Éditeur(s) : Amer Geophysical Union
Résumé : Since Last Glacial Maximum (23-19 ka), Earth climate warming and deglaciation occurred in two major steps (Bolling-Allerod and Preboreal), interrupted by a short cooling interval referred to as the Younger Dryas (12.5-11.5 ka B. P.). In this study, three cores (MV-33, MV-66, and MD-40) collected in the central part of Pandora Trough (Gulf of Papua) have been analyzed, and they reveal a detailed sedimentary pattern at millennial timescale. Siliciclastic turbidites disappeared during the Bolling-Allerod and Preboreal intervals to systematically reoccur during the Younger Dryas interval. Subsequent to the final disappearance of the siliciclastic turbidites a calciturbidite occurred during meltwater pulse 1B. The Holocene interval was characterized by a lack of siliciclastic turbidites, relatively high carbonate content, and fine bank-derived aragonitic sediment. The observed millennial timescale sedimentary variability can be explained by sea level fluctuations. During the Last Glacial Maximum, siliciclastic turbidites were numerous when the lowstand coastal system was located along the modern shelf edge. Although they did not occur during the intervals of maximum flooding of the shelf (during meltwater pulses 1A and 1B), siliciclastic turbidites reappear briefly during the Younger Dryas, an interval when sea level rise slowed, stopped, or perhaps even fell. The timing of the calciturbidite coincides with the first reflooding of Eastern Fields Reef, an atoll that remained exposed for most of the glacial stages.
Journal Of Geophysical Research-earth Surface (0148-0227) (Amer Geophysical Union), 2008-03-29 , Vol. 113 , N. F01S19 , P. 1-15

Droits : Copyright 2008 by the American Geophysical Union.
http://archimer.ifremer.fr/doc/00079/19014/16592.pdf
DOI:10.1029/2006JF000649
http://archimer.ifremer.fr/doc/00079/19014/

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/