Palaeoaltitude of the Sila Massif (Southern Apennines, Italy) and distribution of the vegetation belts at ca. 2.4 Ma (Early Pleistocene)

Abstract

Palynological studies are considered as an excellent tool for palaeoaltitude estimates as sedimentary basins receive abundant pollen grains from surrounding uplands, especially through riverine detritic inputs. Here, we provide new evidence for estimating the palaeoaltitude of the Sila Massif (southern Apennines, Italy) ca. 2.4Ma, based on vegetation data derived from pollen analysis of the Semaforo succession. The past vegetation changes reflect shifts in the vegetation belts on the Sila Massif in Calabria, 30km north of Semaforo. Changes from subtropical forests to open-herbaceous formations indicate climate variability ranging from warm and humid interglacial to cold and/or dry glacial conditions. The climate reconstruction for Calabria, at sea-level, infers that mean annual temperatures were ~4°C higher than today during the interglacial period, while mean annual temperatures were similar to the present-day during the glacial period. Therefore, pollen-based altitude estimates provide evidence that during the lower Pleistocene the southern part of the Apennines reached between 1600 and 2100m above sea-level while the Crotone region was 500m below sea-level. Although the Crotone Basin has been uplifted approximately 650m since 2.4Ma, it is not possible to calculate accurately to what extent the Sila Massif has been submitted to the same uplift, as this basin is a fault-bounded basin. Nevertheless, as the southern Apennines did not attain high elevations, the interglacial refugia for microthermic arboreal species such as Abies or Picea were certainly situated northward in the Apennines at higher altitudes, or on the northern slopes of the Sila Massif exposed to cooler and more humid conditions.