Cryptic compositional variation of olivine between interlayered troctolite and net-textured Fe-Ti oxide ore in the Baima layered intrusion, SW China: Implications for the origin of banded Fe-Ti oxide ores

•Banded ores of the Baima intrusion consist of troctolite and net-textured ore layers.•Olivine is rounded in ne-textured ore but granular and poikilitic in troctolite layers.•Olivine shows cryptic variation of Fo content along the profile.•Slumping of immiscible Fe-rich melt with a troctolitic mush is proposed.