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Variability of Mg/Ca and Sr/Ca between and within the planktonic foraminifers Globigerina bulloides and Globorotalia truncatulinoides

Anand, Pallavi and Elderfield, Henry (2005). Variability of Mg/Ca and Sr/Ca between and within the planktonic foraminifers Globigerina bulloides and Globorotalia truncatulinoides. Geochemistry Geophysics Geosystems, 6(11)

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1029/2004GC000811
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Abstract

The variability in Mg/Ca and Sr/Ca within individual tests and chambers of tests, and samples consisting of differing numbers of individuals, was determined for Globigerina bulloides and Globorotalia truncatulinoides in a North Atlantic core top sample (52.918°N 16.917°W′). The variability in Mg/Ca and Sr/Ca within individual tests and chambers was determined by electron microprobe, and samples consisting of variable sample size were measured using inductively coupled plasma optical emission spectrometer (ICP-OES). Large compositional heterogeneity was found within individual chambers, and within the test as a whole, of the two species and the presence of regions with up to ∼10 mmol/mol Mg/Ca, especially in G. bulloides. Mean Mg/Ca decreases in successive chambers of G. bulloides (especially the 300–355 μm fraction) and is accompanied by decreasing variance but is not statistical significant. Sr/Ca is much more homogeneously distributed, with a normal distribution, and shows no differences from chamber to chamber. The variability of Mg/Ca and Sr/Ca decreases with increasing sample size, from single to five to twenty tests per sample, approximately as for a normal distribution, with greater variability for G. bulloides than for G. truncatulinoides, equivalent to uncertainties in temperature (n = 20) of 1.1°C and 0.7°C for the two species within the whole of the sediment mixed layer.

Item Type: Journal Article
ISSN: 1525-2027
Keywords: electron microprobe; Mg/Ca; planktonic foraminifera; sample size; single test; Sr/Ca;
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 9295
Depositing User: Pallavi Anand
Date Deposited: 01 Oct 2007
Last Modified: 02 Dec 2010 20:04
URI: http://oro.open.ac.uk/id/eprint/9295
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