Sedimentación cuaternaria en la plataforma y el talud continentales del Golfo de León (Mediterráneo nor-occidental). 1- parte: Estratigrafía sísmica de baja y alta resolución

Abstract

This paper is focused on the seismic stratigraphy of the Culf of Lions continental shelf and slope, off the present Rhone Delta. A low resolution multichannel seismic profile allows to divide the Plio-Quaternary section in 10 seismic units (S9-Sf0) bounded by unconformities. The Plio-Quaternary boundary has been tentatively correlated on this profile from oil-exploration wells drilled near the study area. High-resolution seismic profiles allows a more detailed analysis of the uppermost part of the sedimentary section. The continental shelf section is divided into 6 major units (A-F) bounded by unconformities.

■ These units are Quaternary in age and correlate with units 5? and S,0 on multichannel seismic records. Units B-F shows a wedge shaped geometry and reach a maximum thickness at the shelf edge. These wedge-shaped seismic units are traced onto the slope in an intercanyon area. Detailed analysis of the seismic facies on the slope shows that the sedimentary series defines cycles. Each basic cycle is composed of a couplet of two different sub-units: a lower mostly transparent sub-unit which correlates with a wedge shaped seismic unit on the shelf, and an upper mosdy layered seismic unit on the slope which correlates with an erosiona/ unconformity on the shelf. These sedimentary cycles are supposed to be related with sea-level fluctuations