Quantitative chemical analyses of rocks with X-ray fluorescence analyzer: Major and trace elements in ultrabasic rocks

Abstract

Analytical procedures for major and trace elements (SiO_2, TiO_2, Al_2O_3, Fe_2O_3, MnO, MgO, CaO, Na_2O, K_2O, P_2O_5, Ba, Co, Cr, Cu, Nb, Ni, Rb, Sr, V, Y, Zn, Zr) in ultrabasic rocks by means of an X-ray fluorescnece analyzer RIGAKU RIX3000 at the National Institute of Polar Research are summarized. Because ultrabasic rocks are generally characterized by relatively low SiO_2, high MgO and FeO, and extremely high concentration of Cr, Ni and Co, we newly draw calibration curves by synthesizing standard samples. These standards were prepared by mixing preexisting geochemical standards, chemical reagents and standard solutions for atomic absorption analysis in order to cover the possible chemical compositions of natural ultrabasic rocks. For the elemental analyses, glass beads were prepared from powder samples that were diluted two times by Spectroflux No. 100B (80% LiBO_2+20% Li_2B_4O_7). The matrix correction method and the peak-over-back method were adopted for the measurements of major elements and trace elements, respectively.