Journal: Geostandards and Geoanalytical Research

Abbreviation

Geostand. Geoanal. Res

Publisher

Wiley

Journal Volumes

ISSN

1639-4488
1751-908X

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2016 - 201942020 - 20224
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Publications 1 - 8 of 8
  • Chemical Separation of Tungsten and Other Trace Elements for
    Item type: Journal Article
    Peters, Bradley J.; Mundl-Petermeier, Andrea; Horan, Mary F.; et al. (2019)
    Geostandards and Geoanalytical Research
  • NanoSr - A New Carbonate Microanalytical Reference Material for In Situ Strontium Isotope Analysis
    Item type: Journal Article
    Weber, Michael; Lugli, Federico; Hattendorf, Bodo; et al. (2020)
    Geostandards and Geoanalytical Research
    The in situ measurement of Sr isotopes in carbonates by MC‐ICP‐MS is limited by the availability of suitable microanalytical reference materials (RMs), which match the samples of interest. Whereas several well‐characterised carbonate reference materials for Sr mass fractions > 1000 µg g−1 are available, there is a lack of well‐characterised carbonate microanalytical RMs with lower Sr mass fractions. Here, we present a new synthetic carbonate nanopowder RM with a Sr mass fraction of ca. 500 µg g−1 suitable for microanalytical Sr isotope research (‘NanoSr’). NanoSr was analysed by both solution‐based and in situ techniques. Element mass fractions were determined using EPMA (Ca mass fraction), as well as laser ablation and solution ICP‐MS in different laboratories. The 87Sr/86Sr ratio was determined by well‐established bulk methods for Sr isotope measurements and is 0.70756 ± 0.00003 (2s). The Sr isotope microhomogeneity of the material was determined by LA‐MC‐ICP‐MS, which resulted in 87Sr/86Sr ratios of 0.70753 ± 0.00007 (2s) and 0.70757 ± 0.00006 (2s), respectively, in agreement with the solution data within uncertainties. Thus, this new reference material is well suited to monitor and correct microanalytical Sr isotope measurements of low‐Sr, low‐REE carbonate samples. NanoSr is available from the corresponding author.
  • In Situ Th-230/U-238 Geochronology of Young Volcanic Rocks on Inclusion-Bearing Ilmenite
    Item type: Journal Article
    Keller, Franziska; Guillong, Marcel; Popa, Răzvan-Gabriel; et al. (2022)
    Geostandards and Geoanalytical Research
    Precise age determinations of volcanic deposits from the Late Pleistocene and Holocene are fundamental for hazard assessment. Retrieving accurate radiogenic ages typically relies on analysing specific minerals (such as zircon or sanidine), which are in many cases lacking in the deposits. We present a new Th-230-U-238 disequilibrium dating method by LA-ICP-MS for inclusion-bearing ilmenite, and discuss its details and challenges. The technique is tested on ilmenites from the 86.4 +/- 1.1 ka Aso-4 super-eruption, Japan, and from the Lower Pumice (63.1 +/- 4.7 ka) and Upper Pumice (58.4 +/- 2.7 ka) eruptions of Nisyros volcano, Greece. Ilmenites of the Aso-4 eruption produce well-defined global isochrons yielding ilmenite crystallisation ages of 89 +/- 10 ka (2s) and 81 +/- 15 ka (2s). Two-point isochron model ages from the Nisyros eruptions produce youngest population ages of 66.3 +/- 5.7 ka (1s) for the Lower Pumice and 61.2 +/- 4.4 ka (1s) for the Upper Pumice. The age determinations obtained during this study are compatible with data reported from conventional techniques. These results demonstrate the applicability of this new method to date young volcanic deposits in a quick, reproducible way, and without relying on zircon or K-bearing phases.
  • New Methods for the Chemical Isolation and Stable Isotope Measurement of Multiple Transition Metals, with Application to the Earth Sciences
    Item type: Journal Article
    Sun, Mingzhao; Archer, Corey; Vance, Derek (2021)
    Geostandards and Geoanalytical Research
    Rapid advances in multi-collector inductively coupled plasma-mass spectrometry have made the routine, precise and accurate measurement of metal stable isotope ratios feasible, providing an opportunity to investigate past and present geochemical processes using transition metal abundances, abundance ratios and stable isotope compositions. Many studies have stressed the matrix of different controls on different metals and highlight the potential utility of studies of multiple metals on the same samples. Here we describe a new, multi-step chemical separation procedure that allows robust, and with blank contamination-free, measurements of the isotope systems of the transition metals Mo, Cu, Fe, Zn and Ni at high precision from a single sample aliquot and from a range of sample types. We test the approach via the isotopic analysis of four USGS rock reference materials: two basalts (BCR-2, BHVO-2) and two Fe-Mn nodules (Nod-A1 and Nod-P1) as well as a shale (SGR-1). The good 'reproducibility', and the agreement between measured values and reference values where available, demonstrates the validity and efficacy of our multi-step protocol. We also discuss in detail the key requirements of the approach, and the potential pitfalls that are encountered.
  • GZ7 and GZ8 - Two Zircon Reference Materials for SIMS U-Pb Geochronology
    Item type: Journal Article
    Nasdala, Lutz; Corfu, Fernando; Schoene, Blair; et al. (2018)
    Geostandards and Geoanalytical Research
    Here, we document a detailed characterisation of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.84 g) each; both came from placer deposits in the Ratnapura district, Sri Lanka. The U‐Pb data are in both cases concordant within the uncertainties of decay constants and yield weighted mean 206Pb/238U ages (95% confidence uncertainty) of 530.26 Ma ± 0.05 Ma (GZ7) and 543.92 Ma ± 0.06 Ma (GZ8). Neither GZ7 nor GZ8 have been subjected to any gem enhancement by heating. Structure‐related parameters correspond well with the calculated alpha doses of 1.48 × 1018 g−1 (GZ7) and 2.53 × 1018 g−1 (GZ8), respectively, and the (U‐Th)/He ages of 438 Ma ± 3 Ma (2s) for GZ7 and 426 Ma ± 9 Ma (2s) for GZ8 are typical of unheated zircon from Sri Lanka. The mean U mass fractions are 680 μg g−1 (GZ7) and 1305 μg g−1 (GZ8). The two zircon samples are proposed as reference materials for SIMS (secondary ion mass spectrometry) U‐Pb geochronology. In addition, GZ7 (Ti mass fractions 25.08 μg g−1 ± 0.18 μg g−1; 95% confidence uncertainty) may prove useful as reference material for Ti‐in‐zircon temperature estimates.
  • Nano‐Powdered Calcium Carbonate Reference Materials: Significant Progress for Microanalysis?
    Item type: Journal Article
    Jochum, Klaus P.; Garbe-Schönberg, Dieter; Veter, Marina; et al. (2019)
    Geostandards and Geoanalytical Research
    Homogeneity, mass fractions of about forty trace elements and Sr isotope composition of Ca carbonate reference materials (RMs) between original and nano‐powdered pellets are compared. Our results using nanosecond and femtosecond LA‐(MC)‐ICP‐MS show that the nano‐pellets of the RMs MACS‐3NP, JCp‐1NP and JCt‐1NP are about a factor of 2–3 more homogeneous than the original samples MACS‐3, JCp‐1 and JCt‐1, and are therefore much more suitable for microanalytical purposes. With the exception of Si, the mass fractions of the synthetic RM MACS‐3 agree with its fine‐grained analogue MACS‐3NP. Very small, but significant, differences between original and nano‐pellets are observed in the RMs JCp‐1 and JCt‐1 for some trace elements with very low contents, indicating the need for re‐certification. Strontium mass fractions in the analysed RMs are high (1500–7000 mg kg−1), and their isotope compositions determined by LA‐MC‐ICP‐MS in the original and the nano‐pellets agree within uncertainty limits.
  • SS14-28: An Age Reference Material for Zircon U-Th Disequilibrium Dating
    Item type: Journal Article
    Marsden, Ruby C.; Danišík, Martin; Schmitt, Axel K.; et al. (2022)
    Geostandards and Geoanalytical Research
    U-Th disequilibrium dating uses the ratio of the intermediate Th-230 daughter isotope to the U-238 parent isotope to date zircon crystallisation for volcanic and plutonic rocks in Pleistocene-Holocene deposits. It is frequently used to constrain the duration and rate of magma recharge in volcanic systems. While less than or similar to 350 ka zircon is not in secular equilibrium in the Th-230 system, the current U-Th disequilibrium methodology uses reference materials that are > 350 ka. No reference material less than or similar to 350 ka has been available to validate the accuracy of the approach and ensure methods are repeatable across laboratories. This study presents zircon SS14-28 from Jeju Island (South Korea) as a suitable reference material for U-Th disequilibrium dating. Zircon SS14-28 was analysed using two analytical approaches (SIMS and LA-ICP-MS) and four instruments: CAMECA IMS 1280, ASI SHRIMP II, sector field high-resolution LA-ICP-MS and multi-collector LA-ICP-MS, in four laboratories. These methods each individually result in isochrons gradients within uncertainty (2s) of each other (CAMECA: 0.532 +/- 0.051 (MSWD = 0.64); SF-HR-LA-ICP-MS: 0.536 +/- 0.054 (MSWD = 1.3); MC-LA-ICP-MS: 0.533 +/- 0.041 (MSWD = 0.67); SHRIMP II: 0.68 +/- 0.22 (MSWD = 0.3)). The age proposed in this study is 82 +/- 6 ka calculated from a combined isochron gradient of 0.529 +/- 0.025 (MSWD = 0.87, n = 132).
  • High-Precision Mass-Dependent Molybdenum Isotope Variations in Magmatic Rocks Determined by Double-Spike MC-ICP-MS
    Item type: Journal Article
    Willbold, Matthias; Hibbert, Kate; Lai, Yi-Jen; et al. (2016)
    Geostandards and Geoanalytical Research
    Small mass‐dependent variations of molybdenum isotope ratios in oceanic and island arc rocks are expected as a result of recycling altered oceanic crust and sediments into the mantle at convergent plate margins over geological timescales. However, the determination of molybdenum isotope data precise and accurate enough to identify these subtle isotopic differences remains challenging. Large sample sizes – in excess of 200 mg – need to be chemically processed to isolate enough molybdenum in order to allow sufficiently high‐precision isotope analyses using double‐spike MC‐ICP‐MS techniques. Established methods are either unable to process such large amounts of silicate material or require several distinct chemical processing steps, making the analyses very time‐consuming. Here, we present a new and efficient single‐pass chromatographic exchange technique for the chemical isolation of molybdenum from silicate and metal matrices. To test our new method, we analysed USGS reference materials BHVO‐2 and BIR‐1. Our new data are consistent with those derived from more involved and time‐consuming methods for these two reference materials previously published. We also provide the first molybdenum isotope data for USGS reference materials AGV‐2, the GSJ reference material JB‐2 as well as metal NIST SRM 361.
Publications 1 - 8 of 8