Late BarremianeEarly Aptian palaeoenvironmental change: The Cassis-La Bédoule section, southeast France Melody Stein a, * , Stéphane Westermann b , Thierry Adatte a , Virginie Matera c , Dominik Fleitmann d , Jorge E. Spangenberg e , Karl B. Föllmi a a Institut de Géologie et Paléontologie, Université de Lausanne, Anthropôle, 1015 Lausanne, Switzerland b School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ, United Kingdom c Institut National de Recherche et de Sécurité,1 rue du Morvan, CS60027, 54519 Vandoeuvre, France d Institute of Geological Sciences, University of Bern, Baltzerstrasse 1-3, 3012 Bern, Switzerland e Institut de Minéralogie et Géochimie, Université de Lausanne, Anthropôle, 1015 Lausanne, Switzerland article info Article history: Received 2 November 2011 Accepted in revised form 27 March 2012 Available online 20 April 2012 Keywords: Aptian Barremian Stable carbon isotopes Cassis-La Bédoule Clay mineralogy OAE 1a Phosphorus Redox-sensitive trace elements abstract The well-dated section of Cassis-La Bédoule in the South Provencal Basin (southern France) allows for a detailed reconstruction of palaeoenvironmental change during the latest Barremian and Early Aptian. For this study, phosphorus (P) and clay-mineral contents, stable-isotope ratios on carbonate (d 13 C carb ) and organic matter (d 13 C org ), and redox-sensitive trace elements (RSTE: V, U, As, Co, and Mo) have been measured in this historical stratotype. The base of the section consists of rudist limestone, which is attributed to the Urgonian platform. The presence of low P and RSTE content, and content of up to 30% kaolinite indicate deposition under oligotrophic and oxic conditions, and the presence of warm, humid climatic conditions on the adjacent continent. The top of the Urgonian succession is marked by a hard- ground with encrusted brachiopods and bivalves, which is interpreted as a drowning surface. The section continues with a succession of limestone and marl containing the first occurrence of planktonic fora- minifera. This interval includes several laminated, organic-rich layers recording RSTE enrichments and high C org :P tot ratios. The deposition of these organic-rich layers was associated with oxygen-depleted conditions and a large positive excursion in d 13 C org . During this interval, a negative peak in the d 13 C carb record is observed, which dates as latest Barremian. This excursion is coeval with negative excursions elsewhere in Tethyan platform and basin settings and is explained by the increased input of light dissolved inorganic carbon by rivers and/or volcanic activity. In this interval, an increase in P content, owing to reworking of nearshore sediments during the transgression, is coupled with a decrease in kaolinite content, which tends to be deposited in more proximal areas. The overlying hemipelagic sediments of the Early Aptian Deshayesites oglanlensis and D. weissi zones indicate rather stable palaeoenvironmental conditions with low P content and stable d 13 C records. A change towards marl-dominated beds occurs close to the end of the D. weissi zone. These beds display a long decrease in their d 13 C carb and d 13 C org records, which lasted until the end of the Deshayesites deshayesi subzone (corresponding to C3 in Menegatti et al., 1998). This is followed by a positive shift during the Roloboceras hambrovi and Deshayesites grandis subzones, which corresponds in time to oceanic anoxic event (OAE) 1a interval. This positive shift is coeval with two increases in the P content. The marly interval equivalent to OAE 1a lacks organic-rich deposits and RSTE enrichments indicating that oxic conditions prevailed in this particular part of the Tethys ocean. The clay mineralogy is dominated by smectite, which is interpreted to reflect trapping of kaolinite on the surrounding platforms rather than indicating a drier climate. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The Barremian/Aptian boundary time interval witnessed impor- tant palaeoenvironmental change, which preceded the Early Aptian oceanic anoxic event (OAE) 1a. Near the Barremian/Aptian boundary, Urgonian-type carbonate production was interrupted by the depo- sition of Orbitolina-enriched sediments in tropical and subtropical * Corresponding author. Present address: Ruhr-Universität Bochum, Institut für Geologie, Mineralogie und Geophysik, D-44870 Bochum, Germany. E-mail address: melody.stein@rub.de (M. Stein). Contents lists available at SciVerse ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes 0195-6671/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.cretres.2012.03.021 Cretaceous Research 37 (2012) 209e222