PODIFORM CHROMITITE IN THE ARC MANTLE - CHROMITITE XENOLITHS FROM THE TAKASHIMA ALKALI BASALT, SOUTHWEST JAPAN ARC

Chromitite xenoliths from the Takashima alkali basalt in the Southwest Japan arc are classified into two types: Type 1 chromitite in thin layers in dunite or wehrlite xenoliths; and Type 2 chromitite in discrete xenoliths which has an orbicular texture, previously documented only from podiform chromitites in ophiolites. Type 1 may be equivalent to layered chromitities in ophiolitic cumulates and Type 2 to podiform chromitites in the transition zone of ophiolites. This example of podiform chromitite from the Southwest Japan arc suggest that these podiform chromitites may exist in the upper mantle beneath an arc, where their formation is favored.