| 1. |
- Du, Andao, et al.
(författare)
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Preparation and certification of Re-Os dating reference materials: Molybdenites HLP and JDC
- 2004
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Ingår i: Geostandards and Geoanalytical Research. - 1639-4488 .- 1751-908X. ; 28:1, s. 41-52
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Tidskriftsartikel (refereegranskat)abstract
- Two Re-Os dating reference material molybdenites were prepared. Molybdenite JDC and molybdenite HLP are from a carbonate vein-type molybdenum-(lead)-uranium deposit in the Jinduicheng-Huanglongpu area of Shaanxi province, China. The samples proved to be homogeneous, based on the coefficient of variation of analytical results and an analysis of variance test. The sampling weight was 0.1 g for JDC and 0.025 g for HLP. An isotope dilution method was used for the determination of Re and Os. Sample decomposition and pre- concentration of Re and Os prior to measurement were accomplished using a variety of methods: acid digestion, alkali fusion, ion exchange and solvent extraction. Negative thermal ionisation mass spectrometry and inductively coupled plasma-mass spectrometry were used for the determination of Re and 187Os concentration and isotope ratios. The certified values include the contents of Re and Os and the model ages. For HLP, the Re content was 283.8 ± 6.2 µg g-1, 187Os was 659 ± 14 ng g-1 and the Re-Os model age was 221.4 ± 5.6 Ma. For JDC, the Re content was 17.39 ± 0.32 µg g-1, 187Os was 25.46 ± 0.60 ng g-1 and the Re-Os model age was 139.6 ± 3.8 Ma. Uncertainties for both certified reference materials are stated at the 95% level of confidence. Three laboratories (from three countries: P.R. China, USA, Sweden) joined in the certification programme. These certified reference materials are primarily useful for Re-Os dating of molybdenite, sulfides, black shale, etc. .
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| 2. |
- Jeon, H., et al.
(författare)
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A Critical Evaluation of U–Pb Calibration Schemes Used in SIMS Zircon Geochronology.
- 2015
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Ingår i: Geostandards and Geoanalytical Research. - 1639-4488 .- 1751-908X. ; 39, s. 443-452
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Tidskriftsartikel (refereegranskat)abstract
- Precision and accuracy in SIMS zircon geochronology strongly depend on the method of determination of the interelement ion ratios (e.g., 206Pb/238U) from the measured secondary ion ratios (206Pb+/238U+). Six possible U–Pb calibrations (Pb/U–UO2/U, Pb/U–UO/U, Pb/U–UO2/UO, Pb/UO–UO2/U, Pb/UO–UO/U, Pb/UO–UO2/UO) based on simple power law relationships, and Pb/UO2-related one- and two- (a power law) dimensional ones were compared using data acquired on the 91500 zircon reference material from one hundred measurement sessions, to determine the most statistically reliable scheme. Taking advantage of U oxide species (UO and UO2) over atomic U, due to their similar energy distribution to Pb and higher intensities, the data calibrated with Pb/UO–UO2/UO showed the smallest mean uncertainties and dispersions, and provided the best-fit calibration curve consistently. Although it was demonstrated with Temora 2 that the unknown zircon age was not changed significantly by different calibrations, its precision could be improved using the Pb/UO–UO2/UO calibration in zircon geochronology.
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| 3. |
- Rodushkin, Ilya, et al.
(författare)
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Evaluation of simultaneous analyte leaching/vapour phase introduction for direct os isotope ratio measurements in solid samples by double focusing sector field ICP-MS
- 2007
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Ingår i: Geostandards and Geoanalytical Research. - 1639-4488 .- 1751-908X. ; 31:1, s. 27-38
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Tidskriftsartikel (refereegranskat)abstract
- The analytical performance of a hyphenated method for Os isotope ratio measurements by double focusing, sector field ICP-MS (ICP-SFMS) was evaluated. The method is based on several optimised, concurrent processes: Os extraction from samples in hot concentrated nitric acid; separation of Os from the digest solution by formation of volatile osmium tetroxide accelerated by continuous hydrogen peroxide addition; transport of analyte vapour by an oxygen flow into the ICP; and isotopic analysis by ICP-SFMS. Due to the very efficient analyte utilisation (in excess of 0.5‰), isotope ratio measurement can be performed at low pg Os levels. Combined with the ability to process sample sizes up to 2 g (up to 50 g if the organic matrix of biological or botanical samples is eliminated by ashing), materials with Os concentrations in the low, or even sub-pg g-1 range can be analysed by the method. Given that two complete digestion/distillation systems are available for interchangeable use, throughputs of up to 15 samples per 8-hour shift can be achieved. The method precision, evaluated as the long-term reproducibility of 187Os/188Os ratio measurements in a commercial Os standard containing 0.5 ng Os, was 0.16% relative standard deviation (RSD, 1 s). The method has been applied to perform replicate 187Os/188Os ratio measurements in a suite of 50 reference materials of various origins and matrix compositions, with Os concentrations varying from <0.1 pg g-1 to >100 ng g-1, yielding an average precision of 3% RSD. Though none of the materials tested are certified for Os content or Os isotope composition, comparison of the obtained data with published Os isotope information for similar sample types revealed close agreement between the two. The method can also be used for the simultaneous, semi-quantitative approximation of Os concentrations.
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| 4. |
- Tulej, Marek, et al.
(författare)
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CAMAM : A Miniature Laser Ablation Ionisation Mass Spectrometer and Microscope-Camera System for In Situ Investigation of the Composition and Morphology of Extraterrestrial Materials
- 2014
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Ingår i: Geostandards and Geoanalytical Research. - 1639-4488 .- 1751-908X. ; 38:4, s. 441-466
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Tidskriftsartikel (refereegranskat)abstract
- Performance studies of a microscope-camera system (MCS) and a laser ablation/ionisation mass spectrometer (LIMS) instrument (referred to here as a laser mass spectrometer or LMS) are presented. These two instruments were designed independently for in situ analysis of solids on planetary surfaces and will be combined to a single miniature instrument suite for in situ chemical and morphological analysis of surface materials on planetary bodies. LMS can perform sensitive chemical (elemental, isotope and molecular) analyses with spatial resolution close to micrometre-sized grains. It allows for studies with mass resolution (M/M) up to 800 in ablation mode (elemental composition) and up to 1500 in desorption mode (molecular analysis). With an effective dynamic range of at least eight orders of magnitude, sensitive and quantitative measurements can be conducted of almost all elements and isotopes with a concentration larger than a few ppb atoms. Hence, in addition to the major element composition, which is important for the determination of mineralogical constituents of surface materials, trace elements can also be measured to provide information on mineral formation processes. Highly accurate isotope ratio measurements can be used to determine in situ geochronology of sample material and for investigations of various isotope fractionation processes. MCS can conduct optical imagery of mm-sized objects at several wavelengths with micrometre spatial resolution for the characterisation of morphological surface details and to provide insight into surface mineralogy. Furthermore, MCS can help in the selection of sample surface areas for further mass spectrometric analysis of the chemical composition. Surface auto-fluorescence measurements and images in polarised light are additional capabilities of the MCS, to identify either fluorescing minerals or organic materials, if present on the analysed surface, for further investigation by LMS. The results obtained by investigations of NIST reference materials, amino acid films and a natural graphite sample embedded in silicate rock are presented to illustrate the performance of the instruments and their potential to deliver chemical information for mineral and organic phases in their geological context.
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| 5. |
- Alcott, Lewis J., et al.
(författare)
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Development of Iron Speciation Reference Materials for Palaeoredox Analysis
- 2020
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Ingår i: Geostandards and Geoanalytical Research. - : Wiley. - 1639-4488 .- 1751-908X. ; 44:3, s. 581-591
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Tidskriftsartikel (refereegranskat)abstract
- The development and application of geochemical techniques to identify redox conditions in modern and ancient aquatic environments has intensified over recent years. Iron (Fe) speciation has emerged as one of the most widely used procedures to distinguish different redox regimes in both the water column and sediments, and is the main technique used to identify oxic, ferruginous (anoxic, Fe(II) containing) and euxinic (anoxic, sulfidic) water column conditions. However, an international sediment reference material has never been developed. This has led to concern over the consistency of results published by the many laboratories that now utilise the technique. Here, we report an interlaboratory comparison of four Fe speciation reference materials for palaeoredox analysis, which span a range of compositions and reflect deposition under different redox conditions. We provide an update of extraction techniques used in Fe speciation and assess the effects of both test portion mass, and the use of different analytical procedures, on the quantification of different Fe fractions in sedimentary rocks. While atomic absorption spectroscopy and inductively coupled plasma-optical emission spectrometry produced comparable Fe measurements for all extraction stages, the use of ferrozine consistently underestimated Fe in the extraction step targeting mixed ferrous–ferric minerals such as magnetite. We therefore suggest that the use of ferrozine is discontinued for this Fe pool. Finally, we report the combined data of four independent Fe speciation laboratories to characterise the Fe speciation composition of the reference materials. These reference materials are available to the community to provide an essential validation of in-house Fe speciation measurements.
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| 6. |
- Axelsson, Emelie, et al.
(författare)
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Rutile R632-A New Natural Reference Material for U-Pb and Zr Determination
- 2018
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Ingår i: Geostandards and Geoanalytical Research. - : Wiley. - 1639-4488 .- 1751-908X. ; 42:3, s. 319-338
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Tidskriftsartikel (refereegranskat)abstract
- A new natural rutile reference material is presented, suitable for U-Pb dating and Zr-in-rutile thermometry by microbeam methods. U-Pb dating of rutile R632 using laser ablation ICP-MS with both magnetic sector field and quadrupole instruments as well as isotope dilution-thermal ionisation mass spectrometry yielded a concordia age of 496 +/- 2Ma. The high U content (>300gg(-1)) enabled measurement of high-precision U-Pb ages despite its young age. The sample was found to have a Zr content of 4294 +/- 196gg(-1), which makes it an excellent complementary reference material for Zr-in-rutile thermometry. Individual rutile grains have homogeneous compositions of a number of other trace elements including V, Cr, Fe, Nb, Mo, Sn, Sb, Hf, Ta and W. This newly characterised material significantly expands the range of available rutile reference materials relevant for age and temperature determinations.
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| 7. |
- Cruz-Uribe, Alicia, et al.
(författare)
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A New LA-ICP-MS Method for Ti in Quartz: Implications and Application to HP Rutile-Quartz Veins from the Czech Erzgebirge
- 2017
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Ingår i: Geostandards and Geoanalytical Research. - : Wiley. - 1639-4488 .- 1751-908X. ; 41:1
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Tidskriftsartikel (refereegranskat)abstract
- Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti-in-quartz (TitaniQ) geothermometer applicable to geological conditions up to ~ 20 kbar. We present a new method for determining 48Ti mass fractions in quartz by LA-ICP-MS at the 1 μg g−1 level, relevant to quartz in HP-LT terranes. We suggest that natural quartz such as the low-CL rims of the Bishop Tuff quartz (determined by EPMA; 41 ± 2 μg g−1 Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are insignificant, thus allowing for the use of 48Ti as a normalising mass. Average titanium mass fraction from thirty-three analyses of low temperature quartz from the Czech Erzgebirge is 0.9 ± 0.2 μg g−1 (2s) using 48Ti as a normalising mass and Bishop Tuff quartz rims as a reference material. The 2s average analytical uncertainty for individual analyses of 48Ti is 8% for 50 μm spots and 7% for 100 μm spots, which offers much greater accuracy than the 21–41% uncertainty (2s) incurred from using 49Ti as an analyte.
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| 8. |
- Gutjahr, Marcus, et al.
(författare)
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Sub‐Permil Interlaboratory Consistency for Solution‐Based Boron Isotope Analyses on Marine Carbonates
- 2021
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Ingår i: Geostandards and Geoanalytical Research. - : John Wiley & Sons. - 1639-4488 .- 1751-908X. ; 45:1, s. 59-75
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Tidskriftsartikel (refereegranskat)abstract
- Boron isotopes in marine carbonates are increasingly used to reconstruct seawater pH and atmospheric pCO2 through Earth’s history. While isotope ratio measurements from individual laboratories are often of high quality, it is important that records generated in different laboratories can equally be compared. Within this Boron Isotope Intercomparison Project (BIIP), we characterised the boron isotopic composition (commonly expressed in δ11B) of two marine carbonates: Geological Survey of Japan carbonate reference materials JCp‐1 (coral Porites) and JCt‐1 (giant clam Tridacna gigas). Our study has three foci: (i) to assess the extent to which oxidative pre‐treatment, aimed at removing organic material from carbonate, can influence the resulting δ11B; (ii) to determine to what degree the chosen analytical approach may affect the resultant δ11B, and (iii) to provide well‐constrained consensus δ11B values for JCp‐1 and JCt‐1. The resultant robust mean and associated robust standard deviation (s*) for un‐oxidised JCp‐1 is 24.36 ± 0.45‰ (2s*), compared with 24.25 ± 0.22‰ (2s*) for the same oxidised material. For un‐oxidised JCt‐1, respective compositions are 16.39 ± 0.60‰ (2s*; un‐oxidised) and 16.24 ± 0.38‰ (2s*; oxidised). The consistency between laboratories is generally better if carbonate powders were oxidatively cleaned prior to purification and measurement.
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| 9. |
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| 10. |
- Marks, Michael A. W., et al.
(författare)
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The F, Cl, Br and I Contents of Reference Glasses BHVO-2G, BIR-1G, BCR-2G, GSD-1G, GSE-1G, NIST SRM 610 and NIST SRM 612
- 2017
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Ingår i: Geostandards and Geoanalytical Research. - : Wiley. - 1639-4488 .- 1751-908X. ; 41:1, s. 107-122
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Tidskriftsartikel (refereegranskat)abstract
- Halogen contents for the widely distributed reference glasses BHVO-2G, BIR-1G, BCR-2G, GSD-1G, GSE-1G, NIST SRM 610 and NIST SRM 612 were investigated by pyrohydrolysis combined with ion chromatography, total reflection X-ray fluorescence analysis, instrumental neutron activation analysis, the noble gas method, electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. Glasses BHVO-2G, GSD-1G and GSE-1G have halogen contents that can be reproduced at the 15% level by all bulk techniques and cover a significant range in halogen mass fractions for F (~ 20–300 μg g−1), Cl (~ 70–1220 μg g−1) and Br (~ 0.2–285 μg g−1) and I (~ 9–3560 ng g−1). The BIR-1G glass has low F (< 15 μg g−1), Cl (~ 20 μg g−1), Br (15 ng g−1) and I (3 ng g−1). The halogen contents for the silica-rich NIST SRM 610 and 612 glasses were poorly reproduced by the different techniques. The relatively high Cl, Br and I abundances in glasses GSD-1G and GSE-1G mean that these glasses are well suited for calibrating spatially resolved micro-analytical studies on silicate glasses, melt and fluid inclusions. Combined EPMA and laser ablation-inductively coupled plasma-mass spectrometry data for glass GSE-1G demonstrate homogeneity at the 10% level for Cl and Br.
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