Palynological characterization of late Quaternary architectural elements from the Mediterranean coastal record (Arno and Po delta plains).

Pollen is commonly used to study palaeoclimate variations at a high-resolution scale. However, coastal-deltaic sedimentary successions are still underexplored because of several stratigraphic features unfavourable for palynological studies. However, these potentially weak-points are an opportunity to investigate the interactions among environment, vegetation and climate in areas strongly affected by glacio-eustatic variations. This Thesis focuses on these weak-points to understand climatic-environmental dynamics in Mediterranean coastal systems by studying two cores retrieved in the subsurface of the Po (core EM2, 40 m-long) and Arno (core PA1, 31.5 m-long) delta plains. In the Po delta plain, a facies characterization was performed on the Holocene freshwater paludal succession. The distinction of different types of swamps via water-table oscillations allowed the identification of the landward equivalents of flooding surfaces and of the maximum flooding surface. It was also possible to identify some Holocene cooling events by peaks of montane taxa. This vegetation-climate variability recalls the cyclicity of Bond events. Moreover, for the first time, pollen from a continental succession of the Adriatic area outlined the effects of the 8.2 ka cooling event on both vegetation and depositional dynamics. In the Arno delta plain, within the 31.5 m-thick succession, two transgressive-regressive cycles were identified and related to the glacial-interglacial fluctuations of the MIS5e-MIS1 interval, with interglacials dominated by mesophilous-Medierranean taxa and glacial dominated by Conifers-upland herbs. The former correspond to lagoon-deltaic deposits, whereas the latter to a pedogenised alluvial succession. For the first time a lagoon assigned to MIS5e was palynologically detected, shedding new light on the stratigraphy of the area. The almost synchronous response of coastal environments to late Quaternary climate forcing was documented at a sub-Milankovitch timescale, as an increase in montane broadleaves occurs at the top of the Holocene lagoon, peaking within the sandy body that records its final infilling.