Oxygen isotope measurements of terrestrial silicates using a CO2-laser BrF5 fluorination technique and the slope of terrestrial fractionation line

Here we report oxygen isotopic compositions (both delta O-18 and delta O-17) of San Carlos olivine, Juan de Fuca basalt glass, garnet standard at University of Wisconsin (UWG-2 garnet), National Bureau of standard #28 quartz (NBS-28 quartz), a hydrothermal quartz from China (CQ4 quartz), chert flint standard and a serpentine measured with a CO2-laser BrF5 fluorination system installed at Korea Polar Research Institute. In addition we measured VSMOW (Vienna standard mean ocean water) and SLAP (standard light Antarctic precipitation) with the same line; a scaling factor of 1.056 was obtained to fit the measured SLAP data to the recommended value of delta O-18(SMOW) = -55.5aEuro degrees. All the other data were corrected using the VSMOW-SLAP scaling factor. Majority of the samples in this work have been measured by several laboratories; our data in general agree very well with previous data. We report data using the delta prime notation, since linearity of a mass-dependent fractionation line holds in delta'O-17 vs. delta'O-18 diagram for wide range of oxygen isotopic compositions. Average delta'O-18 values and 2 sigma standard error of means are 5.27 +/- 0.04aEuro degrees for San Carlos olivine, 5.49 +/- 0.02aEuro degrees for Juan de Fuca basalt glass, 5.73 +/- 0.05aEuro degrees for UWG-2 garnet, 9.18 +/- 0.08aEuro degrees for NBS-28 quartz, 23.14 +/- 0.36aEuro degrees for CQ4 quartz, 33.97 +/- 0.16aEuro degrees for chert flint standard and 0.78 +/- 0.07aEuro degrees for the serpentine. Slope of terrestrial fractionation was obtained using these data, which is 0.5248 +/- 0.0003 (R-2 = 0.99992).