Discovery of an Autunian macroflora and lithostratigraphic re-investigation on the western border of the Lodeve Permian basin (Mont Senegra, Herault, France). Paleoenvironmental implications

Re-investigation of the western edge of the Lodeve basin allows reassignment of one sandstone-conglomerate formation previously identified as terminal Stephanian to Early Autunian. The existence of two unconformable (Stephanian and Autunian) megasequences, separated by a sedimentary gap, which had been rejected, is thus re-affirmed. The authors also found, less than 20 m above the basal Autunian conglomerate, a macroflora with taxa characteristic of the famous Tuilieres flora from a site, located in the eastern part of the basin near Lodeve, in the Grey Autunian group. This confirms that the new Mont Senegra fossiliferous beds belong to the Lower Autunian. Moreover, the taxonomic differences between these plants and those from the underlying coal-bearing Stephanian beds indicate an important change in the vegetation between the Stephanian and the Autunian. The first Autunian sequences were initially deposited within a distal alluvial fan environment, which developed vertically into a floodplain, within an active volcanic context. (C) 2013 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.