Late Carboniferous to Late Permian carbon isotope stratigraphy: A new record from post-Variscan carbonates from the Southern Alps (Austria and Italy) Werner Buggisch a , Karl Krainer b , Maria Schaffhauser b , Michael Joachimski a, ⁎, Christoph Korte c a GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Schlossgarten 5, D-91054 Erlangen, Germany b Institut of Geology and Paleontology, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria c Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark abstract article info Article history: Received 16 November 2014 Received in revised form 1 May 2015 Accepted 19 May 2015 Available online 27 May 2015 Keywords: Carboniferous Permian Carbon isotopes Diagenesis An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertak- en in order to better constrain δ 13 C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ 13 C carb and 396 δ 13 C org analyses. The carbon isotope record of dia- genetically unaltered samples from the Carnic Alps (Austria) and Karavanke Mountains (Slovenia) shows gener- ally high δ 13 C values, but Late Carboniferous and Early Permian successions are affected by a diagenetic alteration as consequence of glacio-eustatic sea level changes. Negative δ 13 C excursions are related to low-stand deposits and caused by diagenetic processes during subaerial exposure. The comparison with δ 13 C records from other parts of the world demonstrate that δ 13 C 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 car- bon isotope composition of the global oceanic carbon pool cannot be confirmed, except for the Permian–Triassic boundary interval. © 2015 Elsevier B.V. All rights reserved. 1. Introduction The carbon isotope composition of seawater has considerably fluctu- ated during Late Palaeozoic times. The variations in δ 13 C are generally ascribed to changes in the deposition and erosion of carbonates as well as organic matter but may be influenced by methane release or overturning of anoxic bottom waters (Korte et al., 2004). In addition, upwelling of isotopically light intermediate to deep waters or enhanced continental runoff may influence the carbon isotope signature especial- ly of shelfal waters (Patterson and Walter, 1994a,b; Holmden et al., 1998; Immenhauser et al., 2002; Saltzman and Thomas, 2012). Changes in δ 13 C of seawater dissolved inorganic carbon (DIC) have successfully been reconstructed by analyzing whole rock carbonates which may preserve their original δ 13 C signals. In contrast, the oxygen isotope ratios of whole rock carbonates are generally altered during dia- genetic stabilization (e.g.,Weissert et al., 2008). In order to reconstruct changes in the carbon isotope composition of Late Palaeozoic seawater, continuous successions of unaltered carbonate rocks are required. How- ever, the waning and waxing of continental ice sheets during the Late Palaeozoic Ice Age (LPIA) and thus subaerial exposure of shelfal areas as well as the Variscan Orogeny hampered the development in the con- tinuous carbonate successions in many areas at that time. Vast Late Carboniferous to Early Permian epicontinental carbonate platforms are known from the US Midcontinent and the Moscow basin where sedimentary successions are characterized by stacked glacio-eustatic sedimentary cyclothems deposited in subtidal to supratidal environments (Heckel, 1996; Isbell et al., 2003; Joachimski et al., 2006; Fielding et al., 2008; Rygel et al., 2008). However, the δ 13 C values of the carbonates were altered during lowstand periods through early diagenetic imprint of 12 C enriched meteoric waters (Elrick and Scott, 2010; Buggisch et al., 2011). In order to overcome the problem of shallow water diagenesis, deep-water limestones (slope or basin) or limestones deposited in fast subsiding tectonic active areas are of first interest. In Europe, Late Carboniferous compression and subse- quent extension as consequence of the Variscan Orogeny created such sediment basins that are required for a promising carbon isotope stra- tigraphy, although increased siliciclastic inputs from the ascending mountain chains suppressed persisting carbonate sedimentation. Therefore no continuous limestone successions were developed in these areas and the knowledge of the Late Palaeozoic carbon isotope re- cord is rather patchy. The focus of this study is to present a δ 13 C record based on the anal- ysis of whole rock carbonates from fast subsiding basins in the Southern Alps. After evaluating the preservation state of the samples in terms of diagenetic alteration, a carbon isotope record of the Late Carboniferous and Permian carbonates from the Southern Alps (Fig. 1) will be com- pared with published δ 13 C curves from other parts of the world. Palaeogeography, Palaeoclimatology, Palaeoecology 433 (2015) 174–190 ⁎ Corresponding author. E-mail address: michael.joachimski@fau.de (M. Joachimski). http://dx.doi.org/10.1016/j.palaeo.2015.05.012 0031-0182/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo