Abstract: Abnormal profiles of organic matter maturation in abnormally high pressure sequences,which express the retardation of maturation,are a worldwide phenomenon.The reason is that thermal evolution of source rock is restrained in abnormal pressure sequences.But normal and catalyzed profiles of vitrinite reflectance are found in abnormal pressure sequences and suppressed profiles of vitrinite reflectance are found in normal pressure sequences.This research takes the Well Niu 38 and Well Wang 35 of Dongying Depression as examples to discuss the phenomenon.Vitrinite reflectance retardation are found in Well Niu 38 and Well Wang 35.They are in similar sedimentary environment and they have similar organic matters.Well Niu 38 is in abnormally high pressure,but Well Wang 35 is in normal pressure.The content of some major and trace elements are identified from many source rock samples.These findings suggest that petroleum generation is influenced by subsurface chemical environments,and that R_o is influenced by inorganic chemical environments except abnormal pressure.Acidic environment surrounding organic matter facilitates organic matter reaction.Content of Ca and ratio of Sr/Ba correlate with vitrinite reflectance inversely.The richness of paleosalinities environment restrains organic matter reaction.

Key words: vitrinite reflectance, retardation/catalysis, trace elements, inorganic matters condition, abnormally high pressure