Milankovitch-scale palaeoclimate changes in pale-dark bedding rhythms from the Early Cretaceous (Hauterivian and Barremian) of eastern England and northern Germany

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: Mutterlose, Jörg, Ruffell, Alastair
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1999
• Subjects: Arctic
• Online Access: https://pure.qub.ac.uk/en/publications/3ff8e2d5-94a0-4b87-a267-f123383ac206; https://doi.org/10.1016/S0031-0182(99)00107-8

Early Cretaceous (Valanginian–Albian) successions in northwestern Europe occupy an ideal palaeoceanographic location in which to study the interplay between the Arctic–Boreal and Tethyan seaways or realms. Marine Early Cretaceous sediments of the North Sea borderlands (north Germany, eastern England) are dominated by fine-grained siliciclastic deposition with carbonates. Occasionally this succession is characterised by visually striking bedding rhythms, comprising calcareous and less calcareous clays or pale–dark alternations on a scale of 0.5–1 m. Such rhythmic sedimentation becomes most dominant in the early to late Hauterivian, parts of the early Barremian and in the Aptian. This study concentrates on late Hauterivian sections in England and Germany, which have remained relatively unaffected by deep burial, tectonism or diagenesis. Changes in geochemistry are related to floral and faunal alternations and thus directly to palaeoenvironment. The wide range of palaeontological and geochemical analyses show conclusively how bedding rhythms, developed in the Milankovitch band, are the result of palaeoclimate change. Pale layers were `Tethyan influenced' in their microflora and fauna, indicating warm surface waters that were poor in nutrients and developed during warm, seasonally arid hinterland climates. Dark layers were `Boreal influenced', displaying features consistent with cooler waters, rich in nutrients. Such dark layers reflect cooler, more humid hinterland conditions. The coincidence of Tethyan taxa with bundles of pale layers displaying high gamma-ray emission and elevated radioactive element contents suggests transgressive or condensed beds. The bundling of pale–dark rhythms coincides with the long-term Milankovitch eccentricity cycle. This paper documents direct links between the reaction of hinterland weathering, marine floras and floras to Milankovitch-scale changes in bed lithology and thickness.