Integrated stratigraphy (radiolarians, calcareous nannofossils, carbon and strontium isotopes) of the Sinemurian–Pliensbachian transition at Mt. Rettenstein, Northern Calcareous Alps, Austria

A 95 m thick succession of grey siliceous limestone and marl on Mount Rettenstein in the Northern Calcareous Alps allowed us to study well-preserved diverse radiolarian assemblages across Sinemurian–Pliensbachian boundary. The distribution 31 most characteristic species is presented. Ammonites Jamesoni Subzone, topmost subzone Zone, have been previously found upper part section. data are complemented with calcareous nannofossil biostratigraphy, carbon strontium isotope analyses bulk carbonate samples. negative stable excursion (CIE) occurs middle section correlated supraregional Sinemurian – Pliensbachian Boundary Event. Radiolarian below CIE belong Canutus rockfishensis Wrangellium thurstonense Jacus? sandspitensis zones. Katroma clara several other belonging subsequent tipperi Zone first occur at beginning CIE. occurrence Similiscutum cruciulus, which defines base NJ4 Nannofossil was recognized near top CIE, 10 above inferred stage ratio due diagenetic alteration micrite systematically shifted higher values, but clearly decreases This decrease compatible trend standard 87Sr/86Sr curve established skeletal calcite. time zones boundary Europe can be tied chemostratigraphy also calibrated chronostratigraphy. These results contribute stability Lower Jurassic will allow recognition deep-marine successions where ammonites absent.