江西菖蒲盆地中生代火山岩系划分的新认识

The New Recognition of Mesozoic Volcanic Rock Series Division in Changpu Basin Jiangxi Province

本文分析了江西寻乌菖蒲盆地中生代晚期火山岩系划分的现状及存在的问题，提出了以不整合面为界，将火山岩系划分为上、下两个不同时期的火山岩系，即下火山岩系称为余田群，上火山岩系称为版石群。依据岩性岩相特征，可进一步将余田群划分为水头迳组和菖蒲组，版石群划分为合水组和优胜组。余田群菖蒲组玄武岩全岩Ｒｂ－Ｓｒ等时线年龄为１７６Ｍａ，流纹岩全岩Ｒｂ－Ｓｒ等时线年龄为１５０Ｍａ；版石群优胜组流纹岩全岩Ｒｂ－Ｓｒ等时线年龄为１０４Ｍａ。因此，余田群的地质时代为中侏罗世—晚侏罗世早期，版石群的地质时代为早白垩世。

The paper analyses the actuality and the existing question about the division of late Mesozoic volcanic rock series in Changpu basin, Xunwu,Jiangxi. Based on the on the unconformity interface, the volcanic rock series of the basin can be divided into two different age volcanic rock series——upper and lower volcanic rock series. Lower volcanic rock series is named Yutian Group, and upper volcanic rock series is named Banshi Group. According to the characteristic of lithology and lithofacies, the Yutian group can be subdivided into Shuitoujing Formation and Changpu Formation, and Banshi Group can be subdivided into Heshuo Formation and Yousheng formation. The whole rock Rb Sr isochrone ages of the basalt and rhyolite of Changpu Formation separately are 176Ma and 150 Ma. The whole rock Rb Sr isochrone age of the rhyolite of Yousheng Formation is 104 Ma. The data of Isotopic age show that the geologic period of Yutian Group is from middle jurassic epoch to early stage of late jurassic epoch, and the geologic period of Banshi Group is early Cretaceous epoch.