Reduced bottom water oxygenation in the northern Indian Ocean during the Last Glacial Maximum

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology Pub Date : 2024-11-19 DOI:10.1016/j.margeo.2024.107437

Kumari Nisha , Sushant Suresh Naik

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引用次数: 0

Abstract

Reconstructing variations in the past bottom water oxygenation of the oceans is crucial for understanding the current global ocean deoxygenation and increased respired carbon storage. Changes in the deep water circulation have significantly influenced the oxygenation conditions of bottom water in the past. This study tracks the changes in bottom water oxygenation and carbonate dissolution in the northern Indian Ocean for the past 25 kyr BP using a multi-proxy record of surface porosity of epifaunal benthic foraminifera Cibicidoides wuellerstorfi, foraminiferal fragmentation percentage, CaCO₃ content, size index, and authigenic uranium concentration in sediments, from a gravity core SSD-044/GC-01 recovered from a water depth of 3160 m. Results suggest that during the Last Glacial Maximum (LGM) and the Heinrich Stadial 1 (HS1), low-O₂ and CO₂-rich deep water mass existed in the northern Indian Ocean, probably due to an increased proportion of southern sourced Antarctic Bottom Water (AABW) at the core location, which indicates increased respired carbon storage in the deep water of the northern Indian Ocean, suggesting it was part of a large carbon reservoir. At the onset of the Bølling-Allerød (at around ∼14.5 kyr BP), there was an incursion of O₂-rich and CO₂-poor NADW at the core site. Furthermore, a well‑oxygenated deep water mass prevailed in the northern Indian Ocean during the Holocene.

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末次冰川极盛期印度洋北部底层水含氧量降低

重建过去海洋底层水含氧量的变化对于了解当前全球海洋脱氧和呼吸碳储存增加的情况至关重要。深水环流的变化极大地影响了过去底层水的含氧条件。本研究利用从水深 3160 米处打捞的 SSD-044/GC-01 号重力岩芯的有孔虫表面孔隙度、有孔虫碎裂率、CaCO3 含量、尺寸指数和沉积物中的自生铀浓度等多代理记录，追踪了北印度洋过去 25 千年（BP）底层水含氧量和碳酸盐溶解度的变化。结果表明，在末次冰期（LGM）和海因里希恒河1期（HS1）期间，北印度洋存在低O2和富含CO2的深层水团，这可能是由于岩芯位置的南源南极底层水（AABW）比例增加所致，表明北印度洋深层水的呼吸碳储量增加，表明它是大型碳库的一部分。在博林-阿勒勒德期开始时（大约在公元前 14.5 千年），富含 O2 和贫 CO2 的 NADW 涌入岩芯地点。此外，在全新世期间，北印度洋普遍存在含氧量高的深水区。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Marine Geology 地学-地球科学综合

CiteScore

6.10

自引率

6.90%

发文量

175

审稿时长

21.9 weeks

期刊介绍： Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.