浙江省中生代晚期地层多重划分对比新认识

NEW IDEAS ABOUT THE STRATIGRAPHIC DIVISION OF THE LATE MESOZOIC IN ZHEJIANG

将浙江省中生代晚期地层自下而上划分为３个岩系：（１）下部岩系为建德群和磨石山群，主体时代为晚侏罗世，顶部祝村组和横山组跨入早白垩世；底部以兰江运动形成的不整合面与下伏中侏罗统渔山尖组和毛弄组分开，其底界年龄为１５０～１５５Ｍａ。（２）中部岩系是永康群，成岩时代为早白垩世，以闽浙运动的区域不整合与下伏地层接触，其底界年龄为１２０～１２５Ｍａ。（３）上部岩系由衢江群和天台群构成，成岩时代以晚白垩世为主，底部中戴组和塘上组属于早白垩世沉积，以丽水运动形成的区域不整合面为底界，时代为１０５～１１０Ｍａ。

On the basis of recent field geological surveys and laboratory data, the Late Mesozoic strata in Zhejiang are divided in ascending order according to the regions and ages into three rock series. (1) The lower series is composed of the Jiande and Moshishan Groups. Its rock-forming age is mainly Late Jurassic. Its bottom overlies the Middle Jurassic strata with unconformity formed by the Lanjiang movement, with a lower boundary age of 150—155 Ma. (2) The middle series is marked by the Yongkang Group, whose rock-forming age is middle Early Cretaceous. The bottom lies on the underlying strata with unconformity formed by the Fujian—Zhejiang movement, with a lower boundary age of 120—125 Ma. (3) The upper series consists of the Qujiang and Tiantai Groups and is late Early Cretaceous to Late Cretaceous in age. Its bottom rests on the underlying strata with unconformity formed by the Lijiang movement, with a lower boundary age of 105—110 Ma. In addition, this paper makes a detailed analysis and study on the sequences of various groups and formations and lithological changes, characteristics of three biotas (Jiande, Yongkang and Qujiang) and correct use of available isotopic data and fully presents the latest achievements in the revision of the stratigraphic classification in Zhejiang province.