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

Sun Y, Wiedenbeck M, Joachimski M, Beier C, Kemner F, Weinzierl C (2016)

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2016

Journal

Publisher: Elsevier

Book Volume: 440

Pages Range: 164-178

DOI: 10.1016/j.chemgeo.2016.07.013

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.

Authors with CRIS profile

Involved external institutions

Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ Germany (DE)

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://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: Download