Probable aestivation burrows from the Eocene/Oligocene transition in south-eastern France and their palaeoenvironmental implications

摘要: Enigmatic biogenic structures are reported from the Palaeogene of south-eastern France in Castellane-Blieux area (Alpes de Haute-Provence French Department). They occur at Eocene/Oligocene transition top Marnes Bleues Formation, which corresponds to a clearly defined regressive sequence, where thick marls overlain by lacustrine limestones or sandstones. The have abundant shallow marine fauna and upper part Formation rapid non-marine deposits. studied exhibit three main morphologies: vertical shafts, furrows, tunnels. can also form dense clusters cross-cut marginal crustacean burrows such as Psilonichnus. By comparison with modern fossil examples, these trace fossils interpreted probably aestivation burrows. possible trace-makers could be lungfish (in particular for common burrows) amphibians (for furrows tunnels). occurrence different defines border basin indicates increasing droughts on coastal plain. This reflect well-known development arid conditions beginning Oligocene.