Foraminiferal Biostratigraphy Of Permian In Beiya,Guangxi

Geological survey in Yizhou area, Guangxi work began in 1920 s,a great deal of geological data and survey achievements has been obtained.The determination of the formation age is the basis to further carry in the geological survey. Located in Yizhou, Guangxi Province, the study area structurely lies in the conjunctive region between the southeast passive margin basin of the Upper-Yangtze Block and the Xiang(Hunan)-Gui(Guangxi) passive continental margin basin. A set of Palaeozoic continuous sedimentary sequences yielding abundant microfossils such as foraminifera and conodont, are exposed in the study area, which provides a good basis for the establishment of biostratigraphic sequence and the age determination of the strata.Based on the features of foraminifera assemblage from Beiya, Guangxi, this thesis tries to establishes foraminiferal biostratigraphic sequence, and then determines the time of each lithostratigraphic unit(Qixia, Maokou, and Heshan formations) of Permian of the study area, which can to provide basis biostratigraphic information for the geological survey in Guangxi.Based on the detailed study on the foraminiferal assemblages from the Beiya, 66 species of 39 genera are identified in this thesis which can be devided into three foraminiferal zones: Misellina claudiae Zone, Pseudovidalina delicata- Langella lepida Zone, Neoschwagerina Zone.The feature of the foraminiferal assemblages from Beiy suggests that the age of the upper Maping Formation and the lower Qixia Formation should be Early Qixia Stage of Early Permian, the age of the upper Qixia Formation and the lower Maokou be the Middle Qixia stage of Middle-Late Permian, and the age of the upper Maokou be the Early Maokou Stage of Middle Permian.