Mid-Burdigalian Paratethyan alkenone record reveals link between orbital forcing, Antarctic ice-sheet dynamics and European climate at the verge to Miocene Climate Optimum

Abstract

AbstractThe Early Ottnangian Cooling (EOC), a distinct cold-spell in European climate at ~18Ma preceding the Miocene Climate Optimum, is frequently reported in Paratethys records; however, the duration, magnitude, and underlying causes are poorly understood. A new palaeoclimatic data-set provides unexpected insights into this event.UK'37-based sea-surface temperatures>24°C between ~18.1 and 17.7Myrs substantially exceed existing estimates, and indicate a significantly warmer European climate than previously assumed for this usually poorly recovered time interval. The EOC is expressed as an average drop of 2–3°C in Paratethyan water temperatures between ~18.1 and 17.8Myrs with two distinct cold snaps at ~17.86Ma and ~17.81Ma. The short duration of the EOC excludes Tethyan Seaway closure as its underlying cause, although the enhanced palaeoclimatic sensitivity of the Paratethys due to this palaeogeographic configuration potentially contributed to the magnitude of SST deterioration during the EOC. The revealed palaeoclimatic pattern shows a strong correlation with isotope event Mi-1b in deep-sea δ18O records, and we propose a tight palaeoclimatic link between the Southern Ocean and the Paratethys/Mediterranean realm as an alternative hypothesis. The interplay of modulations in the long-term (~400kyrs) and short-term (~100kyrs) eccentricity cycles most likely acted as pacemaker of this palaeoclimatic interaction