Éditeur(s) : Elsevier Science Bv
Résumé : On the Mediterranean continental shelves the post-glacial transgressive succession is a complex picture composed by seaward progradations, related to sea level stillstands and/or increased sediment supply to the coasts, and minor flooding surfaces, associated to phases of enhanced rates of sea level rise. Among Late Pleistocene examples, major mid-shelf progradations have been related to the short-term climatic reversal of the Younger Dryas event, a period during which the combination of increased sediment supply from rivers and reduced rates of sea level rise promoted the formation of progradations up to tens-meter thick. While the documentation of coastal and subaqueous progradations recording the Younger Dryas interval are widely reported in the literature, the model of compound progradation within transgressive deposits is not proposed so far. Here we present the documentation of a deltaic system where both delta front sands and related fine-grained subaqueous progradations (prodeltaic to shallow marine) have been preserved. The Paleo Gargano Compound Delta (PGCD) formed offshore the modern Gargano Promontory (southern Adriatic Sea), and is composed by a coastal coarse-grained delta of reduced thickness and a muddy subaqueous clinoform, up to 30 meters thick. The PGCD, probably the first worldwide documentation of a compound delta within the transgressive record, provides the opportunity to investigate the processes controlling the formation of a compound delta system during an overall sea level rise and the factors that allowed its preservation. The finding of the PGCD provides the opportunity of a comparison with modern worldwide compound systems.
Marine Geology (0025-3227) (Elsevier Science Bv), 2015-04 , Vol. 362 , P. 43-59

Droits : 2015 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00250/36158/34714.pdf
DOI:10.1016/j.margeo.2015.01.010
http://archimer.ifremer.fr/doc/00250/36158/

Éditeur(s) : Elsevier
Résumé : Clinoforms on modern shelves and slopes, as well as in ancient rock records, are widely recognized as a fundamental building element of continental margin growth. Regardless of their dominant lithology, clinoforms are composed of three geometric elements: topset, foreset and bottomset. Traditionally, much emphasis in the study of clinoforms was put on the geometry of the topset, viewed as the most energetic portion of a clinoform and studied to discern if aggradation was active rather than erosional truncation, and on the foreset, the area with the highest sediment accumulation rates. Here we focus on the factors forcing clinoforms to taper out and on the inferred mechanisms for bottomset creation. We base our analysis on muddy shelf clinoforms, a particular class of clinoforms that is typical of low-gradient settings and is characterized by a substantial component of shore-parallel sediment transport. This paper is based on a large dataset of CHIRP-sonar profiles, bathymetric and isopach maps of the Late Holocene clinoform on the Adriatic shelf, where integrated stratigraphic studies from sediment cores allow a very high (in some cases century-scale) chronological resolution. Knowledge on the dominant oceanographic regime affecting sediment dispersal and, ultimately, clinoform development, has been recently refined during the EuroSTRATAFORM collaboration. Muddy clinoforms are markedly three-dimensional features that cannot be entirely understood solely on two-dimensional shore normal sections. We suggest that this class of clinoform is advection dominated and that an increase in the energy regime at the toe of the foreset may prevent sediment from reaching beyond the transition to the bottomset region.
Continental Shelf Research (0278-4343) (Elsevier), 2007-02 , Vol. 27 , N. 3-4 , P. 506-525

Droits : 2006 Elsevier Ltd All rights reserved
http://archimer.ifremer.fr/doc/2007/publication-2409.pdf
DOI:10.1016/j.csr.2006.11.013
http://archimer.ifremer.fr/doc/00000/2409/