11:00 AM - 11:15 AM
[SGL37-08] Strontium and Hydrogen Isotopes of Apatite Inclusion in Archaean Zircon
Keywords:Archaean, Strontium isotopes, Hydrogen isotopes, U-Pb dating, NanoSIMS
We collected samples from the tonalitic unit of the Nuvvuagittuq Supracrustal belt in Quebec, Canada. Extracted zircon grains from the tonalite were mounted in epoxy resin disk together with QGNG standard and polished until the mid-section was exposed. Both 238U-206Pb and 207Pb-206Pb dating was conducted by a conventional method using the NanoSIMS. For 87Sr/86Sr measurements of apatite, we focused the primary beam of 0.5 nA to 5-micron diameter. Observed data were calibrated against our standard. For D/H measurements, Cs+ ion was used as a primary beam with intensity of 200pA and a crater size of 1-micron diameter. Primary beam was rastered in a region of 10x10-micron and secondary ions from the inner part of 2.5x2.5-micron were detected.Observed D/H ratios were calibrated against our standard apatite.
Average of U-Pb and Pb-Pb ages of zircon samples are 3537+/-76 Ma and 3624+/-7 Ma, respectively, showing slightly discordant signature. For apatite inclusions in zircon, 87Sr/86Sr ratios vary from 0.7095 to 0.7153. There is a positive correlation between 87Rb/86Sr and 87Sr/86Sr ratios, suggesting either an isochron or two component mixing. D/H ratios and water contents of apatite are ranging from -210permil to 65permil and 0.15% to 1.32%, respectively. There is a positive correlation between the ratio and content, suggesting a mixing trend.