吉林省中泥盆世变质火山岩系的发现:来自原机房沟(岩)组(群)中锆石LA-ICP-MS U-Pb测年的证据

Discovery of Middle Devonian metavolcanite series in Jilin:evidence from zircon LA-ICP-MS U-Pb age of original Jifanggou Formation

通过对"机房沟岩群"调查研究,确证其是一套由构造岩片堆叠组成的构造地层。笔者于九台县上河湾镇下洼子村后山、原"机房沟岩群"层型剖面变质酸性-中酸性火山岩系的两件样品(Pm001-6-2,Pm001-7-4)中,获锆石LA-ICP-MS U-Pb年龄分别为(389.4±3.0)Ma、(388.3±3.9)Ma,确定在吉林省内有中泥盆世吉维特期(Givetian)的火山岩地层存在。结合内蒙古自治区、黑龙江省及松嫩地块相对应的火山岩地层进行了对比研究,认为在"佳蒙地块"南缘,从老秃顶子—宝泉—下洼子—放牛沟过松嫩盆地至满都拉,存在一条早泥盆纪晚期—晚泥盆纪初期的火山岩带。

Based on the study of Jifanggou rock group,the authors confirmed that it is a set of structure strata which is composed of tectonic slices. By collecting two samples （Pm001-6-2, Pm001-7-4） in the behind the Xiawazi of Shanghewan in Jiutai County, which is the original Jifanggou rock group metamorphic acid-intermediate acidic volcanic rocks, the authors obtained the zircon LA-ICP-MS U-Pb age of（389.4±3.0）Ma and（388.3±3.9）Ma, determining that there exists volcanic rock formation of Givet Period of Middle Devonian in Jilin Province. Integrating the correlation with volcanic rock formations in Inner Mongolia, Heilongjiang and Songnen massif, it is concluded that in the southern margin of Jia-Meng massif from Laotudingzi-Baoquan-Xiawazi-Fang-niugou through Songnen Basin to Mandula, there exists a volcanic rock belt in late Early Devonian- early Late Devonian.