Recognition of n-alkyl and isoprenoid algaenans in marine sediments by stable carbon isotopic analysis of pyrolysis products of kerogens

Analysis of the pyrolysis products of several marine kerogens revealed that the stable carbon isotopic composition of the n-alkanes (C10–C25) are quite similar to those of the n-alkenes. This suggests that they have a common origin such as algal biopolymers. The isoprenoid alkanes (C13–C20) also have similar isotopic compositions but can differ significantly from the values of the n-alkanes and n-alkenes. These isoprenoids could be derived from an isoprenoid algaenan similar to that biosynthesized by the freshwater algae Botryococcus braunii race L.