An integrated multi-proxy study of cyclic pelagic deposits from the north-western Tethys: The Campanian of the Postalm section (Gosau Group, Austria)

Abstract

The Upper Cretaceous Postalm section in the Northern Calcareous Alps (Austria) exposes pelagic depositsof the northwestern Tethys whose cyclostratigraphy and palaeoenvironments were examined in thisstudy.The section displays rhythmic deposits of Santonian to late Campanian age (Gosau Group). The San-tonian/Campanian transition is characterised by condensed greyish carbonates, while the younger de-posits are composed of reddish foraminiferal packstones displaying distinct limestone-marl alternations.A biostratigraphic framework based on planktonic foraminifera and calcareous nannofossils is supportedby carbon and strontium isotope stratigraphy as well as magnetostratigraphy. The carbon isotope dataallow to correlate the Postalm section to other Tethyan reference sites and to identifyd13C events, such asthe Late Campanian Event. Spectral analyses of three independently assessed proxies (d13C, Fe contentand the thickness of limestone/marl couplets) in the upper, continuously exposed section part identified17 to 18 405 ka cycles spanning the mid to upper Campanian (Contusotruncana plummeraetoGansserinagansseriZones or CC21/UC15c to CC23a/UC16 nannofossil zones).