内蒙古宝音图钼矿床花岗岩稀土元素地球化学特征及花岗岩成因

REE Geochemical Characteristics and Genesis of Granites in Baoyintu Molybdenum Deposit,Inner Mongolia

宝音图钼矿床是近几年在内蒙古西部地区发现的大型斑岩型钼矿床。重点研究该钼矿床成矿花岗岩稀土元素地球化学特征,探讨花岗岩成因。通过对稀土元素配分模式和特征值(∑REE-LREE/HREE、δEu-LREE/HREE相关性)的分析,对比幔源岩浆及南岭花岗岩稀土元素组成特点,结合岩石化学组成,推断宝音图成矿花岗岩属于陆壳熔融成因花岗岩。由斜长花岗岩→二长花岗岩→钾长花岗岩→细晶花岗岩,岩体成分逐渐变化。岩浆演化中有成分分异,有利于成矿,特别是晚期钾长花岗岩富集成矿元素和矿化剂元素。

The Baoyintu molybdenum deposit,located in western Inner Mongolia,is a large scale porphyry molybdenum deposit which is discovered in recent years. This paper focuses on discussing REE geochemistry of ore-forming granites and genesis of granites. Based on analyses of REE distribution patterns,characteristic value （including ∑REE LREE/HREE and δEu LREE/HREE） and petrochemical compositions,comparisons with REE compositions of mantle-derived magma and Nanling granites,authors deduce that genesis of ore-forming granites is related to melting of the continental crust. The compositions of granites vary in the sequence of plagiogranite → monzoniticgranite → K-feldspar granite → graniteaplite. The chemical variation during the magmatic evolution process is in favour of mineralization,especially the late-stage K-feldspar granites.