Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID–TIMS, ELA–ICP–MS and oxygen isotope documentation for a series of zircon standards

Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?

“…The data were reduced in a manner similar to that described by Williams 60 . The U/Pb ratios and U-Th concentrations were calculated relative to the Temora-2 zircon standard 61 . Pb*/U (where Pb* indicates radiogenic Pb) ratios were calculated by assuming 206 Pb/ 238 U-207 Pb/ 235 U age concordance (Supplementary Table 6).…”

REE-assisted U–Pb zircon age (SHRIMP) of an anatectic granodiorite: Constraints on the evolution of the A Silva granodiorite, Iberian allochthonous complexes

“…Zircon with the most transparent habit and highest length-to-width ratios were selected to avoid inherited and metamorphic grains as much as possible. Two aliquots of A Silva-l and one of A Silva-2 were mounted separately on glass slides with a double-sided adhesive in 1 x 6 mm parallel rows together with some grains of zircon standard R33 (Black et al, 2004) and set in epoxy resin. After the resin was cured, the mounts were ground down to expose their central portions by using 1500 grit wet sandpaper and polished with 6 Jlm and 1 Jlm diamond abrasive on a lap wheel.…”

“…Data for each spot were collected utilizing five-cycle runs through the mass stations, and the counting time for 206Pb was increased according to the Paleozoic age of the samples to improve counting statistics and precision of the 206PbP38U age. The isotopic compositions were calibrated against R33 czo6Pb",/ 23 8U=0.06716, equivalent to an age of 419 Ma, Black et al, 2004) which was analyzed every fourth analysis. Calibration errors for 206PbP38U ratios of R33 for the different analytical sessions were 0.91 %, 0.64%, and 0.49% (20).…”

The Corredoiras orthogneiss (NW Iberian Massif): Geochemistry and geochronology of the Paleozoic magmatic suite developed in a peri-Gondwanan arc

“…Zircon sep aration was carried out at the Universidad Complutense (Madrid) fol lowing standard techniques, including crushing, pulverizing, sieving, Wil f ley were handpicked under a binocular microscope and representative grains were chosen in accordance with their size, length-to-breadth ratio, roundness, color, and other salient morphological features. They were mounted on a double-sided adhesive on glass slides in 1 x 6 mm parallel rows together with some chips of zircon standard R33 (Black et al, 2004). After being set in epoxy resin, the zircon grains were ground down to expose their central portions.…”

“…Five scans were collected, and the counting time for 2 06Pb was increased according to the Pal eo zoic age of the sample to improve counting statistics and precision of the 2 06PbP 3 8U age. Concentration data for zircon are standardized against zircon standard CZ3 (550 ppm U, Pidgeon et al, 1995), and isotope ratios were calibrated against R33 c z o6*Pb/238U = 0.06716, equivalent to an age of 419 Ma, Black et al, 2004) which were ana lyzed repeatedly throughout the duration of the analytical session. Data reduction follows the methods described by Ireland and Williams (2003) and Williams (1998), and SQUID (version 1.08) and ISOPLOT (version 3.00) software (Ludwig, 2002(Ludwig, , 2003 were used.…”