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Twelve species of the conifer family Araucariaceae, including Araucaria (6 species), Agathis (3 species) and Wollemia (1 species) genera, were submitted to artificial maturation by confined pyrolysis. The aim of these experiments is to transform the biomolecules synthesized by these species into their homologous geomolecules in laboratory conditions. Determination of the diagenetic molecular signatures of Araucariaceae through experimentation on extant representatives allows us to complete our knowledge in botanical palaeochemotaxonomy. Such knowledge is relevant to palaeoenvironmental, environmental and archaeology purposes. All artificially diagenetic species of Araucariaceae are firstly characterized by a predominance of saturated tetracyclic diterpenoids including ent-beyerane, phyllocladanes and ent-kauranes. Moreover, Araucaria genus shows a high relative abundance of bicyclic sesquiterpenoids, particularly the cadalane-type compounds accompanied by those of eudesmane and bisabolane types as well as chamazulene and pentamethyl-dihydroindenes. Diterpenoids are of labdane, isopimarane and abietane types (essentially derived from abietanoic acids) as well as isohexyl alkylaromatic hydrocarbons. Compared to the tetracyclic diterpenoids, these compounds show a relatively lower abundance, reaching trace levels in the case of saturated abietanes. Distributions of sesquiterpenoids and diterpenoids of Agathis show some similarities to that of Araucaria, with the exception of one species, in which the tetracyclic compounds are absent and the abietane type (essentially derived from abietanoic acids) predominant. High similarities between the Wollemia and Araucaria genera are observed. Both are characterized by some high relative abundance of tetracyclic compounds with no predominance of other specific diterpenoids

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AbstractThe composition of the soluble organic matter of the Oxfordian–Kimmeridgian Flodigarry Shale Member (Isle of Skye, Scotland) is presented for the first time. A continuous succession of silty clays and nodular limestone beds is exposed on a rocky shore to the north of Staffin Bay. This succession is proposed as a potential stratotype of the boundary between the Oxfordian and Kimmeridgian stages. This paper points out the exceptional preservation and very low thermal degradation of the organic matter. Indeed, the molecular composition is characterized by the abundance of unsaturated biomarkers (hopenes and diasterenes) as well as undamaged bioterpenoids (ferruginol and sugiol). The abundance of long-chainn-alkanes characterized by an odd-over-even predominance reveals a dominant continental contribution. This is also attested to by the relatively high amounts of plant biomarkers (e.g. ferruginol, sugiol, cadalene and retene), which suggest a palaeovegetation largely composed of pinophytes, especially Cupressaceae, Taxodiaceae and Cheirolepidiaceae, on the nearest emerged lands. The water column of the depositional environment was oxic in its upper part and rather dysoxic in its lower part. The composition of the organic matter does not significantly change along the Flodigarry Shale Member. In other words, no evolutionary events or drastic change in palaeoenvironments can be deduced from the molecular content of these sedimentary rocks, and it does not allow us to support a precise location for the Oxfordian/Kimmeridgian boundary in the succession.

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