1986 Values for Fifteen GSJ Rock Reference Samples, “Igneous Rock Series”

Abstract

During the five‐year period (April 1981 ‐ March 1986), a series of fifteen rock reference samples, “Igneous rock series”, has been prepared by the Geological Survey of Japan (GSJ). Based on the data available (published and communicated), consensus values for major, minor and trace elements have been derived; these values are presented for this second series of samples as well as for the first series of two samples, Granodiorite JG‐1 and Basalt JB‐1.

143Nd/144Nd ratios of twelve GSJ rock reference samples and reproducibility of the data.

“…(e.g., Faure, 1986;Gromet and Silver, 1983;Henderson, 1984). As the JG-1 and JG-la standard rocks are Cretaceous in age (85 Ma) (Ando et al, 1987), the present values of '43Nd / 144Nd are expected to be different between mineral phases. If there exists difference in rela tive abundances of those minerals between ali quots of the powdered samples, a discordance would appear in Sm / Nd ratio, hence in the 143Nd/144Nd ratio .…”

“…On the other hand, five measurements of JG-1 and two measurements of JG-la gave lager uncertain ties of 0.000021 and 0.000018, respectively. Since the total blank of Nd is low as compared with the concentrations of Nd in JG-1 and JG-la (about 20 ppm: 2-3#g Nd in 100-150 mg powdered samples) (Ando et al, 1987), it is difficult to assume that the relatively larger uncer tainties for the granite samples were brought in by the blank Nd. It is generally recognized that granitic and granodioritic rocks are not easily decomposed completely by acids compared with mafic rocks (Tanaka, 1985 and others).…”

“…The chemical heterogeneity correlates with the heterogeneity in modal composition (rel ative abundances of minerals) of the powdered samples. In granitic rocks, rare earth elements (Tanaka et al, 1987), 143Nd / 144Nd = 0.512370, Crystalliza tion age=85 Ma (Ando et al, 1987). * The percentage of deviation of Sm/Nd ratio from the mean value.…”

“…The determination of isotope com positions of standard rock samples is particu larly important for checking the precision of data and for interlaboratory comparison of the data. For 87Sr/86Sr ratios of the GSJ (Geological Survey of Japan) rock reference samples, many data have been accumulated and their evaluation has been made (Ando et al, 1987;Ando and Shibata, 1988;Kagami et al, 1989). However there is not enough data for 143Nd/ 144Nd ratios of the GSJ rock reference samples.…”

87Sr/86Sr and 143Nd/144Nd ratios of GSJ rock reference samples; JB-1a, JA-1 and JG-1a.

“…As de scribed in Analytical Procedures, sample of 0.15 g was used for Sr and Nd separations. The Sr and Nd concentrations of the GSJ-RRS are taken from Table 1 of Ando et al (1987). The 87Sr / 86Sr ratio of blank is 0 .709 (Kagami et al, 1982) and the 143Nd/ 144Nd ratio is assumed based on the data of terrestrial materials corre sponding to 87Sr/86Sr=0.709 on the 87Sr/86Sr vs. 143Nd/ 144Nd diagram , which is 0.5125.…”