Values are calculated as such that the sample with more TOC is divided by the sample which less TOC, leading mostly to values >1. POtop, top of postsapropelic unit (core top); PObot, bottom of postsapropelic layer; OStop, top of oxidised layer (manganese marker bed); OSbot, bottom of the oxidised sapropel; VStop, top of the visible sapropel; VSbot, bottom of the visible sapropel; PRtop, top of the subsapropelic layer (presapropel); oo=infinitive due to absence of compound in the more oxidised sample; and no value due to absence of compound in both samples.