Petrographical and geochemical study of modern lacustrine sedimentary organic matter (Lagoa do Caçò, Maranão, Brazil): Relationship between early diagenesis, organic sedimentation and lacustrine filling

► Nature and diagenetic fate of the OM studied. ► Organic petrography and Rock-Eval parameters for origin and preservation state determined. ► Accumulation (>6 m) of OM-rich sediment in an oligotrophic lake. ► Relationship between gelification of palynological fractions and depth of lake exists.