吉林色洛河群的重新认识

色洛河群出露于吉林省色洛河—华集岭一带,位于华北克拉通北缘东段,长期以来一直被认为是中新元古代地层。最近的野外调查和定年研究表明,它包含了时代、成因、构造样式、变质程度不同的变质地层和变形的花岗岩,作为一个岩石地层单位已不合适,应予解体。原划分的色洛河群至少由4部分组成:新太古代变质火山-沉积地层(锆石SHRIMP年龄为2517~2534 Ma)、晚古生代变质火山-沉积地层(英安岩锆石SHRIMP年龄为252 Ma)、二叠纪片麻状杂岩体(锆石SHRIMP年龄为260 Ma)和侏罗纪糜棱岩化花岗岩(锆石SHRIMP年龄为168 Ma)。前人在色洛河一带定义的色洛河岩群为一套变质火山-沉积岩系,可能是形成于晚古生代的一套地层,也可能是由不同时代的构造岩片构成的构造杂岩。

Reconsideration of the Seluohe Group in Seluohe Area, Jilin Province

The Seluohe Group is located in eastern portion of the northern margin of the North China craton,Seluohe-Huajiling area,Jilin Province,China, and has been considered to be the Meso-Neoproterozoic metamorphic strata for long time.Based on the recent filed investigation and dating,however,the original Seluohe Group is actually composed of metamorphic strata and deformed granites with different ages,geneses,tectonic styles and metamorphic grades,so this lithostratigraphpic unit is no longer valid and should be dismembered.The original Seluohe Group contains at least four parts: Late Archean metamorphic rocks(zircon SHRIMP protolith ages 2 517-2 534 Ma),Late Paleozoic metamorphosed volcanic-sedimentary strata(zircon SHRIMP 252 Ma),Permian gneissic granitic complex(zircon SHRIMP 260 Ma),and Jurassic mylonitized granites(zircon SHRIMP 168 Ma).The so-called Seluohe Group-complex defined previously in the Seluohe area is in fact a suit of low-grade metamorphosed volcanic-sedimentary sequences which were probably generated during the late Paleozoic,or a complex composed of tectonic slices with various ages.