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The Volgian-Valanginian shallow-water deposits from the Olenek key section (Anabar-Lena region, Arctic Siberia) were studied by sedimentological, palaeontological and geochemical methods. High-resolution biostratigraphy of the studied interval is based on ammonites, foraminifera, and marine and terrestrial palynomorphs. An almost complete succession of ammonite zones provides biostratigraphic control for the upper part of the Buolkalakh Formation and the boundary between the Volgian and Boreal Berriasian stages. Foraminiferal and palynological zones have important regional implications providing well-constrained biostratigraphy of the Anabar-Lena region. Several levels important for interregional correlations are defined in the Volgian and Berriasian on the basis of taxonomic changes in microfossil assemblages as well as lowest and highest occurrences of indicative taxa. Combined sedimentological, geochemical studies and ecological analysis of microfossil associations (foraminifera, marine and terrestrial palynomoprhs) allowed the palaeoenvironmental reconstructions for the marginal area of the Anabar-Lena palaeosea and coastal land areas.Le texte complet de cet article est disponible en PDF.
Keywords : Upper Jurassic, Lower Cretaceous, Arctic Siberia, Foraminifera, Palynomorphs, Stratigraphy, Palaeoenvironments