In situ Oxygen Isotope Determination in Serpentine Minerals by Ion Microprobe: Reference Materials and Applications to Ultrahigh-Pressure Serpentinites

Scicchitano, Maria Rosa; Rubatto, Daniela; Hermann, Jörg; Shen, Tingting; Padron-Navarta, Jose-Alberto; Williams, Ian S.; Zheng, Yong-Fei (2018). In situ Oxygen Isotope Determination in Serpentine Minerals by Ion Microprobe: Reference Materials and Applications to Ultrahigh-Pressure Serpentinites. Geostandards and Geoanalytical Research, 42(4), pp. 459-479. Wiley 10.1111/ggr.12232

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We present the first investigation of in situ oxygen isotopes in serpentine minerals by sensitive high-resolution ion microprobe (SHRIMP). Chemically homogeneous samples of antigorite (d18O = 8.30 ± 0.12‰), chrysotile (d18O = 4.37 ± 0.02‰) and lizardite (d18O = 5.26 ± 0.20‰) analysed by laser fluorination are identified as potential reference materials. They were analysed by SHRIMP to assess their homogeneity compared with the San Carlos olivine, as well as for potential matrix bias and crystal orientation effects. The reproducibility achieved for all samples was ± 0.30–0.55‰ (95% confidence level). Matrix bias between antigorite/olivine and antigorite/lizardite was up to ~ +3‰ and -1‰, respectively. Crystal orientation effects were identified only in chrysotile, and no matrix bias was observed over the investigated compositional range within each serpentine mineral. The new reference materials were used to measure the oxygen isotope composition of serpentines in an ultrahigh-pressure metamorphic belt from Tianshan (China). By combining oxygen isotopes and trace element microanalyses, several stages of serpentinisation were recognised: (a) seafloor alteration, (b) recycling of internal metamorphic fluids during isothermal decompression and (c) shallow interaction with meteoric water during exhumation. No interaction with fluids derived from the surrounding metapelites during subduction was identified.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Isotope Geology

UniBE Contributor:

Rubatto, Daniela and Hermann, Jörg

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1639-4488

Publisher:

Wiley

Language:

English

Submitter:

Daniela Rubatto

Date Deposited:

14 Dec 2018 09:27

Last Modified:

14 Dec 2018 09:27

Publisher DOI:

10.1111/ggr.12232

BORIS DOI:

10.7892/boris.121891

URI:

https://boris.unibe.ch/id/eprint/121891

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