Fusulinids Fauna Of The Benxi And Taiyuan Formations In The Baitu Area Of Xiaoxian County In Anhui

In this thesis,the stratigraphic profile from the Late Carboniferous to the Early Permian in Baitu area,Xiaoxian County,Anhui Province,is taken as the main research object.Through field survey,specimen collection,fossil processing and identification,and comprehensive analysis of data,a systematic study of fusulinids paleontology and biological stratigraphy has been carried out.The fusulinids in the thin sections of the Benxi and Taiyuan formations were systematically described under polarized light microscopy,and 2 families,6 genera and 18 species of fusulinids were identified in the Benxi formation and 3 families,11 genera and 32 species of fusulinids were identified in the Taiyuan formation,including two new species of Schwagerina xiaoxianensis sp.nov.Zhai and Rugosofusulina xiaoxianensis sp.nov.Zhai.Based on the systematic description of the fusulinids,the thesis summarizes the nature and characteristics of the fusulinids in the Benxi and Taiyuan formations in the study area.The combined zones of fusulinids in the study area were established:Taiyuan group: Pseudoschwagerina zone;2.Occidentoschwagerina leei shanxiensis-Rugosofusulina valida combined subzone;1.Quasifusulina longissima-Pseudofusulina exgi roaffti combined subzone;Benxi group: Ozawainella vozhgalica-Profusulinella parva combined zone.The thesis compares the combination zone of fusulinids in the study area with those in other regions of China,analyzes the distribution characteristics of fusulinids in the stratigraphy from the Late Carboniferous to the Early Permian,determines the geological age of each combination zone,establishes the stratigraphic sequence of the region,and proposes to place the Carboniferous and Permian boundary in the study area at the bottom of the Pseudoschwagerina zone of fusulinids,which tends to be synchronized with the position of the boundary at home and abroad.The long-standing problem of stratigraphic age delineation and comparison in this area has been solved.Through a series of studies,a comparative table of multiple stratigraphic divisions of the Carboniferous and Permian was established to provide a more specific basis for the delineation of the boundary line.