Geomorphology of the northern and southern continental margins of the Iberian Peninsula: Quaternary interplay of tectonics and sedimentation

Abstract

Through a comparison of the physiography and Quaternary deposits and features of three tectonically deformed Iberian continental margins by the NW–SE convergent Eurasia-Iberian-Africa plates, we attempt to address the influence of the interplay of tectonics and sedimentation on their geomorphology. The areas include the currently active southern Iberian Alboran and Gulf of Vera margins in the SW Mediterranean and the inactive northern Iberian Cantabrian margin in the Atlantic. The margin study comprises two major physiographic compartments, the continental shelf and the distal margin, where the latter also includes the adjacent bathyal water depths. Similarities and differences are highlighted in the tectonic influences and their signatures in the sedimentary geomorphology during the Quaternary. On the continental shelf, the active or inactive onshore uplift appears to have conditioned the seafloor gradients and the preservation of the Quaternary deposits, which subsequently influenced their width. In the distal continental margin, offshore regional structural features (whether active or inactive) govern the complex and oversteepened topography, overall geometry of the sea basin, along-margin intraslope basins and regional tectonic tilting, influencing all the downslope and alongslope sedimentary processes. Thus, Quaternary tectonic processes and/or inherited morphotectonic parameters have influenced the geomorphology of shelf regressive deposits, canyons, gullies, fans, mass movement deposits, and contourites. Two types of tectonic margins based on sedimentary geomorphology are characterised: dismantled (Gulf of Vera and Cantabrian margins) and constructional (Iberian Alboran margin). This study has relevance far beyond the Iberian regional scale because it provides insights into the tectonic signatures of sedimentary geomorphology. The categorised margin types may serve as analogues for contemporary marine sedimentary basins where tectonics plays a prominent role in sediment transport, deposition, erosion, and remobilisation via their influence on both active and inactive topography.