The Le Danois Contourite Depositional System (Cantabrian margin): a record of the MOW palaeoceanography

Abstract

We describe the morphology and Plio-Quaternary seismic stratigraphy and evolution of the Le Danois Contourite Depositional System (DCDS) in order to decode Mediterranean Outflow Water (MOW) paleoceanography. This system is composed of several drift depositional (elongated mounded and separated drifts and plastered drifts) and erosive (moats) features. The seismic stratigraphic analysis allows us to define seismic divisions at three different scales: sequences, units and subunits. The major regional discontinuities LPR (4.2 Ma), UPR (2.4 Ma) and MPR (0.9/0.92 Ma) define the three main sequences (from oldest to youngest: A1c, A1b and A1a). These sequences are characterized by different types of contouritic deposits (confined, mounded elongated and separated, and plastered drifts with superimposed sediment waves). The DCDS depositional history involved several relocations and changes in drift type. The DCDS is a consequence of MOW action. From early to middle Pleistocene, development and evolution of the DCDS was controlled by MOW interaction with the seafloor along the continental slope. From middle Pleistocene to the present-day the key factors controlling the DCDS have been: the local morphology of the margin, sediment supply and the local oceanographic behaviour of MOW