Abstract:

The Jinchuan deposit is the largest NiCu sulfide deposit in China. The intrusion is composed mainly of sulfide peridotite, harzburgite, lherzolite and pyroxenite. Samples for segment II of the Jinchuan intrusion, according to the petrographic observations, combined the analysis of geochemical features of major oxides and trace elements, the paper attempts to research the magma differential evolution in magma rising process. The authors consider that the fractional crystallization process of segment II of the Jinchuan intrusion contain the spinelolivine fractional crystallization in the deep magma chamber and pyroxenite and plagioclase crystallization in the shallow magma chamber, and crustal contamination occur in the whole magma rising processes. In addition, the crustal contamination is the major factors of saturated sulfur. The above magma differentiation evolution supports the mineralization model proposed by Tang Zhongli.

Key words: segment II of the Jinchuan intrusion, magmatic NiCu sulfide deposit, fractional crystallization, crustal contamination, Gansu