Podiform Chromitites: Their composition, origin and environment of formation

摘要

Podiform chromitities are nominally either high-Cr or high-Al in composition and typically only one type occurs in any given ophiolite. 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 arc 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.