Two remarkable Permian petrified forests: correlation, comparison and significance
Published:January 01, 2006
Ronny Rössler, 2006. "Two remarkable Permian petrified forests: correlation, comparison and significance", Non-Marine Permian Biostratigraphy and Biochronology, Spencer G. Lucas, Giuseppe Cassinis, Joerg W. Schneider
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Two outstanding Permian petrified forests, those of Chemnitz, in Germany, and northern Tocantins, in Brazil, contribute to the understanding of the composition, peculiarities and dynamics of Early Permian wetland ecosystems. These assemblages represent seasonally influenced, essentially contemporaneous but quite comparable, tree-ferndominated plant communities in the Northern and Southern Hemispheres. The Chemnitz fossils are embedded in coarse-grained pyroclastics of the Zeisigwald Tuff Horizon (Leukersdorf Formation, Erzgebirge Basin), whereas those of Tocantins occur in different lithofacies of a cyclic alluvial succession (Pedra de Fogo/Motuca formations, Parnaíba Basin). The outstanding three-dimensional preservation of particularly large fossil remains, made possible by siliceous permineralization, provides the opportunity to study the gross morphology, anatomy and internal organization of plant tissues, as well as taphonomical and ecological aspects of late Palaeozoic plants in a way not allowed by other preservational states. Recent studies of newly collected material permit a re-evaluation of the popular reconstructions of Early Permian floras. Various plant-plant and plant-animal interactions add to our understanding of two diverse lowland ecosystems that, irrespective of their different palaeogeographic position and taphonomic modes, show striking similarities.
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Non-Marine Permian Biostratigraphy and Biochronology
During the Permian, the single supercontinent Pangaea stretched from pole to pole. Early Permian glacial deposits are found in southern Gondwana. Along the sutures of Pangaea, mountain ranges towered over vast tropical lowlands. Interior areas included dry deserts where dune sands accumulated. Gypsum and halite beds document the evaporation of hot, shallow seas that formed the most extensive salt deposits in the geological record. The Permian period (251 to 299 Ma) encompasses nine ages (stages) arranged into three epochs (series). Most of the Permian marine timescale has been defined by global stratotype sections and points for the stage boundaries. This volume presents new data regarding the biostratigraphy and biochronology of the non-marine Permian and provides a basis for temporally ordering Permian geological and biotic history on land, and correlating that history to events in the marine realm.