Accurate and precise Re-Os molybdenite dates from the Galway Granite, Ireland. Critical comment on “Disturbance of the Re-Os chronometer of molybdenites from the late-Caledonian Galway Granite, Ireland, by hydrothermal fluid circulation” by Suzuki et al., Geochemical Journal, 35, 29-35, 2001

SAMPLES AND ANALYTICAL METHODOLOGYFor Galway Mace, the same sample used by Suzuki et al. (2001) was used here, but for Galway Murvey, a new sample was collected from the same location as the original (figure 1, location 1 and 2 of Suzuki et al., 2001).Molybdenite descriptions were not reported by Suzuki et al. (2001), and thus are given here.For Galway Mace, abundant molybdenite of 2 to 4 mm size occurs disseminated and as rosettes of ~1 cm diameter on the vein margin adjacent to alteration selvage.For Galway Murvey, minor disseminated molybdenite of 1 to 4 mm is present within the granite.A full mineral separate was obtained for each sample using conventional isolation techniques (cf., Selby et al., 2003), yielding ~2 g of molybdenite for the Galway Mace sample, and a total of 900 mg molybdenite from ~9 kg of rock for Galway Murvey.The 187 Re and 187 Os concentrations in molybdenite were determined from an aliquot (Table 1) of the mineral separate by isotope dilution mass spectrometry at the University of Alberta Radiogenic Isotope Facility using Carius tube, solvent extraction and chromatographic techniques (Selby and Creaser, 2001a).Rhenium and Os isotope ratios were measured using negative thermal ionization mass spectrometry (Creaser et al., 1991;Völkening et al., 1991) on a Micromass Sector 54 mass spectrometer using Faraday collectors.The Re-Os data for the Galway Mace and Galway Murvey molybdenite samples are presented in Table 1. RESULTSThe Re and 187 Os contents and Re-Os dates of

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.