Understanding Himalayan erosion and the significance of the Nicobar Fan

Lisa C. Mcneill (1) , Brandon Dugan (2) , Jan Backman (3) , Kevin T. Pickering (4) , Hugo Pouderoux (5) , Timothy J. Henstock (1) , Katerina E. Petronotis (6) , Andrew Carter (7) , Farid Chemale Junior (8) , Kitty Milliken (9) , Steffen Kutterolf (10) , Hideki Mukoyoshi , Wenhuang Chen , Sarah Kachovich , Freya L. Mitchison , Sylvain Bourlange (11) , Tobias A. Colson , Mari Frederik , Gilles Guérin (12, 13) , Mari Hamahashi (14) , Brian M. House , Andre Hüpers , Tamara N. Jeppson , Abby R. Kenigsberg , Mebae Kuranaga , Nisha Nair , Satoko Owari , Yehua Shan , Insun Song , Marta E. Torres , Paola Vannucchi , Peter J. Vrolijk , Tao Yang (15) , Xixi Zhao , Ellen Thomas

1 NOC - National Oceanography Centre [Southampton]
2 Colorado School of Mines
3 Stockholm University
4 UCL - University College of London [London]
5 GR - Géosciences Rennes
6 Texas A&M University [College Station]
7 Department of Earth and Planetary Sciences [UCL/Birkbeck]
8 UNISINOS - Universidade do Vale do Rio dos Sinos
9 Bureau of Economic Geology
10 GEOMAR - Helmholtz Centre for Ocean Research [Kiel]
11 CRPG - Centre de Recherches Pétrographiques et Géochimiques
12 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
13 GEOTRAC - Géochrononologie Traceurs Archéométrie
14 Department of Earth and Planetary Science [Tokyo]
15 Shenyang Agricultural University

A holistic view of the Bengal–Nicobar Fan system requires sampling the full sedimentary section of the Nicobar Fan, which was achieved for the first time by International Ocean Discovery Program (IODP) Expedition 362 west of North Sumatra. We identified a distinct rise in sediment accumulation rate (SAR) beginning ∼9.5 Ma and reaching 250–350 m/Myr in the 9.5–2 Ma interval, which equal or far exceed rates on the Bengal Fan at similar latitudes. This marked rise in SAR and a constant Himalayan-derived provenance necessitates a major restructuring of sediment routing in the Bengal–Nicobar submarine fan. This coincides with the inversion of the Eastern Himalayan Shillong Plateau and encroachment of the west-propagating Indo–Burmese wedge, which reduced continental accommodation space and increased sediment supply directly to the fan. Our results challenge a commonly held view that changes in sediment flux seen in the Bengal–Nicobar submarine fan were caused by discrete tectonic or climatic events acting on the Himalayan–Tibetan Plateau. Instead, an interplay of tectonic and climatic processes caused the fan system to develop by punctuated changes rather than gradual progradation.

Mots clés: Indian Ocean; Bengal–Nicobar Fan; Asian monsoon; submarine fan; Himalayan tectonics

Domaines: Tectonique

Lisa C. Mcneill, Brandon Dugan, Jan Backman, Kevin T. Pickering, Hugo Pouderoux, et al.. Understanding Himalayan erosion and the significance of the Nicobar Fan. Earth and Planetary Science Letters, 2017, 475, pp.134-142. ⟨10.1016/j.epsl.2017.07.019⟩. ⟨insu-01579460⟩