Post glacial sediment partitioning on a tectonically controlled, narrow shelf (Calabro-Tyrrhenian margin, Italy): Issues in defining S2S budget

The re-analysis of high-resolution seismic profiles collected along the narrow (2–9 km) shelf facing ~90 km of the Calabro-Tyrrhenian coastline has enabled the reconstruction of its sequence-stratigraphic architecture, along with the quantification of sediment volumes accommodated during the last post-glacial sea level rise and highstand. The shelf volumes are compared with the gross volumes supplied by the short and steep rivers draining the uplifted hinterland area, obtained from morphometric analysis and inferred denudation rates (derived from uplift rates) of the drainage basins. The study area is divided in two main sectors based on the different morpho-stratigraphic setting and fluvial network controlling sediment distribution on the shelf. The Coastal Range sector is characterized by closely spaced mountainous rivers and narrow coastal plains; on the shelf, the post-LGM deposits show a main depocenter (up to 60 m thick) elongated ~27 km parallel to the coastline. This shelf sector hosts up to 80% of the sediment sourced from rivers, with a small percentage of sediment loss, mainly related to off-shelf export along a network of shelf-indenting submarine canyons. Sediment deficit due to river aggradation is considered negligible based on the narrow and V-shaped thalwegs typical of the rivers in this sector. The Santa Eufemia sector is characterized by larger rivers and a wider coastal plain, with a major depocenter (up to 50 m thick) confined off the Amato River. In this sector, the entire post-LGM sequence accounts only for about 30% of the sediment supplied by rivers (60% considering only the HST), indicating that, in addition to sediment exported off-shelf, a significant part is trapped by river aggradation within the coastal plain. The volumetric comparison has also evidenced local but significant discrepancies in sedimentary budget between adjacent sub-sectors, likely related to the effect of northward-directed shelf currents on sediment distribution along the shelf.