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Chronostratigraphy of Euramerican continental Late Pennsylvanian and Permian deposits – state of the art.

The super-continent Pangea was characterised by strong continentality because of climatic change from an icehouse earth during late Pennsylvanian and early Permian via an increasingly warm earth during middle–late Permian into the early Triassic super-hot house. Consequently, marine incursions, caused by the glacial cycles (cyclothems), decreased during the early Permian. Because of increasingly absent marine deposits in the Permian, the correlation of the continental deposits with marine zone-fossils (ammonoids, conodonts, fusulinids) becomes complicated. Very helpful for the correlation would be radioisotopic ages from intercalated volcanites. Unfortunately, during late early Permian, volcanism decreased in the continental Euramerica. In the middle and late Permian, no radioisotopic ages exist so far for Euramerica. Newest Late Pennsylvanian and earliest Permian radioisotopic ages based on the U-Pb CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionisation mass spectrometry) method fit well with continental and marine biostratigraphic correlations. However, some new high-precision U-Pb CA-ID-TIMS ages, especially from the Thuringian Forest Basin, conflict with the biostratigraphy and other radioisotopic ages in European basins. They are even in contrast to the climate-stratigraphy in Euramerica, particularly to the outspread of wet and, later, dry reds beds, which, of course, only provide rough interregional time markers. The question arises, what do these highly precise radioisotopic ages tell us? Are they really the decisive eruption ages or do they represent (far) older crystallisation processes in the magma chamber? In any case, we should only trust ages (and even biostratigraphic data) that are supported by cross-correlations with data from different independent stratigraphic methods.

Details

Author
Joerg W. Schneider1, Spencer G. Lucas2, Ronny Rößler3, Sebastian Voigt4, Ralf Werneburg5, Frank Scholz5, Abouchouaib Belahmira6, Hafid Saber6, Steffen Trümper7, Frank Loecse3, Stanislav Opluštil8, Alexander Repstock9, Evelyn Kustatscher10, Ulf Linnemann11
Institutionen
1Technical University Bergakademie Freiberg, Germany; 2New Mexico Museum of Natural History and Science, USA; 3Museum für Naturkunde Chemnitz, Germany; 4Urweltmuseum GEOSKOP, Burg Lichtenberg, Germany; 5NaturHistorisches Museum Schloss Bertholdsburg, Germany; 6Chouaïb Doukkali University, Morocco; 7University of Münster, Germany; 8Charles University in Prague, Czech Republic; 9Department for Geology (Geological Survey), Saxony, Germany; 10Museum of Nature South Tyrol, Bolzano, Italy; 11Senckenberg Naturhistorische Sammlungen Dresden, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/5v22-3981