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| Titel |
Ion microprobe assessment of the heterogeneity of Mg/Ca, Sr/Ca and Mn/Ca ratios in Pecten maximus and Mytilus edulis (bivalvia) shell calcite precipitated at constant temperature |
| VerfasserIn |
P. S. Freitas, L. J. Clarke, H. Kennedy, C. A. Richardson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 7 ; Nr. 6, no. 7 (2009-07-20), S.1209-1227 |
| Datensatznummer |
250003910
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| Publikation (Nr.) |
 copernicus.org/bg-6-1209-2009.pdf |
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| Zusammenfassung |
| Small-scale heterogeneity of biogenic carbonate elemental composition can be
a significant source of error in the accurate use of element/Ca ratios as
geochemical proxies. In this study ion microprobe (SIMS) profiles showed
significant small-scale variability of Mg/Ca, Sr/Ca and Mn/Ca ratios in new
shell calcite of the marine bivalves Pecten maximus and Mytilus edulis that was precipitated during a
constant-temperature culturing experiment. Elevated Mg/Ca, Sr/Ca and Mn/Ca
ratios were found to be associated with the deposition of elaborate shell
features, i.e. a shell surface stria in P. maximus and surface shell disturbance marks
in both species, the latter a common occurrence in bivalve shells. In both
species the observed small-scale elemental heterogeneity most likely was not
controlled by variable transport of ions to the extra-pallial fluid, but by
factors such as the influence of shell organic content and/or crystal size
and orientation, the latter reflecting conditions at the shell
crystal-solution interface. In the mid and innermost regions of the P. maximus shell
the lack of significant small-scale variation of Mg/Ca ratios, which is
consistent with growth at constant temperature, suggest a potential
application as a palaeotemperature proxy. Cross-growth band element/Ca ratio
profiles in the interior of bivalve shells may provide more promising
palaeo-environmental tools than sampling from the outer region of bivalve
shells. |
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