Re–Os Isotopic Age of the Hongqiling Cu-Ni Sulfide Deposit in Jilin Province,NE China and its Geological Significance

摘要

The major Hongqiling Cu-Ni sulfide deposit in central Jilin Province is located in the eastern part of the Central Asian Orogenic Belt. Rhenium and osmium isotopes in sulfide minerals from the deposit have been used to determine the timing of mineralization and the source of osmium and, by inference, the ore metals. Sulfide ore samples have osmium and rhenium concentrations of 0.28-1.07ppb and 2.39-13.17ppb, respectively. Ten sulfide analyses yield an isochron age of 223 ± 9 Ma, indicating that the Cu-Ni sulfide mineralization formed in the Early Triassic. The initial 187Os/188Os ratio is 0.295 ± 0.019 (MSWD = 1.14). This data indicates that the mineralization was derived mainly from a mantle source with some quantities of crustal components introduced into the rockforming and ore-forming systems during mineralization and magmatic emplacement. Together with the widespread occurrence of late Carboniferous-Permian mafic–ultramafic complexes and associated Permian Cu-Ni deposits in the western part of the Central Asian Orogenic Belt (Northern Xinjiang), we conclude that mantle-crustal interactions were active during the accretion-collisional processes that led to the Cu-Ni mineralization and considerable continental growth in the late Carboniferous-Permian to mid-Triassic.