Comparison of Magmatic Cu-Ni Deposits in Huangshan Area, East Tianshan and Its Implications for Prospecting

The Huangshan area is the one of the most important ore field of nickel in the East Tianshan area and include the Huangshandong, Huangshanxi and Huangshannan magmatic sulfide Ni-Cu deposits. On the basis of the previous research achievements, we discuss the similarities and differences of the magmatic sulfide Ni-Cu deposits in Huangshan area in this paper. The zircon age and geochemistry characteristics show that Huangshandong, Huangshanxi and Huangshannan intrusions have the similar magmatic sources. The olivine Fo and estimated results indicate that the parental magma of these intrusions is supposed to be high Mg in composition and experienced the early olivine crystallization. The isotope and trace elements data show that the magma of these intrusion was formed by the mixing of a mafic magma derived from a depleted mantle with a granitic melt derived from a juvenile arc crust and occurred sulfide segregation in depth. Compared with the Huangshandong and Huangshanxi deposits, the 100% sulfide of the Huangshannan deposit have the higher contents of Ni, Cu, Pt and Pd. The simulated calculation show that the Huangshannan deposit have the higher R factor than Huangshandong and Huangshanxi deposits, which indicated there are more silicate magmas reacted with the sulfide liquid in the Huangshannan deposit. The high oilvine Fo content and low sulfide Cu/Pd ratio in the Huangshannan intrusion indicate the time of olivine fractional crystallization and sulfide segregation is before the Huangshandong and Huangshanxi deposits. Combined with the profile shapes and cover depth of these intrusions, we suggest that the Huangshannan intrusion can be regarded as magma conduits between magma chamber while the Huangshandong and Huangshanxi intrusions may be the lower part of the magma chambers. The bottom of Huangshan intrusion and the underlying deep magma conduit have experienced multi-stage continuous emplacement, recharge, and sulfide accumulation. These processes indicate favorable ore-forming potential, particularly within the structural space created by the slowing down of the deep channel system.