We analyzed 180 samples of Pleistocene to Tithonian sediments, using the pyrolysis technique. The results show a preponderance of detrital continental organic matter. Most samples contain altered organic matter and are in an immature stage of evolution. A detailed examination of the pyrolysis and depth data shows a correlation between lithology and depositional environment.

Petrographic observations confirm the continental origin of the organic matter and the presence of reworked, altered organic material in the sediments from DSDP Sites 370 and 416. The reflectance of the primary vitrinite-huminite population establishes that these samples are in the mature stage of evolution. The very low organic-carbon content of these samples makes ESR interpretation particularly difficult.