Showing papers in "Geostandards and Geoanalytical Research in 2022"
TL;DR: In this article , the authors proposed to use a range of geologically relevant initial 87Sr/86Sr compositions rather than one fixed value: (1) 0.703 ± 0.003 (for mantle derived magmatic rocks), (2)0.715 ±0.015 (for evolved magmatic mines), and (3) 0.,730 ± 0.,030 (for crustal mines).
Abstract: Due to developments in reaction cell technologies, it is now possible to collect large 87Rb/86Sr and 87Sr/86Sr data sets using LA-ICP-MS/MS. Until now, LA-ICP-MS/MS Rb-Sr ages were constrained using conventional isochrons on a contiguous set of Rb-Sr data. In this contribution, we present a straightforward procedure on how to measure, calculate and validate Rb-Sr ages from individual laser spots even from detrital grains devoid of context. This approach does not only allow provenance studies of detrital micas, but also furthermore opens the opportunity to produce age maps with unprecedented spatial resolution, both for zoned single crystals and targeting different textural domains. The main challenge for calculating single-spot Rb-Sr ages is the estimation of the initial 87Sr/86Sr composition, if it cannot be constrained through analysis of a paragenetic phase. In this case, we propose to use a range of geologically relevant initial 87Sr/86Sr compositions rather than one fixed value: (1) 0.703 ± 0.003 (for mantle derived magmatic rocks), (2) 0.715 ± 0.015 (for evolved magmatic rocks) and (3) 0.730 ± 0.030 (for crustal rocks). Modelling shows that the 87Sr/86Sr ratio of the targeted material delineates the accuracy and precision of single-spot Rb-Sr ages. If the measured Sr isotopic composition is sufficiently radiogenic [87Sr/86Sr of > 1.0 for scenario (1) to > 4.5 for scenario (3)], the calculated age and its uncertainty are not significantly influenced by the initial 87Sr/86Sr composition. Using Mica-Mg as the primary reference material, single-spot Rb-Sr dating was tested on biotite (Mount Dromedary, La Posta, McClure Mountain), muscovite (Högsbo) and a nano-powder tablet (Mica-Fe) that we further propose using as secondary reference materials for Rb-Sr geochronology.
12 citations
TL;DR: The AusGeochem platform as discussed by the authors is an open, cloud-based data repository and a data analysis tool for geochemical data, which can be used to preserve, disseminate and collate geochronology and isotopic data.
Abstract: To promote a more efficient and transparent geochemistry data ecosystem, a consortium of Australian university research laboratories called the AuScope Geochemistry Network assembled to build a collaborative platform for the express purpose of preserving, disseminating and collating geochronology and isotopic data. In partnership with geoscience‐data‐solutions company Lithodat Pty Ltd, the open, cloud‐based AusGeochem platform (https://ausgeochem.auscope.org.au) was developed to simultaneously serve as a geosample registry, a geochemical data repository and a data analysis tool. Informed by method‐specific groups of geochemistry experts and established international data reporting practices, community‐agreed database schemas were developed for rock and mineral geosample metadata and secondary ion mass spectrometry U‐Pb analysis, with additional models for laser ablation‐inductively coupled‐mass spectrometry U‐Pb and Lu‐Hf, Ar‐Ar, fission‐track and (U‐Th‐Sm)/He under development. Collectively, the AusGeochem platform provides the geochemistry community with a new, dynamic resource to help facilitate FAIR (Findable, Accessible, Interoperable, Reusable) data management, streamline data dissemination and advanced quantitative investigations of Earth system processes. By systematically archiving detailed geochemical (meta‐)data in structured schemas, intractably large datasets comprising thousands of analyses produced by numerous laboratories can be readily interrogated in novel and powerful ways. These include rapid derivation of inter‐data relationships, facilitating on‐the‐fly data compilation, analysis and visualisation.
8 citations
TL;DR: In this paper , the trace element and the U-Pb, Sm-Nd and Sr-Sr isotope composition of the Sumé apatite (from NE Brazil) were determined to assess its suitability as a primary/secondary reference material for LA-ICP-MS.
Abstract: This study has determined the trace element and the U-Pb, Sm-Nd and Sr-Sr isotope composition of the Sumé apatite (from NE Brazil) to assess its suitability as a primary/secondary reference material for LA-ICP-MS. Reproducibility tests demonstrate that one batch (~ 100 g) of the Sumé apatite (Sumé-570) is uniform in terms of Nd-Nd and U-Pb isotope compositions. Bulk isotope dilution TIMS/ICP-MS and LA-MC-ICP-MS analyses confirm that the apatite is well suited for use as quality control material for Nd isotopes and U-Pb geochronology. U-Pb ID-TIMS analyses yield weighted mean ratios of 0.09211 ± 0.00053 (2s; 206Pb*/238U) and 0.06120 ± 0.00063 (2s; 207Pb*/206Pb*) and a weighted mean 206Pb*/238U date of 568 ± 3 Ma (95% c.l.). U-Pb LA-(SF/MC)-ICP-MS runs using Sumé-570 as a primary RM and reproduces the dates of other established RMs within 1% deviation (except for Durango 2–4%). Major and trace element abundances show that Sumé-570 is a fluorapatite derived from a syenitic source. It also strongly shows LREE-enriched chondrite-normalised REE patterns with significant negative Eu anomalies, due to crystallisation of plagioclase in the residue.
8 citations
TL;DR: In this article , the authors present in-situ U.S. ThPb ages and isotope compositions for nine allanite samples considered as potential reference materials (CAPb, Tara, Daibosatsu, LE40010, LE 40010, CA, LE2808, LE 2808, A007, A011, A012 and SQ 51).
Abstract: Allanite is a common accessory mineral that generally incorporates considerable amounts of Th, U and light rare Earth elements in its structure, making it a useful mineral for in situ U‐Th‐Pb geochronology and Sm‐Nd isotope measurements. Here, we present in situ U‐Th‐Pb ages and Sm‐Nd isotopic compositions for nine allanite samples considered as potential reference materials (CAPb, Tara, Daibosatsu, LE40010, LE2808, A007, A011, A012 and SQ‐51), with ages ranging from ~ 2650 Ma to ~ 12 Ma. Our study indicates that Daibosatsu and LE40010 have relatively homogeneous 147Sm/144Nd and 143Nd/144Nd isotopic compositions (147Sm/144Nd ratio variation is less than 2%) and, thus, can serve as primary reference materials for Sm‐Nd microanalysis. In contrast, CAPb, Tara, LE2808, A007, A011 and A012 all show homogeneous calculated initial 143Nd/144Nd isotopic compositions, but with variable 147Sm/144Nd compositions, and thus can be used only as secondary reference materials for Sm‐Nd microanalysis. Of these materials, LE40010 allanite can serve as a suitable primary reference material for in situ U‐Pb dating, CAPb allanite can serve as a suitable primary reference material for in situ Th‐Pb dating, and LE2808, LE40010, A007, A011 and A012 can serve as suitable secondary reference materials for in situ U‐Pb geochronology. In addition, Daibosatsu is suitable as a secondary reference material for Cenozoic Th‐Pb dating to monitor data reproducibility.
6 citations
TL;DR: In this paper , the oxygen isotope compositions of four apatite reference materials (chlorapatite MGMH#133648 and fluoraphatite specimens MGMH #128441A, MZ•TH and ES•MM) were reported.
Abstract: Here we report on the oxygen isotope compositions of four proposed apatite reference materials (chlorapatite MGMH#133648 and fluorapatite specimens MGMH#128441A, MZ‐TH and ES‐MM). The samples were initially screened for 18O/16O homogeneity using secondary ion mass spectrometry (SIMS) followed by δ18O determinations in six gas source isotope ratio mass spectrometry laboratories (GS‐IRMS) using a variety of analytical protocols for determining either phosphate‐bonded or “bulk” oxygen compositions. We also report preliminary δ17O and Δ’17O data, major and trace element compositions collected using EPMA, as well as CO32− and OH− contents in the apatite structure assessed using thermogravimetric analysis and infrared spectroscopy. The repeatability of our SIMS measurements was better than ± 0.25 ‰ (1s) for all four materials that cover a wide range of 103δ18O values between +5.8 and +21.7. The GS‐IRMS results show, however, a significant offset of 103δ18O values between the “phosphate” and “bulk” analyses that could not be correlated with chemical characteristics of the studied samples. Therefore, we provide two sets of working values specific to these two classes of analytical methodologies as well as current working values for SIMS data calibration.
5 citations
TL;DR: In this article , the authors presented a new low-level, highly radiogenic chalcopyrite reference material for Re-Os geochronology, which was acquired from the Xiaotongchang (XTC) copper deposit in Yun'nan Province, China.
Abstract: As the application of the rhenium–osmium (Re‐Os) chronometer in low‐level (low Re mass fraction) sulfides becomes more popular, there is increasingly a need for a corresponding reference material for analytical quality control. This study presents a new low‐level, highly radiogenic chalcopyrite reference material for Re‐Os geochronology. Chalcopyrite was acquired from the Xiaotongchang (XTC) copper deposit in Yun’nan Province, China. Homogeneity tests were used by performing Re‐Os analyses on eleven randomly selected aliquots of powdered chalcopyrite using ICP‐MS. We also performed stability tests on four bottles of powdered chalcopyrite samples over a period of 36 months. The results from analysis of variance and Student’s t‐test indicated that the XTC sample was homogeneous with respect to Re, 187Os mass fractions and model age. Three laboratories participated in an inter‐laboratory comparison scheme for certification, performed using N‐TIMS and MC‐ICP‐MS, and employing two different spiking techniques. The reported values for model ages obtained for the XTC chalcopyrite in this study resulted in an age RM value of 229.3 ± 3.7 Ma at the 95% confidence level (95% conf.). Additionally, Re and 187Os mass fractions of 26.5 ± 1.9 ng g−1 and 63.7 ± 4.7 pg g−1 (95% conf.), respectively, are also reported, providing further information values.
5 citations
TL;DR: In this article , the authors investigated the use of Khan River and Bear Lake titanites as potential reference materials for LA-ICP-MS applications and showed that both titanites can be used as RMs for Nd-isotope analyses.
Abstract: The Khan River (Namibia) and Bear Lake (Canada) titanites are investigated as potential reference materials (RM) for LA‐ICP‐MS applications. The Bear Lake titanite is texturally and compositionally homogeneous. The Khan River titanite is texturally heterogeneous and characterised by variable trace element compositions and total rare earth element contents. However, both titanites have consistent U‐Pb and Nd‐isotope ratios. U‐Pb isotope dilution‐thermal ionisation mass spectrometry analyses yielded Pbc‐uncorrected intercept ages of 516.3 ± 1.3 Ma (2s, n = 5, MSWD = 2.4) and 1067.81 ± 0.74 Ma (2s, n = 4, MSWD = 0.35) for Khan River and Bear Lake titanites, respectively. Multiple U‐Pb LA‐SF/MC‐ICP‐MS analyses gave consistent Pbc‐uncorrected intercept ages for both, Khan River (517 ± 1/5 Ma, 2s, n = 262, MSWD = 1.5) and Bear Lake (1070 ± 1/11 Ma, 2s, n = 325, MSWD = 0.88). U‐Pb SHRIMP analyses on the same material returned identical (within uncertainty) ages. Khan River and Bear Lake gave internally consistent solution MC‐ICP‐MS 143Nd/144Nd ratios of 0.511587 ± 0.000027 (2s, n = 2) and 0.512321 ± 0.000004 (2s, n = 2), respectively. The 143Nd/144Nd ratios via solution‐MC‐ICP‐MS and LA‐ICP‐MS all agree within uncertainty and suggest that both titanites can be used as RMs for Nd‐isotope analyses.
4 citations
TL;DR: A new matrix matched reference material NFHS-2-NP (NIOZ Foraminifera House Standard 2-Nano-Pellet) with element mass fractions, and isotope ratios resembling that of natural foraminiferal calcium carbonate was developed in this paper .
Abstract: A new matrix‐matched reference material has been developed – NFHS‐2‐NP (NIOZ Foraminifera House Standard‐2‐Nano‐Pellet) – with element mass fractions, and isotope ratios resembling that of natural foraminiferal calcium carbonate. A 180–355 µm size fraction of planktic foraminifera was milled to nano‐particles and pressed to pellets. We report reference and information values for mass fractions of forty‐six elements measured by six laboratories as well as for 87Sr/86Sr (three laboratories), δ13C, δ18O (five laboratories) and 206,207,208Pb/204Pb isotope ratios (one laboratory) determined by ICP‐MS, ICP‐OES, MC‐ICP‐MS, isotope ratio mass spectrometry, WD‐XRF and TIMS. Inter‐ and intra‐pellet elemental homogeneity was tested using multiple LA‐ICP‐MS analyses in two laboratories applying spot sizes of 60 and 70 µm. The LA‐ICP‐MS results for most of the elements relevant as proxies for palaeoclimate research show RSD values < 3%, demonstrating a satisfactory homogeneous composition. Homogeneity of 87Sr/86Sr ratios of the pellet was verified by repeated LA‐MC‐ICP‐MS by two laboratories. Information values are reported for Pb isotope ratios and δ13C, δ18O values. The homogeneity for these isotope systems remains to be tested by LA‐MC‐ICP‐MS and secondary‐ion mass spectrometry. Overall, our results confirm the suitability of NFHS‐2‐NP for calibration or monitoring the quality of in situ geochemical techniques.
4 citations
TL;DR: In this paper , the results of the last 25 years of the proficiency testing program for the geochemical analysis of geological materials, organised by the International Association of Geoanalysts (GePT), have been analyzed.
Abstract: Data submitted over the past 25 years to GeoPT, the highly successful proficiency‐testing programme for the geochemical analysis of geological materials, organised by the International Association of Geoanalysts, provide a valuable resource that permits detailed investigation of contrasting results associated with different sample preparation and measurement principles. Highlighted issues include the following: recurring problems with the dissolution of the refractory minerals zircon and chromite, which produce a large dispersion in data obtained when acid digestion is involved; issues related to different XRF sample preparation methods, whereby a significant divergence of pressed powder pellet results compared with those from fused glass discs is observed; high relative dispersion of data both at low mass fractions, and those higher than normally found in silicate rocks, due to incomplete method validation, in particular due to an overconfidence in estimating reporting limits and to the employment of limited working ranges. In addition, an example for Sr in an ancient pegmatite with extremely high Rb abundance is presented, where ICP‐MS results amount to only to a third of the XRF results, severely underestimated due to the disregard of the radiogenic ingrowth from 87Rb decay. Recommendations are made both for improving data quality and the selection of test materials for future GeoPT rounds.
4 citations
TL;DR: The use of RMs for calibration and quality control purposes of analytical techniques is essential for geoanalytical research and related scientific fields to obtain reliable results as discussed by the authors , and a systematic review encompasses RMs used in traditional geochemistry as well as for palaeoclimate research or environmental and other related applications.
Abstract: The use of RMs for calibration and quality control purposes of analytical techniques is essential for geoanalytical research and related scientific fields to obtain reliable results. This review encompasses RMs used in traditional geochemistry as well as for palaeoclimate research or environmental and other related applications. The systematic research comprises more than 7200 individual publications from nineteen scientific (i.e., peer-reviewed) journals. Additionally, some specific publications of further journals are included. A total of 630 of these articles present measurement results for RMs, which represent about 9% of all surveyed publications (Table 1; Figure 1). In 2020, publications included data that were obtained by new analytical developments or improved analytical protocols for established RMs. In addition, this year’s survey identified some
4 citations
TL;DR: In this article , an externally calibrated quantification method based on an optimised online preconcentration method coupled with ICP-MS/MS was used for the quantification of thirty-four elements.
Abstract: Concentrations of elements in the aquatic environment are a key parameter for various scientific fields such as biogeochemistry, biology and environmental science. Within this context, the scientific community asks for new analytical protocols to be able to quantify more and more elements of the periodic table. Therefore, the requirements for aqueous reference materials have increased drastically. Even though a wide variety of CRMs of different water matrices are available, certified values of many elements (e.g., rare earth elements (REE), technology‐critical elements, such as Ga and In, and generally those elements which are not part of current monitoring regulations) do not yet exist. Therefore, the scientific community relies on published elemental concentrations of many CRMs provided by other researchers. Some elements of interest, such as the REE, are well studied and plenty of literature values exist. However, less studied elements, such as Ga and In, are rarely studied. In this study, an ‘externally’ calibrated quantification method based on an optimised online preconcentration method coupled with ICP‐MS/MS was used for the quantification of thirty‐four elements. The method was applied to seventeen water CRMs covering freshwater, brackish water and seawater. The measured data are combined with a comprehensive literature review on non‐certified values in selected water CRMs, and new consensus values are suggested for various non‐certified elements.
TL;DR: In this article , three natural geological glasses (andesitic glass OJY•1, and rhyolitic obsidians OH•1 and OA•1) of specimen sizes 50-150'g were characterised as reference materials for in-situ microanalysis of major and trace elements, and Pb isotope ratios.
Abstract: Three natural geological glasses (andesitic glass OJY‐1, and rhyolitic obsidians OH‐1 and OA‐1) of specimen sizes 50–150 g were characterised as reference materials for in situ microanalysis of major and trace elements, and Pb isotope ratios. Utilised techniques include isotope‐dilution analyses by TIMS and MC‐ICP‐MS, bulk analyses by XRF, ICP‐OES, ICP‐MS, and microanalysis (10–120 μm spot size) by electron probe microanalyser, LA‐ICP‐MS and LA‐MC‐ICP‐MS. Microanalyses (10–120 μm) indicate that all three glasses are homogeneous with respect to fifty‐four out of fifty‐eight determined elements and Pb isotope ratios, except for Ni in OJY‐1, and Cu, Zr and Ce in OH‐1. The determination of reference values as well as their uncertainties at the 95% confidence level closely followed International Organization for Standardization (ISO) guidelines and the certification protocol of the International Association of Geoanalysts (IAG). These three glasses are fully natural without any subsequent heat treatment, and they represent useful additions to the widely distributed MPI‐DING, USGS and CGSG reference glasses for microanalytical techniques such as electron probe microanalysis, μ‐XRF, LA‐ICP‐MS and SIMS.
TL;DR: In this paper , a laser ablation coupled with filter (LAF) sampling method was proposed for precise isotopic measurements of small-sized geological materials, compared with conventional micromilling techniques.
Abstract: Microscale isotopic measurements in geological materials are becoming of significant importance in geochemistry. This study evaluated the potential of a new microsampling method called laser ablation coupled with filter (LAF) for precise isotopic measurements of small‐sized geological materials, compared with conventional micromilling techniques. We optimised the system to maximise the sample collection rate and minimise the extent of the contamination. Isotope ratios (87Sr/86Sr, 142Nd/144Nd, 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) of the glass reference material NIST SRM 610 collected using LAF were measured by thermal ionisation mass spectrometry, and no isotopic fractionation or blank effect was observed. This indicates that LAF can be applied for high‐precision isotope ratio measurement of these elements. Considering the total procedural blanks in LAF sampling, the minimum amounts required for high‐precision isotope measurement were 50, 2 and 20 ng for Sr, Nd and Pb, respectively. The LAF method has advantages over the conventional method. It also causes less damage in the test sample’s depth direction and can be applied to samples with complex shapes. It is expected therefore that the LAF sampling method will be applied to geology and other research fields that require microsampling.
TL;DR: In this article , the applicability of different leaching methods used to extract secondary oxides from silicate solids for lithium isotope (δ7Li) measurement was examined.
Abstract: To examine the applicability of different leaching methods used to extract secondary oxides from silicate solids for lithium isotope (δ7Li) measurement, this study has conducted leaching experiments on five different types of silicate solids, including a fresh basalt, two weathered basalts, a Yellow River sediment (loess‐dominated) and a shale. Four factors were assessed in the experiments: the concentration of the leaching reagent hydroxylamine hydrochloride (HH), the leaching temperature (20 °C vs 95 °C), the leaching time and the reagent/solid ratio. Based on elemental concentrations and Li isotopes, 0.04 mol l−1 hydroxylamine hydrochloride (HH) in 25% v/v acetic acid at room temperature for 1 h with 40 ml g−1 reagent/solid ratio is recommended. At high temperatures, low δ7Li and high magnesium/iron ratios indicate that minerals other than secondary oxides are dissolved. With increased leaching time, there is no evidence for Li isotopic fractionation at room temperature. However, longer leaching time or increased reagent/solid ratios may increase the risk of leaching from non‐oxide phases. Meanwhile, results suggest that low concentrations of HH are not sufficient to target the secondary oxides evenly, while high concentrations of HH can leach out more non‐oxides. We also examined the optimal oxide leaching method within a full sequential leaching procedure (i.e., exchangeable, carbonate, oxide, clay and residual phases). Elemental concentrations show that no elements exist exclusively in oxides, so it is essential to analyse multi‐elemental concentrations to verify that the leaching has accessed this phase in a given sample. Comparing secondary oxides with their corresponding solutions, we estimate the isotopic fractionation (Δ7Lioxide‐solution) is −16.8‰ to −27.7‰.
TL;DR: In this article , the authors used a collision/reaction cell for in situ Rb-Sr analysis of silicate minerals via laser ablation inductively coupled plasma tandem mass spectrometry (LA•ICP•MS/MS) with a collision or reaction cell, complemented by isotope dilution (ID) MC-ICP-MS analyses of GL•O and Mica•Mg.
Abstract: Reference materials (RMs) with well‐characterised composition are necessary for reliable quantification and quality control of isotopic analyses of geological samples. For in situ Rb‐Sr analysis of silicate minerals via laser ablation inductively coupled plasma tandem mass spectrometry (LA‐ICP‐MS/MS) with a collision/reaction cell, there is a general lack of mineral‐specific and matrix‐matched RMs, which limits wider application of this new laser‐based dating technique to certain minerals. In this work, pressed nano‐powder pellets (NP) of four RMs, GL‐O (glauconite), Mica‐Mg (phlogopite), Mica‐Fe (biotite) and FK‐N (K‐feldspar), were analysed and tested for in situ Rb‐Sr dating, complemented by isotope dilution (ID) MC‐ICP‐MS Rb‐Sr analyses of GL‐O and Mica‐Mg. In addition, we attempted to develop alternative flux‐free and fused ‘mineral glasses’ from the above RMs for in situ Rb‐Sr dating applications. Overall, the results of this study showed that among the above RMs only two NP (Mica‐Mg‐NP and GL‐O‐NP) were suitable and robust for in situ dating applications. These two nano‐powder reference materials, Mica‐Mg‐NP and GL‐O‐NP, were thus used as primary RMs to normalise and determine Rb‐Sr ages for three natural minerals: MDC phlogopite and GL‐O glauconite grains, and also Mica‐Fe‐NP (biotite). Our in situ analyses of the above RMs yielded Rb‐Sr ages that are in good agreement (within 8%) of published ages, which suggests that both Mica‐Mg‐NP and GL‐O‐NP are suitable RMs for in situ Rb‐Sr dating of phlogopite, glauconite and biotite. However, using secondary RMs is recommended to monitor the quality of the obtained ages.
TL;DR: In this paper , the exact equations and the bias of the approximations are presented, and calculations are illustrated by real-world examples for obtaining a single delta measurement and for repeated measurements.
Abstract: Isotope ratio applications are on the increase and a major part of which are delta measurements, because they are easier to perform than the determination of absolute isotope ratios while offering lower measurement uncertainties. Delta measurements use artefact‐based scales and therefore scale conversions are required due to the lack of the scale defining standards. Such scale conversions often form the basis for comparing data being generated in numerous projects and therefore need to be as accurate as possible. In practice, users are tempted to apply linear approximations, which are not sufficiently exact, because delta values are defined by nonlinear relationships. The bias of such approximations often is beyond typical measurement uncertainties and its extent can hardly be predicted. Therefore, exact calculations are advised. Here, the exact equations and the bias of the approximations are presented, and calculations are illustrated by real‐world examples. Measurement uncertainty is indispensable in this context and therefore, its calculation is described as well for determining delta values but also for scale conversions. Approaches for obtaining a single delta measurement and for repeated measurements are presented. For the latter case, a new approach for calculating the measurement uncertainty is presented, which considers covariances between the isotope ratios.
TL;DR: The authors measured the RePGE (Os, Ir, Ru, Pt and Pd) mass fractions, as well as 187Os/188Os isotope ratios of five shale reference materials (RMs), including USGS SGR•1b (oil shale), SBC•1 (marine shale), SCo•2 (silty marine shale), ShTX‐1 (calcareous organic-rich shale), and ShCX•1(calCareous shale) and one oil RM, NIST RM 8505.
Abstract: At present, reported data for Re‐PGE mass fractions (in particular) and 187Os/188Os isotope ratios of organic‐rich reference materials (RMs) are rare, hampering the comparison of data quality between different laboratories. In this study, we measured the Re‐PGE (Os, Ir, Ru, Pt and Pd) mass fractions, as well as 187Os/188Os isotope ratios of five shale RMs, including USGS SGR‐1b (oil shale), SBC‐1 (marine shale), SCo‐2 (silty marine shale), ShTX‐1 (calcareous organic‐rich shale) and ShCX‐1 (calcareous shale), and one oil RM, NIST RM 8505. The results show that the five shale RMs have similar upper continental crust‐normalised PGE‐Re patterns and are generally homogeneous in Re‐PGE mass fractions and 187Os/188Os isotope ratios at test portions of 0.2–0.5 g, and thus can be used as matrix‐matched RMs for Re‐Os and PGE of shale samples. The oil RM NIST 8505 and its asphaltene separates are also roughly homogeneous in Re‐PGE mass fractions and 187Os/188Os isotope ratios at test portions of 0.1–0.3 g and can potentially be used as an oil RM for Re‐Os and PGE.
TL;DR: Two megacrysts were collected from Cenozoic alkali basalts in the Hannuoba region of China and characterised for major and trace element compositions for in situ microanalysis as mentioned in this paper .
Abstract: Two clinopyroxene megacrysts, DMP‐2 and DMP‐3, were collected from Cenozoic alkali basalts in the Hannuoba region of China. They were characterised for major and trace element compositions for in situ microanalysis. EPMA and LA‐ICP‐MS analyses indicate homogeneity in the element mass fractions in both clinopyroxene samples. Bulk analyses using various techniques (XRF, ICP‐OES and solution ICP‐MS) also reveal good consistency in their major and trace element data. They, thus, can be used as potential reference materials for elemental in situ microanalysis. Accordingly, element mass fractions are recommended for thirty‐two elements.
TL;DR: In this article , the stable Nd isotopic compositions of twenty-seven widely available geological reference materials (RMs) including silicates, sediments, soils and carbonates were reported.
Abstract: Here, we report the stable Nd isotopic compositions of twenty‐seven widely available geological reference materials (RMs) including silicates, sediments, soils and carbonates. Nd was purified from geological samples using a single TODGA resin column. The Nd isotopic ratios were determined via MC‐ICP‐MS using the combined standard‐sample bracketing and internal normalisation method. The (long‐term) intermediate measurement precision of δ146/144Nd values relative to the reference material JNdi‐1 was greater than 0.030‰ (2s). Measurements of five previously analysed RMs yielded δ146/144Nd values that were consistent with those obtained using the double‐spike method. The igneous rocks showed minimal variations in their δ146/144Nd values, which ranged from ‐0.039‰ to +0.015‰. The sediments displayed large stable Nd isotopic fractionations ranging from ‐0.099‰ to +0.057‰, implying differences in their sources. The soil RMs showed a range of ‐0.093‰ to ‐0.010‰, likely owing to complex geological processes such as the degree of chemical weathering. The sedimentary rock dolomite had the heaviest δ146/144Nd values at +0.147 ± 0.032‰ (2s, n = 3). Of the analysed RMs, the δ146/144Nd values of thirteen of them are being reported for the first time. The datasets presented here should play fundamental role in quality assurance and allow for universal comparisons for stable Nd isotope systematics.
TL;DR: In this paper , a solution containing forty-five elements representative of the periodic table was used to supply the ions to react with CO2 in the collision/reaction cell (CRC).
Abstract: Carbon dioxide (CO2) was used as a reaction gas to investigate the gas‐phase ion‐molecule interactions using the Agilent 8900 ICP‐MS/MS. A solution containing forty‐five elements representative of the periodic table was used to supply the ions to react with CO2 in the collision/reaction cell (CRC). The only significant product ions formed were monoxides. The general reactivity was shown to be consistent with density functional theory (DFT)‐predicted reaction enthalpies, such that all predicted exothermic reactions produced product ions at levels of at least 1% of the unreacted ion. Most endothermic reactions observed had sufficient kinetic energy in excess of the reaction enthalpies. Our results suggest that reaction enthalpy is a reasonable predictor of reactivity with CO2 on the timescales of the interactions in non‐thermal ICP‐MS/MS systems. The ease and rapidity of data collection with the ICP‐MS/MS and DFT calculations using the NWChem suite has value given the scarcity of thermochemical data of CO2 reactions in the literature. These studies are especially useful for the identification of targeted reaction chemistries to be leveraged for analytical method development, such as for the inline separation of isobaric interferences from analytes of interest.
TL;DR: In this article , internal water in tropical coral skeletons was extracted and measured for its oxygen and hydrogen isotope ratios by crushing pieces of coral hard tissue in a percussion device connected to either a cavity ringdown spectroscopy (CRDS) system or an isotope ratio mass spectrometry (IRMS) system.
Abstract: Internal water in cold‐water and tropical coral skeletons was extracted and measured for its oxygen and hydrogen isotope ratios. Water was extracted by crushing pieces of coral hard tissue in a percussion device connected to either a cavity ring‐down spectroscopy (CRDS) system or an isotope ratio mass spectrometry (IRMS) system. Despite most samples yielding sufficient water, each analytical system produces distinct isotope patterns. Experiments show that several characteristics specific to biominerals give rise to discrepancies and analytical artefacts that preclude the acquisition of reproducible isotope data. The main complication is that internal water in biogenic carbonates is distributed in an open interconnected micro‐network that readily exchanges with external water and potentially facilitates interaction with hydration water in the finely dispersed organic matrix in the coral skeleton. Furthermore, only an isotopically fractionated part of the internal water is released from the coral skeletons upon crushing. Altogether, isotope ratio measurement of internal water in corals with bulk crushing techniques does not give primary fluid isotope ratios useful for (palaeo‐)environmental or microbiological studies. As the resulting isotope patterns can show systematic behaviour per technique, isotope data may be erroneously interpreted to reflect the original calcifying fluid when using only a single technique to isotopically characterise internal fluids in coral skeletons.
TL;DR: In this paper , high-precision calcium isotopic ratios of thirty-four Chinese geological reference materials, including igneous, metamorphic and sedimentary rocks, river/marine sediments and soils, are reported.
Abstract: High‐precision calcium isotopic ratios of thirty‐four Chinese geological reference materials, including igneous, metamorphic and sedimentary rocks, river/marine sediments and soils, are reported. Measurements were conducted by thermal ionisation mass spectrometry (Triton TIMS) using a 42Ca–43Ca double spike. These reference materials cover a wide range of chemical compositions with CaO ranging from 0.10 to 51.1% m/m. The δ44/40Ca variation of igneous rocks was up to 0.75‰, ranging from 0.61 ± 0.06‰ to 1.35 ± 0.04‰. Two metamorphic rocks yielded δ44/40Ca of 0.39 ± 0.02‰ and 0.86 ± 0.02‰, respectively. δ44/40Ca values of sedimentary rocks varied from −0.14 ± 0.09‰ to 0.98 ± 0.12‰, suggesting significant isotopic fractionation during low‐temperature processes. Like sedimentary rocks, river/marine sediments and soil displayed large Ca isotopic variations, with δ44/40Ca spanning from 0.12 ± 0.06‰ to 0.77 ± 0.03‰ and −0.09 ± 0.11‰ to 0.74 ± 0.08‰, respectively. The comprehensive data set reported in this study serves as a reference for quality assurance and inter‐laboratory comparison for high‐precision Ca isotopic studies.
TL;DR: In this article , the authors presented Rb and Sr mass fraction and 87Sr/86Sr isotope ratio measurement results for four reference materials (RMs) obtained from the Service d'Analyse des Roches et des Minéraux (SARM), Nancy, France: MicaMg, Mica•Fe, GL•O and FK•N.
Abstract: We present Rb and Sr mass fraction and 87Sr/86Sr isotope ratio measurement results for four reference materials (RMs) obtained from the Service d'Analyse des Roches et des Minéraux (SARM), Nancy, France: Mica‐Mg, Mica‐Fe, GL‐O and FK‐N. These four RMs have different chemical compositions spanning the range of those of most K‐bearing feldspars and micas, making them potential calibration materials for in situ Rb‐Sr dating of natural minerals by LA‐ICP‐MS/MS. Selected grains and flakes from the four RMs present variable degrees of heterogeneity observable by SEM‐EDS and EPMA imaging, and chemical mapping. This heterogeneity is mainly related to inclusions of minerals within flakes and grains and to chemical substitutions linked to crystallographic control and alteration processes. The Mica‐Mg RM is the least affected. The powders available at the SARM were analysed by ID‐TIMS (87Sr/86Sr and Sr) and ID‐MC‐ICP‐MS (Rb) after digestion and separation. The mean 87Rb/86Sr ratios are 155.6 ± 4.7% (2s, as for other RMs) for Mica‐Mg, 1815 ± 14% for Mica‐Fe, 36.2 ± 11% for GL‐O and 69.9 ± 5.9% for FK‐N. The mean 87Sr/86Sr ratios are 1.8622 ± 0.36% (2s, as for other RMs) for Mica‐Mg, 7.99 ± 13% for Mica‐Fe, 0.75305 ± 0.12% for GL‐O, and 1.2114 ± 0.17% for FK‐N. The four RMs each show dispersion in 87Sr/86Sr and Rb and Sr mass fractions, to degrees that differ between RMs and that reflect the heterogeneity of their original crystals. The most heterogeneous RMs are GL‐O and Mica‐Fe. The calculated mean Rb‐Sr isotopic ages are 521 ± 24 Ma for Mica‐Mg, 287 ± 55 Ma for Mica‐Fe, 89.2 ± 9.9 Ma for GL‐O and 512 ± 30 Ma for FK‐N. The proposed age for Mica‐Fe may be unreliable due to the elevated dispersion of individual analysis linked to the highly radiogenic composition of the biotite and to the presence of numerous mineral inclusions. We recommend use of these proposed working values of 87Sr/86Sr and 87Rb/86Sr ratios and associated uncertainties when using the four RMs for in situ Rb‐Sr dating by LA‐ICP‐MS/MS. The availability of these four well‐characterised RMs will allow progress in the development and application of the Rb‐Sr dating approach by LA‐ICP‐MS/MS.
TL;DR: In this article , the tin mass fraction and the δ120/118Sn relative to NIST SRM 3161a were measured for ten geological reference materials among which the Sn isotopic values of W 2a, JA 2, JG 2, G 2, GBW07316, NOD•A•1 and SGR•1 are reported for the first time.
Abstract: The tin mass fraction and the δ120/118Sn relative to NIST SRM 3161a were measured for ten geological reference materials among which the Sn isotopic values of W‐2a, JA‐2, JG‐2, G‐2, GBW07316, NOD‐A‐1 and SGR‐1 are reported for the first time. The sample preparation procedure implemented in this study was based on acid digestion and matrix separation by two‐stage chromatographic using AG‐MP‐1 and TRU‐Spec resin. Isotopic measurements were carried out by multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS), using a 117Sn–119Sn double‐spike technique to correct for the instrumental mass fractionation effects. The overall precision of this method is estimated to be ± 0.03‰ (2s, n = 81) and ± 0.07‰ (2s, n = 6) for the NIST SRM 3161a and a geological reference material BHVO‐2, respectively.
TL;DR: In this paper , the micro-homogeneity of zinc isotope composition of the NIST SRM 683 and NBS 123 reference materials using femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fsLA•MC‐ICP‐MS) was examined.
Abstract: This study examined the micro‐homogeneity of zinc isotope composition of the NIST SRM 683 and NBS 123 reference materials using femtosecond laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (fsLA‐MC‐ICP‐MS). NIST SRM 683 and NBS 123 are homogeneous in Zn isotope composition based on numerous measurements performed on twenty chips and four mounts of sphalerite using solution nebulisation (SN)‐MC‐ICP‐MS and fsLA‐MC‐ICP‐MS. The mean δ66ZnJMC‐Lyon values of NIST SRM 683 and NBS 123 determined by SN‐MC‐ICP‐MS were 0.11 ± 0.02‰ (2 standard deviation (2s), n = 100) and 0.16 ± 0.02‰ (2s, n = 62), respectively. The mean δ66ZnJMC‐Lyon values determined by fsLA‐MC‐ICP‐MS analyses for NIST SRM 683 and NBS 123 were 0.12 ± 0.05‰ (2s, n = 200) and 0.16 ± 0.05‰ (2s, n = 212), consistent with the bulk isotope compositions within uncertainty. The in situ measurement precision for NIST SRM 683 and NBS 123 was better than 0.06‰ (2s), suggesting NIST SRM 683 and NBS 123 are suitable to serve as microanalytical reference materials for Zn isotope measurement. Zinc isotopic compositions of Zn‐rich materials were also determined using fsLA‐MC‐ICP‐MS under wet/dry plasma conditions. Their δ66ZnJMC‐Lyon values were in agreement with those obtained by SN‐MC‐ICP‐MS analysis, suggesting that fsLA‐MC‐ICP‐MS is suitable to measure Zn isotopic ratios in Zn‐rich materials. Thus, this method could potentially analyse spatially resolved Zn isotope compositions at the mineral or even sub‐mineral scale, such as to address the process of ore formation or Zn redistribution in near‐surface environments.
TL;DR: In this article , the authors present the results of over 100 measurement sessions over 6' years for seven common zircon reference materials and calculate a characteristic excess variance for each of them.
Abstract: Inter‐session excess variance of U/Pb and Pb/Pb ratios in LA‐ICP‐MS zircon dating is the largest contributor to systematic errors, which in turn limit the accuracy of age determinations. Quantifying long‐term excess variance of reference materials allows for the estimation of excess variance in samples, but such compilations are not available in the literature. Here, we present the results of over 100 measurement sessions over 6 years for seven common zircon reference materials and calculate a characteristic excess variance for each. For 206Pb/238U ages, these values (2s) are as follows: AusZ7‐1 = 1.7% (115 sessions), AusZ7‐5 = 0% (74), OD‐3 = 0.6% (19), Temora2 = 1.2% (86), Plešovice = 1.1% (100), 91500 = 1.0% (146) and Mud Tank = 3.0% (12). For 207Pb/206Pb ages, smaller excess variances are observed: Temora2 = 0.3%, Plešovice = 0.4%, Mud Tank = 1.7% and 91500 = 0.4%. These values are well‐constrained estimates of inter‐session excess variance for the ETH Zürich LA‐ICP‐MS laboratory using a sector‐field ICP‐MS, and may provide either a first‐order estimate for other laboratories or a value to compare against their own reference material compilations.
TL;DR: In this paper , reference glasses of USGS and glasses synthesised from powders of other rock RMs were analyzed to evaluate well-known reference materials (RMs) as quality control materials for EPMA measurement of F, Cl, Nb and P mass fractions.
Abstract: Quantitative in situ electron probe microanalysis (EPMA) was applied to determine the F, Cl, Nb and P contents of glass materials. Using reference glasses with low FeOT (< 10% m/m) mass fractions to construct a F calibration line to correct the Fe interference on the F peaks, is unsuitable for analysing natural Fe‐rich melt inclusions with up to 21% m/m FeOT, which commonly occur in picritic, nephelinitic and basanitic samples. For this reason, this study presents a series of seven F‐free glasses, which show a wider range of FeOT (1–20% m/m) that were synthesised to improve the overlap correction of Fe on F. Using this improved method, reference glasses of USGS and glasses synthesised from powders of other rock RMs were analysed to evaluate well‐known reference materials (RMs) as quality control materials for EPMA measurement of F, Cl, Nb and P mass fractions. The results show that amongst the tested RMs, USGS BHVO‐2G is the most appropriate RM for F‐Cl determination because different pieces of this glass RM analysed by different laboratories yielded results that agree within uncertainty.
TL;DR: In this paper , depth profiling measurements of rare earth elements (REEs) and U-Pb ages from zircons were conducted using a time-of-flight based inductively coupled plasma mass spectrometer (ICP•ToF•MS) coupled with laser ablation sampling.
Abstract: Depth‐profiling measurements of both the abundances of rare earth elements (REEs) and U‐Pb ages from zircons were conducted using a time‐of‐flight based inductively coupled plasma‐mass spectrometer (ICP‐ToF‐MS) coupled with laser ablation sampling. To improve ion transmission, a dry plasma cone from Nu Instruments was applied to the ICP‐ToF‐MS system employed. The signal‐to‐noise ratios for the analytes were further improved using a multiple spot‐laser ablation (msLA) protocol. Moreover, constructing a ‘moat’ around an analysis area obviated the risk of mixing of particles released from different layers. With the technique developed here, reproducible analyses of REE abundances and U‐Pb ages for three reference material zircons (91500, Plešovice and OD‐3) were performed for sampling depths in the range 0.59–0.66 μm. The present technique was also applied to zircon samples collected from the Himalayan orogen. The combination of REE abundances and U‐Pb isotopic ratios suggested that the discordant trend in U‐Pb isotopic ratios observed in this study was mainly due to mixing among three components in grains (thin outer layer, inner rim and core). The geochemical data obtained demonstrate that the combination of the msLA technique and ICP‐ToF‐MS system is a powerful tool to decode the multiple thermal events contributing to sample formation.
TL;DR: In this paper , a new 230Th−238U disequilibrium dating method for inclusion-bearing ilmenite was proposed, which is tested on ilmenites from the 86.4 ± 1.1 ka Aso‐4 super-eruption, Japan, and from the Lower Pumice (63.1µ±µ 4.7µ) and Upper Pumices (58.4µ 2.7‵) eruptions of Nisyros volcano.
Abstract: 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 230Th‐238U 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.
TL;DR: In this article , the authors developed calibrations for lithium content and lithium isotope measurements in kerogen, using secondary ion mass spectrometry techniques to study trace elements in organic samples where matrix compositions vary spatially.
Abstract: Secondary ion mass spectrometry techniques are used to study trace elements in organic samples where matrix compositions vary spatially. This study was conducted to develop calibrations for lithium content and lithium isotope measurements in kerogen. Known concentrations of Li ions (6Li and 7Li) were implanted into organic polymers, with a range of H/C and O/C ratios similar to kerogen, along with glassy carbon (SPI Glas‐22) and silicate glass (NIST SRM 612). Results show that Li content calibration factors (K*) are similar for carbonaceous samples when analysed using a 5 kV secondary ion accelerating voltage. Using a 9 kV secondary ion accelerating voltage, K* factors are negatively correlated with the sample O content, changing ~ 30% between 0 and 15 oxygen atomic %. Thus, to avoid the matrix effect related to O content, using a 5 kV secondary ion accelerating voltage is best for quantification of Li contents based on 7Li+/12C+ ratios. Under these analytical conditions, Li ppm (atomic) = (132 (± 8) × 7Li+/12C+) × 12C atom fraction of the sample measured. Lithium isotope ratio measurements of SPI Glas‐22 and NIST SRM 612 are within uncertainty; however, the organic polymer samples as a group show a 10‰ higher δ7Li than NIST SRM 612.