FN Archimer Export Format
PT J
TI Modern sedimentation and geochemical imprints in sediments from the NW Madagascar margin
BT 
AF Pastor, Lucie
   Brandily, Christophe
   Schmidt, S.
   Miramontes, E.
   Péron, Maela
   Appere, Dennis
   Chéron, Sandrine
   Boissier, Audrey
   Jouet, Gwenael
AS 1:1;2:1;3:2;4:3;5:1;6:1;7:4;8:4;9:5;
FF 1:PDG-REM-EEP-LEP;2:PDG-REM-EEP-LEP;3:;4:;5:PDG-REM-EEP-LEP;6:PDG-REM-EEP-LEP;7:PDG-REM-GM-LCG;8:PDG-REM-GM-LCG;9:PDG-REM-GM-LGS;
C1 IFREMER, Centre de Bretagne, REM/EEP, Laboratoire Environnement Profond, F-29280 Plouzané, France
   UMR5805 EPOC, CNRS, OASU, Université de Bordeaux, 33615 Pessac, France
   MARUM – Center for Marine and Environmental Sciences, University of Bremen, Klagenfurter Straße 2-4, Bremen 28359, Germany
   IFREMER, Centre de Bretagne, REM/GM, Laboratoire Cycles Géochimiques et Ressources, F-29280 Plouzané, France
   IFREMER, Centre de Bretagne, REM/GM, Laboratoire Géodynamique et Enregistrement Sédimentaire, F-29280 Plouzané, France
C2 IFREMER, FRANCE
   UNIV BORDEAUX, FRANCE
   UNIV BREMEN MARUM, GERMANY
   IFREMER, FRANCE
   IFREMER, FRANCE
SI BREST
SE PDG-REM-EEP-LEP
   PDG-REM-GM-LCG
   PDG-REM-GM-LGS
IN WOS Ifremer UPR
   copubli-france
   copubli-europe
   copubli-univ-france
IF 3.548
TC 4
UR https://archimer.ifremer.fr/doc/00628/73964/73323.pdf
LA English
DT Article
CR PAMELA-MOZ01
   PAMELA-MOZ04
BO L'Atalante
   Pourquoi pas ?
DE ;Episodic sedimentation;Madagascar margin;Betsiboka river;Mahavavy river;Progradation;methane;Geochemistry;Sediment
AB The NW Madagascar continental margin receives high loads of terrigenous particulate organic matter during the wet season and especially linked to extreme events, originating from two major rivers, the Betsiboka and the Mahavavy Rivers. This particulate matter contains a high content of iron minerals from the weathering of red ferruginous/ferralitic soils of Madagascar. The presence of pockmarks, i.e. gas or fluid expulsion features on the continental slope, testifies to past/present methane migration through the sedimentary column, associated with early diagenetic processes. This study globally aims at deciphering the interactions between episodic sedimentation and geochemical processes influenced by fluids upward migration, using a sediment trap mooring and interface sediment cores at two sites on the continental slope. The present-day sedimentation along this margin undergoes two patterns. During the wet season, high continental fluxes generally result in an increase in particle fluxes on the slope. Longshore currents may deflect river plumes alongslope resulting in some periods of low particle flux on the slope during the wet season. During the dry season, the particles collected in the water column are probably originated from sediment remobilization from the shelf and slope. The observed progradation of the Mahavavy River delta and prodelta between 1984 and 2016 argues for an increase in temporary connections of the river with the canyon head during extreme events, inducing pulsed sedimentation offshore. This pulsed sedimentation could be responsible for enhancing pyritization on surface sediments, due to higher inputs of terrigenous organic matter and iron oxides. Finally, methane upward migration also influences the pyritization process through anaerobic oxidation of methane using sulfate as an electron acceptor and methanotrophs associated with this reaction significantly impact the δ13C of organic carbon towards more negative values. 
PY 2020
PD AUG
SO Marine Geology
SN 0025-3227
PU Elsevier BV
VL 426
UT 000540488000001
DI 10.1016/j.margeo.2020.106184
ID 73964
ER

EF