Origin of giant magmatic Fe-Ti-V oxide deposits hosted in layered intrusions in the Pan-Xi area, Sichuan Province, SW China

Abstract

Layered intrusions in the Pan-Xi region, SW China, are parts of the 260 Ma Emeishim Large Igneous Province, SW China. They host certain giant Fe-Ti-V oxide deposits, and have been major producers of these metals in China. Unlike the oxide deposits in classic layered intrusions, such as the Bushveld Complex, those in the Pan-Xi region occur as layers andlor lenses within the gabbros and are generally concentrated in the lower parts of the intrusions. Available geochemical evidence suggests that the intrusions were formed from highly evolved Fe-Ti-V-rich ferrogabbroic or ferropicritic magmas. Ore textures and associated mineral assemblages indicate that the orebodies were formed by late-stage crystal1i:zation of V-rich titanomagnetite from oxide liquids. The abundant accessory hydrous phases suggest that addition of fluids from upper crustal rocks might have induced the separation of the immiscible oxide melts and subsequently gave rise to the oxide orebodies.