Application of diamondoids to distinguish source rock facies

Diamondoid distributions in solvent extracts from marine siliciclastic shales, marine carbonates, and coals of a wide variety of maturities were determined by GC–MSD. For this sample set, published diamondoid maturity parameters did not change systematically throughout the oil window. It was found that several novel diamondoid ratios were indicative of source. It was possible to distinguish between terrigenous, marine carbonate and marine siliciclastic facies. The proposed dimethyl diamantane facies ratios are virtually unaffected by maturity, while the ethyl adamantane ratio appears to be affected by maturity in the late gas-window range.