Diversity and paleoenvironment of the flora from the nodules of the Montceau-Les-Mines Biota (Late Carboniferous, France)
Résumé
The flora from the Montceau-les-Mines Lagerstatte (Massif Central, France, Late Pennsylvanian) is preserved in small sideritic concretions and was studied in three locations in the (1) Saint-Louis, (2) Saint-Francois, and (3) Sainte-Helene opencast mines. Qualitative and quantitative analyses of plant diversity and floristic composition in 6812 nodules indicate substantial variations in the floral composition of these opencast mines. More than 50 taxa are recognized and belong to groups typical of the Late Pennsylvanian flora (lycopsids, sphenopsids, tree ferns, and pteridosperms). Arborescent sphenopsids and tree ferns were the major components at Saint-Louis, whereas the flora from Saint-Francois consisted mainly of pteridosperms; the one from Sainte-Helene has a more balanced composition. Taphonomic and sedimentological data show that the flora contained in the nodules was hypoautochthonous to parautochthonous. The Montceau Basin displayed a mosaic of paleoenvironments (e.g., deltaic lacustrine, paludal to fluvial) which favored colonization by plants and animals.