The first multi-proxy palaeoclimate record (~115ky-110ky) from the Island of Sardinia

Although occupying a critical position at the center of the Mediterranean Sea, the Island of Sardinia (Italy) has never been the focus of multi proxy data-based palaeoclimate studies. An excellent way to obtain information about late Quaternary terrestrial climate oscillations in the region is the study of carbonate speleothems, because they allow the reconstruction of palaeohydrology through the geochemical properties of the their growth layers (Fairchild and Treble, 2009; McDermott, 2004) and are highly suited to accurate independent chronologies (Richards and Dorale, 2003; Scholz et al., 2012). To this end, U-Th series dating, δ18O and δ13C isotope analysis and petrographic observations have been applied to a ~30 cm long stalagmite (BMS1) sampled in the Bue Marino coastal cave (western Sardinia) providing the first palaeoclimate record for this area. Seventeen U-Th ages attest to the formation of BMS1 during MIS5d, between ~110 and ~115 thousand years BP, a period of intense climate perturbations that followed the last interglacial peak (Dansgaard et al., 1993). A positive correlation between δ18O and δ13C, and its correspondence with carbonate fabric variations, reflects variations in drip rate, in turn related to secular variation in the rainfall quantity reaching the cave site during its formation. Furthermore, a hiatus at around 111ky BP marks the interruption of a general isotopic enrichment trend, and probably corresponds to the arrival of a short-lived arid-cold period in the region comparable to a sub-D-O cycles (Capron et al., 2010). The presence of intra millennial climate events has already been reported in Alpine speleothems (Boch et al., 2011) but never in the Mediterranean sea region. For this reason further analyses are planned in order to better understand this variability in Sardinia, that represents an exceptional opportunity to correlate existing and future palaeoclimate records from the peri-Mediterranean European and African mainland. Boch, R., Cheng, H., Spötl, C., Edwards, R. L., Wang, X., and Häuselmann, P., 2011, NALPS: a precisely dated European climate record 120–60 ka: Climate of the Past, v. 7, no. 4, p. 1247-1259. Capron, E., Landais, A., Chappellaz, J., Schilt, A., Buiron, D., Dahl-Jensen, D., Johnsen, S. J., Jouzel, J., Lemieux-Dudon, B., Loulergue, L., Leuenberger, M., Masson-Delmotte, V., Meyer, H., Oerter, H., and Stenni, B., 2010, Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period: Climate of the Past, v. 6, no. 3, p. 345-365. Dansgaard, W., Johnsen, S. J., Clausen, H. B., Dahl-Jensen, D., Gundestrup, N. S., Hammer, C. U., Hvldberg, C. S., Steffensen, J. P., Sveinbjornsdottir, A. E., Jouzel, J., and Bond, G., 1993, Evidence for general instability of past climate from a 250-kyr ice-core record: Nature, v. 364, p. 218-220. Fairchild, I. J., and Treble, P. C., 2009, Trace elements in speleothems as recorders of environmental change: Quaternary Science Reviews, v. 28, no. 5-6, p. 449-468. McDermott, F., 2004, Palaeo-climate reconstruction from stable isotope variations in speleothems: a review: Quaternary Science Reviews, v. 23, no. 7-8, p. 901-918. Richards, D. A., and Dorale, J. A., 2003, Uranium-series chronology and environmental applications of speleothems, Volume 52. Scholz, D., Hoffmann, D. L., Hellstrom, J., and Bronk Ramsey, C., 2012, A comparison of different methods for speleothem age modelling: Quaternary Geochronology, v. 14, p. 94-104