Late Carboniferous to Late Permian carbon isotope stratigraphy: A new record from post-Variscan carbonates from the Southern Alps (Austria and Italy)

•A carbon isotope record for the Late Paleozoic of the Southern Alps is presented.•Eustatic sea-level fluctuations/subaerial exposure results in diagenetic alteration.•Negative carbon isotope excursions seen as consequence of diagenetic resetting•An overall negative trend in δ13C during the Permian is not confirmed.

An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertaken in order to better constrain δ13C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ13Ccarb and 396 δ13Corg analyses. The carbon isotope record of diagenetically unaltered samples from the Carnic Alps (Austria) and Karavanke Mountains (Slovenia) shows generally high δ13C values, but Late Carboniferous and Early Permian successions are affected by a diagenetic alteration as consequence of glacio-eustatic sea level changes. Negative δ13C excursions are related to low-stand deposits and caused by diagenetic processes during subaerial exposure. The comparison with δ13C records from other parts of the world demonstrate that δ13C values are high in most unaltered samples, an overall negative trend during the Permian, as recently published, is not obvious and negative excursions related to changes in the carbon isotope composition of the global oceanic carbon pool cannot be confirmed, except for the Permian–Triassic boundary interval.