GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 1.2 221 UPPER PLATE QUATERNARY EVOLUTION OF THE TYRRHENIAN-APENNINE HINGE ZONE IN RESPONSE TO LOWER PLATE DYNAMICS A. Milia 1 , M.M. Torrente 2 , P. Iannace 2 , M. Tesauro 3 1 CNR-IAMC Napoli, Italy 2 Università del Sannio, Benevento, Italy 3 Utrecht University, Utrecht, Netherlands Introduction. Active tectonics and volcanism characterize the eastern Tyrrhenian Margin - southernApennine system. The hinge zone of this backarc-chain system (Fig. 1) is affected by the opening of the youngest sedimentary basins. The study of the margin at different geologic scale greatly improves our understanding of the geodynamics of the central Mediterranean, since it records the mode of extension of a backarc migration toward the continental area and is located in correspondence of the northern boundary of the Ionian subducting plate. The stratigraphic and tectonic study of the sedimentary basins located on the upper plate provides constraints on the timing and duration of the rifting phases and overall geometry of rift basins that evolve in responce to the subducting slab dynamics. Within this frame, the analysis of these sedimentary basins gives fundamental constraints on the reconstruction of the geodynamic evolution and clarifies the relationships between deep and shallow structures in convergent regions. Seismic tomography studies of the central Mediterranean (e.g. Wortel and Spakmann, 2000) revealed an extended high velocity zone interpreted as the subducting Adriatic and Ionian slab. The continuity of the Adriatic slab is interrupted in correspondence of the southern Apennine, as observed from the low velocity anomaly located in the uppermost mantel. The existence of a gap in the structure of the subducted slab is interpreted as a slab detachment due to tears formation. These authors suggested that the slab edges correspond to Subduction Transform Fig. 1 – A) Index map of Italy and Tyrrhenian Sea. Dashed yellow line shows location of the regional section, dashed white polygons the study area, and white numbers the sedimentary basins. Abbreviations stand as follows: NCM= Northern Campaniamargin,SCM=Southern Campania margin, CM= Calabria margin, 1=Paola Basin, 2= Salerno Bay Basin, 3=Salerno Valley, 4= Salerno-Cilento Basin, 5= Cilento Basin, 6= Campi Flegrei-Naples Bay Basin, 7=Southern Gaeta Bay Basin, 8= Campania Plain Basin, 9=Central Gaeta Bay Basin, 10=Northern Gaeta Bay Basin. B) Crustal geological cross-sections from the Tyrrhenian Sea to the Apennine foredeep, based on the interpretation of seismic profiles CROP04 and M6B (Milia et al. , 2016). Abbreviations stand as follows: SSZ= strike-slip fault zone. PQ=Plio-Quaternary deposits, APP=Apennine platform unit, LIG=Liguride units, LM=Lagonegro-Molise unit, APU=Apulian platform unit.