Facies and Sequence Stratigraphy of the Global Stratotype Sections for the Boundary between the Guadalupian and Lopingian

Key words: 
• the global stratotype section /
• Penglaitan /
• Tieqiao /
• facies /
• sequences stratigraphy

Abstract: Two sections, at Penglaitan and Tieqiao, where the global stratotype sections for the boundary between the Guadalupian and Lopingian are located in the Laibin area of Guangxi province, respectively, are extensively eposed along the two banks of the Hongshui River and are chosen for analyses of facies and sequence stratigraphy. At the two sections, fourteen facies are recognized in the Maokou (Guadalupian) and Heshan (Lopingian) Formations, and these facies are further grouped into four main facies associations , which are basin, lower slope, upper slope and platform margin. Based on these facies, their vertical stacking patterns and the lateral distribution of facies associations, six transgressive-regressive (TR) sequences, TR1 to TR6, are identified and well correlated by detailed conodont zones. They are the TR1 ( J. nankingensis zone), TR2 ( J. aserrata to J. shannoni zone), TR3 ( J. shannoni zone to early  C. p. postbitteri zone), TR4 ( C. p. postbitteri zone to early  C. transcaucasia zone), TR5 (C. transcaucasia zone to C. orientalis zone) and TR6 (C. orientalis zone to C. inflecta zone).
  Based on the transgressive-regressive sequences of the two sections, (high-resolution) sequence-based lithofacies and paleogeographic evolution in the study area were carried on, which provides important implications for the relationship among some events during this time, such as the global regression, the Emeishan volcanism and the end-Guadalupian mass extinction.