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An efficient digestion method for the determination of major and trace elements in Ti-rich minerals by ICP-MS.

An accurate method for ultratrace rare earth elements quantification in highly saline water with small volume sample consumption by laser ablation solution sampling ICP-MS.

Lunar soil is a fine mixture of local rocks and exotic components. The bulk-rock chemical composition of the newly returned Chang’E-5 (CE-5) lunar soil was studied to understand its chemical homogeneity, exotic additions, and origin of landing site basalts. Concentrations of 48 major and trace elements, including many low-concentration volatile and siderophile elements, of two batches of the scooped CE-5 soil samples were simultaneously obtained by inductively coupled plasma mass spectrometry (ICP-MS) with minimal sample consumption. Their major and trace elemental compositions (except for Ni) are uniform at milligram levels (2–4 mg), matching measured compositions of basaltic glasses and estimates based on mineral modal abundances of basaltic fragments. This result indicates that the exotic highland and KREEP (K, rare earth elements, and P-rich) materials are very low (

In this study, we measure the absolute isotope ratios of ytterbium (Yb) by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) using an optimized regression model for mass bias correction. A rhenium (Re) reference material (NIST SRM 3143), which has been characterized previously, is selected as a primary calibrator to calibrate the absolute Yb isotope ratios for three Yb materials (GSB, Alfa Yb, and GBW). The three-isotope plot for all collected data indicates that the results of Yb isotope ratios obtained are not affected by any polyatomic interferences and the mass-independent isotopic fractionation. Furthermore, the recalibrated Hf historical isotope ratios by using the absolute Yb isotopic composition obtained in this study for the isobaric interference correction on Hf isotopes are in agreement with the original historical values. This work has further demonstrated the applicability of the regression model for the calibrated measurements of absolute isotope ratios using MC-ICP-MS. The three mono-elemental Yb standard solutions are thus proposed as the reference materials for Yb isotope ratio measurements in environmental and geoscience applications.

The Carnian Pluvial Event (CPE) was an interval marked by global climatic and environmental change, along with biotic turnover, which occurred during the early Late Triassic. Although the causes and consequences of this event remain unclear, one possible scenario is enhanced volcanism injecting greenhouse gases into the atmosphere, perturbing the global carbon cycle, and negatively impacting the global environment. However, there is an underlying challenge in showing a true cause- and-effect relationship between volcanism and the CPE, as both the sedimentary and volcanic records are difficult to date accurately enough to demonstrate temporal correspondence. However, mercury (Hg) can be used to fingerprint catastrophic volcanism in the sedimentary record. We examined two sections that record the CPE at Laishike and Wayao in Guizhou Province, southwest China, which display high Hg contents along with spikes of Hg/total organic content (TOC), Hg/Al, Hg/total sulfur (TS), and Hg/(Mo/Al) during the CPE that indicate a shift to excess Hg loading. These Hg anomalies are correlative with the global negative excursion in δ13Ccarb values at the CPE, which suggests that increased volcanism injected both massive amounts of Hg and isotopically light carbon into the atmosphere, and these were ultimately recorded in marine sediments. This interpretation is supported by slightly negative or near-zero Δ199Hg values that are consistent with a volcanic Hg source. Our study supports the hypothesis that enhanced volcanism played a major role in the evolution of biota and the environment during the CPE.

This work evaluates the use of femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS) for Zr isotopic analysis in zircons. The mass fractionation caused by instrumental mass discrimination was corrected by a combination of internal correction using Sr as an internal standard (coming from a NIST SRM 987 standard solution) and external correction using a matrix-matched standard. Several important instrument parameters were investigated, such as the effect of the addition of N2 and “wet” plasma condition, the mass fractionation behaviors between Zr isotopes and Sr isotopes, the position effect in laser ablation cell and the effect of laser ablation parameters (laser spot size and energy density). The Zr isotope compositions of seven zircons (GJ-1, 91500, Plešovice, Rak-17, Paki, Aus and Mala) were determined by the developed fs-LA-MC-ICP-MS and thermal ionization mass spectrometry (TIMS). Our fs-LA-MC-ICP-MS results for Zr isotope compositions agreed with TIMS analyses within analytical uncertainties, indicating the presented method is a suitable tool to resolve isotopic zoning in natural zircons. The results also suggest that GJ-1, 91500, Plešovice, Paki, Aus and Mala had the homogenous Zr isotope composition and could be considered as the potential candidates for the Zr isotope analysis in zircons, except Rak-17 which presented the large Zr isotope variation.

Accurate and precise Mg isotopic analysis by fs-LA-MC-ICP-MS can be performed with low mass resolution and non-matrix-matched calibration.

A combination of ultra-fine sulfide powders and a PAS technique to synthesize pyrite and chalcopyrite reference materials for in situ iron and sulfur isotope analysis.

Tianyu-Py pyrite is investigated as the natural reference material for in situ iron isotopic ratios microanalysis.

This study reports a method for in situ determination of stable carbon (δ13C‰) isotope compositions for various carbonate matrices including calcite, dolomite, magnesite and siderite by fs-LA-MC-ICP-MS with a precision of 0.37–0.68‰.

Subduction of oceanic lithosphere is a diagnostic characteristic of plate tectonics. However, the geodynamic processes from initiation to termination of subduction zones remain enigmatic mainly due to the scarcity of appropriate rock records. We report the first discovery of early Paleozoic boninitic blueschists and associated greenschists from the eastern Proto-Tethyan North Qilian orogenic belt, northeastern Tibet, which have geochemical affinities that are typical of forearc boninites and island arc basalts, respectively. The boninitic protoliths of the blueschists record intra-oceanic subduction initiation at ca. 492–488 Ma in the eastern North Qilian arc/forearc–backarc system, whereas peak blueschist facies metamorphism reflects subsequent subduction of the arc/forearc complex to high pressure at ca. 455 Ma. These relations therefore record the life circle of an intra-oceanic subduction zone within the northeastern Proto-Tethys Ocean. The geodynamic evolution provides an early Paleozoic analogue of the early development of the Izu–Bonin–Mariana arc and its later subduction beneath the extant Japanese arc margin. This finding highlights the important role of subduction of former upper plate island arc/forearcs in reducing the likelihood of preservation of initial subduction-related rock records in ancient orogenic belts.

The metasomatized sub-continental lithospheric mantle (SCLM) is increasingly proposed to play a key control in the formation of giant gold (Au) deposits. However, the extent of Au enrichment in metasomatized SCLM and the Au contents of its derivative partial melts remain poorly constrained. Lamprophyres are derived from low-degree melting of metasomatic and fusible components in the SCLM, and could provide fundamental information about the metasomatized source and metal release compared to mantle peridotites and/or pyroxenites. The giant Jiaodong Au province (> 5000 tons, ∼ 120 Ma) in the eastern part of the North China Craton (NCC) is an ideal locality to assess the Au endowment of metasomatized SCLM which may serve as the source of Au, as indicated by the presence of mantle-dominated volatiles in auriferous fluids associated with the deposits. Based on detailed petrological studies, we analyzed Au, S, Cu and platinum-group element (PGE) contents of the SCLM-derived lamprophyres that are temporally (130–121 Ma) and spatially associated with the Jiaodong lode Au deposits. The lamprophyre dykes were emplaced in the deep crust and did not experience significant degassing and sulfide segregation, and the sulfide saturation occurred at a late stage during magma cooling, as demonstrated by sulfide petrography, S contents, Cu/S and Cu/Pd ratios of the lamprophyres. The relatively oxidized (ΔFMQ +1 – +2), hydrous (2–4 wt.% H2O) lamprophyres display variable and generally low Au contents (0.04–3.59 ng/g, mainly 1–3 ng/g, n = 31), as well as low PGE and Cu contents. Their high Au/Cu(N) and Au/Pd(N) ratios together with high Ba/Nb indicate a discernible Au addition to their source, resulting from multi-stage mantle metasomatism related to subduction. However, the average Au contents of the metasomatized SCLM before large-scale Au mineralization are heterogeneous and overall in a range of 0.5–1.5 ng/g. The values are higher than that of depleted SCLM (

In this study, we present a new high-precision method to analyze Ba isotope ratios in barite samples by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). Barite international standard materials (NBS127, IAEA-SO-5 and IAEA-SO-6) were sintered under high pressure using a multi-anvil device to stabilize reference materials for in situ analysis of Ba isotopes in barite samples. The isobaric interference of 134Xe and polyatomic interference on Ba isotopes were found to be insignificant, and no significant matrix effect was found between the sintered standards and natural barite samples. Small ablation spots (16–44 μm) and a low ablation frequency (1 Hz) were used in this study. This high spatial resolution mode combined with a signal smoothing device improved the analytical precision by 12.5 times compared to the results obtained without a signal smoothing device. The long-term external precision obtained for δ137/134BaNBS127 is 0.09‰ (2SD). Two sintered barite international standard samples (IAEA-SO-5 and IAEA-SO-6) and six natural barite samples (Ba-FJ, Ba-FRA, Ba-YN, Ba-HN, 2JS-11 and LT-1) from different areas were measured by LA-MC-ICP-MS. The δ137/134BaNBS127 values of these sintered barite standards and natural barite samples determined by LA-MC-ICP-MS are in good agreement with those of double-spike measurements, confirming the reliability and accuracy of the proposed method for in situ analysis of Ba isotopes in barite. Additionally, the Ba isotope ratios of natural barite samples Ba-FJ and Ba-HN were found to be homogeneous, suggesting that these references can be used as in-house reference materials for LA-MC-ICP-MS analysis of Ba isotopes.

Using boron as a test analyte, laser ablation (LA) solution sampling multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is proposed and validated as a fast method for isotopic analysis in natural liquids and digested samples without any prior purification process. We demonstrated that the solution reference standard can be used as a bracketing standard for in situ δ

Figure S1a illustrates the comparison between the Grt/Cpx partition coefficients of garnet lherzolite (Chijiadian) and experiment data. Figure S1b calculates the REE compositions of metasomatic melts. Figure S1a illustrates the comparison between the Grt/Cpx partition coefficients of garnet lherzolite (Chijiadian) and experiment data. Figure S1b calculates the REE compositions of metasomatic melts. Tables S1 to S3 supply the major and trace elements of bulk rock and minerals, as well as Sr isotopes in situ used in this article. Table S4 gives the partition coefficients related to the calculations of Figure S1.

We proposed a new laser analytical mode, which used the high-frequency laser ablation to deliberately obtain the peak-shape signal profile, combined with the linear regression calibration (LRC) method to calculate elemental or isotopic ratios. In order to access the performance of the new laser analytical mode for the application in the field of earth science, we systematically investigated the elemental quantitative analysis with high spatial resolution (10 µm), rapid U-Pb dating in zircons and accurate Sr-Hf isotope analysis in geological samples. The new high-frequency laser analysis technology (20 Hz, 100 pulses) reduced the limit of detection (LOD) of 25 elements to 0.005–0.16 µg g−1 with crater diameters of 10 µm, which are significantly lower (decrease to 2–20%) than previous researches. The quantitative analysis of five silicate glass reference materials showed that the precision and accuracy of the 25 trace elements (with the concentration ranging from 0.17 to 683 µg g−1) were better than 16% and 15%, respectively. The new methods raised the analytical throughput of zircon U-Pb dating, Sr isotope ratios and Hf isotope ratios to 250 analyses per hour, 144 analyses per hour and 120 analyses per hour in theory, while the analytical accuracy and precision did not be compromised. The detailed investigations showed that the proposed new laser analytical mode has good application effects in the field of earth sciences.

Bastnasite is widespread in alkali granite, carbonatite and REE ore deposits. The U-Th-Pb ages of bastnasite can constrain the mineralization age. Currently, the lack of suitable in situ analysis reference material is the major obstacle of bastnasite U-Th-Pb geochronology. In this study, the matrix effects of U-Pb and Th-Pb age determination in bastnasite using glass NIST 610 as the external calibration reference were evaluated with the 193-nm excimer LA-ICP-MS analysis in normal and additional gases laser ablation modes. The obtained U-Th-Pb ages of bastnasite were approximately 7–11% lower than their reference values in the normal analytical mode (without additional gas). Fortunately, the determined systematic age biases in U-Th-Pb dating were significantly reduced (less than 1–2%) with the addition of water vapor within the ablation chamber. This reduction may be attributed to the observed significant suppression of 206Pb/238U and 208Pb/232Th downhole fractionation in both NIST 610 glass and bastnasite by introducing a small quantity of water vapor in the ablation chamber. In addition, the obtained 206Pb/238U and 208Pb/232Th ages of bastnasite K-9, LZ1384, and MAD809 showed great consistency with their corresponding recommended values. The obtained results show that accurate and precise U-Th-Pb ages of bastnasite can be simultaneously obtained by using glass NIST 610 as the primary calibration standard in 193-nm LA-ICP-MS with the water vapor-assisted method. This simple and effective water vapor-assisted non-matrix-matched laser ablation method helps to promote the geological application of bastnasite U-Th-Pb geochronology.

High sensitivity and minimized spectral interference are prerequisites for precise and accurate measurement results of ultra-trace REEs (Sc and Y, rare earth elements) in geological samples (e.g., carbonates and peridotites). In this study, we designed a heating-condensing system for the direct determination of mass fractions of ultra-trace REEs in carbonates and peridotites by Ar–N2 mixed plasma ICP-MS combined with different skimmer cones. Compared to those under normal conditions (without a heating-condensing system), the signal sensitivities of the investigated 47 elements were improved by 5–8 and 6–24 fold at a heating temperature of 180 °C when using the H skimmer cone and the X skimmer cone, respectively. Our results firstly indicate that the geometry of the skimmer cone has an important effect on signal enhancement when using the heating-condensing system in ICP-MS. The addition of nitrogen (3–9 ml min−1) in the central channel of the plasma was found to significantly reduce the oxide ratios (CeO+/Ce+) by a factor of approximately 5–10. This reduction is important for the determination of ultra-trace REEs, which are well known to be interfered by oxides of Ba and light REEs. We successfully applied this method to directly determine ultra-trace REEs in eight reference carbonates and peridotites. This simple and rapid method shows great potential for the direct determination of ultra-trace REEs in geological samples and other technogenic materials with a high matrix and low REE abundances.

We present detailed characterization of Tanz zircon megacrysts for the microbeam determination of U–Pb ages, Zr isotopes, Hf isotopes, O isotopes and trace element mass fractions. This batch of dark brown zircon megacrysts from Tanzania contains 269 ± 103 μg g−1 U (Th/U ∼ 0.154), and its total weight is 9.06 kg. The largest Tanz zircon megacryst in this batch weighs 366 grams. The calculated average accumulated alpha-radiation dosage is 0.54 × 1018 events per g for the Tanz zircon, which correlates with a ‘well crystallized’ structure. Through a large number of laser ablation ICP-MS, laser ablation MC-ICP-MS and SIMS measurements, it is found that Tanz zircon megacrysts are quite uniform in U–Pb ages, O isotopes and Zr isotopes at scales of tens of microns. The Tanz zircon has chemical abrasion isotope dilution TIMS (CA-ID-TIMS) determined mean isotopic ratio values of 0.09180 ± 0.00013 (2SD, n = 47) for 230Th corrected 206Pb/238U, 0.7473 ± 0.0014 (2SD, n = 47) for 207Pb/235U and 0.059069 ± 0.000067 (2SD, n = 47) for 230Th corrected 207Pb/206Pb. The CA-ID-TIMS method yielded a mean 230Th corrected 206Pb/238U age of 566.16 ± 0.77 Ma (2SD, n = 47). The determined mean δ18OVSMOW and δ94/90ZrSRM3169 values of the Tanz zircon megacrysts are 6.52 ± 0.28‰ (2SD, n = 29) and −0.01 ± 0.06‰ (2SD, n = 35) by gas source mass spectrometry and double spike TIMS, respectively. All of these values are in good agreement with the statistical mean values of microbeam measurements and are proposed as the best reference values for Tanz zircon megacrysts. These features make the Tanz zircon megacrysts suitable as primary U–Pb age and Zr–O isotope reference materials for microbeam analysis. However, our LA-MC-ICP-MS data suggest a relatively wide distribution of Hf isotope compositions in the Tanz zircons (0.281821 ± 0.000042, 2SD, n = 321), which makes Tanz zircons not an ideal Hf isotope reference material for microbeam analysis. We propose the Tanz zircon megacrysts as a potential reference material for the primary external calibration or monitoring of analytical validation for microbeam determination of U–Pb ages and Zr–O isotopes.

Highly precise and accurate measurements of Fe isotope ratios for fourteen reference materials from the USGS, MPI-DING and CGSG were successfully carried out using a developed analytical technique by fs LA-MC-ICP-MS. A synthetic standard, i.e., Cr-979S, was produced as a calibration standard for instrumental mass bias and isobaric interference corrections. The results for samples with low Cr concentration (54Cr/54Fe 0.0001), e.g., BHVO-2G, δ56Fe values deviated from reference values when using the standard-sample bracketing method alone. Combining the standard-sample bracketing method with Cr-979S standard corrections and standard sample cone + H skimmer cone, the measured Fe isotopic compositions of GOR128-G and GOR132-G with extremely high Cr concentrations (54Cr/54Fe > 0.01) were identical to reference values within errors (δ56Fe = −0.01 ± 0.13‰, 2SD, n = 18; δ56Fe = 0.00 ± 0.13‰, 2SD, n = 13; respectively). A series of reference materials with varying Cr concentrations, including the USGS reference glasses (BCR-2G, BHVO-2G, BIR-1G, TB-1G, NKT-1G, GSD-1G and GSE-1G), MPI-DING reference glasses (KL2-G, ML3B-G, GOR128-G and GOR132-G) and CGSG reference materials (CGSG-1 and CGSG-4), were used to test our developed method of in situ Fe isotopic measurements using the combined standard-sample bracketing method and Cr-979S standard corrections by fs LA-MC-ICP-MS. All the reference materials yield relatively homogeneous Fe isotopic compositions with δ56Fe values ranging from −0.03‰ to 0.13‰ and δ56Fe reproducibility is below 0.15‰ (2SD), suggesting that the proposed isobaric interference correction and mass bias correction method is a useful tool for providing high-quality in situ Fe isotopic data of geological samples with both low and high Cr concentrations.

Zircon U–Pb geochronology and Hf–O isotope composition provide important information on geological events. This matrix-matched reference material is routinely used to yield accurate and precise zircon U–Pb ages and Hf–O isotope ratios with in situ techniques. In this study, a new potential zircon reference material (Jilin) separated from gabbro diorite was introduced for microbeam U–Pb age and Hf–O isotope analysis. The obtained average U, Th, Pb, Lu and Hf concentrations were 439 ± 26 ppm (1 s), 378 ± 39 ppm (1 s), 67.6 ± 1.6 ppm (1 s), 54.6 ± 6.5 ppm (1 s), and 9135 ± 510 ppm (1 s) respectively. The chemical abrasion isotope dilution thermal ionization mass-spectrometry (CA-ID-TIMS) method yielded a Th-corrected weighted mean 206Pb/238U age of 117.63 ± 0.04 Ma (2 s, MSWD = 1.9). The homogeneity of U–Pb ages in Jilin zircon was also investigated in two independent secondary ion mass spectrometry (SIMS) laboratories and four different laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) laboratories. The obtained mean 206Pb/238U ages with SIMS and LA-ICP-MS were 116.8 ± 2.9 Ma and 117.8 ± 2.7 Ma, respectively, which are consistent with the CA-ID-TIMS value within the analytical uncertainties. The distribution of Hf isotopic composition was evaluated with LA-multicollector-ICP-MS (LA-MC-ICP-MS) and solution MC-ICP-MS. The results acquired in two LA-MC-ICP-MS laboratories were identical to the solution value with a mean 176Hf/177Hf ratio of 0.282926 ± 0.000014 (2SD, n = 17). The O isotope obtained with the laser fluorination method is also in agreement with the SIMS analysis with the recommended mean δ18O value of 6.05 ± 0.25‰ (2SD, n = 8). The results obtained with multianalytical techniques clearly indicate that the U–Pb age and Hf–O isotopic composition are homogenous in Jilin zircon grains. We propose the Jilin zircon as a potential reference material for the primary external calibration or monitoring of analytical validation for Mesozoic U–Pb geochronology and Hf–O isotopic measurements.

Significance Zircon, a common accessory mineral in crustal rocks, records plentiful and critical information on the Earth’s history. The isotopes of its major component, Zr, could be another powerful but unexplored tracer. We apply high-precision, high–spatial-resolution, in situ laser ablation Zr isotope measurements of magmatic zircons in continental arc plutonic rocks. Single zircon grains show impressive internal zoning with lighter Zr isotopes in the core but heavier ones toward the rim, solving a fundamental but controversial issue on how zircon fractionates Zr isotope in evolving magmas. Our results also reveal a strong temperature dependence of Zr isotopic fractionation. The Zr isotope is thus very promising in deciphering the differentiation history of magmatic systems and possibly the continental crust through time., Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD

The oceanic crust consists mainly of a lower layer of cumulate gabbroic rocks and an upper layer of differentiated basalts. The thicknesses and proportions of the gabbroic and basaltic layers in different oceans are largely controlled by spreading rate, magma supply, and magmatic differentiation processes. Evaluating the effects of complex magmatic differentiation as a function of spreading rate on Ca isotope composition is critical to understanding whether the Ca isotope compositions of oceanic crust from different oceans are homogeneous and thus whether the observed considerable variation of δ44/40Ca in basalts (up to 0.4‰) results from magmatic differentiation or mantle source heterogeneity. To address the question, we present δ44/40Ca measurements of a series of gabbroic rocks (n = 38) and mineral separates from the 810-m-long U1473A hole drilled into the gabbroic lower crust at the ultraslow-spreading Southwest Indian Ridge (SWIR), along with 12 mid-ocean ridge basalts (MORBs) from the slow-spreading South Mid-Atlantic Ridge (SMAR) and the fast-spreading East Pacific Rise (EPR). Although the gabbroic rocks of the SWIR reflect several events of magma supply and strong magmatic differentiation (bulk rock Mg# of 64–79 for each event), their δ44/40Ca values (0.85 ± 0.09‰, 2sd, n = 37) are uniform. The results are consistent with limited inter-mineral Ca isotope fractionation between plagioclase (Pl) and co-existing clinopyroxene (Cpx) in the accumulated gabbros (average Δ44/40CaPl-Cpx = −0.10‰, n = 5). This indicates that no measurable Ca isotope fractionation occurs during formation of ultraslow-spreading oceanic crust. The MORBs from the SMAR and EPR show consistent δ44/40Ca values (0.82 ± 0.08‰ (2sd, n = 4) and 0.86 ± 0.09‰ (2sd, n = 8), respectively), regardless of the degree of fractional crystallization. On the whole, the ultraslow-, slow- and fast-spreading gabbroic cumulates and MORBs display indistinguishable δ44/40Ca within analytical uncertainty, suggesting a homogenous Ca isotope composition for the global igneous oceanic crust (δ44/40Ca = 0.85 ± 0.09‰, 2sd, n = 49) even if they experience complex magmatic differentiation. Comparison with values for fertile mantle rocks (δ44/40Ca = 0.94 ± 0.10‰) reveals that partial melting triggers only slight Ca isotope fractionation (0.09 ± 0.02‰, 2se). In this light, the considerable variation of previously reported δ44/40Ca values for basalts may result from their different mantle sources, and is probably attributable to the recycling of crustal materials.