• journal_title：Bollettino della Societa Geologica Italiana
• Contributor：Paolo Giannandrea ; Luigi La Volpe ; Claudia Principe ; Marcello Schiattarella
• Publisher：The Electrochemical Society
• Date：2006-
• Format：text/html
• Language：en
• journal_abbrev：Bollettino della Societa Geologica Italiana
• issn：2038-1719
• volume：125
• issue：1
• firstpage：67
• section：Structural geology

The survey for a new geological map of the Monte Vulture Volcano in the Lucanian Apennine, southern Italy, has allowed an accurate revision of the stratigraphic setting of the area by using unconformity-bounded units (Ubsu, after Salvador, 1994) and permitted a reliable reconstruction of its palaeomorphology and evolutionary history. The aim of this paper is to furnish detailed explanatory notes of that UBSU-based map and to define the principal steps of the palaeogeographic evolution of the area, including several continental sedimentary basins, during the Pleistocene. The composite volcano of Monte Vulture, middle Pleistocene in age, was built in a time-span of about 550 ka on the external (i.e. eastern) belt of the southern Apennines, in association with a deep-seated transfer fault (Linea del Vulture, after Schiattarella et alii, 2001, 2005), which represents a breakoff of the Apulian plate subducting toward the W-SW. The differential E-directed roll-back of the segmented lower plate allowed the magma ascent responsible for the evolution of the volcano. Such a mechanism has been also responsible for the kinematical disjunction and uplift of adjoining sectors of the Bradano foredeep and Apulian foreland, for the deformational and morphostructural evolution of Monte Vulture and for the tectonic and sedimentary record of the adjacent fluvial-lacustrine basins. Several slack periods during the entire eruptive activity are testified by the presence of epiclastic sediments and/or palaeosols interbedded in the volcanic products (La Volpe & Principe, 1994), also marking the shifting of different tectonic regimes (Beneduce & Schiattarella, 1997; Schiattarella et alii, 2001). The cartographic portrayal and organisation of both volcanic and sedimentary deposits have been indeed deeply revised by grouping or separating the former volcano-stratigraphic units (cf. La Volpe & Principe, 1994) into basic synthemic units, which are not internally separated by unconformities or significant quiescence periods (generally marked by palaeosols and/or erosional surfaces). Two supersynthems, containing several synthems and subsynthems, have been established. The volcanic edifice is localised on a structural high of the pre-Pliocene and Pliocene sedimentary bedrock, planed by an erosional flat surface representing the basal unconformity of the Mount Vulture stratigraphic succession. The major unconformity within the volcanic complex has been instead observed at the contact of the upper cooling units on the basal ignimbrites, suggesting that an important tectonic deformation occurred at the passage from early to middle Pleistocene (Beneduce & Schiattarella, 1997; Schiattarella et alii, 2001, 2005). The earlier volcanic morphology has been further modified by summit and lateral volcano-tectonic collapses (Schiattarella et alii, 2005), generating another relevant stratigraphic discontinuity. The revised stratigraphy of the volcanic units has been therefore firstly produced on the grounds of a detailed geological survey (Giannandrea et alii, 2004), but also on the basis of stratigraphic, sedimentological, structural and morphotectonic analyses, supported by the revision and statistical treatment of a large geochemical data-set available from the wide literature on the volcano (Schiattarella et alii, 2005). Many unconformities have been observed and mapped in both the volcanic products and the sedimentary deposits from the Ofanto, Atella, Melfi, Arcidiaconata and Venosa basins. As remarked above, such stratigraphic discontinuities constituted the basis for the application of the criteria related to the unconformity-bounded stratigraphic units (Salvador, 1994). The volcanic units have been grouped into the Monte Vulture Supersynthem and the Monticchio Supersynthem, which have been also distinguished on a regional scale in the Quaternary sedimentary basins. The boundary between supersynthems coincides with the Melfi Synthem, locally represented by a palaeosol suturing the tectonic structures responsible for the down-throwing of the southern half of the volcanic edifice and the collapse of its south-western sector. The Monte Vulture Supersynthem includes the Foggianello, Barile, and Melfi synthems, whereas the Monticchio Supersynthem contains the Valle dei Grigi-Fosso del Corbo and the Laghi di Monticchio synthems. The boundary separating the Foggianello and Barile synthems consists of an erosional surface with epiclastic deposits, marked by a map-scale buried morphology of a caldera generation. The Valle dei Grigi-Fosso del Corbo and Laghi di Monticchio synthems are separated by an erosive contact marked by a palaeosol. In both cases, fault re-activation is documented. The Foggianello Synthem groups three subsynthems linked to different eruptive stages. Alluvial deposits and dykes crossing the pre-eruptive bedrock located north-east of the volcano are present at the base of the stratigraphic succession. The overlying synthems are respectively constituted of pyroclastic fall and ignimbrites (Fara d'Olivo Volcano-Stratigraphic Unit, after La Volpe & Principe, 1994).