粒间显微结构对镁铁-超镁铁质层状岩体的岩浆演化过程和巨量铁钛氧化物堆积机制的指示

我国攀西地区出露数个赋含大型-超大型钒钛磁铁矿矿床的镁铁-超镁铁质层状岩体，巨量钒钛磁铁矿的堆积机制一直是研究热点。在这些岩体中，钒钛磁铁矿多呈粒间相产出在多数矿石和岩石中。粒间显微结构是堆晶矿物之间的岩浆（粒间熔体）的结晶产物，其结构特征和矿物成分可为研究层状岩体的岩浆演化过程提供直接证据。本项目拟选择岩石类型和主要矿石层产状存在明显差异的红格和白马岩体为研究对象，在详细的野外考察和岩相学观察基础上，利用现代微束微区分析技术对粒间显微结构进行精细研究，查明两个岩体不同层位的粒间显微结构特征及其分布规律，揭示不同类型粒间显微结构中矿物组成的变化规律，反演层状岩体的岩浆演化过程，阐述巨量钒钛磁铁矿堆积的制约因素。本研究的开展不但可以进一步揭示攀西地区大型-超大型钒钛磁铁矿矿床的形成机制，而且也将有助于深化对玄武质岩浆分异演化过程的认识。

There are several mafic-ultramafic layered intrusions that host giant Fe-Ti-V oxide deposits in the Panxi region, SW China. The Fe-Ti oxides mainly occur as interstitial phase in the disseminated and net-textured ores and the rocks of the intrusions. It has been debated on the mechanism of the enrichment of massive Fe-Ti oxides in these intrusions. Interstitial microstructures among cumulus minerals are products of interstitial liquid and can provide direct evidence for the evolution history of interstitial liquids. The Hongge and Baima layered intrusions have different rock-types and stratigraphic levels of Fe-Ti oxide ore layers. The interstitial microstructures in the rocks of these two intrusions will be investigated based on detailed petrographic observation. The compositional variations of the minerals in the microstructures will be analyzed and used to trace the evolution path of magmas during formation of the layered intrusions, and finally to constrain the mechanism of accumulation of massive Fe-Ti oxides. This project will not only provide new evidences on the formation of the giant Fe-Ti-V oxide deposits in the Panxi region, but also help to understand the differentiation process of basaltic magmas.