Late-Quaternary terraced marine deposits as tools for wide-scale correlation of unconformity-bounded units in the volcanic Aeolian archipelago (southern Italy)

Late-Quaternary raised terraced marine deposits are commonly interlayered with volcanic deposits along the coasts of the Aeolian archipelago. They mostly reflect the interplay between long-term crustal vertical movements and glacio-eustatic sea-level changes during marine isotope stages (MIS) 5 and 9. Key discontinuity surfaces are represented by those bounding terraced marine deposits formed in correspondence of recurrent, individual interglacial sea-level peaks. They are the basal ravinement surface formed during gradual sea-level rise at the onset of a sea-level peak, and the upper surface of subaerial erosion developed during ensuing sea-level fall and lowstand. The discontinuity surfaces are classified according to their sequence-stratigraphic significance, field documentation and areal extent. MIS 5 marine deposits are bounded by the first-order UI and UII unconformities. The UI unconformity is the ravinement surface formed during MIS 5e sea-level rise (age between 130 and 124 ka). The UII unconformity is the surface of subaerial erosion and non-deposition developed during sea-level lowering after MIS 5a (age < 81 ka) and sealed by widespread Brown Tuff pyroclastic deposits (age > 70 ka). Unconformities UI and UII are correlated throughout the entire Aeolian archipelago thus assuming a regional stratigraphic significance. By linking to the global sea-level curve, they are assigned a relative age and assume a substantial chronostratigraphic significance and potential for dating of volcanic rocks. Further correlation on most of the Aeolian archipelago is provided by the L3 unconformity that is the ravinement surface formed during sea-level rise of MIS 5c (~ 100 ka). Moreover, the F1 unconformity bounds at the base marine deposits older than the last interglacial (i.e., MIS 9) and is ascribed of an inter-island stratigraphic outcome. These allogenic unconformities driven by sea-level fluctuations allow definition of a regional unconformity-bounded framework for the Aeolian archipelago into which local volcanic successions subdivided by autogenic unconformities of volcanic origin may be arranged.