Unprecedented occurrence of novel C26–C28 21-norcholestanes and related triaromatic series in evaporitic lacustrine sediments

A novel series of C26–C28 21-norcholestanes and their triaromatic analogs have been tentatively identified as major components in Eogene evaporitic sediments in Jinxian Sag of the Bohai Bay basin, northern China. These compounds may be viewed as representatives of a new class of molecules whose biological or diagenetic origin remains to be determined. Their unprecedented high abundance in the evaporitic lacustrine sediments, and related oils, show important source and/or depositional environment controls in addition to thermal maturity.