma is an important reason for sulfide enrichment in Xiangshan rock mass.
【作者单位】：国土资源部岩浆作用成矿与找矿重点实验室西安地质调查中心;中国地质大学(北京)地球科学与资源学院;
【基金】：国土资源部公益性行业科研专项(201511020) 青年自然科学基金(41302052、41402071)联合资助~~
【分类号】：P588.125;P618.2

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