Publication Date:
2020-12-23
Description:
Highlights
• Sediment accumulation rates in Nicobar Fan abruptly increase 9.5 Ma.
• Increased sediment flux to eastern Indian Ocean and restructuring of sediment routing.
• Nicobar Fan holds significant record of Indian Ocean sedimentation in late Neogene.
• Shillong Plateau and Indo–Burmese wedge uplift drive sediment south in late Miocene.
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.
Type:
Article
,
PeerReviewed
Format:
text
DOI:
10.1016/j.epsl.2017.07.019
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