Paleoenvironmental implications of the calcium isotope characteristics in the MD81349 from the Nintyeast Ridge in the In
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Paleoenvironmental implications of the calcium isotope characteristics in the MD81349 from the Nintyeast Ridge in the Indian Ocean WANG Feng1, FANG Nianqiao2*, HU Chaoyong3, GOLDSMITH Sarah4, XU Yonghang1, DING Xuan2, WANG Aijun1, CHEN Ping5, BAO Rui6 1 Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China 2 Institute of Marine Geology and Geophysics, China University of Geosciences (Beijing), Beijing 100083, China 3 School of Earth Sciences, China University of Geosciences, Wuhan 430074, China 4 Demo Laboratory, Ctd. MicroMass, Mantchestt M139PL, United Kingdom 5 School of Earth Science Environmental Engineering, Anhui University of Science and Technology, Huainan 232001,
China 6 Climate and Environment Sciences Laboratory of the institute Pierre Simon Laplace (LSCE), Gif sur Yvette 75000,
France Received 23 October 2017; accepted 23 March 2018 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2018
Abstract
A δ44Ca curve from shells of the planktonic foraminifera Globigerinoides sacculifer in calcareous biogenic oozes has been extracted from the Nintyeast Ridge in the Indian Ocean since 300 ka. By combining terrigenous inputs (e.g., grain size, magnetic susceptibility, and turbidite frequency) with the oceanic productivity (e.g., biogenic content and Neogloboquadrina dutertrei content), it is found that the curve’s variations are closely related to the historical evolution of the oceanic calcium cycle. The δ44Ca value is in lower tendency and has small oscillation during Marine Isotope Stage (MIS) 6, when the supply of terrigenous detrital is highest. In contrast, during MIS 3, 5 and 7, the δ44Ca values are in higher tendency, and their fluctuations are consistent with the variations of the productivity proxies. These results suggest that the calcium isotopes are mainly influenced by the input of the Himalayan erosion products to the northern Indian Ocean. In addition, the developmental stages of calcareous planktons may have a secondary impact on the fluctuations of the calcium isotope ratio of sea water. Key words: Nintyeast Ridge, calcium isotope, paleoceanography, Indian Ocean Citation: Wang Feng, Fang Nianqiao, Hu Chaoyong, Goldsmith Sarah, Xu Yonghang, Ding Xuan, Wang Aijun, Chen Ping, Bao Rui. 2018. Paleoenvironmental implications of the calcium isotope characteristics in the MD81349 from the Nintyeast Ridge in the Indian Ocean. Acta Oceanologica Sinica, 37(9): 59–66, doi: 10.1007/s13131-018-1264-7
1 Introduction The variations of light isotope ratios, such as those of oxygen and carbon, have positive correlations with paleoceanographic conditions. In contrast, calcium isotopes of the paleoenvironmental implications are not well constrained (e.g., Russell et al., 1978; Skulan et al., 1997; De La Christina and DePaolo, 2000; Farkaš et al., 2007; Griffith et al., 2008a). Calcium is an important component of the pelagic plankton shells that participate in the cycles of a lithosphere, a hydrosphere and a biosphere, however, the calcium
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