Geological statistical methods are used to analyze the changing regularities of the chemical components of the sediments from the studied section, to investigate the relationships among the elements, and finally to reveal the factors affecting the sediments and their chemical components, as well as the palaeoenvironmental evolution of the strata. According to the Rtype and Qtype factor analyses, the sediments and their chemical components of the section are mainly affected by terrigenous materials. The volcanic material is the second most important influencing factor, while diagenesis and biogenic materials only play a limited role. The palaeoenvironmental evolution was a mixture of the above four types of sediments with different origins, and during the depositional process, volcanic eruption happened at least seven times. These volcanic events and volcanic materials might seriously affect the living environment of marine reptiles and other animals, and thus, they may be one of the most important causes which led to their massive deaths during this period.