HR: 1330h
AN: V32C-1044    [PDF]
TI: Comprehensive and systematic MC-ICP-MS/TIMS isotopic characterization of USGS Standards
AU: * Mahoney, J B
EM: mahonej@uwec.edu
AF: University of Wisconsin, Department of Geology, Eau Claire, WI 54701
AU: Weis, D
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Keiffer, B
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Hanano, D
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Williams, G
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Pretorius, W
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Barling, J
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Scoates, J
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Friedman, R
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Goolaerts, A
AF: University of British Columbia, Earth and Ocean Sciences, Vancouver, BC V6T 1Z4
AU: Mattielli, N
AF: Universit‚ Libre de Bruxelles, (ULB), Brussels, B-1050 Belgium
AU: Maerschalk, C
AF: Universit‚ Libre de Bruxelles, (ULB), Brussels, B-1050 Belgium
AB: The Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia has undertaken a systematic analysis of isotopic (Nd, Sr, Hf, Pb) composition and concentration of a broad compositional range of United States Geological Survey standards, including basalt (BCR-1, 2; BHVO-1, 2; BIR-1), dunite (DNC-1), andesite (AGV-1, 2), rhyolite (RGM-1, 2), syenite (STM-1, 2) and granite (G-2). USGS rock standards are geochemically well-characterized, but there is no systematic methodology nor database for radiogenic isotopic analyses, even for the widely used BCR-I. This investigation represents the first comprehensive, systematic analysis of the isotopic concentration and composition of USGS standards, and will provide an important database for the isotopic community. The wide range of equipment at PCIGR, including a Nu MC-ICPMS, a Triton TIMS, and an ElementII HR-ICPMS, permits a rigorous assessment and comparison of precision and accuracy in isotopic analyses. Our separation technique involves an HF/HNO3 dissolution in Teflon bombs, standard cation exchange elutriation for Sr and REE separation, and HDEHP Teflon columns for Nd separation. Samples are unspiked, and elemental concentration is determined by HR-ICPMS. Isotopic composition is determined by both thermal ionization mass spectrometry (Sr, Nd) and by multi-collector inductively coupled plasma mass spectrometry (Nd, Hf, Pb). Replicate runs of La Jolla Nd standard demonstrate excellent agreement between MC-ICPMS (143Nd/144Nd=0.511846$\pm$14 [n=100]) and TIMS (0.511850$\pm$16 [n=67]). Replicate analyses of strontium standard NBS987 yield 86Sr/87Sr values of 0.710256$\pm$15 [n=130]. Neodymium isotopic analyses (143Nd/144Nd values and Sm/Nd ratios) of previously characterized standards, such as BCR-1 (143Nd/144Nd=0.512623$\pm$2 [Nu; n=2]; 0.512627$\pm$8 [Triton; n=8]; Sm/Nd=0.1389) and BHVO-1 (0.512972$\pm$5 [Nu; n=2]; 0.512973$\pm$6 [Triton; n=14]; 0.1522-0.1532) are within error of published values. Replicate analyses of previously uncharacterized standards, such as AGV-1 (0.512776$\pm$4 [Nu; n=4]; 0.512781$\pm$7 [Triton; n=7]) and RGM-1 (0.512799$\pm$2 [Triton; n=2]), and second generation standards, such as BCR-2 (0.512639$\pm$6 [Triton; n=3]), BHVO-2 (0.512984$\pm$3 [Triton; n=3]), and AGV-2 (0.512792$\pm$1 [Triton; n=2]), provide the first reproducible data for these standards. Strontium analyses of BCR-1 (87Sr/86Sr= 0.705027$\pm$8 [Triton; n=4]) and BHVO-1 (0.703482$\pm$13 [Triton; n=6]) yield 86Sr/87Sr values that replicate known values. Replicate analyses of other standards, such as BCR-2 (0.705024$\pm$5 [Triton; n=3]), BHVO-2 (0.703487$\pm$9 [Triton; n=4]) and AGV-1 (0.703997$\pm$8 [Triton; n=7]) provide the first data for these standards. Hafnium and lead isotopic analyses on the same suite of samples are underway.
DE: 1040 Isotopic composition/chemistry
DE: 1065 Trace elements (3670)
DE: 1094 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting