Mg/Ca composition of benthic foraminifera Miliolacea as a new tool of paleoceanography

Sadekov, Aleksey Yu. and Bush, Flora and Kerr, Joanna and Ganeshram, Raja and Elderfield, Henry (2014) Mg/Ca composition of benthic foraminifera Miliolacea as a new tool of paleoceanography. Paleoceanography, 29 (10). 2014PA002654. ISSN 1944-9186 DOI https://doi.org/10.1002/2014PA002654

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Abstract

The Mg/Ca compositions of benthic foraminifera from the superfamily Miliolacea have been studied to explore the use of these high-Mg foraminifera as a proxy for deep ocean conditions. Taxonomic analyses, relative abundance, and depth distributions of different Miliolacea species were carried out on a collection of core top samples, covering a depth range of 131 m to 2530 m, along the Australian coast of the Timor Sea. Pyrgo sp., composed of Pyrgo sarsi and Pyrgo murrhina, was found to be the most suitable for proxy studies. Mg/Ca values of this group of foraminifera show a strong correlation with bottom water temperatures and carbonate ion saturation described by the linear relationship: Mg/Ca = 2.53(±0.22) × BWT + 0.129(±0.023) × Δ[CO32−] + 4.63(±0.53), within the −1°C to 8°C temperature range. Absolute Mg/Ca values of Pyrgo sp. calcite and their temperature sensitivity are similar to those observed for inorganic calcite, suggesting that Mg composition of Pyrgo sp. calcite is mainly controlled by inorganic processes. The Mg/Ca composition of Pyrgo sp. calcite provides a new tool for reconstructing both water temperature and carbonate ion saturation when combined with other proxies for one of these parameters. A down core record from the Eastern Equatorial Pacific has been generated to illustrate how Mg/Ca values can be used for paleoclimate studies. This down core record shows large changes in Pacific bottom waters [CO32−] across glacial-interglacial transition, implying an increase in [CO32−] during the glacial period.

Item Type:	Article
Uncontrolled Keywords:	2014AREP; IA68;
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems 08 - Green Open Access
Journal or Publication Title:	Paleoceanography
Volume:	29
Page Range:	2014PA002654
Identification Number:	https://doi.org/10.1002/2014PA002654
Depositing User:	Sarah Humbert
Date Deposited:	22 Dec 2014 18:06
Last Modified:	25 Apr 2015 00:00
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3179

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