广西来宾铁桥剖面中上二叠统沉积微相

对广西来宾铁桥剖面中二叠统茅口组和上二叠统吴家坪组进行了详细的沉积相研究，共识别出4个沉积相和10个微相，分别为:盆地相（含层状硅质岩微相、含透镜状灰岩的层状硅质岩微相）、下斜坡相（含与灰岩互层的层状硅质岩微相、夹层状硅质岩的灰岩微相、浊流沉积的灰岩微相）、上斜坡相（含夹硅质条带或薄层的灰岩微相、夹硅质团块或条带灰岩微相、灰岩微相、碎屑流等重力流沉积的灰岩微相）和台地边缘相（钙质海绵礁灰岩微相）。野外观测表明，茅口组和吴家坪组各为一个向上变浅的沉积旋回，但两个旋回的演化具有明显的差异，茅口组整体上是由盆地相向斜坡相演化的过程，以发育浊流、碎屑流等重力流沉积为特征，而吴家坪组是由盆地相到斜坡相至台地边缘相，再到斜坡相的演化过程，沉积微相变化频繁。该剖面的沉积微相交替记录了海平面变化过程，表现为茅口期持续下降，吴家坪早期快速上升，中期逐步下降，晚期又升高的特征。

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

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. 