C and O isotopes in deep-sea corals (Lophelia pertusa) measured by ion microprobe
Blamart, D.; Rollion-Bard, C.; Cuif, J.P.; Juillet-Leclerc, A.; Lutringer, A.; van Weering, T.; Henriet, J.P. (2003). C and O isotopes in deep-sea corals (Lophelia pertusa) measured by ion microprobe. Erlanger Geol. Abh. Sonderband 4(109): 22 In: Erlanger Geologische Abhandlungen. Institut für Geologie der Universität Erlangen-Nürnberg: Erlangen. ISSN 0071-1160, more |
Available in | Authors | | Document type: Summary
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Authors | | Top | - Blamart, D.
- Rollion-Bard, C.
- Cuif, J.P.
- Juillet-Leclerc, A.
| - Lutringer, A.
- van Weering, T., more
- Henriet, J.P., more
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Abstract | We have determined the d18O and d13C values of azooxanthellate corals (Lophelia pertusa ) at a micrometre scale using an ion microprobe (SIMS-Secondary Ion Mass Spectrometry). Coral skeletons are composed of two different microstructures:- Centres of calcification, and
- surrounding fibres.
In Lophelia pertusa centres of calcification are large (50µm) and arranged in lines of centres of calcification. Our results show that centres of calcification in Lophelia pertusa have a restricted range of variation in d18O (-2.8 ± 0.3‰ (V-PDB)), and a larger range in d13C (14.3 to 10.9‰ (V-PDB)). Surrounding skeletal fibres exhibit large isotopic variation both for C and O (up to 12‰), and d13C and d18O are positively correlated. The C and O isotopic compositions of the centre of calcification deviate from this linear trend at the lightest d18O values of the surrounding fibres. The variation of d18O at a micrometre scale is probably the result of two processes:- An isotopic equilibrium calcification with at least 1 pH unit variation in the calcification fluid as indicated by direct measurements of coelenteron pH in the coral Galaxea fascicularis (Al-Horani et al., 2003), and
- a kinetic fractionation.
The d13 apparent disequilibrium in Lophelia pertusa may be the result of mixing between depleted d13C metabolic CO2 (respiration) and DIC coming directly from seawater. |
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