Cyclic Variations in Calcareous Nannofossil Assemblage: Evidence from the Piacenzian and Gelasian Type Sections (Sicily, Italy)

The present study integrates high-resolution calcareous nannofossil data from two reference sections spanning the Pliocene-Pleistocene transition: the Punta Piccola and Monte San Nicola sections, which represent the Global Stratotype Sections and Points (GSSPs) for the Piacenzian and Gelasian stages, respectively. The investigated composite succession (~42 m thick) includes deposits from the Trubi Formation and the overlying Monte Narbone Formation, within which sapropel clusters O and A are recorded. The studied interval spans approximately 800 kyr (from 3.3 to 2.5 Ma), encompassing the termination of the Pliocene Warm Period and the progressive intensification of Northern Hemisphere Glaciation (iNHG). Quantitative analyses of calcareous nannofossil assemblages were carried out to assess their response to this major climatic transition, with particular focus on taxa sensitive to hydrographic changes driven by insolation forcing, such as Florisphaera profunda and Coccolithus pelagicus. The observed variations are primarily interpreted in terms of changes in sea-surface temperature and nutricline dynamics. These results are further compared with established humidity-aridity proxies from Northwest Africa. Wavelet analysis was applied to the time series dataset to identify orbital- and millennial-scale periodicities influencing the distribution patterns of selected environmental proxies through time. The response of calcareous nannofossils to the emergence of millennial-scale climate variability associated with the iNHG is examined. This study provides the first continuous high-resolution calcareous nannofossil record across the Piacenzian-Gelasian interval, offering new insights into cyclic changes within the Mediterranean region during the Pliocene-Pleistocene transition.