Morfología y procesos sedimentarios recientes en dos cañones submarinos en el margen norte del Mar de Alborán

Abstract

In this work, we characterize the morphology and recent sedimentary processes of two shelf-indenting submarine canyons (Motril and Carchuna) on the northern margin of the Alboran Sea. To achieve this aim, we used multibeam bathymetric data, seafloor imagery and short sediment cores (up to 50 cm). The Carchuna Canyon is deeply incised in the shelf, as its head is located just 200 m off the coastline. It shows a straight morphology with 2 km maximum width and 226 m of maximum inci- sion. In general, muddy sands prevail along the thalweg and the canyon walls are relatively steep. In contrast, the head of the Motril Canyon is wider (4.3 km) at the shelf edge. The canyon valley exhibits a sinuous morphology with 1 km wide and 179 m of maximum incision. Its walls are gentler than the Carchuna Canyon and the surficial sediment on the canyon floor is mainly composed of muds. These geomorphological and sedimentary differences indicate that, at present, the Carchuna and Motril canyons have different dynamic behaviour. In the Motril Canyon, the higher sinuosity and the surficial sediments indi- cate a high influence of depositional processes. In contrast, the significant incision of the Carchuna Canyon and its proximity to the coastline would favour the capture of littoral drift sediments, its subsequent transport and redeposition in deep-water settings, as revealed by the occurrence of interbedded sands in the shallow sediment record.