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Article Dans Une Revue Facies Année : 2012

Middle Lutetian climate in the Paris Basin: Implications for a marine hotspot of paleobiodiversity

Résumé

The present study reports the evolution of environmental conditions and seawater temperatures during the establishment of a marine hotspot of paleobiodiversity that took place in the Paris Basin during the Lutetian. The stable isotope compositions (δ 18O and δ 13C) of three species of molluscs (two bivalves: Cubitostrea plicata and Venericardia imbricata, and one gastropod: Sigmesalia multisulcata) collected along the reference section of Grignon (Falunière) are used for paleoenvironmental and paleoclimatic reconstructions. Additional high-resolution analyses on one specimen of Haustator imbricatarius allow the documentation of seasonal changes for temperature. The high-resolution profiles of the δ 18O signatures of S. multisulcata reveal that these gastropods mineralized their shell during the warm months of the year, as did V. imbricata, which probably had a short life span (less than 1 year). These two species thus only yield temperatures for the summer period, from 22 to 30 °C. The δ 18O of C. plicata shells indicate mean annual sea surface temperatures ranging between 15 and 23 °C during the Middle Lutetian, with minimal temperatures probably reflecting greater depth at the base of the section. The seasonal contrasts reconstructed in the upper part of the section, from the large gastropod H. imbricatarius, ranged between 18 and 30 °C. Comparison of the isotopic values of the species indicates that the δ 13C of the three taxa seems to be mostly influenced by ecological features, leading to differences between endobenthic (V. imbricata) and epibenthic species (C. plicata); or the food habits. The paleoclimatic reconstructions show that the Lutetian climate was relatively stable in the Paris Basin with long-term cooling of the mean annual sea-surface temperatures. Nevertheless, this study shows that despite a context of colder conditions compared to the Early Eocene, the climate provided a favorable context for the increase of marine biodiversity in the Paris Basin during the Middle Lutetian. © 2012 Springer-Verlag.

Dates et versions

hal-00909770 , version 1 (26-11-2013)

Identifiants

Citer

Damien Huyghe, D. Merle, F. Lartaud, E. Cheype, Laurent Emmanuel. Middle Lutetian climate in the Paris Basin: Implications for a marine hotspot of paleobiodiversity. Facies, 2012, 58 (4), pp.587-604. ⟨10.1007/s10347-012-0307-3⟩. ⟨hal-00909770⟩
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