High resolution paleoenviromental variability in the Ionian Sea (Core KC01B) trough MIS 9-13

The Eastern Mediterranean Core KC01B (Ionian Sea) was studied using calcareous plankton assemblages and geochemical analyses in order to investigate climate dynamics through Marine Isotope Stages (MIS) 13-9 (500-300 ky). This is a time interval of significant climate modification which includes the Mid-Brunhes Event and the warm and prolonged interglacial MIS 11 considered as potential analogue of the Holocene due to the similar orbital configuration and atmospheric composition. The studied Core represents a reference marine record for the Mediterranean planktonic foraminifera DO18 isotope chronology and for the sapropel-tuned astronomical timescale for the last 1.1 My (Lourens, 2004). Quantitative investigations have been performed with a time resolution of about 400 yrs for planktonic foraminifera and of 600-800 yrs for calcareous nannofossils. Calcareous plankton assemblages display high-amplitude variations which provide evidence of variability in surface water conditions with peculiar features at Terminations V and IV. The biological and geochemical paleoclimate proxies are well comparable and document a climate dynamic at Milankovitch to millennial scale. Warm phases are partially coupled with increase in paleoproductivity possibly linked to changes in surface water stratification and mesoscale hydrographic variability. Complex paleoenvironmental conditions occur during MIS 12-11 transition. Specifically, the interval is characterized by a marked increase in surface water paleoproductivity and a late surface water warming with respect to Termination V. The onset of full interglacial-like condition is almost coeval with deposition of sapropel S11; a climate optimum, lasting about 15 ky (403-389 ky), is then recorded during a period of low insolation forcing centred at 398 ky. In the lowermost part of MIS 11 (421-407 ky) paleoproxies evidence an interval characterized by the presence of low salinity/turbid waters, possibly induced by higher fresh water input at the core location. This scenario is remarkably consistent with the evidences of a pronounced humid period/monsoonal precipitations over North Africa in the early MIS 11 documented in the subtropical East Atlantic (Helmke et al., 2008) and also with the late oceanic warming following the long lasting glacial-interglacial MIS 12-11 transition at subpolar North Atlantic sites (Kandiano and Bauch, 2007). Our results provide evidences of a connection between Mediterranean and Atlantic climatic regime.