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Linkages between East China Sea Deep-sea Oxygenation and Variability in the East Asian Summer Monsoon and Kuroshio Current over the last 400,000 years
  • +4
  • Nishant Vats,
  • Raj K. Singh,
  • Manisha Das,
  • Ann Holbourn,
  • Anil K. Gupta,
  • Stephen John Gallagher,
  • Dhananjai Kumar Pandey
Nishant Vats
Indian Institute of Technology Bhubaneswar, Indian Institute of Technology Bhubaneswar

Corresponding Author:nv11@iitbbs.ac.in

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Raj K. Singh
Indian Institute of Technology, Bhubaneswar, Indian Institute of Technology, Bhubaneswar
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Manisha Das
Indian Institute of Technology Bhubaneswar, Indian Institute of Technology Bhubaneswar
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Ann Holbourn
Institute of Geosciences, Christian-Albrechts-University, Institute of Geosciences, Christian-Albrechts-University
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Anil K. Gupta
Indian Institute of Technology Kharagapur, Indian Institute of Technology Kharagapur
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Stephen John Gallagher
University of Melbourne, University of Melbourne
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Dhananjai Kumar Pandey
National Centre for Polar and Ocean Research, National Centre for Polar and Ocean Research
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Abstract

The East China Sea (ECS) seasonally receives a high organic input due to the terrestrial organic matter influx, which is controlled by the East Asian Summer Monsoon (EASM), and the increased productivity driven by upwelling of the subsurface Kuroshio Current (KC). Changes in benthic foraminiferal assemblage composition in combination with paleoceanographic proxy data (CaCO3 (%), TOC (%), δ13Cpf, and δ18Obf) are used to reconstruct bottom water oxygenation and organic export flux variability over the last 400 kyr in the ECS. Multivariate analyses of benthic foraminiferal census data identified six biofacies characteristic of varying environmental conditions. These results suggest that enhanced EASM precipitation and KC upwelling directly influenced organic export flux and bottom water oxygen content in the ECS. The ECS bottom water was suboxic during Marine Isotope Stage (MIS) 11 to 8; suboxic to dysoxic between MIS 7 and 6, strongly dysoxic between mid-MIS 5 and 4, and exhibited high variability between MIS 3 and 1. Spectral analysis of relative abundances of representative genera Quinqueloculina (oxic), Bulimina (suboxic), and Globobulimina (dysoxic) reveals a robust 23 kyr signal, which we attribute to precessionally-paced changes in surface productivity and bottom water oxygenation related to EASM and KC variability over the past 400 kyr.
Dec 2021Published in Paleoceanography and Paleoclimatology volume 36 issue 12. 10.1029/2021PA004261