大兴安岭中生代高分异花岗岩（高硅流纹岩）的成因及其与铍成矿关系研究

本项目围绕“关键金属元素成矿机制与规律”这一关键科学问题，拟通过对大兴安岭地区中生代高分异花岗岩（高硅流纹岩）及堆晶花岗岩的岩石学、同位素年代学、矿物学与地球化学的系统研究，查明高分异花岗岩的期次、岩石组合及其地球化学属性；利用锆石Hf-O、磷灰石Sr-Nd及全岩同位素和磷灰石-石榴石-白云母微量元素比值以及磷灰石挥发分组成揭示高分异花岗岩浆的源区性质、分异程度，分析高分异花岗岩与Be成矿的关系；利用不同矿物的不同世代流体包裹体组成、性质、物化条件等，查明流体随岩浆演化的变化及其对Be元素运移的控制因素；通过含Be矿物的流体包裹体的温压条件和流体的组成，结合矿区构造分析等限定铍矿的成矿条件；最终揭示高分异花岗岩的形成对关键金属铍超常富集的制约，揭示Be元素成矿的源-运-聚过程和机理。该研究不仅是国家战略需求的要求，而且在揭示花岗岩浆高度分异演化与Be成矿关系方面具有重要的理论和实践意义。

This project focuses on the key scientific issue of “the mechanism and law of mineralization of key metal elements”. Systematic petrological, isotope geochronological, mineralogical and geochemical studies will be conducted for the Mesozoic highly fractionated granite (high-silica rhyolite) and cumulated granite in the Great Xing’an Range, in order to investigate the period, rock association and geochemical feature of the highly fractionated granitic magmatism. Isotopic geochemistry of zircon Hf-O, apatite Sr-Nd, and whole rock Sr-Nd-Pb-Hf, trace element ratios of apatite, garnet, and muscovite, as well as volatile compositions of apatite will be used to reveal the source characteristic and fractionated degree of the highly fractionated granitic magma as well as their relationships with beryllium mineralization. The composition, origin and physicochemical condition of fluid inclusions of different generations in different minerals will be discussed to further determine the fluid changes along with the magma evolution and their control factors on beryllium migration. Through analysis of the P-T conditions and compositions of the fluid inclusions in beryllium-bearing minerals, as well as the tectonic features of the metallogenic areas, the metallogenic conditions of beryllium mineralization will be well constrained. The purpose of this integrated study is to eventually look insight into the genetic relationship of the formation of the highly fractionated granite and the extraordinary enrichment of beryllium element, as well as the source-migration-aggregation processes and mechanism of beryllium mineralization. This project is not only the demand of the national strategic requirements, but also has important theoretical and practical values for revealing the relationship of the highly fractionated evolution of granitic magma and the beryllium mineralization.