The compositional variation of chromite in Ni-laterites: Implications for their origin

摘要

The investigation of the chromite composition in representative Ni-laterite deposits, both al-lochthonous and with in situ features from northern Greece, indicate that the chromite, either of primary or secondary composition, provides valuable insights for the origin of these laterites. Comparison between the primary composition of chromite provides evidence for: (a) the descrimination between Fe-Ni ores linked with in situ weathering and those derived by transportation to some extent, although they are found lying on saprolite zones, and (b) the level of Zn, Co and Mn enrichment in zoned chromite grains that is restricted in certain laterite deposits. Such enrichment is considered to be a redox-controlled process and it is probably related to the re-deposition and diagenesis-metadiagenesis stage rather than the stage of weathering.