Chapligin B. auteur aut IRD Leng M. J. auteur aut IRD Webb E. auteur aut IRD Alexandre A. auteur aut IRD Dodd J. P. auteur aut IRD Ijiri A. auteur aut IRD Lucke A. auteur aut IRD Shemesh A. auteur aut IRD Abelmann A. auteur aut IRD Herzschuh U. auteur aut IRD Longstaffe F. J. auteur aut IRD Meyer H. auteur aut IRD Moschen R. auteur aut IRD Okazaki Y. auteur aut IRD Rees N. H. auteur aut IRD Sharp Z. D. auteur aut IRD Sloane H. J. auteur aut IRD Sonzogni C. auteur aut IRD Swann G. E. A. auteur aut IRD Sylvestre Florence auteur aut IRD Tyler J. J. auteur aut IRD Yam R. auteur aut IRD text journalArticle eng text/pdf born digital access Several techniques have been introduced in the last decades for the dehydration and release of O-2 from biogenic silica (opal-A) for oxygen-isotope analysis. However, only one silica standard is universally available: a quartz standard (NBS28) distributed by the IAEA, Vienna. Hence, there is a need for biogenic silica working standards. This paper compares the existing methods of oxygen-isotope analyses of opal-A and aims to characterize additional possible working standards to calibrate the delta O-18 values of biogenic silica. For this purpose, an inter-laboratory comparison was organized. Six potential working standard materials were analysed repeatedly against NBS28 by eight participating laboratories using their specific analytical methods. The materials cover a wide range of delta O-18 values (+23 to +43 parts per thousand) and include diatoms (marine, lacustrine), phytoliths and synthetically-produced hydrous silica. To characterize the proposed standards, chemical analyses and imaging by scanning electron microscopy (SEM) were also performed. Despite procedural differences at each laboratory, all methods are in reasonable agreement with a standard deviation (SD) for delta O-18 values between 0.3 parts per thousand and 0.9 parts per thousand (1 sigma). Based on the results, we propose four additional biogenic silica working standards (PS1772-8: 42.8 parts per thousand; BFC: 29.0 parts per thousand; MSG60: 37.0 parts per thousand; G95-25-CL leaves: 36.6 parts per thousand) for delta O-18 analyses, available on request through the relevant laboratories. specialized 064 75 22 7242-7256 2011 0016-7037 https://www.documentation.ird.fr/hor/fdi:010054158 10.1016/j.gca.2011.08.011 0016-7037 [F B010054158] https://www.documentation.ird.fr/hor/fdi:010054158 https://www.documentation.ird.fr/intranet/publi/2011/11/010054158.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2011-11-30 2017-08-23 fdi:010054158 fre