The Coupling Developments Of Microbial Genetic Structures And Metazoan Bioturbated Structures Of The Cambrian Miaoling Series In Western Henan

A large number of microbial genetic structures(microbialites)and metazoan bioturbated structures(trace fossils)developed in the Cambrian Miaoling Series in Henan.Due to frequent changes in sea level and sedimentary environments,different types of microbial genetic structures such as stromatolites,thrombolites,and oncolites and metazoan bioturbated structures such as vertical burrows Skolithos,near-horizontal burrows Planolites,or three-dimensional burrow system Thalassinoides,etc.Coupling develop or evolve each other in carbonate deposits of the Mantou,Zhangxia and Gushan Formations of Miaoling Series in study area.The purpose of this paper is to analyze the coupling relationship and control factors between the microbial genetic structures and metazoan bioturbated structures from the Cambrian Miaolingian in Henan,and to provide a basis for exploring the interaction between the Cambrian microbes,metazoa and their environments.The Mantou Formation Member 2 in Mianchi area is characterized by the alternating developments of oncoids and vertical burrows.Sea level changes and the injection of terrigenous mud have caused their alternating developments;the lower part of the Mantou Formation Member 3 in Dengfeng area is dominated by the alternating developments of stromatolites and vertical burrows.The storm events and sea level changes have led to their alternating developments.The bottom of the Zhangxia Formation in Dengfeng area consists of the alternations of thrombolites and bioturbated structures,as well as the changes from oncoids to bioturbated structures.Sea level changes,terrigenous mud injection,and sedimentary environment variations have led to their alternations.Alternating developments of stromatolites and bioturbated structures occur in the Gushan Formation of Weihui area.Sea level changes,environment variations and the injection of terrestrial mud have led to their alternations.When the hard substrate and stable hydrodynamic conditions are conducive to the formation of microbial mats or films,the microbial genetic structures would widely develop.When the soft substrate and high-energy conditions of continuous agitation are not suitable for the development of microbial mats or microbial films,metazoa began to burrow in the sediments,leaving various bioturbated structures.The coupling development of Cambrian microbial genetic structures and metazoan bioturbated structures rarely appears in the strata after the Cambrian,which reflects that the Cambrian was in a special period before the Ordovician Radiation in the biological evolution history.In the Cambrian after the Great Explosion,the radiation of biological evolution was basically at a standstill,and the diversities of body fossils and trace fossils did not increase significantly.The burrowing ability of metazoa is not strong enough to occupy all niches.Therefore,microorganisms and metazoa can thrive together in the sediments and leave corresponding biogenic structures or rock types.Sea level changes and sedimentary environment variations jointly control the coupling developments of microbial genetic structures and metazoan bioturbated structures.