Ichnofossil Zoophycos And Ichnofabric Of The Lower Permian Taiyuan Formation In The Southwest Of North China

On basis of the detail observation and description of the Lower Permian TaiyuanFormation exposed in Jiaozuo and Yuzhou areas of Henan province and Lingchuan areaof Shanxi province located in the southwest of north China basin, this project mainlydeals with the composition of ichnofossil, morphologic feature and behaviour ofZoophycos, ichnofabric types, microfacies of carbonate rocks as well as carbonatemicroform types and their environment evolutional characteristics, five aspects ofresults are chiefly obtained as follows:(1) Based on the fossil composition andlithologic character of limestones of the Taiyuan Formation in study area,15kinds ofmicrofacies of carbonate rocks were divided and their composition were discussed;(2)13ichnogenus and18ichnospecies were recognized and described according toichnotaxonomy regulation, meanwhile, from observations of the morphology ofZoophycos spreiten in approximately vertical sections, at least three kinds of spreitelaminae are distinguished, including ligular, crescentic and rectangular forms, and4kinds of make-trace behaviours formed a spreiten lamina were suggested;(3)5types ofichnofabrics in the carbonate rocks of the Taiyuan Formation were recognized,including TypeA-Gordia—Planolitesichnofabric,TypeB-Rhizocorallium–Thalassinoidesichnofabric, Type C-Zoophycos–Taenidium ichnofabric, Type D-Zoophycos–Speckleburrow (intensively bioturbation) ichnofabric and Type E-Chondrites–Nereitesichnofabric, in which Type C was further subdivided into Type C-1, Type C-2and TypeC-3based on their occurrence feature, and designed a sedimentary environment model ofichnofabrics in the Taiyuan Formation;(4) On basis of the fine observation ofmicroscopic, ultramicroscopic composition and carbonate microform constituents in thered, black, grey and off-white burrow filling of Zoophycos ichnofossils and the analysisof morphologic characteristics containing constituents and main elements in the fillingof Zoophycos burrow in this formation,6kinds of carbonate microform types （singlemineral and aggregates） related to microbe as Spheroid-like, rhabditiform, net-like,areatus，vase-like and harns-like globe were recognized;(5) From aforesaid research,vertical evolutional characteristics of ichnofossils, ichnofabrics and microfacies types ofcarbonate rocks in the Lower Permian Taiyuan Formation of this study area were summarized and the chart of synthetical evolution was also draw out.