The role of crustal contamination in the formation of the Jinchuan Ni-Cu-(PGE) sulfide deposit, northwest China

摘要

The Jinchuan Ni-Cu-(PGE) sulphide deposit, NW China, is hosted in a relatively small ultramafic dike-like intrusion. The Jinchuan intrusion is dominantly composed of lherzolite and dunite. Half of the intrusion is sulfide-mineralized.The sulfide orebodies are mainly hosted in the dunite. Silicate rocks in the Jinchuan intrusion have high MgO contents, but low CaO and Al2O3contents. They are rich in LREE relatively to HREE and have a large range of PGE contents (e.g. 0.6-196 ppb Pt and 1.2-135 ppb Pd). High Th/Ta ratios(2.5 and 6.5) and high Th/Nb ratios (0.15 and 0.5)suggest that the magmas experienced assimilationfractional crystallization (AFC) process before they intruded the Jinchuan chamber. The AFC process played an important role for S-saturation.