Shift in detrital sedimentation in the eastern Bay of Bengal during the late Quaternary

Journal of Earth system science

J N Pattan1²  P Govil4¹  D K Ray2⁴  N Basavaiah3³  K Dutta2⁴  C Prakash Babu1²  G V Ravi Prasad2⁴ 

[1] National Centre for Antarctic and Ocean Research, Headland Sada, Vasco 403 804, Goa, India.$$;National Institute of Oceanography (CSIR), Dona Paula 403 004, Goa, India.$$;Indian Institute of Geomagnetism, Kalamboli, New Panvel, Navi Mumbai 410 218, India.$$;AMS Radiocarbon Laboratory, Institute of Physics, Bhubaneswar 751 005, Orissa, India.$$

关键词: Bay of Bengal;    sediment core;    calcium carbonate;    dilution;    detrital;    biogenic;    turbidite;    Ganges–Brahmaputra.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Down-core variations of granulometric, geochemical and mineral magnetism of a 70-cm long sediment core retrieved from the eastern Bay of Bengal abyssal region were studied to understand sedimentation pattern and sediment provenance during the last ∼12 kyr BP. Based on down-core physical and elemental variations, three units were identified: unit 3 (70–43 cm) is a ∼30 cm thick clayey silt organic carbon-rich (0.5–0.92%) turbidite probably delivered by the Brahmaputra River during the late Quaternary period. Units 2 (43–24 cm) and 1 (24–0 cm) represent enhanced and reduced supply of coarse-grained detrital sediments from the Ganges River during early and late Holocene period, respectively. Increased terrigenous supply dilutes calcium carbonate (CaCO3) and biogenic elements (P, Ba and Cu) in units 3 and 2. On the contrary, a reduction in detrital input enhances CaCO3 and biogenic elements in unit 1. Lithogenic elements (Ti, Al, K and Rb) and shale-normalized REE patterns in all three units suggest terrigenous source. The shift in provenance from the Brahmaputra to the Ganges derived sediments is evident by a sharp increase in sediment grain size, increased concentration and grain size assemblages of magnetic minerals, lithogenic elements concentration and Lan/Ybn ratio. This study highlights terrigenous dilution on biogenic sedimentation in the eastern Bay of Bengal sediments.

【 授权许可】

Unknown