Podiform chromitites: Their composition, origin and environment of formation

Abstract

Podiform chromitities are nornmally either high-Cr or high-Al in composition and typically only one type occurs in any given ophiolile. Despite some superficial similarities, high-Cr and high-Al chromitities differ significantly in mineral and bulk-rock geochemistry. Many podiform bodies have been deformed and recrystallized by continued mantle flow but their magmatic origin is widely accepted. We suggest that podiform chromitities occur in the upper parts of ophiolitic or island are mantle and are formed by reaction between rising melts and the host peridotites. High-Cr and high-Al ores are sightly different in their environment of formation.