title: 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: The Early Ottnangian Cooling (EOC), a distinct cold-spell in European climate at ~ 18 Ma 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 17.7 Myrs 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 17.8 Myrs with two distinct cold snaps at ~ 17.86 Ma and ~ 17.81 Ma. 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 (~ 400 kyrs) and short-term (~ 100 kyrs) eccentricity cycles most likely acted as pacemaker of this palaeoclimatic interaction.
authors.affiliation: Institute for Earth Sciences, University of Graz, NAWI Graz, Heinrichstraße 26, 8010 Graz, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Grunert
authors.affiliation: Department of Geological Sciences, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, USA.
authors.forename: Alexandrina
authors.initials: A
authors.lastname: Tzanova
authors.affiliation: Geological-Paleontological Department, Natural History Museum Vienna, Burgring 7, 1030 Vienna, Austria.
authors.forename: Mathias
authors.initials: M
authors.lastname: Harzhauser
authors.affiliation: Institute for Earth Sciences, University of Graz, NAWI Graz, Heinrichstraße 26, 8010 Graz, Austria.
authors.forename: Werner E
authors.initials: WE
authors.lastname: Piller
keywords: Burdigalian; Early Ottnangian Cooling; Paratethys; alkenones; orbital forcing; palaeoclimate
references.citation: Nature. 2006 Oct 12;443(7112):687-91
references.pmid: 17036002
references.citation: Science. 2006 Dec 22;314(5807):1894-8
references.pmid: 17185595
references.citation: Nature. 2008 Jan 17;451(7176):279-83
references.pmid: 18202643
references.citation: Rev Palaeobot Palynol. 2000 Nov;112(4):247-286
references.pmid: 11134709
references.citation: Science. 2001 Apr 13;292(5515):274-8
references.pmid: 11303100
references.citation: Nat Commun. 2014;5:2999
references.pmid: 24385005
references.citation: Science. 2001 Apr 27;292(5517):686-93
references.pmid: 11326091