2 POSSIBLE PATHWAYS OF FORMATION OF PRISTANE AND PHYTANE FROM CHLOROPHYLLS ON DIAGENESIS - CARBON ISOTOPIC RESULTS FROM LABORATORY HEATING OF CHLOROPHYLL-A

Carbon isotopic ratios of C-20 and C-19 isoprenoid hydrocarbons (ISOPs ) produced on laboratory heating (250 degrees C to 350 degrees C) of c hlorophyll-a (Chl-a) were measured to understand the linkage between t he phytyl chain of Chl-a and the ISOPs found in petroleum and geologic al samples. About 1 parts per thousand difference in carbon isotopic r atio was observed between the C-20 and the C-19 ISOPs. This difference almost agrees with that observed by Trindade et al. for the ISOPs in several petroleum mixtures.