Zircon SHRIMP U-Pb dating of Heishan mafic-ultramafic complex in the Beishan area of Gansu Province and its geological significance

The Heishan copper-nickel deposit is located in the rift zone of the Beishan Mountain northeast of the Tarim plate, on the southern side of Miaomiaojing -Shuangyingshan fault. The ore-bearing mafic-ultramafic complex intruded into Dahuoluoshan Formation of Qingbaikou System and Cambrian Shuangyingshan Formation. Mineralization mainly occurred in peridotite and hornblende-gabbro complex. SHRIMP U-Pb dating of zircon from the ore-bearing hornblende-gabbro body yieldes an age of 374.6 Ma±5.2Ma, which suggests that the intrusion of the ore-bearing complex and the mineralization both occurred in Late Devonian. The obtaining of this age has important significance in understanding geological evolution of Beishan Mountain area and also in indicating targets for copper-nickel ore prospecting in Beishan Mountain area.