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中亚造山带是世界上最大的显生宙增生造山带之一。中国阿尔泰造山带作为其重要组成部分，分布有十万余条伟晶岩脉，是我国重要的稀有金属产区之一。由于国内稀有金属产能难以满足市场需求量，因此亟待实现找矿突破和资源增储。基于前期工作，本课题组认为位于新疆可可托海矿区的小虎斯特91号伟晶岩脉是一条具有较大成矿潜力的脉体。因此，本文选取91号脉为研究对象，探讨91号伟晶岩脉的岩浆-热液演化过程，并对稀有金属Li、Be、Nb和Ta进行含矿性评价。由于伟晶岩内部分带以及矿物粒径悬殊，难以获得可靠的全岩化学组成，因此系统的矿物学研究通常用于指示伟晶岩岩浆-热液演化过程。本文通过电子探针(EPMA)和激光剥蚀等离子体质谱(LA-ICP-MS)对各结构带不同产状的云母进行主、微量成分分析，旨在揭示91号伟晶岩脉岩浆-热液演化过程。此外，通过对91号脉刻槽取样样品的稀有金属含量的分析，评估该脉体中Li、Be、Ta和Nb的稀有金属储量。本次研究结果如下：(1)、小虎斯特91号脉从围岩蚀变带、伟晶岩边缘带、外侧带、中间带到核部带，依次发育富镁黑云母、白云母、富锂白云母和锂云母，伟晶岩中云母类矿物呈白云母向锂云母演化趋势。Li在白云母和富锂云母（锂白云母和锂云母）中的置换机制不同，分别可能为2SiIV + LiVI?3AlTot和Si+Li?AlTot+Fe（Zn,Mn,Mg）（白云母）和3LiVI?AlVI + 2□VI（富锂云母，□代表空位）。(2)、91号伟晶岩脉经历了岩浆-热液的演化过程。随着演化进行，云母中K/Rb、Mg/Li比值显著降低，Li、Rb、Cs、F含量显著增大，指示分离结晶作用是晚期熔体相Li、Rb、Cs、F富集的主要机制。但云母类主、微量元素组成显示岩浆-热液过渡阶段体系特征不明显，岩浆体系很快由正岩浆阶段转化为热液阶段体系。(3)、小虎斯特91号伟晶岩脉可能达到了中型锂矿床的规模，其Li2O资源量大约为10000 t。

The Central Asia Orogenic Belt (CAOB) is known as one of the largest Phanerozoic accretionary orogenic belts in the world. As an important part of CAOB, the Chinese Altai orogenic belt,in which more than 100,000 pegmatites are distributed,was regarded as one of the major producting areas of rare metals. Due to the contradiction between the decreased producing capcity and increased market requirement of rare metals, it is required to implement the breakthough of ore prospecting for the increase of rare metal reserves.The Xiaohusite No. 91 pegmatite, located in the Koktokay area, Xinjiang,is regarded as a potential rare metal-mineralizaed dyke, based on the previous works by our research grouop. Therefore, the No. 91 pegmatite has been chosen for studying the magmatic-hydrothermal evolution and evaluating its potential mineralization of rare metals Li, Be, Nb, Ta. Systematically mineralogical studies are usually used to indicate the magmatic-hydrothermal evolution of pegmatites, as it is difficult to obtain reliable bulk composition of the pegmatite due to the internal zonation and variable sizes of minerals in the pegmatite. The major and trace elements of mica minerals from the No. 91 pegmatite are analyzed by using electron probe micro analysis(EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), respectively, aiming to reveal the magmatic-hydrothermal evolution of the pegmatite. In addition, the scientific reserves of rare metals including Li, Be, Ta and Nb of the pegmatite were obtained, based on the analysis of rare metals elements of channel samples of the Xiaohusite No. 91 pegmatite. The results of this study are given above:(1)、Mg-rich biotite, muscovite, Li-muscovite and lepidolite minerals are successively developed in the wallrock alteration zone , and margin wall zone, lateral zone, intermediate zone and core zone of the No.91 pegmatite.Micas from margin to core of the pegmatite show an evolution trend from muscovite to lepidolite. The substitution mechanism of Li in muscovite is distractively different to that in Li-rich micas(Li-muscovite and lepidolite) with expressions of 2SiIV+LiVI?3AlTot or Si+Li?AlTot+Fe(Zn,Mn,Mg)(muscovite)、3LiVI?AlVI + 2□VI (Li-rich micas,where□ represents a vacancy), respectively.(2)、The No. 91 pegmatite has experienced the magmatic-hydrothermal evolution process, which is reflected by the decrease K/Rb and Mg/Li ratios in mica and the highly increase Li, Rb, Cs and F contents from early to late stages, indicating that fractional crystallization is the main mechanism for the enrichments of Li, Rb, Cs and F in late melt phase. However, the major and trace element compositions of micas show that the characteristic of the magmatic-hydrothermal transition stage is nearly absent, and the system was quickly transformed from the magmatic stage to the hydrothermal stage during the evolution process.(3)、The Xiaohusite No. 91 pegmatite could be a medium-sized ore deposit of lithium with Li2O of about 10000 t.