New progress of the research on the Kemi chromitite deposit in Finland

The Kemi deposit is the largest chromite deposit in Europe.The authors have summarized its geological setting, orebody features, ore genesis and ore indicators in this paper.The deposit is hosted by early Proterozoic Kemi layered complex, which strikes northeastward along the Svecokarelidic Perapohja schist belt.The chromite deposit in the complex has typical layered accumulation characteristics and the ore layers extend steadily.Due to the low Cr/Fe ratio in ore, its grade belongs to low level among similar ore deposits in the world.Isotopic geochronology evidence suggests that the mineralization age is 2.44 Ga, indicating that the metallogenesis of chromitite deposit occurred in early Paleoproterozoic.During the Karelia orogeny, the chromitite was deposited when the input of magma into the Kemi intrusion was contaminated by salic material from the underlying basement complex.This magma was mixed with the fresh input of primitive magma, resulting in chromite saturation.The chromite crystals were formed during mixing in a plume.The Kemi deposit is a layered type chromitite deposit, and its geological features are different from features of podiform type or stratoid type chromite deposits discovered in China.