The Silurian-Devonian boundary in Baizitian, Yanbian, Sichuan and its geological implications

The Silurian strata containing abundant conodont fossils are well developed and comformable with the overlying Devonian strata in the Baizitian region, northern Yanbian, Sichuan. The Baizitian Silurian section is believed to be an idealized section and represents a new type of carbonate sediments in rift basins within the realm of the Yangtze area in China.
The authors have proposed a new classification scheme for the division and correlation of the stratigraphic systems on the basis of lithology and vertical fossil distribution in the Silurian and Lower Devonian strata in the study area. According to this scheme, the Longmaxi Formation is only referred to as the black siliceous and carbonaceous shales at the base of the Silurian strata. All the carbonate rocks above it have been redelineated and redivided into new lithostratigraphic units. The strata in this region consist, from bottom to top, of the Lower Silurian Longmaxi, Guosheng and Xiangjian Formations; Middle Silurian Lower Baizitian Formation and Middle and Upper Silurian Upper Baizitian Formation; Upper Silurian Goukou Formation; latest Silurian Yankou Formation, and Lower Devonian Rongshu and Xiaoliangzi Formations.