Revising the Early Activity of Monte Vulture (Basilicata, Southern Italy): new high precision 40Ar/39Ar and geochemical data

We present fourteen new 40Ar/39Ar ages, based on 287 singles crystals analyzed from proximal and semi-proximal pyroclastic deposits, that significantly refine the chronology of Monte Vulture’s initial volcanic activity (Foggianello synthem). The earliest identified eruption is the Fara d’Olivo A ignimbrite, dated at 784.7 ± 4.7 ka (2σ), closely followed by the Fara d’Olivo B unit at 774.7 ± 0.9 ka (2σ), which encompasses at least four distinct eruptions. We also recognize a new explosive phase at 740.0 ± 1.6 ka (2σ) that we named Rapolla and that preceded the effusive Spinoritola phase (731.5 ± 2.0 ka (2σ)). The youngest activity belonging to the Foggianello synthem, named “Campanile phase”, is composed of pyroclastic deposits dated between 708.4 ± 2.0 ka (2σ) and 700.2 ± 1.2 ka (2σ). According to our results, the duration of the Foggianello system spans approximately ~85 ka, much longer than previously proposed. Geochemical analyses of fresh glass shards indicate a dominating phonolitic magma composition during this interval. However, a progressive change of the magmatic source, probably controlled by crustal contamination, has been observed. Furthermore, our results establish a precise correlation of Fara d’Olivo B Ignimbrite with distal tephra layers from Montalbano Jonico (V4) and Lake Ohrid (OH-DP-2869), showing that this eruption represents a robust regional stratigraphic marker of the Brunhes–Matuyama reversal. Finally, the recognition of inherited sanidines up to ~934 ka potentially pushes back the onset of magmatism at Monte Vulture into the Early Pleistocene, substantially earlier than previously inferred. Our results thus have implications also for the geodynamic evolution of the Apulian slab, suggesting an earlier onset of extensional tectonics and mantle upwelling. Keywords: Monte Vulture, 40Ar/39Ar dating, Geochemistry, Volcanology, Apulian province, Bruhnes/Matuyama