FN Archimer Export Format PT J TI Magnetic fabric of Bengal fan sediments: Holocene record of sedimentary processes and turbidite activity from the Ganges-Brahmaputra river system BT AF Moreno, Eva Caroir, Fabien Fournier, Lea Fauquembergue, Kelly Zaragosi, Sébastien Joussain, Ronan Colin, Christophe Blanc-Valleron, Marie-Madeleine Baudin, François de Garidel-Thoron, Thibault Valet, Jean Pierre Bassinot, Franck AS 1:1;2:2;3:3;4:3;5:3;6:4;7:4;8:5;9:6;10:7;11:8;12:9; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:; C1 Laboratoire d'Océanographie et du Climat: Expérimentations et approches numériques, UMR 7159 CNRS, IRD, Sorbonne Université/MNHN/IPSL. Boîte 100 - 4, place Jussieu, 75252 Paris cedex 05, France UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, Université Lille, CNRS, Université Littoral Côte d'Opale, F 59000 Lille, France UMR CNRS 5805 EPOC, OASU, Université de Bordeaux, Allée Geoffroy Saint-Hilaire - CS 50023, 33615 Pessac cedex, France CNRS, GEOPS, Université Paris-Saclay, 91405, Orsay, France CR2P, UMR 7207, Muséum National d'Histoire Naturelle, 43 Rue Buffon - CP38, Paris, France ISTeP - Institut des Sciences de la Terre Paris, Sorbonne Université, 4 place Jussieu, CP 117, 75005 Paris, France CNRS, IRD, Coll. de France, INRAE, CEREGE, Aix-Marseille Université, Technopôle de l'Arbois - BP80, 13545 Aix-en-Provence cedex 04, France Institut De Physique Du Globe De Paris, 1, Université de Paris, 1 rue Jussieu, 75238 Paris cedex 05, France Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France C2 LOCEAN, FRANCE UNIV LILLE, FRANCE UNIV BORDEAUX, FRANCE CNRS, FRANCE MNHN, FRANCE UNIV SORBONNE, FRANCE CNRS, FRANCE IPGP, FRANCE LSCE, FRANCE IF 3.548 TC 6 UR https://archimer.ifremer.fr/doc/00652/76388/77402.pdf https://archimer.ifremer.fr/doc/00652/76388/77802.pdf LA English DT Article CR MD 191 / MONOPOL BO Marion Dufresne DE ;Bengal fan;Holocene;Turbidite activity;Magnetic fabric;Magnetic mineralogy AB We present here a study based on the Anisotropy of Magnetic Susceptibility (AMS) and magnetic mineralogy carried out on the composite core MD17&18taken from the eastern levee of the active channel of the middle Bengal Fan in the Indian Ocean. Based on C-14 dating, the sedimentary sequence covers 9.8 ka in 39 m of sediment. It therefore records at very high resolution the variations in continental material exported to the ocean by the Ganges-Brahmaputra river system during the Holocene. This sequence was divided into two units according to turbidite activity: Unit 1 from 9.8 to 9.2 ka cal. Representing 39 m of coarse-grained turbidite sequences (coarse silts to fine sands) and extremely high sedimentation rates. Unit 2 of 9.2 ka cal. BP to the present characterized by a sharp decrease in the sedimentation rate, the presence of fine-grained turbidites characterized by strong decrease in the ln(Ti/Ca) ratio. Our AMS results indicate that the magnetic fabric is highly sensitive to the mode of deposition. The turbidite sequences are clearly characterized by very high F and Pj values, not only of the coarse-grained turbidite levels in unit 1, but also of the fine turbidites in unit 2. We suggest that this strong degree of anisotropy is the result of the strong and rapid deposition during the turbidite sequences which induces an additional compaction effect. Furthermore, LT SIRM measurements revealed that the magnetic minerals representative of the Ganges and Brahmaputra drainage area are magnetite, hematite and goethite. A higher supply in fine-grained magnetite was observed during the turbidite sequences in phase with an increase in sediment grain size. PY 2020 PD DEC SO Marine Geology SN 0025-3227 PU Elsevier BV VL 430 UT 000595643300016 DI 10.1016/j.margeo.2020.106347 ID 76388 ER EF