The separation and analysis of the diastereoisomers of pristine(2,6,10,14-tetramethylpentadecane)in these highly and overly mature coal samples from the Junggar Basin were carried out by gas chromatography mass spectrometry(GC/MS),and the relativity of the pristane isomerization ratio(PIR)and the reflectances(Ro)of these coal samples were studied.The results show that the PIR keeps quite linear relation with the Ro,and the line-arity is up to 0.995 1.Furthermore,verified test with source rocks of the Sichua...