Integration of High and Very High-resolution Seismic Reflection Profiles to Study Upper Quaternary Deposits of a Coastal Area in the Western Gulf of Lions, SW France

Abstract

High resolution (HR – sparker) and very high resolution (VHR – boomer) seismic reflection data acquired in shallow water environments of the Roussillon coastal area are integrated to provide an accurate image of the stratigraphic architecture of the Quaternary deposits. The complementary use of the two systems is shown to be of benefit for studies of shallow water environments. The HR sparker data improved the landward part of a general model of Quaternary stratigraphy previously established offshore. They document an incised valley complex interpreted as the record of successive late Quaternary relative sea-level cycles. The complex is capped by a polygenetic erosional surface developed during the last glacial period (>18 ky) and variably reworked by wave ravinement during the subsequent post-glacial transgression. The overlying transgressive systems tract is partly preserved and presents a varying configuration along the Roussillon coastal plain. The VHR boomer data provide information on the architecture of the uppermost deposits, both in the near-shore area and in the lagoon. These deposits overlie a maximum flooding surface at the top of the transgressive systems tract and constitute a highstand systems tract composed of two different architectural elements. In the near-shore area, a sandy coastal wedge is subdivided into a lower unit and an upper unit in equilibrium with present day dynamics. In the Salses-Leucate lagoon area, the sedimentary architecture is highly complex due to the closure of a former embayment and the formation of the present beach barrier.