Abstract
Organic maturity indexes, statistical thermal alteration index (stTAI) and vitrinite reflectance (Ro) were applied to geological phenomena, namely diagenesis, unconformity, faulting and contact metamorphism. As diagenesis of sedimentary rocks progresses, generally stTAI decreases but Ro increases. The effects of unconformity and faulting appear in stTAI more than in Ro. The values of Ro regularly increase with decreasing distance from the igneous dyke, but those of stTAI have no decreasing trend. It is concluded from these measurements that stTAI is more sensitive to heating time and Ro is more sensitive to heating temperature. The studies by means of these organic maturity indexes combined with inorganic mineral indexes might be able to clarify various geological phenomena.
