Striker magma and magma channel in the Jinchuan copper-nickel sulfide magmatic deposit

Abstract：The Jinchuan copper-nickel deposit is the third largest nickel, copper sulfide magmatic deposit in the world, which has aroused much attention among deposit geologists both in China and abroad. The Ⅳ mining area is an component part of the Jinchuan copper-nickel deposit, but the production and research are rather insufficient due to the low grade (Ni 0.71%, Cu 0.48%) and the great buried depth (below the depth of 140 m). Owing to the impact of the F23 fracture structure, researchers have regarded it as the eastward extension of the No. 2 pluton of the Ⅱ mining area since the beginning of the exploration work. However, recent detailed drilling investigation has obtained systematic test samples, and the results show that the ore-bearing pluton of the Ⅳmining area is an independent ore-bearing pluton mass with its unique evolution process; its Ni / Cu ratio is by far higher than the Ni/Co ratios of other ore-related pluton; its PGE is strongly depleted, and its "R" factor value is low (30). Trace elements and REE distribution also shows independent complex evolution, and rock structures and lithofacies change significantly, with the characteristics of a typical striker magma of magma channel. A comparison of ore-forming elements and PGE characteristics between several major ore-bearing rock masses has led to the preliminary determination of the spatial location of the magma channel in the Jinchuan copper-nickel sulfide deposit; in addition, some key problems concerning the exploration of the Jinchuan deep resources and the exploration direction are also discussed in this paper.