The discovery of the Palaeogene strata and their fossil assemblages in the Lushan Formation, Lianhe region, Hongya, Sichuan

The Palaeogene strata have been distinguished in the previously defined Cretaceous Guankou Formation strata in the Lianhe syncline in Hongya, Sichuan. The spatial distribution, lithologic associations and sedimentary environments are discussed on the basis of measured stratigraphic sections in this study and the previous data. The fossil assemblages include one ostracod assemblage zone Pinnocypris-Limnocythere-Ilyocypris and two charophyte assemblage zones Gyrogona qianjiangic-Obtusochara jianglingensi and Maedlerisphaera chinensis-Obtasochara brevicylindrica. It can be deduced from the fossil assemblages cited above that the geological ages of the Lushan Formation may be traced back to the late Eocene to the middle Oligocene.