The sedimentary organic matter from a Lake Ichkeul core (far northern Tunisia): Rock-Eval and biomarker approach

The distributions of n-alkanes (C17 to C34), isoprenoid (iso) alkanes (pristane and phytane), terpanes and steranes showed that the OM is a mixture of marine algal and bacterial source and emergent and floating higher plant origin. In addition, the distributions, as well as several biomarker ratios (n-alkanes, iso-alkanes/n-alkanes), showed that the OM is a mixture of immature and mature. Significant downcore fluctuation was observed in the molecular composition. This indicates intense microbial activity below ca. 50 cm core depth under an anoxic and brackish environment.