Pleistocene lignite seams outcrop in the Bilene area constitute a lagoon deposit associated with a system of coastal lakes with large movable dunes. The organic and inorganic geochemical study of five samples of these lignites is herein presented. The organic geochemistry data indicates that these lignites have high ash yield, being therefore considered as carbonaceous rocks. The volatile matter, C, H, N and O contents are considered within the expected for lignites. The total sulfur (St) content is low. The atomic ratios H/C and O/C confirm the rank of these lignites. The major element contents corroborate the mineralogical composition identified in one of the studied samples. CaO and St are associated with organic matter, with Ca occurring as humates. Most trace elements show intermediate affinity. Zr and Hf are slightly to significant enriched and are associated with zircon. In these samples the As exhibits organic affinity. Rb displays inorganic affinity, occurring in silicates.

Este trabalho foi financiado por fundos nacionais através da FCT – Fundação para a Ciência e a Tecnologia, I.P., no âmbito do projecto Refª UIDB/04683/2020 e pelo Projecto PaleoMoz (financiado pelo Museu Nacional de Geologia, Programa Aga-Khan/FCT e National Geographic Society Standard Grant CP-109R-17).