ONGOING ISOTOPIC CHARACTERIZATION OF USGS STANDARDS: MC-ICPMS AND TIMS DATA FROM THE PACIFIC CENTRE FOR ISOTOPIC AND GEOCHEMICAL RESEARCH, UNIVERSITY OF BRITISH COLUMBIA

The 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. Instrumentation 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±14 [n=100]) and TIMS (0.511849±15 [n=42]).

¹⁴³Nd/¹⁴⁴Nd values and Sm/Nd ratios of isotopically known standards, such as BCR-1 (¹⁴³Nd/¹⁴⁴Nd=0.512623±2 [Nu; n=2]; 0.512627±7 [Triton; n=8]; Sm/Nd=0.1389) and BHVO-1 (0.512972±5 [N=2]; 0.512973±6 [T=12]; 0.1522-0.1532) are within error of of published values. Replicate analyses of previously uncharacterized standards, such as AGV-1 (0.512776±4 [N=4]; 0.512781±7 [T=7]) and RGM-1 (0.512800±5[T=1]), and second generation standards, such as BCR-2 (0.512639±6 [T=3]), BHVO-2 (0.512984±3 [T=3]), and AGV-2 (0.512794±2 [T=2]), provide the first reproducible data available for these standards.

Strontium isotopic analyses of BCR-1 (⁸⁷Sr/⁸⁶Sr=0.705027±7 [T=4]) and BHVO-1 (0.703482±13 [T=6]) yield ⁸⁶Sr/⁸⁷Sr values that replicate known values. Replicate analyses of other standards, such as BCR-2 (0.705024±5 [T=3]), BHVO-2 (0.703487±9 [T=4]) and AGV-1 (0.703997±10 [T=6]) provide the first data for these standards.

Hafnium and lead isotopic analyses are underway. This investigation provides the first complete isotopic characterization of USGS standards.

Presentation Time: 1:30 PM-5:30 PM
ONGOING ISOTOPIC CHARACTERIZATION OF USGS STANDARDS: MC-ICPMS AND TIMS DATA FROM THE PACIFIC CENTRE FOR ISOTOPIC AND GEOCHEMICAL RESEARCH, UNIVERSITY OF BRITISH COLUMBIA
MAHONEY, J. Brian¹, WEIS, D.², KIEFFER, B.², FRIEDMAN, R.², PRETORIUS, W.², SCOATES, J.², GOOLAERTS, A.², and MAERSCHALK, C.³, (1) Dept. of Geology, Univ of Wisconsin, Eau Claire, WI 54792-4004, mahonej@uwec.edu, (2) Earth and Ocean Sciences, Univ of British Columbia, Vancouver, BC V6T 1Z4, bkieffer@eos.ubc.ca, (3) Université Libre de Bruxelles (ULB), Brussels The 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. Instrumentation 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±14 [n=100]) and TIMS (0.511849±15 [n=42]). ¹⁴³Nd/¹⁴⁴Nd values and Sm/Nd ratios of isotopically known standards, such as BCR-1 (¹⁴³Nd/¹⁴⁴Nd=0.512623±2 [Nu; n=2]; 0.512627±7 [Triton; n=8]; Sm/Nd=0.1389) and BHVO-1 (0.512972±5 [N=2]; 0.512973±6 [T=12]; 0.1522-0.1532) are within error of of published values. Replicate analyses of previously uncharacterized standards, such as AGV-1 (0.512776±4 [N=4]; 0.512781±7 [T=7]) and RGM-1 (0.512800±5[T=1]), and second generation standards, such as BCR-2 (0.512639±6 [T=3]), BHVO-2 (0.512984±3 [T=3]), and AGV-2 (0.512794±2 [T=2]), provide the first reproducible data available for these standards. Strontium isotopic analyses of BCR-1 (⁸⁷Sr/⁸⁶Sr=0.705027±7 [T=4]) and BHVO-1 (0.703482±13 [T=6]) yield ⁸⁶Sr/⁸⁷Sr values that replicate known values. Replicate analyses of other standards, such as BCR-2 (0.705024±5 [T=3]), BHVO-2 (0.703487±9 [T=4]) and AGV-1 (0.703997±10 [T=6]) provide the first data for these standards. Hafnium and lead isotopic analyses are underway. This investigation provides the first complete isotopic characterization of USGS standards.
2003 Seattle Annual Meeting (November 2–5, 2003)

Session No. 117--Booth# 76 Geochemistry, Aqueous (Posters) Washington State Convention and Trade Center: Hall 4-F 1:30 PM-5:30 PM, Monday, November 3, 2003 Geological Society of America Abstracts with Programs, Vol. 35, No. 6, September 2003, p. 243
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2003 Seattle Annual Meeting (November 2–5, 2003)
Paper No. 117-18