Variability of Shelf Growth Patterns along the Iberian Mediterranean Margin: Sediment Supply and Tectonic Influences

Abstract

Clinoform depositional features along the Iberian Mediterranean margin are investigated in this study, with the aim of establishing the causes of their varied shapes and other characteristics. We have analyzed the broad-scale margin physiography and seismic stratigraphic patterns based on high-resolution bathymetric data and previously interpreted seismic data. In addition, we have evaluated regional supply conditions and the uplift-subsidence regime of the different shelf sectors. The upper Quaternary record is strongly dominated by shelf-margin regressive wedges affected by the prevailing 100 ka cyclicity. However, the margins exhibit considerable lateral variability, as the result of the balance between the amount of sediment supply and the uplift-subsidence relationship. Three major shelf sectors with distinct morpho-sedimentary features have been defined. The relatively narrow northern shelves (Roses, La Planassa and Barcelona) are supplied by discrete river outlets that collectively constitute a linear source and are mainly affected by tectonic tilting. The wide middle shelves (Ebro Shelf, the Gulf of Valencia, and the Northern Arc) receive the sediment supply from the large Ebro River and other medium rivers. Although the tectonic regime changes laterally (strong subsidence in the north and uplift in the south), shelf growth is maintained by lateral advection of sediments. The southern shelves (the Southern Arc and the northern Alboran Shelf) are very abrupt and narrow because of the uplifting Betic Cordillera, and the torrential fluvial regimes that determine a very efficient sediment by-pass toward the deep basin. Submarine canyons deeply incised in the continental margin constitute a key physiographic feature that may enhance the transport of sediment to the deep sea or individualize shelf sectors with specific sedimentation patterns, as occurs in the Catalan margin.

Krill spatial distribution in the Spanish Mediterranean Sea in summer time

“…Krill distributions have been associated with frontal zones (Tarling et al, 1995) and submarine canyons (Santora et al, 2018), which represent regions of enrichment (Howatt and Allen, 2013). In our study area, the krill presence observed along the shelf edge in the Balearic Sea can be explained by the North Current front position, while in Alboran Sea by the upwelling from the submarine canyons due to the specific orographic and oceanographic characteristics (Robinson et al, 2001;Oguz et al, 2014;Durán et al, 2018). North Current variability is mainly related to intensity and wind direction (Berta et al, 2018); moreover, North Current front displacement toward the continental shelf has been described in the Gulf of Lyon (Barrier et al, 2016), and it can favor krill detection during the MEDIAS over the continental shelf.…”

“…In the Northern sector, from Cape Creus to Ebro Delta, the continental shelf width is highly variable, ranging between 9.5 and 41 km, and submarine canyon is present. In the middle sector, from Ebro Delta to Cape Palos, the shelf ranges between 43 and 92 km (Durán et al, 2018). On the other hand, the predominant circulation pattern in the Alboran Sea within the upper 150-200 m involves an incoming meandering buoyant Atlantic jet through the Strait of Gibraltar (Renault et al, 2012;Oguz et al, 2014).…”

“…On the other hand, the predominant circulation pattern in the Alboran Sea within the upper 150-200 m involves an incoming meandering buoyant Atlantic jet through the Strait of Gibraltar (Renault et al, 2012;Oguz et al, 2014). The shelf in the Alboran Sea constitutes the Southern sector of the Spanish shelf, and it is characterized by a very narrow margin, ranging between 0.7 and 17 km, and locally dissected by submarine canyons (Durán et al, 2018). The confluence of the saltier surface water that has stayed longer in the Mediterranean Sea (salinity > 37.5) and the fresher water recently arrived through the Strait of Gibraltar (salinity < 37.5) generate a salinity-driven oceanic front called Balearic Front (Lopez Garcia et al, 1994;Balbín et al, 2014).…”

A Quantitative Evaluation of Hyperpycnal Flow Occurrence in a Temperate Coastal Zone: The Example of the Salerno Gulf (Southern Italy)

“…The accuracy in fact improves when it is applied to cores retrieved in deeper waters (30-70 m of depth), for which a SE error of the S/M Depth experimental relation ranges between 0.03 and 0.006 (green line narrowing with depth-Figure 9). Moreover, in this depth range, the shelf profile often provides a natural morphological bowl to accommodate sediments, preventing post-depositional erosional processes [92,93].…”