REE characteristics of Cu-Ni sulfide deposits in the Hami area, Xinjiang.

On the base of study on the REE geochemistry of ore minerals and host rocks of typical deposits from Huangshan Cu-Ni metallogenic belt, Xinjiang, it was discovered that the host mafic-ultramafic rocks of the Cu-Ni sulfide deposits occurred in orogen are characterized by water-richment. Some REE pattern of sulfides shows particular "triplex curve" model, which suggests that due to coexistence of multiple liquid phase (fluid and melt), the sulfide melt possibly contained a lot of hydrothermal fluid and increasingly derived to gas and liquid-rich ore-forming fluid after the master metallogenic epoch (magmatic segregation stage). REE characteristics of the deposits in this area are quite different from thos of the Cu-Ni deposit occurred in cratonic margin, and the reason of hydrothermal fluid joining in mineralization might be owing to water-rich of ore-bearing rockbody that related to delamination and melting of water-rich oceanic crust in post-collision stage.