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

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. 2.4 Ma, 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, 30 km 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 2100 m above sea-level while the Crotone region was 500 m below sea-level. Although the Crotone Basin has been uplifted approximately 650 m since 2.4 Ma, 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.

► Pollen data allow the altitude of the Southern Apennines at ~ 2.4 Ma to be estimated.
► The Sila Massif was ~ 1600 m high while the Crotone Basin was 500 m below sea-level.
► Interglacial refugia for Abies or Picea were situated northward at high altitudes.