海南岛东南部吊罗山地区中深变质岩锆石U-Pb定年及其地质意义

摘要

The mesometamorphic rocks in the Diaoluoshan area are composed of granulite and gneiss occurring as discrete patches in the Permian granite. Based on lithological comparison, the metamorphic rocks were classified as the Mesoproterozoic Baoban Group in the previous literatures. Our LA-ICP-MS zircon U-Pb results of the granulite and gneiss yielded ages of 255±9 Ma and 247±8 Ma, respectively. The zircon U-Pb ages of the metamorphic rocks demonstrated that the metamorphism of the rocks took place in Hercynian-Indo-Chinese Epoch rather than the previously believed Mesoproterozoic Period.%海南吊罗山地区中深变质岩由变粒岩、二长片麻岩、斜长片麻岩、黑云母麻粒岩等组成，呈孤岛状产于二叠纪花岗岩中。以往根据岩石对比，把它归属为中元古界抱板群。本次研究利用激光剥蚀等离子体质谱(LA-ICP-MS)技术对岩田南部吊罗山地区的变质岩体进行了锆石U-Pb定年，在片麻岩和变粒岩中分别获得了255±9 Ma和247±8 Ma的峰期变质年龄，表明该类岩石变质作用发生于晚二叠世-早三叠世交界之际，而不是以往所认为的中元古代。这一新发现为深入研究海南岛海西–印支期造山运动及其变质作用具有重要的地质意义。