A FIFTY MILLION YEAR (LATE JURASSIC – EARLY CRETACEOUS) CLIMATE RECORD FROM THE BAHAMA-TYPE ADRIATIC PLATFORM, CROATIA

A composite section through the Adriatic platform, Croatia from the Late Jurassic Kimmeridgian to the Early Cretaceous Albian stage provides a high-resolution climate and sea level record spanning fifty million years. The Kimmeridgian was dominated by warm humid conditions (local brackish alga Chara) marked by platform flooding interrupted by two cooling events, sea level fall and breccia development. The Tithonian warms into full-blown greenhouse conditions. The platform became increasingly semi-arid with meter-scale oolitic cycles capped by microbial laminites. Four cooling events punctuate the succession with the last one being in the Early Creataceous Berriasian (multiple subaerial breccia horizons). The Berriasian is cyclic with fenestral laminite or restricted, unfossiliferous lime mudstone capping most parasequences. The Valanginian is dominated by coarse dolomitized shallow subtidal carbonates and rare peritidal laminites. Transition from Valanginian dolomite to basal Hauterivian limestone may be synchronous with oceanic anoxic event (OAE) off the platform. The Hauterivian is dominated by well developed subtidal cycles with rooted horizons and mainly fenestral laminites suggesting humid subtidal to emergent conditions. Multiple emergence horizons at the top-Hauterivian and base-Barremian are associated with microkarsting and paleocave development. The Barremian contains abundant meter-scale cycles suggesting greenhouse conditions, becoming increasingly semi-arid upward (cycle caps become more stromatolitic and less fenestral compared to the lower part). Multiple short term cooling events are marked by black-pebble emergence horizons associated with sea level drops. The Early Aptian is marked by significant warming and shallow flooding of the platform and deposition of non-cyclic shallow carbonates. The Late Aptian is marked by multiple emergence horizons suggesting multiple cooling events and long term sea level fall. The Albian is marked by a regional deepening of the platform (OAE-1B) and deposition of deeper lagoon laminated limestones. This rapidly passes up into meter-scale cycles dominated by fenestral caps suggesting relatively humid conditions.