MIS 5.5 SST ESTIMATION FROM A MACROFOSSIL ASSEMBLAGE: A MULTI-PROXY RECONSTRUCTION

This contribute presents a multi-proxy palaeoclimatic study performed on a macrofauna coming from a MIS 5.5 calcarenite, exposed along the coastline of the Mar Piccolo of Taranto (MP). Three bulk samples returned 120 mollusc species, including four of the tropical “Senegalese Fauna”. Mollusc species with a southern or warm affinity are present in a double percentage in respect to today, whereas the northern or cold affinity species are equally represented, indicating warmer, but not tropical, SST during MIS 5.5. This is supported by the most recurring preferred SST ranges of the assemblage, that indicate 20 °C in average. For further SST estimations, trace elements (Mg/Ca and Sr/Ca), and oxygen stable isotope (δ18O) analyses, were performed on well preserved specimens of Thetystrombus latus, Spondylus gaederopus, Venus verrucosa, Pinna nobilis, and corallites of Cladocora caespitosa. Only some SST estimations, derived from equations available in literature, are realistic and converge on similar mean annual SST, on average of 20.8 ± 0.9 °C. As the modern annual mean SST of the study area ranges from 18 °C to 18.8 °C in the semi-closed MP basin and in the facing open sea Gulf of Taranto (GT) respectively, the final estimate of the MIS 5.5 SST falls in the range 1.2 - 2.0 °C for the GT, and 2.0 - 2.8 °C for the MP. Albeit warmer than today, this is not a firmly warmer tropical-like SST setting as it would be derived from the mean annual SST requirement of the Senegalese T. latus, that would suggest at least +2.7 °C in respect to modern GT, and +3.5 °C in respect to modern MP. To conclude, the approximations and assumptions made for obtaining SST values with any single proxy-based method return a wide uncertainty, strongly suggesting the need of a multi-proxy approach to infer the most reliable SST estimation.