Trace element cartography of Globigerinoides ruber shells using particle-induced X-ray emission

Type Article
Date 2004-12-31
Language English
Author(s) Gehlen M1, Bassinot F2, Beck L3, Khodja H4
Affiliation(s) 1 : CEA Saclay, Lab Sci Climat & Environm, F-91191 Gif Sur Yvette, France.
2 : Lab Sci Climat & Environm, F-91198 Gif Sur Yvette, France.
3 : CEA Saclay, Dept Rech Etat Condense Atomes & Mol, Inst Natl Sci & Tech Nucl, Lab Etud Mat Faisceau Ions, F-91191 Gif Sur Yvette, France.
4 : CEA Saclay, Lab Pierre Sue, F-91191 Gif Sur Yvette, France.
Source Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2004-12-31 , Vol. 5 , N. 12 , P. 1-9
DOI 10.1029/2004GC000822
WOS© Times Cited 11
Keyword(s) foraminifera, Mg/Ca, dissolution, trace elements, instruments and techniques
Abstract Micro particle-induced X-ray emission (PIXE) is a nondestructive elemental analysis technique that can be used to map the distribution of elements with a spatial resolution of +/-4 mum(2) and a penetration depth of +/-2 mum in a calcite matrix. To test its potential to improve our understanding of trace element distribution in foraminifera shells, we mapped the Mg distribution across individual chambers of the planktonic species Globigerinoides ruber. G. ruber shells were picked from equatorial Atlantic surface sediments (Sierra Leone Rise). They ranged from well-preserved to heavily dissolved tests. The mapping of trace elements across test chambers made it possible to discriminate between variability inherent to the shell material and heterogeneity linked to contaminant phases. Contaminating mineral phases were characterized by high Mg concentrations (Mg/Ca = 19.7 mmol/mol) and high levels of Si, Al, and Fe. Mg/Ca values of well-preserved shells ranged from 3.9 to 4.5 mmol/mol. The Mg to Ca ratios of partially dissolved shells varied between 1.8 and 3.4 mmol/mol between outer and inner chambers. Low and homogeneous Mg/Ca values of 2.0 and 2.3 mmol/mol were determined for chambers of a severely dissolved test.
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