Chemical and oxygen isotope composition of gem-quality apatites: Implications for oxygen isotope reference materials for secondary ion mass spectrometry (SIMS)

Journal article
(Original article)


Publication Details

Author(s): Sun Y, Wiedenbeck M, Joachimski M, Beier C, Kemner F, Weinzierl C
Journal: Chemical Geology
Publisher: Elsevier
Publication year: 2016
Volume: 440
Pages range: 164-178
ISSN: 0009-2541


Abstract


Oxygen isotope ratios (δO) of biogenic apatite have become a widely used tool for reconstructing palaeoenvironmental conditions in the past. Ongoing improvements in secondary ion mass spectrometry (SIMS) technology have made in situ δO analyses on sub-nanogram domains within single microfossil samples possible; however this method requires calibration with reference materials (RMs) with a matrix “similar” to that of the samples. Here we evaluated five sources of gem-quality, abiogenic apatites to assess their potentials as SIMS RMs. Our results show that all these gem-quality apatites are low-REEs calcium fluorapatites with δO values between 6.6 and 11.4‰. Large variations in δO have been found for between crystals from a single deposit as well as within individual crystals. Durango apatite has an inter-crystal δO range of 4.4‰ (6.6–11.0‰, N = 9 crystals). Madagascar Green apatite, Madagascar 1st Mine apatite and Ipira apatite have inter-crystal variations in δO of 4.1‰ (7.3–11.4‰, N = 15 crystals), 3.5‰ (7.6–11.1‰, N = 9 crystals) and 3.1‰ (7.1–10.2‰, N = 11 crystals), respectively. South Africa Blue apatite has a smaller inter-crystal δO range of only 0.9‰ (8.7–9.6‰, N = 6 crystals), though this might be an artefact due to the restricted number of samples studied. Intra-crystal δO variations of studied crystals generally range from 0.8 to 1.8‰. However, several gem apatite crystals from Madagascar have minor δO variation within 0.5‰ and represent most promising candidate RM. Gem-quality abiogenic apatites can be used as RMs for calibrating SIMS δO analyses, however these require homogeneity testing at sub-millimetre scale in advance. Durango crystals, commonly used as RMs in earlier SIMS-based studies, display a conspicuous heterogeneity in δO, with intra-crystal variations ranging from 0.7 to 2‰ as detected by both gas source isotope ratio mass spectrometry and large geometry SIMS. Thus, Durango apatite cannot be considered as suitable for SIMS calibration and alternative reference materials need to be sought.



FAU Authors / FAU Editors

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Joachimski, Michael Prof. Dr.
Lehrstuhl für Geologie (Exogene Dynamik)
Kemner, Fabian
Lehrstuhl für Endogene Geodynamik
Sun, Yadong Dr.
Lehrstuhl für Geologie (Exogene Dynamik)
Weinzierl, Christoph
Lehrstuhl für Endogene Geodynamik


External institutions
Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ)


How to cite

APA:
Sun, Y., Wiedenbeck, M., Joachimski, M., Beier, C., Kemner, F., & Weinzierl, C. (2016). Chemical and oxygen isotope composition of gem-quality apatites: Implications for oxygen isotope reference materials for secondary ion mass spectrometry (SIMS). Chemical Geology, 440, 164-178. https://dx.doi.org/10.1016/j.chemgeo.2016.07.013

MLA:
Sun, Yadong, et al. "Chemical and oxygen isotope composition of gem-quality apatites: Implications for oxygen isotope reference materials for secondary ion mass spectrometry (SIMS)." Chemical Geology 440 (2016): 164-178.

BibTeX: 

Last updated on 2018-17-11 at 20:50