Late Quaternary deep and surface water mass evolution in the northeastern Indian Ocean inferred from carbon and oxygen isotopes of benthic and planktonic foraminifera

Devendra, Dhanushka, Zhang, Lan Lan, Su, Xiang, Hewa Bandulage, Asanthi, Thilakanayaka, Vidusanka ORCID:, Zhong, Fu Chang, Yang, Yi Ping and Xiang, Rong (2020) Late Quaternary deep and surface water mass evolution in the northeastern Indian Ocean inferred from carbon and oxygen isotopes of benthic and planktonic foraminifera. Palaeoworld, 29 (4). pp. 807-818. ISSN 1871-174X

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New planktonic and benthic foraminiferal stable isotope records from core YDY05 (northeastern Indian Ocean) provide new insights into paleoceanographic changes in the northeastern Indian Ocean since the last glacial period. The distinct δ18O decrease was observed since the beginning of the deglaciation to the mid-Holocene (∼8–6 kyr BP), possibly reflecting a reduction in surface salinity in the central Bay of Bengal (BoB) water, which probably resulted from strengthened precipitation, concurrent enhanced river discharge and rising sea-level, related to the intensification of Indian Summer Monsoon (ISM). Variations in benthic δ13C and δ13CPlanktonic-Benthic in our core site reflect significant variations in source water characteristics over the LGM-Holocene. The large δ13CPlanktonic-Benthic offset during the glacial period suggests a more sluggish deep water circulation, and lower δ13CPlanktonic-Benthic from the deglaciation to the Holocene suggests an enhanced deep water circulation in the central BoB. The drastic depletion in benthic δ13C during the glacial period suggests a significant reduction of North Atlantic Deep Water (NADW) intrusion and a progressive influx of Antarctic Bottom Water (AABW) and 12C-rich Circumpolar Deep Water (CDW) into the central BoB. In contrast, since the deglaciation, the central BoB experienced a drastically increased intrusion of better ventilated and 13C-rich NADW. The differences in benthic δ18O between the LGM section and the Holocene exceeds the ice volume effect by ∼0.5‰, providing further evidence that the deep water mass of the central BoB was influenced by the less dense NADW, instead of the AABW, since the last deglaciation.

Item Type: Article
Additional Information: Funding Information: The samples used in this study were kindly made available by the shared cruise of the Natural Science Foundation of China (NSFC) (No. 41749910 ). We thank two anonymous reviewers and editors for their helpful comments and constructive suggestions. This research received financial support from the Innovative Development Fund projects of the Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences (No. ISEE2018PY02 ), the NSFC (Grant Nos. 41876063 , 41576044 , 41876056 ) and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11030104 ). Publisher Copyright: © 2020 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS
Uncontrolled Keywords: holocene,last glacial maximum,northeastern indian ocean,stable isotopes,water mass evolution,ecology, evolution, behavior and systematics,stratigraphy,palaeontology ,/dk/atira/pure/subjectarea/asjc/1100/1105
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: LivePure Connector
Date Deposited: 01 Feb 2023 15:30
Last Modified: 28 Nov 2023 02:47
DOI: 10.1016/j.palwor.2020.03.001

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