冀北滦平张家沟大北沟组—大店子组介形类的发现及生物地层界线研究  

Discovery of ostracods in the Dabeigou and Dadianzi Formations at Zhangjiagou,Luanping County,northern Hebei Province of China and new progress in the biostratigraphic boundary study

作　　者：庞其清[1] 李佩贤[2] 田树刚[2] 柳永清[2] 

机构地区：[1]石家庄经济学院资环系,河北石家庄050031 [2]中国地质科学院地质研究所,北京100037

出　　处：《地质通报》2002年第6期329-338,共10页Geological Bulletin of China

基　　金：中国地质科学院地质调查项目"中国地层标志化石及重点层型剖面"(No:DKD2001019)资助。

摘　　要：冀北滦平张家沟大北沟组—大店子组的剖面连续、沉积序列完整、介形类化石十分丰富,可分为:Ⅰ.Luanpin-gella-Eoparacypris-Pseudoparacypridopsis,Ⅱ.Yanshanina-Cypridea-Rhinocypris和Ⅲ.Cypridea-Yanshanina-Timiriasevia3个组合带。Ⅰ组合带分布在大北沟组,显示了晚侏罗世晚期的特征,Ⅱ、Ⅲ组合带分布于大店子组,Cypridea开始大量出现,明显地具有早白垩世早期的特征,故侏罗—白垩系的界线应置于第Ⅰ组合带与第Ⅱ组合带之间,即大北沟组与大店子组之间。两组间的砾岩和砂砾岩在张家沟剖面已相变为砂泥岩互层,其间未找到生物化石的岩层厚度,由大店子东沟剖面的56m至张家沟剖面已减少至仅为9.11m,张家沟剖面优于井上—大店子东沟剖面,可作为中国北方陆相侏罗—白垩系的界线层型剖面进行深入研究。There are a successive section and a complete sedimentary sequence of the Dabeigou and Dadi-anzi Formations at Zhangjiagou,Huodoushan Village,Luanping County,Hebei Province.Abundant ostra-cod fossils were found in the sections ;they may be grouped into three assemblage zones:Ⅰ.Luanpingel-la-Eoparacypris-Pseudoparacypridopsis assemblage zone,Ⅱ.Yanshanina-Cypridea-Rhinocypris assemblage zone,andⅢ.Cypridea-Yanshanina-Timiriasevia assemblage zone.Assemblage zoneⅠ,distributed in the Dabeigou Formation,shows the late Late Jurassic features;whereas assemblage zonesⅡandⅢ,which are found in the Dadianzi Formation and in which Cypridea began to appear in large amount ,evidently show the early Early Cretaceous features.So the Jurassic-Cretaceous boundary should be placed between assem-blage zoneⅠand assemblage zoneⅡ,i.e.between the Dabeigou Formation and the Dadianzi Formation.The conglomerate and sandy conglomerate between the two formations have facially changed into alternat-ing beds of sandstone and mudstone at the Zhangjiagou section.The thickness of the strata in which no fossils have been found decreases from56m at the Dadianzi Donggou section to only9.11m at the Zhangjiagou section.Therefore the Zhangjiagou section is better than the Dadianzi Donggou section and may serve as an ideal candidate section for the non -marine Jurassic-Cretaceous boundary stratotype in northern China.

关 键 词：滦平张家沟 大北沟组 大店子组 介形类 生物地层 

分 类 号：Q915.819.6[天文地球—古生物学与地层学] P534.52[生物学—古生物学]