Downstream evolution of the Stromboli slope valley (southeastern Tyrrhenian Sea)

Abstract

The Stromboli Slope Valley is located in the southeastern Tyrrhenian Sea and has a length in the order of 120 km. It crosses different physiographic domains characterized by highly varied gradients and by a different character of past and recent tectonic activity in the Sicilian and Calabrian margins. Furthermore, the course of the Stromboli Valley is strongly controlled by the distribution of the Aeolian Island arc volcanoes located offshore Sicily and Calabria. Numerous tributaries join the Stromboli Valley from the Aeolian arc slopes and from the Sicilian and Calabrian margins. Six reaches, showing unique morphology and stratigraphic architecture have been identified along the course of the Stromboli Valley, through the analysis of multibeam bathymetric data and seismic lines. The first reach has a canyon morphology with frequent landslides and chaotic deposits infilling the valley floor which is also characterized by three plunge pools. The second reach is characterized by an aggradational infill consisting of high amplitude reflections and by the development of a levee. The third reach presents an inner meandering thalweg associated with discontinuous and thin lateral accreting packages within an entrenched valley. The fourth reach is characterized by a high degree of incision, an inner entrenched thalweg and by the lack of any infill. The fifth reach is an erosional feature that however is at present experiencing deposition within the valley floor. The sixth reach has a depositional multithalweg valley floor often with a braiding pattern. The results of the interpretation have been used to infer the regime of sediment gravity flows in the different reaches of the Stromboli valley. Tectonic and volcanic features are the main elements that control the location of the Stromboli slope valley. In addition, tectonic structures have a large impact on the pattern of erosional and depositional processes along the Stromboli Valley and in the consequent distribution of geomorphic elements and sedimentary architecture.