南秦岭南沟寨铌钽矿床粗面岩锆石U-Pb年代学特征及地质意义

Zircon U-Pb Geochronology Characteristics and Geological Significance of Coarse Rocks in Nangouzhai Nb-Ta Deposit,South Qinling

南秦岭两竹地区出露一套碱性岩浆岩,该套碱性岩浆岩与铌钽稀土矿成矿关系密切,形成了一系列具有大型、特大型规模的铌钽稀土矿床。南沟寨铌钽矿床分布于该带北侧,主要赋矿岩石为粗面岩,锆石U-Pb年代学研究表明,粗面岩结晶年龄为(446.4±4.4)Ma,形成于早志留世,该矿床具有全岩矿化、含矿性稳定等特点,无明显后期热液叠加富集现象,表明其成岩成矿同期;庙垭等正长岩—碳酸岩、土地岭等粗面质火山岩具有相似的地球化学特征,并与南沟寨铌钽矿粗面岩在时空分布上存在紧密联系,反映南沟寨含铌钽矿粗面岩可能与该系列岩石具有同源性。

A set of alkaline magmatic rocks is exposed in Liangzhu area of South Qinling,which is closely related to the mineralization of niobium and tantalum rare earth deposits,forming a series of niobium and tantalum rare earth deposits with large and super large scale.Nangouzhai Nb-Ta deposit is located in the north side of the belt,and the main ore-bearing rock is trachyte.Zircon U-Pb geochronology studies show that the trachyte crystallization age is(446.4±4.4)Ma,which is formed in the early Silurian.The deposit has the characteristics of whole rock mineralization and ore-bearing stability,and there is no obvious hydrothermal superposition and enrichment in the late stage,indicating that its rock formation and mineralization are in the same period.The orthoclase-carbonate rocks such as Miaoya and the coarse-surface volcanic rocks such as Tuling have similar geochemical characteristics,and are closely related to the temporal and spatial distribution of the coarse-surface rocks of Nangouzhai Nb-Ta deposit,reflecting that the coarse-surface rocks of Nangouzhai Nb-Ta deposit may have homology with this series of rocks.