Middle and Upper Permian Sedimentary Microfacies in the Tieqiao Section in Laibin, Guangxi, China

Key words: 
• sedimentary microfacies

Abstract: Based on the sedimentary microfacies study, four sedimentary facies and ten microfacies were identified in the MiddlePermian Maokou Formation and UpperPermian Wujiaping Formation at the Tieqiao section, Laibin, Guangxi. The four sedimentary facies are: basin, including microfacies 1a (bedded chert) and 1b (bedded chert with lensoid limestone); lower slope, including microfacies 2a (bedded chert with limestone intercalation), 2b (limestone intercalated with bedded chert), and 2c (limestone turbidite); upper slope, including microfacies 3a (limestone intercalated by bedded chert), 3b (limestone intercalated by lensoid or nodular chert), 3c (thicklayered limestone) and 3d (limestone of gravityflows); and platform margin, including microfacies 4 (calcareous spongereef limestone). Both Maokou Foramtion and Wujiaping Formation represent a shallowingupward sedimentary cycle, however, they are different in cycle evolution. The Maokou Formation is characterized by evolution from basin to slope, with turbidite and debris flow, while the Wujiaping Formation by evolution from basin to platform, with frequent microfacies alternation. Sea level changes recorded by microfacies alternation are characterized by continuous falling in the Moukou period, but rapid rising, followed by gradual falling then rising in the Wujiaping period. 