EGU2020-11836
https://doi.org/10.5194/egusphere-egu2020-11836
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

New magnetostratigraphy from the Punta Grohmann section (Dolomites, NE Italy): an improvement of the Geomagnetic Polarity Time Scale around the Ladinian/Carnian boundary

Matteo Maron1, Giovanni Muttoni1, Marica Ghezzi1, Manuel Rigo2, and Piero Gianolla3
Matteo Maron et al.
  • 1Department of Earth Sciences "Ardito Desio", University of Milano, Milano, Italy (matteo.maron@unimi.it)
  • 2Department of Geosciences, University of Padova, Padova, Italy
  • 3Department of Physics and Earth Sciences, University of Ferrara, Ferrara, Italy

The Ladinian/Carnian boundary (LCB) is defined at Prati di Stuores (GSSP of the Carnian Stage) with the First Appearance Datum (FAD) of ammonoid Daxatina canadensis and approximated by the FAD of conodont Paragondolella polygnathiformis. The age of the Carnian is currently estimated at ca. 237 Ma using the composite magnetostratigraphy of the main late Ladinian basinal sequences from literature, calibrated with a U-Pb radiometric age of 237.77±0.14 Ma from the Rio Nigra section in Alpe di Siusi (Dolomites, NE Italy). In the attempt to improve the precision of the Geomagnetic Polarity Time Scale (GPTS) around the LCB we investigated for magnetostratigraphy the Punta Grohmann section in the Dolomites. The Punta Grohmann section is calibrated with ammonoids (the FAD of Zestoceras cf. lorigae is considered a proxy of the LCB) and is chronologically constrained by two U-Pb radiometric ages from zircons (237.58±0.04 Ma; 237.68±0.05 Ma). The magnetostratigraphy of the Punta Grohmann section has been successfully correlated to other Ladinian-Carnian magnetostratigraphic sections (Prati di Stuores, Mayerling, Rio Nigra) and compared to the most recent version of the Triassic Geomagnetic Polarity Time Scale (GPTS). The LCB at Prati di Stuores is calibrated through magnetostratigraphy with the U-Pb radiometric datings of Punta Grohmann, obtaining an age of the LCB of ca. 237.4 Ma. Therefore, the Ladinian should be ca. 4 Myr long and the Carnian ca. 10.4 Myr long.

How to cite: Maron, M., Muttoni, G., Ghezzi, M., Rigo, M., and Gianolla, P.: New magnetostratigraphy from the Punta Grohmann section (Dolomites, NE Italy): an improvement of the Geomagnetic Polarity Time Scale around the Ladinian/Carnian boundary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11836, https://doi.org/10.5194/egusphere-egu2020-11836, 2020

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