中南祁连西段余石山铌钽矿成矿过程元素地球化学指标研究及意义

Geochemical Indicators of Metallogenic Processes of the Yusishan Nb-Ta Deposit in the Western Qilian Section and Its Significance

中南祁连西段余石山铌钽矿是近年在国内发现的变粒岩型铌钽矿床,规模已达大型,是一种新的铌钽矿床类型,但对变粒岩中铌钽富集成矿过程中元素地球化学变化尚未开展系统研究。本文通过详细的野外调查和室内综合分析,系统研究了余石山矿区无铌钽矿化变粒岩、含铌钽变粒岩、铌钽矿化体、低品位铌钽矿石、铌钽工业矿石等5类铌钽矿化程度不同变粒岩的元素地球化学特征,结果显示变粒岩型铌钽矿Nb富集成矿过程中Si、Al、Zr、Hf、REE等元素存在规律性变化,总结了成矿过程中有效元素地球化学指标,发现变粒岩中Nb含量与原岩岩石类型关系密切,揭示该矿床经历了新元古代岩浆成矿作用和加里东期热液变质成矿作用,共两期三阶段成矿过程,该研究为中南祁连西段铌钽矿找矿和成矿研究提供了依据。

The Yushishan Nb-Ta deposit in the western section of the central and southern Qilian Mountains is a leptynite-type Nb-Ta deposit discovered in recent years.This Nb-Ta deposit is a new type Nb-Ta deposit with reserves scale of large-sized deposits.However,the geochemical behavior of elements during Nb-Ta enrichment in the leptynites remains unclear.This paper reports the elemental geochemical characteristics of the leptynites with different degrees of Nb-Ta mineralization,including non-mineralized leptynite,Nb-Ta-bearing leptynite,Nb-Ta mineralized leptynite,low-grade Nb-Ta ore,and industrial Nb-Ta ore.The results reveal that there are regular geochemical changes in Si,Al,Zr,Hf,REE,and other elements during the ore mineralization of the Yushishan Nb-Ta deposit,and Nb contents of the leptynites are closely related to the original rock types.The ore forming processes of the Yushishan Nb-Ta deposit consist of Neoproterozoic magmatic mineralization and Caledonian hydrothermal metamorphic mineralization.This study provides a favorable basis for prospecting and metallogenic research on Nb-Ta mineralization in the western section of the central and southern Qilian Mountains.