Ben De Mol

Recent Submarine Landslides on the Continental Slope of Storfjorden and Kveithola Trough-Mouth Fans (North West Barents Sea)

Up to 12 submarine landslides retain a morphological evidence as concave amphitheater-like depressions of various sizes on the middle and upper slope of the Storfjorden and Kveithola Trough-Mouth Fans (TMFs), NW Barents Sea. The largest of them show lateral scarps 35–40 m high that reach the continental shelf edge and cover an area of at least 1,120 km2. Submarine landslides are translational, with headwall and laterals scarps clearly cut into Last Glacial Maximum debris flows deposits. The largest landslides seem to be rooted at the base of a terrigenous/hemipelagic sedimentary unit inferred to be of Middle Weichselian age (Marine Isotopic Stage 3). Stratigraphic, lithological and geotechnical observations suggest that the rapid deposition of a thick sequence of fine-grained, high water content interlaminate plumites is the most important controlling factors in the generation of submarine landslides on the southern Storfjorden and Kveithola TMFs.

Late Miocene sedimentary architecture of the Ebro Continental Margin (Western Mediterranean): implications to the Messinian Salinity Crisis

The Messinian Salinity Crisis (MSC) resulted from a significant multi-phase drop and subsequent reflooding of the Mediterranean Sea from 5.96 to 5.33xa0Ma. Well-developed drainage networks, characterized by step-like profiles and abrasion platforms, are associated to this event. The Ebro Continental Margin (Western Mediterranean) presents an additional complexity since the capture of the drainage of the adjacent subaerial Ebro Basin took place sometime prior to the Messinian stage. Using 3D seismic reflection data, this work provides new insights into the origin of the step-like profile of the Messinian erosional surface (MES) and timing of the capture of the subaerial Ebro Basin. The results obtained indicate a sedimentary-active continental slope and delta progradation during Middle-Late Miocene, in a normal regressive context associated to a pre-Messinian proto-Ebro River. The mature development attained by the Messinian Ebro River network during the MSC corroborates that the capture of the Ebro Basin occurred prior to the MSC. The configuration of the clinoforms below the MES suggests that deltaic sediments of the Messinian Paleo-Ebro River deposited during the Tortonian and initial Messinian sea-level drawdown. The MES formed at the top of the Tortonian Highstand, where a fluvial network was deeply carved, and in the topset region of the Messinian Falling Stage Systems Tract, where minor erosion occurred. Fluvial deposits are outstandingly preserved on the main valleys of the MES. Therefore, the step-like profile of the MES was not created during Zanclean inundation, but during the latest stages of the main Messinian sea-level fall and lowstand.

Extraction of climatic signals from fossil organic compounds in marine sediments up to 11.7 Ma old (IODP-U1318)

This study focuses on the extraction of climate signals and processes using a combined approach which includes the analysis of a high number of lipid molecules in marine sediments, and the chemometric analysis of the acquired data. Neutral and acidic fractions of marine sediments from site IODP-U1318 (south-west of the UK, Porcupine Seabight) were quantified by GC-MS. The alkenone unsaturation index, U(k)37, was estimated from the composition of C37 alkenones and it was then used for the estimation of sea surface temperatures (SST) for reference. Principal component analysis (PCA), explained 77.45% of the total data variance, and differentiated neutral fraction GC-MS total ion current (TIC) profiles according to SST values of the different sediment sections. GC-MS TIC chromatograms were correlated to sea surface temperatures (SST) by partial least squares regression (PLSR). The compounds more robustly in line with SST values at each sediment section explained 93% of the SST variance and they were identified using the variable importance in projection (VIP) scores method. The proposed approach enables an objective identification of organic compounds sensitive to SST variability throughout complete chromatographic profiles. As a result of this multivariate unbiased approach, lipid composition of sediments was differentiated between compounds of marine (long chain n-alkanes, long chain n-alkan-1-ols) and terrestrial (short chain n-alkan1-ols, alkenols, cholesterol, squalene) origin, whose concentrations were directly and inversely correlated to SST, respectively.

Holocene Muddy Bedforms on the Llobregat River Prodelta Wedge

A field of sediment waves on the Llobregat River prodelta, Catalonia, Spain, is examined using high-resolution multibeam bathymetry and seismic reflection profiles. The sediment waves develop on the prodelta front on slope gradients between 3° and 0.2°, within the Late-Holocene highstand mud wedge. Their characteristics and the most likely process at the origin of these structures are evaluated.