Significance of bottom currents in deep-sea morphodynamics: An example from the Alboran Sea

Special issue The contourite log-book: significance for palaeoceanography, ecosystems and slope instability.-- Ercilla, Gemma ... et al.-- 14 pages, 8 figures, 2 tables, supplementary data https://dx.doi.org/10.1016/j.margeo.2015.09.007

We present an interdisciplinary study of the geomorphology, sedimentology and physical oceanography of the Alboran Sea (south-western Mediterranean Sea) to evaluate the potential role of bottom currents in shaping the Spanish and Moroccan continental margins and adjacent basins. Bathymetric and seismic data have allowed the recognition of the contourite deposits, including depositional (plastered, sheeted, channel-related, mounded confined, elongated and separated drifts), erosive (moats, channels and furrows) and mixed (terraces and scarps) features. Hydrographic data offer new insights into the distribution of the Mediterranean water masses, and reveal that bottom circulation of the Western Intermediate Water (WIW) and the Levantine Intermediate Water (LIW) interact with the Spanish slope, and the Western Mediterranean Deep Water (WMDW) on the Moroccan slope, Spanish base-of-slope and deep basins. The integration of distinct datasets and approaches allows a proposal of a new sedimentary model for the Alboran Sea that details the significance of bottom current processes in shaping deep-sea morphology. This model considers the bottom circulation of water masses governs physiography, that interface positions of water-masses with contrasting densities sculpt terraces on a regional scale, and that the morphologic obstacles play an essential role in the local control of processes and water-mass distributions. Our findings demonstrate the pivotal role of bottom water circulation in seafloor shaping and sedimentary stacking patterns for continental margins, establishing a new outlook for future studies of deep marine sedimentation

Funding for this research was provided by the following projects: CONTOURIBER, (CTM2008-06399-C04-04/MAR) MONTERA (CTM-2009-14157-C02-02), TOPOMED (ESF-CGL2008-03474-E/BTE), MOWER (CTM2012-39599-CO3-03), ACTIONS MARGES programme (TOTAL, CNRS-INSU, Ifremer, BRGM), EUROFLEETS (FP7/2007–2013; #228344), and IGCP 619. This work was partially supported by the Continental Margins Group (GMC). This work was also partially supported by the Contourite Research Group at Royal Holloway University of London (UK)

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