Antarctic Intermediate Water properties since 400 ka recorded in infaunal (Uvigerina peregrina) and epifaunal (Planulina wuellerstorfi) benthic foraminifera

Elmore, Aurora C. and McClymont, Erin L. and Elderfield, Henry and Kender, Sev and Cook, Michael R. and Leng, Melanie J. and Greaves, Mervyn and Misra, Sambuddha (2015) Antarctic Intermediate Water properties since 400 ka recorded in infaunal (Uvigerina peregrina) and epifaunal (Planulina wuellerstorfi) benthic foraminifera. Earth and Planetary Science Letters, 428. pp. 193-203. ISSN 0012-821X DOI 10.1016/j.epsl.2015.07.013

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Abstract

Reconstruction of intermediate water properties is important for understanding feedbacks within the ocean-climate system, particularly since these water masses are capable of driving high–low latitude teleconnections. Nevertheless, information about intermediate water mass evolution through the late Pleistocene remains limited. This paper examines changes in Antarctic Intermediate Water (AAIW), the most extensive intermediate water mass in the modern ocean through the last 400 kyr using the stable isotopic composition (δ18O and δ13C) and trace element concentration (Mg/Ca and B/Ca) of two benthic foraminiferal species from the same samples: epifaunal Planulina wuellerstorfi and infaunal Uvigerina peregrina. Our results confirm that the most reasonable estimates of AAIW temperature and Δ[CO2−3] are generated by Mg/CaU. peregrina and B/CaP. wuellerstorfi, respectively. We present a 400 kyr record of intermediate water temperature and Δ[CO2−3] from a sediment core from the Southwest Pacific (DSDP site 593; 40°30′S, 167°41′E, 1068 m water depth), which lies within the core of modern AAIW. Our results suggest that a combination of geochemical analyses on both infaunal and epifaunal benthic foraminiferal species yields important information about this critical water mass through the late Pleistocene. When combined with two nearby records of water properties from deeper depths, our data demonstrate that during interglacial stages of the late Pleistocene, AAIW and Circumpolar Deep Water (CPDW) have more similar water mass properties (temperature and δ13C), while glacial stages are typified by dissimilar properties between AAIW and CPDW in the Southwest Pacific. Our new Δ[CO2−3] record shows short time-scale variations, but a lack of coherent glacial–interglacial variability indicating that large quantities of carbon were not stored in intermediate waters during recent glacial periods.

Item Type:	Article
Additional Information:	This research used samples provided by the International Ocean Discovery Program (IODP) and we would like to thank the Kochi IODP Core Repository for help with core sampling. All previously unpublished data has been archived at: https://www.ncdc.noaa.gov/paleo/study/18918.
Uncontrolled Keywords:	2015AREP; IA69; weekly list
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems 07 - Gold Open Access
Journal or Publication Title:	Earth and Planetary Science Letters
Volume:	428
Page Range:	pp. 193-203
Identification Number:	10.1016/j.epsl.2015.07.013
Depositing User:	Sarah Humbert
Date Deposited:	06 Jan 2016 13:07
Last Modified:	27 Apr 2016 17:31
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3529

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