Trace Fossils Of The Early Cambrian And Their Paleoecological Significances In Xuzhou-Suzhou Area

Xuzhou and Suzhou belong to the southern of North China.The early Cambrian strata in the study area are well exposed,the section is complete,and the paleontological fossils are diverse and abundant.It is one of the idealest areas for studying the early Cambrian 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.(1)During the research period of this thesis,I systematically collected and identified 23 genera of paleontological fossils in the early Cambrian,including 14 genera of remains fossils,5 genera of arthropods,3 genera of molluscs,and 2 genera of brachiopods;and according to the types and combination characteristics of the trace fossils produced in the study area,it is divided into two fossil combinations,and then the trace facies are divided,and they are classified as the Cruziana trace facies;and at the same time,it is inferred that the study area was in the low-medium-energy continental shelf environment of the coastal shallow sea in the early Cambrian,and the low-energy mud shed environment was the main one.(2)The sedimentary rocks of the early Cambrian in the study area are mainly carbonate rocks in endogenous sedimentary rocks and sandy mudstones in terrigenous clastic rocks,and the lithology is mostly a continuous gradual transition in the vertical direction.The paper also divides it into 11 different rock combinations from bottom to top according to the characteristics of strata color,lithology combination,stratigraphic structure,and fossils contained.(3)Most of the fossils in the study area belong to the type of in-situ burial.Taking this as the research object,combined with the sedimentary environment,inferred and discussed the ecological tolerance of individual organisms,the environmental tolerance of life,and the evolution of life in the area during the early Cambrian.