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Istituto di Scienze del Mare, Sezione Geologia Marina Bologna, CNR, Via Gobetti 101, 40129 Bologna, Italy fabiano.gamberi{at}bo.ismar.cnr.it
The Gioia Basin is a small trough located in the southeastern Tyrrhenian Sea between the Aeolian island arc and Sicily and Calabria. It is experiencing a post-rift margin evolution, while tectonic deformation and high rates of vertical movement are still affecting the Sicilian and Calabrian mainland. The analysis of the evolution of the post-rift depositional systems along the various sectors of the Gioia Basin margin has been carried out through the combined interpretation of multibeam bathymetry and seismic reflection data. Two seismic units have been identified and their component geomorphological elements ascertained through the analysis of seismic facies distribution. In general, the depositional architecture of the margin, the sedimentary environments and facies and related geomorphological elements that are active in the shaping of the margin appear to be mainly controlled by the physiography of the basin itself and by the geology of the hinterland that results from the structural evolution of the adjacent land areas. An evolution from a generalized slope bypass setting to a prograding offlapping slope architecture is recognized and explained as due to the transition from an out-of-grade to a graded profile progressing from the early post-rift stage to the later margin growth stage. Along the Sicilian margin, a constructional apron, mainly consisting of channel levee deposits, makes up much of the studied sedimentary package and reflects a high sediment supply related to the large size of river catchments on land. In contrast, the northeastern Sicilian basin sector is a destructional margin that flanks a region where small river drainage systems result in a low sediment supply to the basin and a continued high uplift rate promotes slope instability; as a consequence, the basin infill is here almost completely made up of mass-wasting deposits. In the Calabrian margin, a first phase of low sediment supply probably coinciding with the filling of the further inland Gioia Tauro half-graben was followed by the establishment of the Gioia-Mesima channel-canyon system that, furnishing an effective sediment flux to the margin, allows the formation of an intraslope depositional body consisting of channelized turbidite lobes.
