Geomorphology and sub-surface stratigraphy of a Mediterranean shelf receiving minor fluvial input: The imprint of relict landscapes

Narrow continental shelves such as those surrounding the Mediterranean basin are usually dominated by active depositional features such as major prodeltaic wedges located off major rivers (e.g. the Gulf of Lions, the northern Adriatic Sea), or by infralittoral wedges in settings where fluvial supply is more limited and hydrodynamic regimes are more energetic. However, the knowledge of the geomorphological patterns of undernourished shelves remains much less documented. In this contribution, we aim to characterize the submarine geomorphology and the sub-surface sedimentary bodies of a shelf sector located west of the Guadalfeo River, a major regional source in the northern margin of the Alboran Sea, where fluvial supply is provided by small seasonal rivers. To reach those goals, we analysed a data base comprising multibeam bathymetric and backscatter data, seafloor video images and Parasound acoustic sections. The studied shelf exhibits a distinctive zonation, where three major domains could be characterised. In the inner shelf, the most significant depositional bodies are composed by wedge-shaped deposits with limited lateral extent. Over the surface, several geomorphic indicators reveal the occurrence of high-energy processes in relation to the seasonal inputs of the Verde and Seco rivers. Recent to modern sedimentation seems to be much reduced distally. The middle shelf is marked by two main breaks of slopes, the surficial expression of highly reflective depositional bodies, likely marking the location of ancient paleo-shorelines and extensive development of paleo-coastal plains. The outer shelf is a flat domain covered by several elongated sedimentary bodies, which are disposed oblique to the middle shelf paleo-shorelines. Below those bodies, sub-surface architectures exhibit several unconformity-bounded regressive wedges. We discuss the shelf zonation observed in the study area considering the confinement of recent infralittoral and prodeltaic wedges to the inne