Abstract
Hopanoids occur in sediments as (pseudo) homologous series of saturated, unsaturated, oxygenated or aromatic compounds; S incorporation is another important pathway of hopanoids. Here it is demonstrated that natural sulphurization during early stages of thermal maturation determines the number distribution of the homohopanes, and can account for anomalies of 22S/(22S + 22R) epimer ratios for free homohopanes and homohopanoid sulphides and sulphoxides. The homohopane skeleton speciation and its relation with maturity is investigated for natural samples (oil shales, Bavaria, Germany; kerogenous marls and carbonates from the S Jura Mts, Franch; oil shale carbonate from central Jordan), and a sample artificially matured under hydrous pyrolysis. Hopanoid C number distribution and C skeleton speciation strongly depend on maturity.