Sea Valleys and Related Depositional Systems in the Gulf of Lion and Ebro Continental Margins (1)

Abstract

Four main types of sea valleys, submarine canyons, gullies, channels of turbidite systems, and a mid-ocean channel, have been characterized in the Ebro and the Gulf of Lion distal margins in the Catalan Sea, together with three main types of depositional bodies, Pyrenean Canyon deep-sedimentary body (PCDSB), apron deposits, and channel-levee complexes related to the development of these sea valleys. Erosion and deposition, mainly during the Quaternary, have formed the majority of these sea valleys, although some structurally controlled sea valleys also exist. As an example, a Messinian entrenchment has been confirmed in the Petit Rhone Canyon. The evolution of the drainage patterns is established from the detailed analysis of the sedimentary structure. This analysis revea s the presence of buried sedimentary bodies and older drainage systems differing from those observed in the bathymetric charts. Specific factors determine the evolutionary differences between both margins, including the absence or presence of underlying evaporitic Messinian layers and the regional geodynamic evolution during and after the Alpine orogeny. We propose a dual evolutionary model from the end of the Miocene to the Quaternary.