Rb-Sr concentrations were determined by replicate analyses of pressed powder pellets using X-rays fluorescence. U.S. Geological Survey rock standards were used for calibration; mass-absorption coefficients were obtained from Mo K-alpha Compton scattering measurements. Sr isotopic composition was measured on unspiked samples prepared using standard ion exchange techniques. All measurements were made on a Vacujm-Generators Isomass 54R mass spectrometer automated with a Hewlett-Packard HP-85 computer. Measured ratios were normalized to a 86Sr/88Sr ratio of 0.1194 so that the standard gives a 87Sr/86Sr raatio of 0.71020 +/- 0.00002.
Summary
Rb-Sr concentrations were determined by replicate analyses of pressed powder pellets using X-rays fluorescence. U.S. Geological Survey rock standards were used for calibration; mass-absorption coefficients were obtained from Mo K-alpha Compton scattering measurements. Sr isotopic composition was measured on unspiked samples prepared using standard ion exchange techniques. All measurements were made on a Vacujm-Generators Isomass 54R mass spectrometer automated with a Hewlett-Packard HP-85 computer. Measured ratios were normalized to a 86Sr/88Sr ratio of 0.1194 so that the standard gives a 87Sr/86Sr raatio of 0.71020 +/- 0.00002.
The coordinates are represented in North American Datum of 1927 (NAD27). Location was derived from the following method(s): Location provided in Roeske, S.M., et al., 1989, GSA Bulletin, v. 101, p. 1036