There occur volcanic rocks in the Early permian Gufeng Formation in southern Jiangsu and Anhui and western Zhejiang in the lower Yangtze region. They are interbedded with black cherts; the beds are thin and numerous. The volcanic rocks consist of basic lavas, acid tuffs, and tuffaceous sedimentary rocks. Almost all of them have been argillized but there are still some recognizable characteristics of the textures, structures and mineral composition of volcanics. The intercalated cherts show no marked alteration though the volcanics have been argillized bed by bed. Therefore, the argillization of volcanic rocks is primary low-temperature hydrothermal alteration occurring on the sea floor. The above indicates the occurrence of submarine volcanic-hot spring activity in the region in the Gufengian stage.