FN Archimer Export Format PT J TI Origin and Preservation Conditions of Organic Matter in the Mozambique Channel: Evidence for Widespread Oxidation Processes in the Deep-Water Domains BT AF Torelli, Martina Battani, Anne Pillot, Daniel Kohler, Eric De Azevedo, Joel Lopes Kowalewski, Isabelle Pastor, Lucie Brandily, Christophe Schmidt, Sabine Jouet, Gwenael Deville, Eric AS 1:1;2:1;3:1;4:1;5:1;6:1;7:2;8:2;9:3;10:4;11:1; FF 1:;2:;3:;4:;5:;6:;7:PDG-REM-EEP-LEP;8:PDG-REM-EEP-LEP;9:;10:PDG-REM-GM-LGS;11:; C1 IFP Energies Nouvelles, 1-4 Av. de Bois-Préau, 92852, Rueil-Malmaison Cedex, France IFREMER, Centre, de Bretagne, REM/EEP, Laboratoire Environnement Profond, F-29280 Plouzané, France UMR5805 EPOC, CNRS, OASU, Université de Bordeaux, 33615 Pessac, France IFREMER, Centre, de Bretagne, REM/GM, Laboratoire Cycles Géochimiques et ressources, F-29280 Plouzané, France C2 IFP ENERGIES NOUVELLES, FRANCE IFREMER, FRANCE UNIV BORDEAUX, FRANCE IFREMER, FRANCE SI BREST SE PDG-REM-EEP-LEP PDG-REM-GM-LGS IN WOS Ifremer UPR copubli-france copubli-univ-france IF 3.627 TC 1 UR https://archimer.ifremer.fr/doc/00711/82267/87058.pdf LA English DT Article CR PAMELA-MOZ01 PAMELA-MOZ04 PAMELA-MOZ08 BO L'Atalante Pourquoi pas ? Antea DE ;Organic matter;Transport;Preservation;Oxidation;Mozambique Channel;Rock-Eval;Scanning Electron Microscopy AB The Mozambique and Madagascar margins present major rivers that are responsible for the discharge of large amounts of terrestrial organic matter (OM) which can influence carbon cycling in marine environments. Therefore, the Mozambique channel represents a unique case to study the fate of the organic carbon in deep-water domains. Using a new and extensive data set of sedimentary OM collected from sediment traps, seafloor sediments and core sediments, we address the origin of the OM that is transported and deposited in the Mozambique Channel, its degradation state and preservation conditions. A Rock-Eval 6 survey allowed us to characterize the origin and amount of OM from shallow to deep-water turbidite systems, between 500 and 4400 m water depth. Rock-Eval 6 performed on suspended sediments within particle traps at 47 m above the seabed show that the OM is transported into the deep-water domain with relatively high TOC (between 1.5 and 2.5%). However, the OM is largely oxidized close to the water-sediment interface (Oxygen Index >300 mg CO2/g TOC). Seafloor sediments sampled to a maximum depth of 40 cm show lower TOC values compared to those collected from particle traps suggesting that the degradation of the OM is mainly active at the water-sediment interface. Small concentrations of OM are preserved within the recent sediments of the distal area of the Zambezi turbidite system below 2500 m water depth (TOC < 0.5%). Rock-Eval results show that core sediments from the Majunga slope (NW margin of Madagascar) and the Zambezi slope (Mozambique margin) contain the highest concentration of terrestrial OM (TOC between 1 and 2%). However, the OM within core sediments from the deep-water domain is largely oxidized and degraded, probably due to the conjugate effect of low sediment accumulation rates (SAR) and high permeabilities of the coarse-grained sediments. Consequently, the deep-water domain of the Mozambique Channel does not seem to be an important sink of terrestrial OM. This process is reinforced by important bottom water currents which induce the remobilization and transport of seafloor sediments that lead to higher oxygen exposure time in the uppermost centimeters of sediments. PY 2021 PD OCT SO Marine Geology SN 0025-3227 PU Elsevier BV VL 440 UT 000689714900025 DI 10.1016/j.margeo.2021.106589 ID 82267 ER EF