Monte Vulture Volcano (Basilicata, Italy): an analysis of morphology and volcaniclastic facies

Abstract

The earliest activity of Monte Vulture, central Italy, included ignimbrites but the bulk of the volcano was built up by plinian airfall deposits. Contemporaneous remobilisation of these deposits formed an apron of lahars around the base of the main cone. The volcano was constructed on a ridge; the valley to the east and tributaries to the north and south became sediment traps for volcaniclastic materials emplaced by fluvial reworking and directly from volcanic activity. To the west the valley was swept clear by active downcutting. Instability of the west flank as a result of this erosion was probably a contributory cause of major gravitational sector collapse on the volcano's flank, terminating the main cone-building phase. The resultant scar is an amphitheatre-shaped hollow called here the Valle dei Grigi. Previous workers have attributed this feature to coalescing calderas formed by engulfment. The last volcanic phase was the production of the Monticchio calderas and associated phreatomagmatic explosions producing airfall and surge deposits. Because most of the activity at Vulture has been repeated plinian eruptions producing similar assemblages of products, detailed stratigraphy of the volcano is difficult to accomplish. To characterise Vulture in terms of its products, various facies are identified and interpreted in relation to volcanic processes, distance from vent and environmental conditions.