Sr, Nd isotopic evidence of terrigenous flux variations in the Bay of Bengal: Implications of monsoons during the last ∼34,000 years

Abstract

Sr and Nd isotopic compositions of a sediment core from the Bay of Bengal are used to constrain the provenance and transport pathways of their terrigenous component during the ∼3 to 34 14C kyr BP. The results clearly demonstrate a distinctly different source for detrital fluxes on the Ninetyeast Ridge from that of distal and western Fan sediments. There is a systematic pattern of climate‐related variability in 87Sr/86Sr and ɛNd(o) values at the studied location. Pulses of low 87Sr/86Sr, higher radiogenic Nd and high silt content occurring at ∼5–7 kyr intervals suggest significant changes in the detrital source. Increased supply of Irrawaddy‐derived sediments appears to be the dominant source for these pulses. Our results support the hypothesis that rapid cold events of North Atlantic (Heinrich events) are characterized by the intensified northeast monsoon.

Lithology, Monsoon and Sea-Surface Current Control on Provenance, Dispersal and Deposition of Sediments over the Andaman Continental Shelf

“…K is more abundant in feldspar and illite so that the variations in the K/Al ratio may reflect the variations in feldspar and illite abundances present in the sediments due to inherent source signature or due to weathering and transport. Higher K concentration shows more feldspar and illite (Colin et al, 1999;Singh et al, 2008) (Goldstein and O'Nions, 1981;Bouquillon et al, 1990;France-Lanord et al, 1993;Galy et al, 1996Galy et al, , 2010Winter et al, 1997;Pierson-Wickmann et al, 2001;Clift et al, 2002;Singh and France-Lanord, 2002;Banner, 2004;Ahmad et al, 2005Ahmad et al, , 2009Colin et al, 2006;Singh et al, 2008;Viers et al, 2008;Rahaman et al, 2011;Tripathy et al, 2011;Goswami et al, 2012;Awasthi et al, 2014;Ali et al, 2015). These isotope pairs are used as reliable proxies to track the sediment sources, as there are distinct differences in their composition in the different lithologies supplying these sediments.…”

Quaternary climate modulation of Pb isotopes in the deep Indian Ocean linked to the Himalayan chemical weathering

“…221 We also observe good agreement between sediment leachate data from SK129-CR2 222 and ODP 758 (Figures 2, 3). Since these cores are located in different settings with different 223 local sediment inputs (Ahmad et al, 2005), the effect of any detrital or volcanic 224 contamination during leaching would be expected to differ between the cores. Therefore, the 225 similarity of both temporal changes and absolute values provides independent support for the 226 reliable recovery of a regionally-controlled authigenic signature.…”

Temporal variations in 87Sr/86Sr and ɛNd in sediments of the southeastern Arabian Sea: Impact of monsoon and surface water circulation

“…The Indian subcontinent experiences two monsoons annually, the South-West (summer) and the North-East (winter) monsoons; the former being more pronounced at present. The intensities and patterns of these monsoons have varied during the past [Fleitmann et al, 2003;Gupta et al, 2003;Herzschuh, 2006], these in turn, have affected the erosion distribution of drainage basins [Clift et al, 2008;Rahaman et al, 2009] and supply of sediments to the seas around India [Ahmad et al, 2005;Colin et al, 1999;Tripathy et al, 2011]. These variations, in addition to impacting erosion, also influence the surface water circulation in the Arabian Sea and the Bay of Bengal which determine the sediment dispersal and deposition in them.…”