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The formation of rodingites has been a continually controversial topic, largely due to the absence of minerals that can be unambiguously dated. Here, we present a case study that utilized LA‐ICPMS garnet U–Pb dating, in conjunction with field investigations, petrology and Raman spectroscopy, to reveal the age and petrogenesis of rodingite in the northern North China Craton. The rodingites are spatially associated with mafic and alkaline rocks. Our findings indicate that rodingitization occurred at ca. 388 Ma, making it about 5–10 Myr younger than its mafic protoliths, but contemporaneous with the adjoining alkaline plutons. These observations suggest that the rodingitization may be attributed to hydrothermal fluids from the alkaline magmas. Our study emphasizes the importance of utilizing garnet U–Pb dating to determine the timing of rodingitization and introduces a novel perspective on the relationship between rodingitization and alkaline magmas in extensional continental settings. [ABSTRACT FROM AUTHOR]

The recycling of subcontinental lithospheric mantle back into the asthenosphere during continental breakup is potentially a major but underappreciated process in plate tectonics. Here, we report major and trace elements for detrital peridotite minerals in carbonate breccias dredged from the Marion Rise, Southwest Indian Ridge. With an emphasis on the trace elements of the relatively abundant orthopyroxene detrital grains, the results show that a portion of pyroxene grains was likely derived from a mantle source that experienced hydrous melting and slab‐derived melt metasomatism above a subduction zone. This finding provides a novel view into the mantle geochemistry at midocean ridges, as well as evidence that Marion Rise is at least partially supported by chemically buoyant recycled refractory mantle wedge material. [ABSTRACT FROM AUTHOR]

Vesuvianite is a common accessory mineral that usually occurs in metamorphosed and metasomatised, argillaceous carbonate rocks (i.e., skarn rocks) and as a late crystallising phase in igneous rocks such as nepheline syenites. Vesuvianite is a Ca-rich mineral that preferentially incorporates Sr and light rare earth elements (LREEs). Given that vesuvianite is susceptible to alteration and commonly contains inclusions, in situ laser ablation analysis is the preferred approach for measuring its Sr–Nd isotopic compositions. The use of matrix-matched and homogeneous reference materials is a prerequisite for laser ablation isotope analyses. Two in-house vesuvianite standards M6635 and M659 were used for external correction during in situ laser ablation analysis for Sr and Nd isotopic compositions, respectively. In this paper, we apply in situ Sr and Sm–Nd isotope analyses for 11 vesuvianite samples (M6635, M784, M1377, M660, M1439, M1450, M6601, 13MDL176, Wilui, Hazlov, and Goodall) from different locations. The obtained Sr and Sm–Nd isotopic compositions for these vesuvianite samples are consistent with those obtained by solution-based methods using MC-ICP-MS, which demonstrates the robustness of our analytical methods. We recommend that samples M6635, M784, M1377, and M1450 are suitable vesuvianite reference materials for in situ Sr isotope analyses, and sample M659 is a potential vesuvianite reference material for in situ Sm–Nd isotope analyses. [ABSTRACT FROM AUTHOR]

Rutile stands as a classical mineral within U‐Pb geochronology, offering insights into both magmatic and metamorphic events, and contributing to the understanding of provenance of detrital sedimentary rocks. Addressing the paucity of high‐quality Archaean rutile reference materials suitable for microbeam U‐Pb dating, we present a natural rutile (RKV01) sourced from the Kaap Valley pluton, South Africa, positing it as a potential Archaean reference material. Major element determination was executed via electron probe microanalysis, while trace element determination was conducted using laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). The determination of U‐Pb ages involved the application of isotope dilution‐thermal ionisation mass spectrometry (ID‐TIMS), secondary ion mass spectrometry (SIMS) and LA‐ICP‐MS. The ID‐TIMS mean 207Pb/206Pb age is 3225.61 ± 0.64 Ma (2s, MSWD = 0.83), interpreted as the best estimate for the crystallisation age. The relatively high U mass fraction (~ 83 μg g‐1), extremely low Th mass fraction (~ 0.003 μg g‐1), negligible common Pb and isotopically homogeneous compositions collectively facilitated precise 207Pb/206Pb age determination via microbeam methods. Both LA‐ICP‐MS and SIMS 207Pb/206Pb ages are characterised by reproducibility and were consistent with the ID‐TIMS age within 2s analytical uncertainty. The results underscore the potential of RKV01 rutile as an Archaean reference material for microbeam U‐Pb dating. [ABSTRACT FROM AUTHOR]

Pyrite has been extensively utilized for tracing geological processes through its iron and sulfur isotope micro-analysis. However, the lack of matrix-matched reference materials with characterized Fe and S isotopic compositions poses a challenge. In this study, we examined a natural pyrite sample (IGGPy-1) to evaluate its potential as a matrix-matched reference material for in situ micro-analysis of iron and sulfur isotopes. Electron probe microanalysis (EPMA) confirmed the homogeneity of major elements without any growth zoning in pyrite grains. Random spot isotopic analyses conducted using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) yielded variances in δ56Fe and δ34S of 0.07‰ (2S, N = 105) and 0.13‰ (2S, N = 105), respectively. Based on the results and statistical analysis, it was determined that the IGGPy-1 sample was isotopically homogeneous and had the potential to be used as a reference material. The δ34SVCDT value, measured using elemental analyzer-isotope ratio mass spectrometry (EA-IRMS), was 17.09 ± 0.30‰ (2S, N = 6). Additionally, δ56FeIRMM-014 and δ57FeIRMM-014 values, measured using solution-nebulizing multi-collector inductively coupled plasma mass spectrometry (SN-MC-ICP-MS), were −1.31 ± 0.06‰ (2S, N = 21) and −1.94 ± 0.12‰ (2S, N = 21), respectively. These values are recommended as the isotopic reference values for IGGPy-1. Since the samples with complex core-rim textures resulting from multiple stages in the formation of many sulfide deposits face a significant risk of mismatch in the Fe and S isotopic data obtained from different analytical domains, we presented the technique of simultaneous in situ measurements of Fe–S isotopes in pyrite using a single laser spot by coupling a femtosecond laser ablation system with two sets of MC-ICP-MS. Furthermore, our results clearly demonstrated the significant impact of position effects on the accuracy of Fe and S isotopic data. Therefore, it is crucial to identify appropriate domains within the ablation chamber for placing the "standard" and samples for mitigating these effects. [ABSTRACT FROM AUTHOR]

Precise and accurate determination of major components in alkali silicate glasses provides critical information concerning element distribution, petrogenesis and magmatic evolution. However, as one of the most important in situ microanalytical technologies, the application of electron probe microanalysis (EPMA) was limited by the time-dependent loss of X-ray intensity of alkali ions (especially Na) during electron beam bombardment on alkali silicate glasses. In this study, an optimized analytical method was developed using a JEOL JXA 8100 EPMA, aiming to get a long enough incubation duration suitable for accurate analysis of major element mass fractions. The optimal analytical conditions were determined as follows: 15 kV accelerating voltage, 2 nA beam current, 20 μm beam diameter, 40 s peak counting time, Na and K analyzed with top priority, time-saving mode with no additional detector movement and no peak search functioned. The availability of this low beam current density condition (6.37 × 10−3 nA μm−2) to 24 anhydrous reference glasses, with their compositions covering the entire spectrum from the ultramafic to highly siliceous range, was verified by the good agreement of the EPMA measured data with their GeoReM preferred values. Similarly, the methodology presented here is also suitable for analysis of hydrous glasses with H2O contents up to approximately 9 wt%, accompanied by no obvious Na loss found and no complicated mathematical corrections needed, and therefore can be used for the estimation of H2O contents in H2O-rich (>1 wt%) geological glasses by the difference method. Despite its analytical accuracy and precision (>0.5 wt%) not better than those of SIMS and FTIR, EPMA can be used as a substitute technique for H2O determination with its main advantages of excellent spatial resolution (down to 5–10 μm) and analytical convenience, especially for small melt inclusions or tiny experimental quench products, and the case with no appropriate calibration standards or no reported extinction coefficients available for those compositions of interest. In daily application, our optimized method is low cost and easy to implement and can achieve comparable precision and detection limits with acceptable efficiency (∼4–5 min/point for ten major elements) relative to routine analysis conditions. [ABSTRACT FROM AUTHOR]

Understanding laser ablation behaviors of different target materials is essential for optimum laser parameters, external reference materials selection, as well as for data quality assurance. In this study, ablation behaviors of a 193nm ArF excimer laser for silicate glasses, common minerals, and powder pellets were investigated. Ablation rates influenced by laser parameters (including spot size, energy density, and laser frequency) were evaluated. Topographic images of craters generated during ablation illustrate that glasses and most minerals have controllable ablation behaviors, except for quartz. The worse ablation behavior of quartz may be ascribed to the micro-fluid inclusions, which could result in the overheating effect in laser pits. In general, powder pellets have worse ablation behaviors, but the increase of tableting pressure or reducing the particle grain size could improve the ablation behaviors. Ablation rates gradually decrease if the ablation depth is larger than 1.5 times of the spot size. The maximum ablation depth can reach twice the spot size when the energy density is 3.0 J/cm2 for the RESOlution M-50 laser system). Ablation rates increase with the increase of laser energy density, but ablation rates are not affected by the laser frequency (2-20 Hz). Ablation rates are specific to the individual substrates. In conclusion, the ablation rate data of 43 substrates, in which ablation rates of powder pellets are larger than glasses and minerals, whereas those of carbonates and sulfides are larger than silicate minerals, and those of NIST glasses are larger than geological glasses.

Studies on elemental fractionation and homogeneity of CGSG reference materials (CGSG-1, CGSG-2, CGSG-4 and CGSG-5) promote quality assessment and application. The elemental fractionation and within-unit homogeneity of CGSG reference materials were evaluated using Electron Microprobe and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). Meanwhile, the major and trace element contents were also reported. The results showed that the elemental fractionation of CGSG reference materials was negligible for 50 μm spot size. Electron Microprobe homogeneity index illustrated that the homogeneity of major elements in CGSG reference materials is approvingly acceptable, and most trace elements possess same homogeneity grade with MPI-DING reference materials. Analytical results of major elements by Electron Microprobe and LA-ICP-MS are consistent with published data within 2% and 5% errors, respectively. Analytical results of trace elements by LA-ICP-MS are generally in agreement with the published data. Some elements such as Cr, Ge, Cd, As and Tl show a larger deviation due to the large uncertainties of the analytical technique. In general, the analysis data reported here could supplement the CGSG value database.

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is currently an important microanalysis technique in the geoscience field. Development of related reference materials is a key for this technique. In this paper, the types, elemental distribution, application limits and manufacture method of reference materials for LA-ICP-MS analysis were reviewed. Currently, there are limited accessible Certified Reference Materials (CRMs). Some of the CRMs have low elemental contents and large uncertainties, which has restricted their application. Meanwhile, manufacture methods are immature and the homogeneity test for microanalysis reference material did not reach an agreement. Based on the homogeneity test method for rock powder reference materials, a two-step homogeneity test method was proposed. PGEs and Au contents in reference materials should be appropriate. Reference materials for Pb-S sulfide matrix, carbonate and phosphate matrix with different chemical compositions are urgently needed. With respect the the manufacture method of reference materials, nano-powder tablet technology and homogeneity tests should be developed further.

High-quality Sr isotope data are critically dependent on the quality of reference materials that are used for instrumental calibration and data monitoring during LA-MC-ICP-MS analysis. A suite of natural plagioclase samples (BDL-1, BDL-2 and BDL-3) from the Badaling intrusive complex, Beijing were investigated here to test their suitability as a plagioclase Sr isotope reference material. Major and trace element analyses by EPMA and LA-ICP-MS showed that plagioclase crystals separated from two troctolites (BDL-1 and BDL-3) and one gabbro (BDL-2) were all characterized by extremely low Rb/Sr ratios (0.00012–0.00047), and low heavy rare earth elements (HREEs) and high Sr contents (2377–2836 μg g−1). A total of 200 LA-MC-ICP-MS analyses for plagioclases BDL-1, BDL-2 and BDL-3 showed consistent and homogeneous Sr isotopic compositions with an average 87Sr/86Sr ratio of 0.70535 ± 0.00007 (2SD), which was in good agreement with solution-based data determined by TIMS or SN-MC-ICP-MS (0.70533 ± 0.00004; 2SD, n = 12), thus suggesting that BDL plagioclase can be used as a potential reference material for microbeam Sr isotopic analysis. Compared to the other available plagioclase Sr isotopic reference materials, the large quantities, long-term availability, high Sr content and extremely low isobaric interference (Rb, Er and Yb) of BDL plagioclase make it especially suitable for instrumental calibration and to adjust for inter-laboratory bias of the measured 87Sr/86Sr ratios. [ABSTRACT FROM AUTHOR]

A new natural zircon reference material SA01 is introduced for U‐Pb geochronology as well as O and Hf isotope geochemistry by microbeam techniques. The zircon megacryst is homogeneous with respect to U‐Pb, O and Hf isotopes based on a large number of measurements by laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and secondary ion mass spectrometry (SIMS). Chemical abrasion isotope dilution thermal ionisation mass spectrometry (CA‐ID‐TIMS) U‐Pb isotopic analyses produced a mean 206Pb/238U age of 535.08 ± 0.32 Ma (2s, n = 10). Results of SIMS and LA‐ICP‐MS analyses on individual shards are consistent with the TIMS ages within uncertainty. The δ18O value determined by laser fluorination is 6.16 ± 0.26‰ (2s, n = 14), and the mean 176Hf/177Hf ratio determined by solution MC‐ICP‐MS is 0.282293 ± 0.000007 (2s, n = 30), which are in good agreement with the statistical mean of microbeam analyses. The megacryst is characterised by significant localised variations in Th/U ratio (0.328–4.269) and Li isotopic ratio (−5.5 to +7.9‰); the latter makes it unsuitable as a lithium isotope reference material. [ABSTRACT FROM AUTHOR]