南祁连化隆岩群LA-ICP-MS锆石U-Pb年龄及其地质意义

侵入于化隆岩群中的基性-超基性岩中因产有拉水峡、裕龙沟小型铜镍矿床和一大批铜镍矿点,而备受关注。其化隆岩群形成时代的确定直接影响着祁连山地区铜镍矿找矿方向和找矿工作布署。近年来,随着同位素年代测试技术的不断发展,高精度数据出现,对化隆岩群形成时代的认识逐步明朗化。通过高精度的LA-ICP-MS锆石微区原位U-Pb同位素测年,获得青海省化隆县拉水峡铜镍矿区含矿基性-超基性岩体围岩化隆岩群黑云斜长片麻岩的形成时代为(910±7)Ma,代表着化隆岩群形成时代的下限,结合前人研究成果,进一步确定化隆岩群的形成时代为新元古代。并认为该区有与金川铜镍矿相似的成矿地质背景,含矿基性-超基性岩均为Rodinia超大陆裂解的产物,具有良好的找矿前景。

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.