Pukou Fm

The base of the formation marked by calcareous breccia lies unconformably on the underlying Sinian limestone in the type section.

The top is not observed in the type area. Regionally, it is conformably overlain by the Chishan Fm.

On the Puzhen section, the formation can be taken as a representative of piedmont marginal deposition, in Huaian and down the well No.can-1 of the north Jiangsu plain, the center of the deposition can be regarded as its representative. From bottom upward, it is represented by gray sandy conglomerate interbedded with brown and dark coffee color siltstone and fine sandstone, and gypsum mudstone and mudstone interbedded with rock salt in which there are 22 pure salt beds with a total thickness of 281 m. In Fangshan of Jiangning of south Jiangsu, it is represented by purple red shale, siltstone, fine and medium-grained sandstone and variegated breccia, with a thickness of 206 m. In Dinggong of Maoshan, the lower part of the formation is built up by gray black and brown gray conglomerate and the upper part purple red siltstone and fine sandstone, with a total thickness of about 60 m. In Jinhuashan of the Mingjue township of Lishui, the formation is represented by brown red greywacke and conglomerate and quartz fine sandstone, nearly 200 m thick. Based on the borehole data, it is represented in ascending order by the purple red tuffaceous sandstone member, the purple red clayey siltstone member with stellated gypsum, the purple red silty mudstone member with thin-bedded and vein gypsum, and the interbedded brown red sandstone and mudstone, ranging from 301 to 795 m in thickness.