Preprints
https://doi.org/10.5194/cp-2021-144
https://doi.org/10.5194/cp-2021-144

  18 Nov 2021

18 Nov 2021

Review status: this preprint is currently under review for the journal CP.

An Intertropical Convergence Zone shift controlled the terrestrial material supply on the Ninetyeast Ridge

Xudong Xu1,2,3, Jianguo Liu1,2,4, Yun Huang1, Lanlan Zhang1,2, Liang Yi4,5, Shengfa Liu4,6, Yiping Yang1,2, Li Cao1,2,3, and Long Tan1,2,3 Xudong Xu et al.
  • 1Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China
  • 2Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
  • 3University of Chinese Academy of Science, Beijing 100049, China
  • 4Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
  • 5State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
  • 6Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China

Abstract. Among various climate drivers, direct evidence for the Intertropical Convergence Zone (ITCZ) control of sediment supply on the millennium scale is lacking, and the changes in ITCZ migration demonstrated in paleoclimate records need to be better investigated. Here, we use clay minerals and Sr-Nd isotopes obtained from a gravity core on the Ninetyeast Ridge to track the corresponding source variations and analyze the relationship between terrestrial material supplementation and climatic changes. On the glacial-interglacial scale, chemical weathering weakened during the North Atlantic cold climate periods, and falling sea level hindered the transport of smectite into the study area due to the exposure of islands. However, the influence of the South Asian monsoon on the sediment supply was not obvious on the millennium scale. We suggest that the north-south migration of the ITCZ controlled the rainfall in Myanmar and further directly determined the supply of clay minerals on the millennium scale because the transport of smectite was highly connected with ITCZ location. Furthermore, the regional shift of the ITCZ induced an abnormal increase in the smectite percentage during the late Last Glacial Maximum (LGM) in our records. The smectite percentage in the studied core is similar to distinct ITCZ records in different time periods, revealing that regional changes in the ITCZ were significantly obvious, and that the ITCZ is not a simple N-S displacement and closer connections occurred between the Northern-Southern Hemispheres in the eastern Indian Ocean during the late Last Glacial Maximum (LGM).

Xudong Xu et al.

Status: open (until 13 Jan 2022)

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Xudong Xu et al.

Xudong Xu et al.

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Short summary
Terrestrial materials in marine environments record source information and help us understand how climate and ocean impact sediment compositions. Here, we use evidences on the Ninetyeast Ridge to analyze the relationship between terrestrial material supplementation and climatic change. We find that the ITCZ controlled the rainfall in the Burman source area, and that closer connections occurred between the Northern-Southern Hemispheres in the eastern Indian Ocean during the late LGM.