Geological, Geochemical Characteristics and Metallogenic Model of the Xujiagou Cu Deposit in Lueyang County, Shaanxi Province

The Xujiagou Cu deposit lies in the west side of the Tongchang Cu deposit in "Mianxian-Lueyang-Ningqiang" mineralization concentrated area. The orebodies are hosted in the schistose spilitein the Guojiagou formation of Upper Proterozoic Bikou Group, and they are occurred as stratiformed, lentoid shape, which have similar occurrence with schistose spilite or have replaced the spilite, with obvious hydrothermal replacement texture and deformation features. Trace elements and S isotope compositions of host rocks and ores show that ore-forming materials (Cu, Ni and Co elements) were mainly derived from spilite and magma, respectively. Fluid inclusions of the ores suggest that ore-forming fluids mainly belong to medium-high temperature(166~412℃) and moderate-low salinity(2.6%~10.9% NaCleq) NaCl-H₂O series, which were mainly sourced from magmatic water, combined with few metamorphic water or formation water. According to the geological characteristics, geochemistry compositions, stable isotopes and dating results, it's considered that the Xujiagou Cu deposit was formed in Mesozoic and was formed by volcanic-exhalation, regional metamorphism and magmatic metallogenesis.