【摘要】 安徽巢北地区坐落着一个"M"型的山脉,近年来对该地区的构造、地层和古生物化石已有很多的研究积累,但对于岩浆岩,由于分布和发育有限而研究程度较低。文章应用LA-ICP-MS锆石微区分析技术对该地区出露的岩体进行了精确定年。结果显示,岩体中含大量岩浆成因锆石,以高的w(Th)/w(U)比和振荡结晶环带为特征。样品中16个测点的n(206Pb)/n(238 U)加权平均年龄为(100.8±1.3)Ma,代表该岩体的形成年龄。巢北地区位于下扬子北缘,近年来关于下扬子地区中生代岩浆岩研究的年龄数据尚无小于100 Ma的报道,而在本区西侧紧邻的郯庐断裂带南缘上,其岩浆岩的形成时代介于132~103 Ma之间。因此,巢北地区侵入岩在时代和成因上,和郯庐断裂带的联系更加密切。更多还原

【Abstract】 In the north part of Chaohu City,Anhui Province,here lays a mountain shaping as letter"M".A lot of studies about the tectonics,stratigraphy and paleontology in this area have been carried out in recent years,however as limited by less distribution,research on magmatic rocks is still poor.For this reason,LA-ICP-MS zircon in-situ analysis technique was used to determine the accurate forming age of the magmatic rocks in this area.The results show that there are large amounts of magmatic zircons in the rock mass,which are characterized by high w(Th)/w(U)ratios and characteristic crystal ring oscillators.The weighted average 206Pb/238 U age of 16 measured points gives a mean age of(100.8±1.3)Ma,which represents the forming age of the rocks.The northern Chaohu area locates in northern edge of lower Yangtze region,but no age data younger than 100 Ma has been shown in studies about mesozoic magmatic rocks in lower Yangtze region in recent years.Moreover,in the western part near this area,magmatic rocks cropped in the Tan-Lu fault zone have formed ages of 132-103 Ma.So it can be concluded that the magmatic rocks in northern Chaohu area have close relationship with those cropped in the Tan-Lu fault zone,in temporal and petrogenic aspects.更多还原