Characteristics and genetic models of major chromitite deposit types worldwide

Chromitite is one of China’s scarce strategic mineral resources and has long been supplied largely through import from abroad. Its genesis is closely linked to the evolution the mantle and transformation of tectonic setting. In this study, by taking four major types of chromitite deposits including the layered, podiform, Alaskan-type, and greenstone belt–hosted ones in the world as research objects, we have systematically comparied their orebody geometries, mineral assemblages, and petrological, mineralogical, and geochemical characteristics, and further discussed their genetic mechanisms and tectonic settings based on the comprehensive analysis of previously published data of those deposits. The research results reveal that there are pronounced differences among various types of chromitite deposits in terms of metallogenic environments, magmatic evolution process, and provenance of ore-forming materials. The formation of these deposits are jointly controlled by the mantle thermal state, lithospheric structure, transformation of tectonic setting, and subduction-related fluids and their redox conditions. In addition, the chromitite mineralization has obvious characteristics of spatiotemporal segmentation and is closely related to the evolution of mantle and tectonic framework at global scale. This research provides important constraints for understanding the cycling of chromium in deep interior of the Earth and the global metallogenic patterns of chromium.