摘要:
【研究目的】通过对西昆仑东段印支期岩浆活动和伟晶岩的年代学、地球化学的综合研究，探讨印支期岩浆活动与锂铍稀有金属成矿的关系，为下一步找矿方向提供依据。【研究方法】全面总结研究区的地质背景和典型矿床特征，对比分析印支期岩浆活动的时代、岩性组合、岩石地球化学和Hf、Nd、Li等同位素地球化学特征，总结印支期岩浆活动与伟晶岩的的成因联系。【研究结果】西昆仑东段印支期岩浆活动形成的大红柳滩复式岩体控制了区内伟晶岩的空间分布。石英闪长岩、黑云母二长花岗岩和二云母二长花岗岩的岩石地球化学、Hf、Nd同位素特征显示它们可能不是同源岩浆演化。石榴子石和电气石的矿物地球化学和全岩的Li同位素特征指示石榴子石电气石二云母二长花岗岩、含石榴子石电气石白云母伟晶岩和锂辉石钠长石伟晶岩有可能是同源岩浆演化而来。【结论】二云母二长花岗岩、尤其是石榴子石电气石二云母二长花岗岩与稀有金属矿化伟晶岩关系更加密切。阿克塔斯的外围和509道班-泉水沟一带是寻找富锂伟晶岩的有利区段。
Abstract:
This paper is the result of mineral exploration engineering. [Objective] The aim of this paper is to investigate the relationship of Li-Be-rare metal mineralization and Indosinian magmatism in the eastern part of the West Kunlun Orogenic Belt through a comprehensive study of Indosinian magmatic activities, granite chronology, and geochemical characterization. Furthermore, the corresponding metallogenic regularity is summarized, and the exploration prospecting of rare metal pegmatite deposits is given. [Methods] Based on the our recent research, the geological details in the eastern part of the West Kunlun Orogenic Belt, including ages, mineral assemblages, geochemical characteristics, isotopic characteristics (Hf, Nd and Li, etc.) of the Indosinian magmas, are summarized and fully compared for the first time. The genetic link between the pegmatite-hosted Li-Be-rare metal mineralization and Indosinian magmatism is investigated. [Results] The large composite granite pluton formed in Indosinian period in the eastern part of the West Kunlun Orogenic Belt is mainly composed of quartz diorite, biotite monzogranite and two-mica monzogranite (including garnet tourmaline two-mica monzogranite), which was formed due to partial melting of the crust in a post-collision regime. The reliable chronological data show that there is no age difference between the composite granite (216.7~208.8Ma) and the granitic pegmatites (211.9~208.1Ma), suggesting that they were formed at the same time. The characteristics of minerals (garnet, tourmaline) and Li isotopes indicate that the two-mica monzogranite (garnet tourmaline two-mica monzogranite), garnet-bearing tourmaline muscovite granite pegmatite and spodumene-albite pegmatite were likely derived from the same magma source. [Conclusions] Results show that two-mica monzogranite and in particular garnet, tourmaline-bearing two-mica monzogranite exhibit close relationship with the pegmatite-type rare metal deposits. The peripheries of Aktas and the 509 Daoban-Quanshuigou area are favorable section for prospecting lithium-rich pegmatite.
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