摘要:
新疆启鑫镍钴含矿岩体位于北山构造带中南部，是近年来镍钴战略性矿产勘查取得的重要进展之一。岩体由二辉橄榄岩、橄榄辉石岩、橄长岩、辉长苏长岩、橄榄辉长岩和辉长岩等组成，赋矿岩相主要为橄榄岩相和辉长苏长岩相。本文基于对启鑫四个超镁铁质小侵入体橄榄岩中橄榄石主量和微量元素的分析，探讨了岩浆源区性质和硫化物熔离过程。结果显示各个侵入体橄榄岩中橄榄石均有不同程度的Ni亏损(I、II号侵入体Fo：84.0~87.5，Ni：134~2562 ppm，III、IV号侵入体Fo：82.3~86.1，Ni：581~2970 ppm)，但有高Mn/Zn值(＞15），高100*Mn/Fe值(1.4~1.7)，低10000*Zn/Fe值(3.5~9.4)，Ni/Co值(7.3~14.0)，Li含量(1.8~9.8 ppm)。橄榄石微量元素特征显示岩体岩浆源区为富水橄榄岩，基本无再循环洋壳物质的加入，但在岩浆演化过程中受到陆壳物质的混染。橄榄石Fo值、Ni值等组分特征表明I、II号侵入体深部硫化物熔离作用比较显著，深部找矿潜力大，具有更好的成矿条件和找矿潜力，所以矿床勘查工作需要适当聚焦于I、II号侵入体，关注侵入体深部和外围地质找矿。
Abstract:
Xinjiang Qixin Ni-Co mineralized intrusion is located in the south-central of the Beishan orogenic belt. It is one of the important new discoveries in nickel, cobalt other strategic minerals in Beishan orogenic belt in recent years. The intrusion is mainly composed of lherzolite, olivine pyroxenite, troctolite, norite gabbro, olivine-gabbro and gabbro, and mineral bodies are mainly hosted by peridotite and gabbronorite. In this study, we carried out the in-situ composition analysis of olivine major and trace elements in four small ultramafic intrusion of Qixin to identify the nature of mantle source and portray the processes of sulfide segregation. The results show that olivine of peridotite in each intrusion has Ni losses of varying degrees ( the Fo value and Ni concentration of olivine in the No. I and II intrusion are 84.0~87.5 and 134~2562 ppm, the No. III and IV intrusion are 82.3~86.1 and 581~2970 ppm). However, the olivine have high Mn/Zn ratio (>15) and 100*Mn/Fe ratio (1.4~1.7), and low 10000*Zn/Fe ratio (3.5~9.4), Ni/Co ratio (7.3~14.0), and Li concentration (1.8~9.8 ppm).The trace element characterization of olivine indicates that mantle origin of the Qixin intrusion is a peridotite mantle with water-rich component in the source origin and was no added the material from oceanic crust, but mixed by material from continental crust during magmatic evolution. The characteristics of olivine Fo value, Ni concentration and other components suggest that the sulfide segregation of the deep in the intrusion No. I and II are more significant, and there is potential to search for Ni-Co deposit in the deep. Therefore, ore prospecting and exploration need to focus appropriately on intrusion No. I and II, and need to pay attention to the deep and periphery of the intrusion No. I and II.
百度学术
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