New magnetobiostratigraphic results from the Ladinian of the Dolomites and implications for the Triassic geomagnetic polarity timescale

We investigated for magnetostratigraphy the Rio Nigra and Rio Frommer stratigraphic sections from Alpe di Siusi/Seiser Alm (Dolomites, northern Italy) in order to improve the calibration of the Triassic time scale. Both sections are characterized by ammonoid and conodont associations typical of Longobardian (late Ladinian, Middle Triassic) age. Moreover, the Rio Nigra section is constrained by a U-Pb zircon date of 237.77 ± 0.05 Ma. Building on the recently verified Newark-Hartford astrochronological polarity timescale for the Late Carnian-Rhaetian (plus the Hettangian) and through magnetostratigraphic correlations of an updated inventory of Tethyan marine stratigraphic sections from the literature, some of which are provided with U-Pb zircon age constraints, we propose a revised Geomagnetic Polarity Time Scale for the entire Triassic.