新疆南天山波孜果尔碱性花岗岩体中铌钽等元素富集与矿化机制

The Boziguo’er alkali granite pluton, located in the South Tianshan, Xinjiang, is characterized by the strong enrichment in Nb-Ta and other rare metals. Previous studies revealed that the mineralization of these elements was plausibly associated with the magmatic process. However, the nature of the source region(s) of the alkaline granitic magma, the chemical composition of the primary magma, the degree of the enrichment in Nb-Ta and other rare metals at a given stage during the magmatic differentiation and the major the geological/geochemical controls responsible for the enrichment of rare metals have been poorly understood so far. This project plan to clarify afore questions by means of a comprehensive study mainly including silicate melt inclusion, mineral major and trace element composition and zircon Hf isotope analyses. Coupled with previous studies, we try to propose a metallogenetic model for the rare metal-bearing Boziguo’er alkali granite pluton. Furthermore, we try to attempt comparisons between the Boziguo’er pluton and other world-famous, granite-related Nb-Ta deposits, and between it and unmineralized alkali plutonic rocks in the region, aiming to clarify some common features surrounding the extraordinary enrichment of Nb-Ta in peralkaline magmas.

位于新疆南天山的波孜果尔碱性花岗岩体中含有丰富的铌钽等稀有金属资源。研究表明，过碱质岩浆的分异演化很可能是导致岩体中铌钽等元素实现超常富集与矿化的主要原因。然而，人们尚不清楚该岩体的岩浆源区特征和早期岩浆的性质、岩浆演化不同阶段中铌钽等元素的富集程度以及导致该岩体成矿的关键性地质和地球化学条件。本项目拟通过硅酸盐熔体包裹体研究、单矿物化学成分分析和锆石Hf同位素研究为主要手段查明上述问题。在此基础上，结合先前的研究成果，建立波孜果尔碱性花岗岩体的成岩成矿模型。同时，综合对比波孜果尔岩体与境内外典型的花岗岩型和碱性岩型铌钽矿床在成岩成矿条件方面的异同，以及波孜果尔岩体与区域上不成矿碱性岩在岩石成因上的差别，为分析过碱质岩浆体系中铌钽等元素实现超常富集与矿化的一般规律提供重要依据。