新疆阿尔泰稀有金属矿地质特征及成矿作用

Geological Characteristics and Metallogenesis of Rare Metal Deposits in Altay, Xinjiang

在前人工作和野外调查基础上,文章总结了新疆阿尔泰稀有金属矿地质特征、时空分布和成矿背景。稀有金属矿分为花岗伟晶岩型和花岗岩型,以前者为主,分布于哈龙-青河稀有金属成矿亚带和加曼哈巴-大喀拉苏稀有金属成矿亚带的9个矿集区中。依据成矿时代稀有金属成矿作用分为4期:奥陶纪-早志留世(476～436 Ma)、晚泥盆世(～370 Ma)、二叠纪(296～258 Ma)和三叠纪-侏罗纪(250～151 Ma),其中三叠纪-侏罗纪为主要成矿期。前2个成矿期以形成工业白云母矿伴有稀有金属、稀土矿为特色,形成于板块俯冲阶段,二叠纪到侏罗纪出现了连续成矿作用,以形成稀有金属矿为特色,成矿元素组合复杂。二叠纪为后碰撞环境,三叠纪-侏罗纪为陆内环境,区域大规模伸展是形成大规模稀有金属矿的地球动力学背景。阿斯喀尔特Be-Nb-Mo矿床与白云母钠长花岗岩、大喀拉苏Be-Nb-Ta矿床与黑云母花岗岩存在成因关系,可可托海稀有金属矿床与阿拉尔花岗岩的关系存在很大争议,其他稀有金属矿床与赋矿花岗岩不存在成因关系。

This paper reviews the geological characteristics, spatial and teporal distribution, and tectonic settings of rare metal deposits in Altay, Xinjiang. The rare metal deposits are predominantly of granitic pegmatite type and less granite type. The pegmatite-type rare metal deposits distribute in nine ore dense districts in the Halong-Qinhe and the Jiamanhaba-Dakalasu rare metal ore-forming subzones. Based on isotopic dating results, the rare metal mineralization took place during Ordovicia to Early Siluria(476 – 436 Ma), Late Devonian(ca.370 Ma), Permian(296 – 258 Ma) and Triassic to Jurassic(250 – 151 Ma), and the majority of the ore deposits are formed in the Triassic to Jurassic period. The first two mineralization periods took place in subduction setting and formed muscovite ores with accompanying rare metals and rare earth elements. Ore mineralization during the Permian to Jurassic period is characterized by rare metal deposits with complex ore metla association. The Permian and the Triassic to Jurassic mineralization occurred in postcollision and continental environments, respectively, and the regional large-scale extension background is favorable for the large-scale rare metal mineralization. Results show that the Dakalasu Be-Nb-Ta deposit is genetically related to the biotite granite, while the Arskartor Be-Nb-Mo deposit is related to the muscovite albite granite. However, it is still controversy regarding the genetic relationship between the Keketuohai No.3 pegmatite and the Aral granite. In addition, no genetic relationship between the other rare metal deposits and their ore-hosting granites has been recognised.