Technical note: Single-shell δ11B analysis of Cibicidoides wuellerstorfi using femtosecond laser ablation MC-ICPMS and secondary ion mass spectrometry
| Autor: | Matthieu Buisson, Markus Raitzsch, Klaus-Uwe Richter, Albert Benthien, Jelle Bijma, Ingo Horn, Grit Steinhoefel, Claire Rollion-Bard, Pascale Louvat |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Calcite
010504 meteorology & atmospheric sciences biology Chemistry Mineralogy chemistry.chemical_element biology.organism_classification 01 natural sciences Secondary ion mass spectrometry Foraminifera chemistry.chemical_compound Paleoceanography Benthic zone Abundance (ecology) 14. Life underwater Boron Inductively coupled plasma mass spectrometry 0105 earth and related environmental sciences |
| DOI: | 10.5194/bg-2020-269 |
| Popis: | The boron isotopic composition (δ11B) of benthic foraminifera provides a valuable tool to reconstruct past deep-water pH. As the abundance of monospecific species might be limited in sediments, microanalytical techniques can help to overcome this problem, but such studies on benthic foraminiferal δ11B are sparse. In addition, microanalytics provide information on the distribution of δ11B at high spatial resolution to increase the knowledge of e.g. biomineralization processes. For this study, we investigated the intra- and inter-shell δ11B variability of the epibenthic species Cibicidoides wuellerstorfi, which is widely used in paleoceanography, by secondary ion mass spectrometry (SIMS) and femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS). While the average δ11B values obtained from these different techniques agree remarkably well with bulk solution values to within ± 0.1 ‰, a relatively large intra-shell variability was observed. Based on multiple measurements within single shells, the SIMS and LA data suggest median variations of 4.8 ‰ and 1.3 ‰ (2σ), respectively, where the larger spread for SIMS is attributed to the smaller volume of calcite being analyzed in each run. When analytical uncertainties and volume-dependent differences in δ11B variations are taken into account for these methods, the intra-shell variability is presumably in the order of ~ 3 ‰ and ~ 0.4 ‰ (2σ) on a ~ 20 µm and 100 µm scale, respectively. In comparison, the δ11B variability between shells exhibits a total range of ~ 3 ‰ for both techniques, suggesting that several shells need to be analyzed for accurate mean δ11B values. Based on a simple resampling method, we conclude that ~ 7 shells of C. wuellerstorfi must be analyzed using LA-MC-ICPMS to obtain an accurate average value within ± 0.5 ‰ (2σ) to resolve pH variations of ~ 0.1. Based on our findings, we suggest to prefer the conventional bulk solution MC-ICPMS over the in-situ methods for e.g. paleo-pH studies. However, SIMS and LA provide powerful tools for high-resolution paleoreconstructions, or for investigating ontogenetic trends in δ11B, possibly due to vital effects during chamber formation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|