North–south palaeohydrological contrasts in the central Mediterranean during the Holocene: tentative synthesis and working hypotheses

• DOI: 10.5194/cpd-9-1901-2013
• Publication Date: 2013-04-05T12:06:24Z
• Authors: M. Magny; N. Combourieu Nebout; J. L. de Beaulieu; V. Bout-Roumazeilles; D. Colombaroli; S. Desprat; A. Francke; S. Joannin; O. Peyron; M. Revel; L. Sadori; G. Siani; M. A. Sicre; S. Samartin; A. Simonneau; W. Tinner; B. Vannière; B. Wagner; G. Zanchetta; F. Anselmetti; E. Brugiapaglia; E. Chapron; M. Debret; M. Desmet; J. Didier; L. Essallami; D. Galop; A. Gilli; J. N. Haas; N. Kallel; L. Millet; A. Stock; J. L. Turon; S. Wirth
• Keywords: Proxy (statistics)

Abstract. On the basis of a multi-proxy approach and strategy combining lacustrine marine records along north–south transect, data collected in Central Mediterranean within framework collaborative project have led to reconstruction high-resolution well-dated palaeohydrological assessment their spatial temporal coherency. Contrasting patterns changes been evidenced Mediterranean: south (north) around 40° N latitude, middle part Holocene was characterised by lake-level maxima (minima), during an interval dated ca. 10 300–4500 cal BP 9000–4500 north. Available suggest that these contrasting operated throughout Holocene, both on millennial centennial scales. Regarding precipitation seasonality, maximum humidity humid winters dry summers north N, N. This may explain apparent conflict between palaeoclimatic depending proxies used for as well synchronous expansion tree species taxa with climatic requirements. In addition, first millennium very conditions not only Eastern, but also Western zones reflected low lake levels delayed reforestation. These results that, addition influence Nile discharge reinforced African monsoon, deposition Sapropel 1 has favoured (1) increase winter northern borderlands, (2) summer southern area. The climate reversal following optimum appears punctuated two major 7500 4500 BP. Mediterranean, developed response combination orbital, ice-sheet solar forcing factors. south-central started at 300 BP, correlation decline possible blocking effects North Atlantic anticyclone linked insolation, and/or remnant ice sheets fresh water Ocean. north-central minimum began 9000 when Fennoscandian disappeared prevailing positive NAO-type circulation oscillation 4500–4000 be non-linear gradual decrease, additional key seasonal interhemispherical changes, insolation. scale, successive events which entire central coincided cooling associated deglacial outbursts area decreases activity 11 700–7000 since 7000 onwards. Thus, regarding centennial-scale oscillations, Basin strongly affected over Holocene. model experiments, better understanding factors past atmospheric behind will require further investigation establish selected locations adjacent regions. Special attention should paid greater precision reconstruction, time scales, latitudinal location limit sectors, intensity characteristics periods/oscillations (e.g. thermal versus Neoglacial, as, instance, 8.2 ka event 4 or Little Ice Age), varying geographical from western eastern areas (longitudinal gradients).