The Subsurface Geology and Landscape Evolution of the Volturno Coastal Plain, Italy: Interplay between Tectonics and Sea-Level Changes during the Quaternary

The Volturno alluvial-coastal plain is a relevant feature of the Tyrrhenian side of southern Italy. Its plan-view squared shape is due to Pliocene-Quaternary block-faulting of the western flank of the south-Apennines chain. On the basis of the stratigraphic analysis of almost 700 borehole logs and new geomorphological survey, an accurate paleoenvironmental reconstruction before and after the Campania Ignimbrite (CI; about 40 ky B.P.) eruption is here presented. Tectonics and eustatic forcing have been both taken into account to completely picture the evolution of the coastal plain during Late Quaternary times. The upper Pleistocene-Holocene infill of the Volturno plain has been here re-organized in a new stratigraphic framework, which includes seven depositional units. Structural analysis showed that two sets of faults displaced the CI, so accounting for recent tectonic activity. Yet Late Quaternary tectonics is rather mild, as evidenced by the decametric vertical separations operated by those faults. The average slip rate, which would represent the tectonic subsidence rate of the plain, is about 0.5 mm/yr. A grid of cross sections shows the stratigraphic architecture which resulted from interactions among eustatic changes, tectonics and sedimentary input variations. On the basis of boreholes analysis, the trend of the CI roof was reconstructed. An asymmetrical shape of its ancient morphology—with a steeper slope toward the north-west border—and the lack of coincidence between the present course of the Volturno River and the main buried bedrock incision, are significant achievements of this study. Finally, the morpho-evolutionary path of the Volturno plain has been discussed

Active deformation in Southern Italy , Sicily and southern sardinia from GPS velocities of the Peri-Tyrrhenian Geodetic array (PTGA)

Campaign measurement (1995-2000) of Global Positioning Sys- tem (GPS) site velocities in southern Italy, Central Mediterranean area, document differential displacements within the orogens rim- ming the Tyrrhenian Sea. Within the Southern Apennines, GPS velocities define two laterally juxtaposed belts of deformation, with transpression in the east and transtension in the west. In the east, ~8 mm/yr convergence between northern Murge-Gargano block and the International GPS System (IGS) site MATE is partitioned across ~east-west striking right-lateral faults, consistent with seismicity and with the offshore geological record. To the south, in northern Calabria, site velocities relative to MATE indicate transpression at ~5 mm/yr, not recorded by seismicity but consistent with the on-land and offshore geological record. In contrast, site velocities along the Tyrrhenian Sea coast to the west diverge from MATE at 2-3.5 mm/yr, and are consistent with the crustal extension documented by seismic- ity and fault slip studies. The transpressional belt is tracked south- ward across the Ionian Sea by oblique convergence of central Sicily sites (2-6 mm/yr) relative to the IGS site NOTO in the Hyblean block. North-western Sicily sites display clockwise rotation, a pattern reflected in the geological and paleomagnetic record. Ssignificant horizontal motion accompanies rotation in north-western Sicily and is probably accommodated by west-northwest – east-southeast and northeast-southwest-striking right- and left-oblique faults, respec- tively, consistent with a regional ~north-northwest – south-southeast trending shortening axis. The ~east-west striking belt of contractional earthquakes observed offshore northern Sicily is consistent with up to ~10 mm/yr geodetic convergence between Sicily and Sardinia. Southern Sardinia sites exhibits differential velocities relative to the IGS site CAGL, suggesting internal deformation which is not recorded by seismicity and might signal incipient fragmentation of the Sardinia margin in response to relative convergence with Sicily