【摘要】 铌 (钽 )铁矿是基性岩与超基性岩中极为罕见的矿物。运用电子探针分析了海南蓬莱与碱性玄武岩有密切成生联系的刚玉巨晶中的铌 (钽 )铁矿包裹体的成分 ,确定其晶体化学式为 (Fe0 .72 6Mn0 .168) 0 .894 (Nb1.80 8Ta0 .0 67Ti0 .2 0 8) 2 .0 83 O6。讨论了铌 (钽 )铁矿的形成与刚玉巨晶的关系 ,认为刚玉巨晶的形成可能和岩浆混合或上地幔流体交代作用有关。更多还原

【Abstract】 Tantalic columbites, rare minerals in basic and ultrabasic magmatic rocks, are found as mineral inclusions in corundum megacryst detritals from eluvial deposits of Tertiary alkali basalts in Penglai, Hainan. The chemical compositions of tantalic columbite inclusions in corundum megacrysts are obtained using EPTA. The crystalline chemistry formula of the tantalic columbite is (Fe\-\{0.726\} Mn\-\{0.168\})\-\{0.894\}(Nb\-\{1.808\}Ta\-\{0.067\}Ti\-\{0.208\})\-\{2.083\}O\-6 calculated from its chemical composition. According to the composition and other evidences, it is concluded that the formation of corundum megacrysts may be related to mixing of magmas or alteration of fluids in the upper mantle.更多还原