Abstract: Clay minerals are important components of argillaceous sedimentary rocks. During the middle and late stages of diagenesis, a
variety of minerals such as smectite, illite, kaolinite, and berthierine are prone to being converted to chlorite due to the combination of
temperature, pressure, cation, water/rock ratio and other factors, resulting in increased chlorite content. However, because the
chloritization conditions and reaction mechanisms of each mineral are different, chemical composition and configuration of chlorite vary
greatly. Therefore, we can use XRD, EMPA and HRTEM to identify different types of chlorite, and further to distinguish different
conversion sequences and analyze their conversion mechanisms. Recognizing the multiple conversion sequences of chloritization can
help study the influence of conversion sequence on the chemical composition of chlorite and further improve the application of chlorite
geothermometer. In addition, in some of the conversion sequences, the chloritization process consumes water and releases hydrogen,
while others consume hydrogen. And hydrocarbon generation is a process of deoxidation and hydrogenation. Therefore, the identification
of different conversion sequences can provide a basis for the study of the influence of mineral evolution on the hydrocarbon generation.

Key words: chloritization, chloritization sequences, chloritization mechanism, chlorite geothermometer, hydrocarbon generation