民和盆地侏罗系生物地层

The Jurassic Biostratigraphy of Minhe Basin

民和盆地侏罗系所产生物化石可划分为4个生物化石组合，2个亚组合。它们分别分布于下侏罗统大西沟组、中侏罗统窑街组、上侏罗统上部享堂组和大通河组下部。2个亚组分布于中侏罗统窑街组一段和窑街组二段。据上述古生物化石的4个分布组合，划分侏罗系下界位于大西沟组与元古界灰绿色千枚岩或白云岩化大理岩之间；下、中侏罗统的界线在大西沟组与窑街组之间；中、上侏罗统的界线在窑街组与享堂组之间；侏罗系上界暂定在大通河组下部与中部之间。

The Jurassic system biotic fossils in Minhe Basin Can be divided into four biocoenosises, twosubbiocoenosises. The four biocoenosises distribute in the Early Jurassic Daxigou Formation, Middle JurassicYiaoie Formation, early Late Jurassic Xiangtang Formation and Late late Jurassic the lower part of DatongheFormation respectively. The swb-biocoenosises distrihute in early middle Jurass the First Member and late Middle Jurassic the second Member of Yiaojie Formation respectively. Based on he biotic fossils dstribution, the bottom boundary of Jurassic is delimitated between Daxigon Formation formations and proterozoic greyish-greenphyllite or dolomized marble; The boundary of Late Middle Jurassic is done between Daxigou Formation andYaojie Formation;The boundary of Middle Early Jurassic done between Yaojie Formation and Xiangtang Formation;The top boundary of Jurassic is delimitated between the lower and middle part of Datonghe Formation.