Uranium and Thorium Concentration and Isotopic Composition in Five Glass (BHVO-2G, BCR-2G, NKT-1G, T1-G, ATHO-G) and Two Powder (BHVO-2, BCR-2) Reference Materials

Abstract

Here we report uranium and thorium isotopic ratios and elemental concentrations measured in solid reference materials from the USGS (BHVO‐2G, BCR‐2G, NKT‐1G), as well as those from the MPI‐DING series (T1‐G, ATHO‐G). Specifically created for microanalysis, these naturally‐sourced glasses were fused from rock powders. They cover a range of compositions, elemental concentrations and expected isotopic ratios. The U‐Th isotopic ratios of two powdered source materials (BCR‐2, BHVO‐2) were also characterised. These new measurements via multi‐collector thermal ionisation mass spectrometry and multi‐collector inductively coupled plasma‐mass spectrometry can now be used to assess the relative performance of techniques and facilitate comparison of U‐Th data amongst laboratories in the geoscience community for in situ and bulk analyses.

A drop in Sahara dust fluxes records the northern limits of the African Humid Period

“…The basalt standards yielded 230 Th/ 232 Th activity ratios of: 0.880 ± 0.005 for BCR-2 ( n = 11, 2σ) and 1.090 ± 0.008 ( n = 6, 2σ) for BHVO-2. These values are in agreement with published values of 0.882 ± 0.002 for BCR-2 and 1.093 ± 0.002 for BHVO-2 52 .…”

Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

“…Duplicate analyses of basalt BCR-2 rock standard (N = 5) yielded a mean ( 234 U/ 238 U) activity ratio of 1.004 ± 0.004, a mean U concentration of 1.685 ± 0.003 ppm, a mean ( 230 Th/ 232 Th) activity ratio of 0.889 ± 0.031, and a mean Th concentration of 5.880 ± 0.057 ppm. These values are consistent with previously published values [33]. In order to improve the degree of certainty of the model for the growth rate, a final U-Th analysis of the outermost rind (close of the 0 age) of sample RGR1_D07_002 was conducted at the University of California, Santa Cruz W.M.…”

New Thorium Isotope Ratio Measurements in Silicate Reference Materials: A‐THO, AGV‐2, BCR‐2, BE‐N, BHVO‐2 and BIR‐1

“…We obtained a mean 230 Th/ 232 Th value of 5.862 ± 0.029 × 10 −6 (Table ), for BHVO‐2 which agrees with the single TIMS result published by Matthews et al . () and which is slightly lower than the single MC‐ICP‐MS value reported by Ruprecht and Cooper (; Figure a). The LMV AGV‐2 mean 230 Th/ 232 Th of 5.097 ± 0.020 × 10 −6 (Table ) is consistent with a recently published single MC‐ICP‐MS analysis (Eppich et al .…”

“…); M‐08 (Matthews et al . ); and R&C‐12 (Ruprecht and Cooper ). For BE ‐N and BIR ‐1, the presented data are the first ones obtained for these references materials so far.…”