Determination of the rare-earth element abundances in 29 international rock standards by instrumental neutron activation analysis: a critical appraisal of calibration errors

A standard additions method has been used to calibrate an in-house multi-element rock standard for the analysis of the rare-earth elements (REE), and Th, Ta, Hf and Co by instrumental neutron activation analysis. This preliminary calibration, with a precision of typically better than 7% (1sigma) has been refined by comparing our analyses of the four U.S.G.S. standard rocks AGV-1, BCR-1, G-2 and GSP-1 with compiled analyses obtained by a critical survey of over 70 published references. Our standard calibration was adjusted by the average discrepancy between our analyses and published analyses for each element for all four U.S.G.S. standards. The accuracy of this final calibration is estimated to be better than 5% absolute and it has been used to determine the above elemental abundances in 29 international rock standards. Five of the REE have been determined by interpolation from chondrite-normalised plots. (Auth.)