Abstract: MID/GC/MS Analysis and Geological Significance of Diamondoid Hydrocarbons in Oil and Extract of Source RockZhao Hong; Wang Zhansheng; Zhu Junzhang; Chen Qi; Wang Peirong(The Organic Geochemistry Research Center,Jianghan Petroleum Institute,Jiangling 434102,Hubei,China)Received 1994-07-20Abstract:It has been reported that low level concentration of diamondoid hydrocarbons incrude oils are detected by MID/GC/MS. In present paper the trace compounds of theadamantane series detected in the extract of marginal mature source rock (Ro 0. 48%)and not only the adamantane and diamantane but also the triamantane series detected inhigh mature crude oil are reported,and thus expanding the class and maturity period ofthe diamondoid hydrocarbons can be detected in crude oils of China. In addition, the geological significance of these compounds are approached, it has been proposed that theformation of the diamondoid hydrocarbons in crude oil and extract of source rock maynot merely be controlled by the thermodynamic action, acid catalysis, that is, effect oflithological character of source rock on its formation should not be neglected to.o. Undoubtedly,there are great significance for research about detemining the maturity of thecrude oil with diamandiod hydrocarbons.Keywords: MID/GC/MS, organic geochemistry, diamondoid.