Lithology and organic geochemistry at DSDP Hole 77-535

Organic matter indigenous to those surrounding limestones was shown to be thermally immature and incapable of yielding the hydrocarbon mixture discovered.

In contrast, the oil-stained and asphaltic material appears to be a post-migration alteration product of a mature oil that has migrated from source rocks deeper in the section, or from stratigraphically equivalent but compositionally different source-facies down-dip from the drill site. Further, hydrocarbons of the altered petroleum residues were shown to be similar to Sunniland-type oils found in Lower Cretaceous rocks of South Florida.