Taphonomy and palaeoecology of the Priabonian flora from the Alès Basin (Gard, France). Comparison with a coeval flora from the Ebro Basin (NE Spain). - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2002

Taphonomy and palaeoecology of the Priabonian flora from the Alès Basin (Gard, France). Comparison with a coeval flora from the Ebro Basin (NE Spain).

Résumé

The upper Eocene from Celas (Alès Basin, France) and Sarral (Ebro Basin, Spain) are two well-known plant localities from SW of Europe which have been studied from taxonomic and palaeoclimatic viewpoints. While the plant taphonomy and paleoecology from Sarral was studied into detail, this remained unstudied until now in Celas. Plant remains from the Alès Basin were found in three outcrops, which represent three taphofacies. 1) Saint-Hyppolite-de-Caton outcrop displays intercalations of finely-laminated grey marls and limestones corresponding to a shallow lake margin. This facies is dominated by bract-scales and well-articulated shoots of Doliostrobus sometimes forming a monospecific assemblage, pinnules of Pteris, rhizomes of Nymphaea, and helophytic plant portions. In less proportion, whole leaves of Comptonia schrankii and elongated leaves that might correspond to Salix or Myrica also occur. Taphonomic data suggest that Doliostrobus, rhizomes of Nymphaea and helophytic plant remains were supplied directly to the lake from a palustrine and marginal lacustrine belt. Beyond this belt Myrica or Salix, Pteris and Comptonia schrankii would grow forming a riparian vegetation with indirect supply to the lake. 2) The Saint-Jean-de-Ceyrargues outcrop shows sandstones with ripple marks interpreted as Gilbert-type delta mouth-bar deposits. It contains abundant leaves of Daphnogene and Laurophyllum, some of them complete while other are broken following the venation pattern, damaged palm costae, whole long leaves of “Ficus” and helophytic plant portions. The whole leaves of “Ficus”, Daphnogene and Laurophyllum are consistent with a direct supply from lake margins, while broken leaves of Daphnogene, Laurophyllum and the damaged palms is consistent with a longer fluviatile transport, suggesting that these plants grew in river banks upstream. All of them represent parts of the riparian forest. 3) Saint-Jean-de-Maruéjols-et-Avéjan outcrop shows bituminous laminated marls, which represents the deeper lake deposits. This facies is composed of disarticulated Doliostrobus shoots and isolated bract-scales of this plant and rhizomes of Nymphaea. The significant fragmentation of the Doliostrobus plant remains and the only occurrence of the rhizomes of Nymphaea indicates long transport and degradation before burial. In comparison with the coeval Sarral plant locality (NE Spain), the palustrine belt is less developed and was only composed of helophytic plants. The riparian vegetation in both localities is formed by laurels and helophytic plants. In Sarral it was associated with Salicaceae, Myrica arenesi, Comptonia schrankii while in Celas they were associated with “Ficus”. The factors that drew these differences may be related to the particular environmental or climatic conditions of each basin. Acknowledgement This study is a contribution to the project IBERINSULA (PID 2020 113912 GB 100) funded by MCIN/AEI/ 10.13039 501100011033 and the European Regional Development Fund (ERDF). This study has also benefitted from the post-doctoral fellowship Margarita Salas funded by the Spanish Ministry of Universities.
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hal-03716124 , version 1 (07-07-2022)

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  • HAL Id : hal-03716124 , version 1

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Aixa Tosal, Mélanie Tanrattana, Anais A Boura, Carles Martín-Closas, Dario De Franceschi, et al.. Taphonomy and palaeoecology of the Priabonian flora from the Alès Basin (Gard, France). Comparison with a coeval flora from the Ebro Basin (NE Spain).. 9th International Conference on Taphonomy and Fossilisation, Jun 2002, Madrid, Spain. ⟨hal-03716124⟩
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