新疆福海县哈龙稀有金属矿床地质特征及成因浅析

哈龙-青河早古生代深成岩浆弧是新疆阿尔泰重要的稀有金属成矿带, 带内分布多个大、中型稀有金属(锂铍、钽铌)矿床, 赋矿伟晶岩时代主要集中于三叠纪(250~205Ma)和侏罗纪(200~180Ma)。其中哈龙-阿祖拜伟晶岩田中含矿伟晶岩主要由微斜长石型伟晶岩、微斜长石-钠长石型伟晶岩和钠长石-锂辉石型伟晶岩组成, 伟晶岩类型及相关矿化依次出现4个水平分带, 以II带铍矿化和III带锂矿化为特征。结合野外地质特征、成岩成矿时代及地球化学特征, 认为哈龙-阿祖拜伟晶岩田稀有金属成矿为伟晶岩自身岩浆-热液演化的产物, 伟晶岩初始岩浆可能与先期存在幔源物质的古老地壳物质部分熔融有关。

Geological Characteristics and Genesis of Halong Rare Metal Deposit in Fuhai County,Xinjiang

The early Paleozoic Halong-Qinghe arc is an important rare metallogenic belt in Altay, Xinjiang. Many large- and medium-scale rare metal (lithium, beryllium, tantalum and niobium) deposits distributed within this belt, and ore-hosted pegmatite were mainly formed in Triassic (250-205 Ma) and Jurassic (200-180 Ma). In Halong-Azubai pegmatite ore field, ore-bearing pegmatite is mainly composed of microcline type pegmatite, microcline-albite type pegmatite and albite-spodumene type pegmatite. The pegmatite type and associated mineralization occurs four horizontal zoning in sequence, characterized by II zone beryllium mineralization and III zone lithium mineralization. Combined with field geological characteristics, petrogenetic and metallogenetic epoch, and geochemical characteristics, we suggest that rare metal mineralization in Halong -Azubai pegmatite ore field was the product of their own pegmatite magmatic-hydrothermal evolution; the initial pegmatite magma may related to the partial melting of mantle material in ancient crust.