Geological Characteristics and Re-Os Isotopic Analysis of Shajia Cu-Ni Ore-Bearing Basic Complex in Hualong County, Qinghai Province

Shajia Cu-Ni ore-bearing basic complex is one of the intrusive rocks in Hualong basic-ultrabasic rocks belt,it is small scale,weak lithological zoning.Orebody are lenticular in the intrusion,and norite is the main host rock for the Cu-Ni ores.The analysis on rock geochemistry indicate that the intrusive is calc-alkaline,iron series,rich in LREE,depleted in high field strength elements such as Nb,Ta.The analysis on the sulfide display that the initial ¹⁸⁷Os/¹⁸⁸Os ratios are from 0.346 9 to 0.407 1,the γ_Os values are from 180 to 228,which suggest that abundant crustal material was mixed with the magma,and the content of crust-derived Os was estimated to 30%.The contamination by crustal material probably played an important role in triggering the sulfide saturation and segregation.