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

Abstract

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 U I and U II unconformities. The U I unconformity is the ravinement surface formed during MIS 5e sea-level rise (age between 130 and 124 ka). The U II 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 U I and U II 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 L 3 unconformity that is the ravinement surface formed during sea-level rise of MIS 5c (~ 100 ka). Moreover, the F 1 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.