内蒙古林西萤石矿床稀土元素地球化学特征及其指示意义

内蒙古林西县萤石矿产资源丰富,已知萤石矿床（点）68处。萤石矿床产出于中生界火山-沉积岩地层中,矿体主要受近 SN 向或 NNE 向断裂破碎带控制。为了研究水头地区萤石矿床的成矿流体来源和成矿机理,文章对矿床稀土元素进行了分析。结果表明萤石和方解石的稀土元素总量（∑REE）为4.37-159μg/g, LREE/HREE比值为0.24-1.80,δEu =0.57-1.60,具弱Ce负异常（0.81-0.98）特征, Y/Ho比值为21-78,平均41。从成矿早阶段到晚阶段,∑REE值及LREE/HREE比值均逐渐减小,晚阶段萤石具有重新活化、重结晶的特征。结合赋矿地层及矿区外围花岗岩体REE特征分析,认为其成矿流体迁移距离较远,稀土元素和成矿元素可能来自下伏高F地体和含Ca赋矿火山-沉积地层,为热液成因-破碎带充填交代型萤石矿床。

REE geochemistry of fluorite from Linxi fluorite deposit and its geological implications,Inner Mongolia Autonomous Region

Fluorite is enormously rich in the Linxi County, Inner Mongolia, with 68 deposits （occurrences） so far recognized. Fluorite deposits are hosted in the strata of the Mesozoic volcano-sedimentary, the orebodies are controlled by the rupture and fracture zones near SN or NNE dipping. In this article, REEs of the fluorites and calcites were analyzed to explain the source of the ore-forming fluids and the metallogenic mechanism. The results are ∑REE, 4.37-159 μg/g, ∑LREE/∑HREE, 0.24-1.80, δEu, 0.57-1.60, Y/Ho, 21-78 （with an average of 41）, with weak Ce anomaly （0.81-0.98）. The values of both ∑REE and ∑LREE/∑HREE decrease gradually from the early to late metallogenic stages. Fluorites at the late stage are of the characteristic of remobilization and recrystallization. Integrating the REE analysis of the strata and related granites, the authors come to the conclusion that the fluorite-forming fluids are migrating at a far distance, REEs and ore-forming elements are from the F-rich terrane and the Ca-rich strata of volcano-sedimentary, the ore deposits are belonging to the hydrothermal type fracture filled metasomatic type.