Seasonality and interannual climate variability during the Late Miocene: Testing and tuning climate models using oxygen isotope stratigraphy, growth increment analysis and new ground data

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Miocene shallow water carbonates are generally considered indaequate for palaeoclimatic analyses, because their stratigraphic record is punctuated by abundant gaps. However, sclerochronological records of corals document atmospheric variability - an spect hitherto unknown to Miocene palaeoclimatology. Skeletons in a pristine state of preservation required for sclerochronology have been detected in debrites intercalated with rhythmically stratified deep-water clay and marl (Tortonian/Messinian age, Krousonas area, Central Crete; Br 1153/7). A multi scale oxygen isotope analysis of based on these periplatform sediments therfore has the potential to track climate variability on annual, decadal and millennial timescale in response to insolation forcing and aridisation of the Mediterranean area over the course of the Late Miocene. Additional outcrops will be explored in Central Crete (Phaistos area). A climate model run based on a single sclerochronological record (for 10 Ma, Central Crete) obtained during a previous project (BR 1153/7) reflects real biofacies distributions superisingly well: warmer than present temperatures in the Mediterranean, and colder temperatures in the E Atlantic. Predicted Late Miocene temperatures and variability ion the E Atlantic will be tested using the classical biofacies approach along the Macronesian transsect (Azores, Madeira, Canary and Cape Verde Islands). Careful palaeontological analysis will provide information regarding long-term climate changes and the location of potential refugia for tropical biota during times of ecological perturbatins in the Mediterranean area.