Multiple Stratigraphic Division And Paleoecology Of Cambrian Second Epoch In Xuzhou-Suzhou Area

The area of Xuzhou and Suzhou belongs to the southern of North China.The strata are well exposed,with rich fossils.It is an ideal area for studying on the strata and the fossils in North China.This article takes the Dabeiwang section in Xuzhou,the Caocun section in Suzhou,and the Jiagou section in Suzhou as the main research objects.Through measured sections,specimen collection,fossil processing and identification,data collation,and comprehensive analysis,the following results are obtained.According to the characteristics of the lithology,the study of rock strata was carried out.After the revision of the lithostratigraphic unit name and the redefinition of the lithostratigraphic boundary,the early Cambrian strata in the area were divided into the Zhushadong Formation and the Mantou Formation.25 species of 16 genera,including 2 new species,were collected and identified,belonging to the Arthropoda,Molluscs,Brachiopods,Algae and Trace fossils.Based on this,the Cambrian Second Series are divided into four fossil zones,from the bottom up: Redlichia chinensis extension zone,Redlichia nobilis extension zone,Qiaotouaspis extension zone,and Yaojiayuella extension zone.Compared with the stratotype section of the Wuliuan of the Miaolingian,the top boundary of the Cambrian Second Series can be roughly placed in the lower part of the third member of the Mantou Formation.Equivalent to the lower part of the Yaojiayuella zone,and higher than the bottom boundary of the “Maozhuang Stage”.The fossils produced are divided into two types,the characteristics of the off-site burial and in-situ burial are discussed.Based on the fossils buried in situ,the individual ecology and environmental tolerance of the early Cambrian organisms in the study area were discussed in combination with the sedimentary environment.