The LA-ICP-MS U-Pb Age and Geological Significance of Hualong Rock Group in South Qilian Mountains

There are many copper-nickel deposits in basic-ultrabasic rocks which invaded in Hualong Rock Group.These deposits received more and more attention in recent years,such as Lashuixia and Yulong small copper-nickel deposits.Formation period of Hualong Rock Group influenced copper nickel ore prospecting and exploration in Qilian Mountain.In recent years,with the isotopic age of the continuous development of testing technology,high-precision age data continue to emerge,period of formation of Hualong rock group gradually become clear.Through high-precision LA-ICP-MS zircon U-Pb in situ dating of biotite-plagioclase gneiss in Hualong County,we got the age of biotite plagioclase gneiss was 910±7Ma in Hualong Rock Group which was wall rock of mineralized basic-ultrabasic rocks in Lashuixia copper-nickel deposits of Qinghai Province.And this age represented the lower period of formation of Hualong rock group.Combined with previous research results,we can conclude that the period of formation of Hualong rock group was Neoproterozoic.The area have a similar geological setting with Jinchuan copper-nickel mine,ore-bearing basic-ultrabasic rocks are the products of cleavage of Rodinia super-continent,with good mineral prospects.