湖北武当—随枣地区中—晚南华世岩石地层序列与年代学研究

Study of Lithostratigraphic Sequences and Chronology of Middle-late Nanhua in Wudang-Suizhou Area

通过对武当—随枣地区原耀岭河群地层剖面考察、验证与修测,新厘定了这一地区中—晚南华世岩石地层序列,将其自下而上划分为高庙组、木渣沟组、前院组三个岩石地层单位。并根据该地层属区域浅变质沉积—火山岩系夹冰成岩构成,而缺乏古生物定年这一特点,有针对性地进行了变质火山岩LA-ICPMS锆石U-Pb测年研究工作,获得了下伏武当群双台组变酸性火山碎屑岩年龄(746.2±11)Ma,属早南华世;高庙组、前院组火山岩年龄分别为(645.2±9.0)—(636.1±6.1)Ma,属晚南华世。首次系统建立了秦岭—大别地区(大巴山—大别山地层区)变质岩系中—晚南华世岩石地层序列及与扬子地层区相应地层的对比关系。

Based on the original Yaolinghe group stratigraphic sectioninvestigation,verification and revision in WudangSuizhou area,middle-late Nanhua lithostratigraphic sequence is divided into three formations including Gaomiao formation,Muzagou and Qianyuan formation with the new theory. According to the stratigraphic area of shallow metamorphic sedimentary rocks with ice volcano rocks,and the lack of characteristics of paleontological dating,LA-ICP-MS zircon UPb dating research work of meta-volcanic rocks,the paper obtains acidic volcano clastic rock age of Shuangtai Formation in the underlying Wudang group is（746.2 ＋ 11） Ma,belongs to Early Nanhua. Volcano rock age of Gaomiao Formation,Qianyuan formation is（645.2 ± 9.0） Ma-（636.1 ± 6.1） Ma,belongs to late Nanhua. Qinling Mountains-Dabie area in late Nanhua lithostratigraphic sequence and corresponding Yangtze stratigraphic region formation are established for the first time.