δ13C and δ18O values of Triassic brachiopods and carbonate rocks as proxies for coeval seawater and palaeotemperature

The δ18O values from well-preserved brachiopods from the Tethyan realm range from − 3.9 to − 0.6‰ V-PDB. These values require open marine Triassic seawater δ18O values close to 0‰ V-SMOW for the calculated temperatures to be within the range of tolerance of the coexisting reef-building corals. A 2‰ δ18O increase within the uppermost Cordevolian and early Julian suggests either a distinct temperature decline in the Southern Alps during that time interval, an increase in seawater salinity, or their combination. Oxygen isotope values for the Muschelkalk brachiopods range between − 6.2 and − 2.0‰ and likely reflect a strong influx of meteoric waters into the Germanic Basin that shifted the oxygen isotopes to more negative values.