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Pyrohydrolysis-IRMS determination of silicate chlorine stable isotope compositions. Application to oceanic crust and meteorite samples

Bonifacie, Magali and Jendrzejewski, Nathalie and Agrinier, Pierre and Coleman, Max and Pineau, Françoise and Javoy, Marc (2007) Pyrohydrolysis-IRMS determination of silicate chlorine stable isotope compositions. Application to oceanic crust and meteorite samples. Chemical Geology, 242 (1-2). pp. 187-201. ISSN 0009-2541. https://resolver.caltech.edu/CaltechAUTHORS:20170412-071903575

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Abstract

This contribution describes the optimization of chlorine extraction from silicate samples by pyrohydrolysis prior to the precise determination of Cl stable-isotope compositions (δ^(37)Cl) by gas source, dual inlet Isotope Ratio Mass Spectrometry (IRMS) on CH_3Clg. The complete method was checked on three international reference materials for Cl-content and two laboratory glass standards. Whole procedure blanks are lower than 0.5 μmol, corresponding to less than 10 wt.% of most of the sample chloride analysed. In the absence of international chlorine isotope rock, we report here Cl extracted compared to accepted Cl contents and reproducibilities on Cl and δ^(37)Cl measurements for the standard rocks. After extraction, the Cl contents of the three international references compared within error with the accepted values (mean yield = 94 ± 10%) with reproducibilities better than 12% (1σ). The laboratory glass standards – andesite SO100DS92 and phonolite S9(2) – were used specifically to test the effect of chloride amount on the measurements. They gave Cl extraction yields of 100 ± 6% (1σ; n = 15) and 105 ± 8% (1σ; n = 7), respectively, with δ^(37)Cl values of − 0.51 ± 0.14‰ and − 0.39 ± 0.17‰ (1σ). In summary, for silicate samples with Cl contents between 39 and 9042 ppm, the Pyrohydrolysis/HPLC method leads to overall Cl extraction yields of 100 ± 8%, reproducibilities on Cl contents of 7% and on δ^(37)Cl measurements of ± 0.12‰ (all 1σ). The method was further applied to ten silicate rocks of various mineralogy and chemistry (meteorite, fresh MORB glasses, altered basalts and serpentinized peridotites) chosen for their large range of Cl contents (70–2156 ppm) and their geological significance. δ^(37)Cl values range between − 2.33 and − 0.50‰. These strictly negative values contrast with the large range and mainly positive values previously reported for comparable silicate samples and shown here to be affected by analytical problems. Thus we propose a preliminary, revised terrestrial Cl cycle, mainly dominated by negative and zero δ^(37)Cl values.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://doi.org/10.1016/j.chemgeo.2007.03.012DOIArticle
http://www.sciencedirect.com/science/article/pii/S0009254107001313PublisherArticle
Additional Information:© 2007 Elsevier B.V. Received 24 August 2006; received in revised form 15 March 2007; accepted 20 March 2007. We wish to thank R. Malik for suggestions and comments about this work. M. Evrard and H. Lazar (Laboratoire de Géochimie des Eaux-Paris 7 and IPGP) and E. Pillet (Laboratoire de Géochimie et Métallogénie-Paris 6) are also thanked for HPLC analysis. M. Girard and J.J. Bourrand are thanked for their invaluable technical assistance. A. Godon is thanked for his relevant contribution on the installation of the “fluids preparation line”. We are also grateful to R. Hékinian, C. Laverne, S. Decitre and A. Godon for samples, and to E. Humler, A. Bézos and A. Jambon, for the microprobe standards. Z. Sharp and anonymous reviewers are thanked for reviews. University of Paris 7-Denis Diderot supported part of this work. This is the IPGP contribution number 2211 and CNRS number 398.
Funders:
Funding AgencyGrant Number
University of Paris 7-Denis DiderotUNSPECIFIED
Subject Keywords:δ^(37)Cl; reference rock; chlorine geochemical cycle; MORB; serpentinite
Issue or Number:1-2
Record Number:CaltechAUTHORS:20170412-071903575
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170412-071903575
Official Citation:Magali Bonifacie, Nathalie Jendrzejewski, Pierre Agrinier, Max Coleman, Françoise Pineau, Marc Javoy, Pyrohydrolysis-IRMS determination of silicate chlorine stable isotope compositions. Application to oceanic crust and meteorite samples, Chemical Geology, Volume 242, Issues 1–2, 30 July 2007, Pages 187-201, ISSN 0009-2541, http://doi.org/10.1016/j.chemgeo.2007.03.012. (http://www.sciencedirect.com/science/article/pii/S0009254107001313)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76528
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:12 Apr 2017 15:46
Last Modified:03 Oct 2019 17:02

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