Laser Ablation Inductively Coupled Plasma Mass Spectrometry Research Articles

Spectroscopy Characteristics and Color-Influencing Factors of Green Iron-Bearing Elbaite

The color-influencing factors and spectroscopy of 22 green elbaite samples were investigated using X-Rite SP62 spectrophotometry, ultraviolet–visible (UV–Vis) spectroscopy, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and infrared spectroscopy. The chromogenic components iron and manganese were found in the green elbaites; however, the bivariate correlation analysis indicated that the Mn content had no impact on the color, whereas the Fe content significantly affected both the lightness and the hue of green elbaites. The primary factors influencing the color of tourmaline were the absorption band at 720 nm caused by the Fe2+ d-d transitions and the 300 to 400 nm wide absorption edge extending to the visible range due to the O2−-Fe3+ charge transfer. Infrared spectroscopy indicated that the color of tourmalines was also influenced by their structure. As the degree of Y and Z octahedral distortion in the tourmaline lattice increased, the lightness of the tourmaline decreased and its color deepened. The hydroxyl region of the infrared spectra of green elbaite showed three distinct peak positions representing two types of hydroxyl vibrations: O1H at the W position and O3H at the V position. The O1H vibrations are attributed to YLiYAlYAl and XNa or X position vacancy, while the O3H vibrations are assigned to ZAlZAlYAl and ZAlZAlYLi. The presence of three peaks in the hydroxyl vibrational region of the IR spectra indicated that these samples were iron-bearing elbaites.

Geochronology of reworked ash and its implications for accommodation space variations in distal foreland basins, McMurray Formation, Alberta, Canada

A bentonite bed consisting of reworked volcanic ash from the Barremian to Aptian lower McMurray Formation is dated using chemical abrasion thermal ionization mass spectrometry (CA-TIMS) on zircon. The bentonite bed is from a cored interval in the McKay Paleovalley in the northern Athabasca Oil Sands Region of Alberta, Canada. Deposition of the lower McMurray Formation took place in the distal portion of the Western Canada Sedimentary Basin early in the Cretaceous-to-Paleocene phase of widespread contractional deformation in the Canadian Cordillera. A 30 g sample of volcanic ash yielded >10,000 very small (<50 µm) zircon grains with the vast majority (~99.7%) being highly abraded and clearly detrital. Twenty-six sharply faceted grains were sufficiently large to be mounted for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis, which yielded seven Lower Cretaceous dates. These Lower Cretaceous grains were further analyzed using CA-TIMS. The five youngest CA-TIMS dates agree with a weighted mean of 121.51 ± 0.11 Ma which is conservatively interpreted as a maximum depositional age (MDA). The good agreement between the five zircon dates indicates the MDA is probably the depositional age. This study demonstrates that with careful analysis of zircon populations, high-confidence MDAs can be derived even from reworked ash beds that are dominated overwhelmingly by detrital zircon. The date from this study overlaps a previously published MDA of 121.39 ± 0.27 Ma for the top of the lower McMurray Formation in Firebag Tributary in the northeastern Athabasca Oil Sands Area. The overlapping dates establish a widespread chronostratigraphic surface within the northern Athabasca Oil Sands Area. Both ages are from ash beds preserved in coal seams, suggesting that the coal-bearing interval is a regional marker bed and that the ash beds may form an intraformational datum. Further, the occurrence of the ash beds in the McMurray Formation in close proximity to regional flooding surfaces suggests that tectonic activity in the emerging Canadian Cordillera influenced accommodation space variations in the distal portions of the adjacent foreland basin.

In situ U–Pb age determination of apatite from carbonatite and kimberlite in the Batain Basin, eastern Oman

Northeastern Oman is characterized by carbonatite and kimberlite complexes, which are the ideal samples for studying the relationship between carbonatite and kimberlite. However, the ages of the Oman kimberlite and carbonatite complexes are still unknown, which restricts the understanding of the relationship between carbonatite and kimberlite in Oman. In this study, we use in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to analyze the apatite from Oman carbonatite, kimberlite, and spessartite. The U–Pb apatite ages are 141.6 ± 6.0 Ma, 137.4 ± 5.2 Ma, and 141.2 ± 6.2 Ma for carbonatite, spessartite (a kind of calc-alkaline lamprophyre), and kimberlite, respectively. These results suggest that the carbonatite and kimberlite were emplaced contemporaneously, followed by calc-alkaline carbonatite (spessartite) emplaced in the Early Cretaceous. The occurrence of carbonatite, kimberlite, and spessartite magmatism of Oman was contemporaneous with the time of the Gondwana breakup during the opening of the Indian Ocean. It is seen that 140 Ma–130 Ma is one of the strongest global kimberlite abundance peaks of the 250 Ma–50 Ma kimberlite bloom, which corresponds with the period of the Pangea supercontinent breakup. The Oman kimberlites and carbonatites are related to a distal effect of the breakup of the Gondwana portion of the Pangea supercontinent, which provided a cool, volatile-fluxed decompression-related circumstance for the formation.

BITS: A Bayesian Isotope Turnover and Sampling model for strontium isotopes in proboscideans and its potential utility in movement ecology

Abstract Strontium isotope ratios (87Sr/86Sr) of incrementally grown tissues have been widely used to study movement ecology and migration of animals. However, the time scale of 87Sr/86Sr incorporation from the environment into tissue and how it may influence data interpretation are still poorly understood. Using the relocation of a zoo elephant (Loxodonta africana) named Misha, we characterise and model the 87Sr/86Sr turnover process using high‐resolution measurements of its tusk dentine. We seek to develop a framework that can improve quantitative interpretation of 87Sr/86Sr data in tissues. The 87Sr/86Sr transition associated with the relocation is measured using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) on a prepared tusk slab. We develop a turnover model (BITS), with a rapidly exchanging central pool and a slowly exchanging peripheral pool, in a Bayesian statistical framework. The measured dentine data are first used to calibrate model parameters. The parameters are then used to estimate possible 87Sr/86Sr input time series from two datasets via model inversion: a fidelity test using Misha's dentine data and a case study using published dentine measurements from an Alaskan Woolly Mammoth (Mammuthus primigenius). The LA‐ICP‐MS data are consistent with a two‐compartment turnover process with equivalent half‐lives of 41 days for the central pool and 170 days for the peripheral pool. The model inversion shows good fidelity when estimating the intake 87Sr/86Sr time series associated with Misha's relocation. In the case study, the model suggests an abrupt pattern of change in, and a much wider range of, intake 87Sr/86Sr values than expressed in the woolly mammoth dentine data themselves. Our framework bridges the gap between environmental 87Sr/86Sr variation and data measured in tusk dentine or other incrementally grown tissues. It could be coupled with movement models and additional isotope tracers to study seasonal residency or the spatial and temporal patterns of movement/migration. The generic turnover processes can be adapted to other isotope systems, additional incremental tissues, or other organisms, thus expanding our modelling toolkit to investigate niche partitioning, life history traits and behavioural patterns in conservation biology, archaeology and paleoecology.

Ore genesis of the Mengya'a distal Pb–Zn deposit in the Lhasa terrane, Tibet, China: Constraints from in situ garnet U–Pb dating and C–H–O–Sr isotopes

A large amount of distal skarn Pb–Zn deposits without any causative intrusions exposed have been discovered along the eastern Nyainqêntanglha metallogenic belt (NMB) in the Gangdese region, Tibet, China. As a typical distal skarn Pb–Zn deposit in the east of NMB, the Mengya'a deposit is adjacent to the Longmala Pb–Zn ± Cu ± Fe deposit. However, the linkage between these two deposits is not unclear due to the chaotic dating results. In situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS) U–Pb dating of reddish‐brown and yellow‐green garnet from Mengya'a yielded lower intersect ages of 53.6 ± 3.1 and 52.4 ± 4.4 Ma, respectively, indicating that Pb–Zn mineralization took place during the main collision stage of the India–Asia plates. The δDSMOW values of garnet, quartz and calcite vary from −148.4‰ to −140.4‰, −123.5‰ to −115.3‰ and −127.9‰ to −121.3‰, with the δ18OH2O values ranging from 5.8‰ to 6.6‰, 0.4‰ to 3.7‰ and 1.0‰ to 1.7‰, respectively. The δ13CV‐PDB and δ18OSMOW values of calcite range from −8.2‰ to −4.7‰ and 9.8‰ to 18.6‰, respectively. These C–H–O isotopic compositions of hydrothermal minerals indicate that the ore‐forming fluids were initially derived from the magmatic water with progressive input of meteoric water from the prograde stage to the retrograde stage. The 87Sr/86Sr(53 Ma) ratios of sphalerite (0.72321–0.73474) are consistent with those of Ando gneiss in the Lhasa‐Golmud area, indicating that the basement gneiss makes a great contribution for the source of ore‐forming materials. The newly obtained garnet U–Pb ages at Mengya'a are consistent with those of mineralization and causative intrusion in the Longmala Pb–Zn ± Fe ± Cu deposit, suggesting that the Mengya'a and Longmala deposits constitute an integrated distal skarn‐type system. This proposed hypothesis suggests that the Fe–Cu ± Pb ± Zn mineralization within the contact zone should focus on the locations beneath the identified Pb–Zn orebodies at Longmala and Pb‐21 orebody at Mengya'a.

Capturing Equatorial Pacific Variability With Multivariate Sr‐U Coral Thermometry

AbstractSr‐U, a coral‐based paleothermometer, corrects for the effects of Rayleigh Fractionation on Sr/Ca by regressing multiple, paired U/Ca and Sr/Ca values. Prior applications of Sr‐U captured mean annual sea surface temperatures (SSTs), inter‐annual variability, and long‐term trends. However, because many Sr/Ca‐U/Ca pairs are needed for a single Sr‐U value as originally formulated, the temporal resolution of the proxy is typically limited to 1 year. Here, we address this limitation by applying laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS) to three Porites colonies from Jarvis and Nikumaroro Islands in the central equatorial Pacific (CEP), generating ∼25 Sr/Ca‐U/Ca pairs per month of skeletal growth. Both Sr/Ca and U/Ca vary significantly over small (sub‐mm) length scales and support the calculation of Sr‐U values using the original regression method. Over the represented temperature range of 24–31°C, the Sr/Ca‐U/Ca‐SST relationships are nonlinear, a finding consistent with predictions of the Rayleigh model. To reflect this non‐linearity, we developed a calibration using multivariate nonlinear regression. The multivariate, three‐coral calibration was applied to 20 years of monthly resolved Sr/Ca and U/Ca of a coral interval not included in the calibration, yielding RMSE = 0.73°C and r2 = 0.85 (p < 0.05; df = 256). The multivariate calibration performed significantly better than Sr/Ca alone (r2 = 0.28). Applying the new calibration to a subfossil Porites from Kiritimati Atoll, CEP (2200 Before Present) yields equivalent phase and amplitude of interannual variability, but water temperatures ∼1.6°C cooler than they are in this region today.

Natural ilmenite reference material for trace elemental in situ microanalysis

Ilmenite is a commonly occurring mineral in both igneous and metamorphic rocks and its major and trace elements have various applications in geology, including as a geothermometer, oxygen barometer, and geochemical tracer. In this study, a 500 g ilmenite megacryst sample (LY) was developed as a reference material for in situ element microanalysis. Twenty-two ilmenite fragments, with grain sizes ranging from 1 to 8 mm, were subjected to major and trace element analysis using electron microprobe analysis (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in four different laboratories. The results indicate that the ilmenite sample is homogeneous with respect to TiO2, FeO, Mg, Sc, V, Cr and Mn, whereas Co and Nb are minor inhomogeneous. Consequently, this sample can be used as a reliable reference material for in situ microanalysis.

Interannual variability in otolith biogeochemical signatures of Japanese Spanish mackerel in the Yellow Sea

Fishes often use multiple habitats to complete their life cycles, leading to their unique otolith biogeochemical signatures. Interannual variability in otolith biogeochemical signatures is expected as fish respond to annual environmental variations in their distribution areas. In this study, we focus on Japanese Spanish mackerel Scomberomorus niphonius, an abundant commercial species in the Yellow Sea. As highly migratory fish that undergo their entire migratory cycle in a year, S. niphonius is susceptible to environmental variations. Consequently, they are believed to exhibit discernibly distinct migration patterns and varying timings of ontogenetic events across different years. Otolith biogeochemical signatures of 1-year-old spawning adults S. niphonius caught in the Yellow Sea from 2016 to 2018 were measured from core to edge using laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). We hypothesized that the year-specific chemical signature could be found in 2016 as a strong El Niño Southern Oscillation event happened. From 2016 to 2018, converse ontogenetic changing patterns was observed for Sr/Ca and Ba/Ca, with Sr/Ca being positively correlated with sea surface salinity while Ba/Ca being negatively. As expected, the year-specific effect was identified for 2016 cohort but it was only significant on Ba/Ca. During this year, a stronger variation of elemental concentration and an earlier downward shift of Ba/Ca were found. These results provide evidence that otolith biogeochemical signatures have useful applications as natural tags, helping understand the interannual variability in migration of marine fish species.

Revealing the Secrets behind the Color and Sea-Wave Patterns of Larimar

In the last century, a blue–green colored gemstone known as Larimar with a special sea-wave pattern was discovered in the Dominican Republic. Larimar is composed of the mineral pectolite, which has a chemical composition of NaCa2Si3O8(OH) and is usually white in color. Cu2+ has always been considered to be the primary genesis of the blue color shown in Larimar, because native copper often grows together with Larimar. To clarify whether copper is the main reason for the origin of blue–green pectolite, we utilized laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) techniques to analyze trace elements in the pectolite samples and compared the relationship between elements and colors. The results show that vanadium and iron are the main origins of the sky-blue and green color of Larimar. We also discovered that it is not only the chemical elements that affect the color shades of the mineral, but the orientation of the radial fiber crystals also plays a critical role. The sea-wave pattern and the changes in the color saturation of radial pectolite are due to the transmittance of visible light through different viewed angles under changing crystal orientations. Our results reveal the chemical and physical factors behind the color and sea-wave pattern of Larimar. In addition, to our knowledge, this is the first time that the formation age of Larimar has been proven to be approximately equal to or younger than 40 ka, using the U-Th dating of calcite growth together with pectolite.

Preliminary Characterisation of New Reference Materials (CaW‐0, CaW‐1 and CaW‐3) for Microanalysis of Rare Earth Elements in Scheelite by Laser Ablation‐Inductively Coupled Plasma‐Mass Spectrometry

In this work, we prepared three CaWO4 single crystals (CaW‐0, CaW‐1 and CaW‐3) doped with rare earth elements (REEs) at nominal mass fractions of 50, 250 and 5000 μg g‐1 using the Czochralski method. Electron probe microanalysis (EPMA) and laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) were employed to evaluate the within‐ and between‐unit homogeneity of major elements and REEs, respectively. The within‐unit variation (sr) of 0.40–0.84% and between‐unit sr of 0.14–1.48% for major elements were obtained. Within‐ and between‐unit sr of 0.53–5.56% were also found for REEs by LA‐ICP‐MS spot analyses. A comparison of the sr of repeat analyses was compared with the analytical uncertainty (u), i.e., the mean square weighted deviation (MSWD), which is close to or slightly higher than 1, indicating that no obvious chemical heterogeneity was found in these crystals. Reference values for these elements were obtained through various analytical methods across four different laboratories and applications of the reference materials to calibrating REE mass fractions in a natural scheelite were performed. No significant difference of the results was found as t values are less than 2.75 at the 99% confidence interval. The excellent linearity (R2 > 0.98) between the REE mass fractions and both LA‐ICP‐MS signal intensity and wafer absorbance was found, but the crater height and the absolute mass transported into ICP‐MS decreased when REE mass fractions as well as the colour of crystals increased. These results suggest that the reference materials have the potential to calibrate REE mass fractions in natural scheelite.

Simultaneous quantification of Gadoxetic acid and Cisplatin in hepatocellular carcinomas using laser ablation-inductively coupled plasma-mass spectrometry.

The gadolinium-based contrast agent Gadoxetic acid and the platinum-based antitumor agent Cisplatin were quantitatively imaged in liver and liver cancer (hepatocellular carcinoma, HCC) tissue of rats by means of laser ablation-inductively coupled plasma-mass spectrometry. HCC bearing rats simultaneously received a tail vein injection of the hepatocyte-specific magnetic resonance imaging contrast agent Gadoxetic acid and a transarterial injection of Cisplatin 15min before sacrifice and liver removal. Resecting HCC with adjacent liver tissue allows the comparison of Gd, Pt, and endogenous elements like Fe, Cu, and Zn in the various tissue types. Region of interest analysis reveals lower concentrations of Gd in HCC and higher Gd content in the adjacent liver, fitting the selective uptake of Gadoxetic acid into hepatocytes. Furthermore, two malignancy grades and their possible impact on the Gadoxetic acid and Cisplatin uptake are compared. For this, four high grade (G3) and two moderate grade (G2) HCCs were analysed, including a control sample each. Gd concentrations were lower in HCC irrespective of the grade of dedifferentiation (G2, G3) compared to adjacent liver. Despite local arterial Cisplatin injection, concentrations of Pt were similar or also reduced in HCC compared to liver tissue. In addition, endogenous Fe, Cu, and Zn were quantified. While Zn was homogenously distributed, higher Fe concentrations were determined in liver tissue compared to HCC. Hotspots of Cu suggest a deregulated copper homeostasis in certain liver lesions. The Gd and Fe distributions are compared in detail with cellular alterations examined by hematoxylin and eosin staining.

Trace Element Composition of Chalcopyrite from Volcanogenic Massive Sulfide Deposits: Variation and Implications for Provenance Recognition

Abstract Chalcopyrite from 51 volcanogenic massive sulfide (VMS) and sea-floor massive sulfide (SMS) deposits from six lithostratigraphic settings was analyzed for trace elements by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to evaluate its potential as an indicator mineral for exploration. Partial least squares discriminant analysis (PLS-DA) results reveal that chalcopyrite from different lithostratigraphic settings has different compositions reflecting host-rock assemblages and fluid composition. Three random forest (RF) classifiers were developed to distinguish chalcopyrite from the six lithostratigraphic settings with a divisive approach. This method, which primarily classifies according to the major host-rock affinity and subsequently according to VMS settings, yielded an overall accuracy higher than 0.96 on test data. The model validation with literature data having the same elements required by the models yielded the highest accuracies (>0.90). In validation using published data with missing elements, the accuracy is moderate to high (0.60–1); however, the performances decrease significantly (<0.50) when the most important elements are missing. Similarly, RF regression models developed using all sets of analyzed elements to determine ccp/(ccp + sp) ratio (ccp = chalcopyrite; sp = sphalerite) in chalcopyrite within a single VMS setting reported high performances, thus showing a potential to predict the Cu/Zn ratio (Cu-rich vs. Zn-rich) of the mineralization based on chalcopyrite composition. This study demonstrates that trace element concentrations in chalcopyrite are primarily controlled by lithotectonic setting and can be used as predictors in an RF classifier to distinguish the different VMS subtypes.

Pigments and Binders Used in Bark Paintings by Aboriginal Artists from Across the Northern Territory and the Kimberly Region in Western Australia

ABSTRACT Bark paintings represent a unique artform that originated in Australia and continues to this day. This paper presents a scientific investigation into both the pigments and binders used by Aboriginal artists from across the Northern Territory (NT) and the Kimberley region in Western Australia (WA) and represents the first major study dedicated to identifying these materials in samples taken from paintings. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), Fourier transform infrared (FTIR) and Raman spectroscopy were used to identify the pigments in the four colors commonly associated with works by Aboriginal artists: red, yellow, black, and white. Iron oxides are used for red and yellow. Typically, kaolin is used for white and carbon or natural manganese ores are used for black, although the use of other pigments such as huntite (white) and battery black were seen in paintings from specific locations. Evidence of trade could not be established during this study; however, analysis shows that artists may use different pigments based on location and availability. A combination of FTIR and pyrolysis-gas chromatography-mass spectrometry (pyrolysis-GC-MS) was utilized to investigate the presence of a binder in the paint. Plant-based materials were identified as the binder in the majority of the paintings. The use of orchid juice was common, both as a preparatory layer on the bark substrate and as a paint binder. The presence of synthetic resins was more widespread than anticipated, attributed to both conservation efforts and more modern painting practices.

Exploring the CAM18 Crystal as a Potential Reference Material for U–Pb Analysis of Zircon

In the process of in situ zircon U–Pb dating, it is an effective means to overcome the matrix effect by using a matrix-matched external reference material. However, the limited number of available zircon reference materials still makes it difficult to meet the research needs. In this paper, we performed a preliminary analysis of the gemological characteristics, trace elements and U–Pb ages of natural zircon CAM18 to assess its suitability as a reference material for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb dating. This tawny, gem-quality zircon has no visible inclusions and weighs approximately 0.55 g. Its density, full width at half maximum (FWHM) of the Raman peak and alpha flux (Dα) indicate that the sample has suffered mild-to-moderate radiation damage without any thermal treatment. The LA-ICP-MS U–Pb dating results reveal that the trace elements content and U–Pb ages of the sample are fairly homogeneous at the 50 μm scale, and there is no obvious loss of radiogenic Pb. The 206Pb/238U age (571.0 ± 3.0 Ma, 2s) and 207Pb/235U age (573.4 ± 6.0 Ma, 2s) are consistent within the analytical uncertainty, and the calculated concordia age is 571.4 ± 1.4 Ma (2s, n = 20). The variation in the 206Pb/238U ages is small, with a measurement repeatability of 0.46% (RSD), which is within the uncertainty of the age accuracy obtained by LA-ICP-MS. The oscillatory zoning, Th/U ratio (0.2) and chondrite-normalized rare-earth element (REE) pattern imply a magmatic origin of zircon CAM18. The Ti-in-zircon temperature ranges from 714 to 742 °C, and the oxygen fugacity ranges from ΔFMQ−2.87 to ΔFMQ−3.17, suggesting that it is crystallized in a reducing environment. All the results show that zircon CAM18 may has great potential in LA-ICP-MS U–Pb dating.

Elemental analysis of vertebrae discerns diadromous movements of threatened non-marine elasmobranchs.

River sharks (Glyphis spp.) and some sawfishes (Pristidae) inhabit riverine environments, although their long-term habitat use patterns are poorly known. We investigated the diadromous movements of the northern river shark (Glyphis garricki), speartooth shark (Glyphis glyphis), narrow sawfish (Anoxypristis cuspidata), and largetooth sawfish (Pristis pristis) using in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on vertebrae to recover elemental ratios over each individual's lifetime. We also measured elemental ratios for the bull shark (Carcharhinus leucas) and a range of inshore and offshore stenohaline marine species to assist in interpretation of results. Barium (Ba) was found to be an effective indicator of freshwater use, whereas lithium (Li) and strontium (Sr) were effective indicators of marine water use. The relationships between Ba and Li and Ba and Sr were negatively correlated, whereas the relationship between Li and Sr was positively correlated. Both river shark species had elemental signatures indicative of prolonged use of upper-estuarine environments, whereas adults appear to mainly use lower-estuarine environments rather than marine environments. Decreases in Li:Ba and Sr:Ba at the end of the prenatal growth zone of P. pristis samples indicated that parturition likely occurs in fresh water. There was limited evidence of prolonged riverine habitat use for A. cuspidata. The results of this study support elemental-environment relationships observed in teleost otoliths and indicate that in situ LA-ICP-MS elemental characterization is applicable to a wide range of elasmobranch species as a discriminator for use and movement across salinity gradients. A greater understanding of processes that lead to element incorporation in vertebrae, and relative concentrations in vertebrae with respect to the ambient environment, will improve the applicability of elemental analysis to understand movements across the life history of elasmobranchs into the future.

Uranium pre-concentration in sandstone-hosted U deposits: A case study from the Hailijin ore field, SW Songliao Basin, NE China

Economic U mineralization in sandstone was commonly attributed to oxygenated fluid infiltration in reduced sandstone, leading to U precipitation in redox front during late diagenetic stage. It was proposed that U can be pre-concentrated before this period based on trace amounts of U in altered products of Fe-Ti oxides, as revealed by electron microprobe analysis (EMPA). However, the obtained trace elements concentrations in altered Fe-Ti oxides (<1 wt%) is generally accompanied with relatively low analytical precision, leading to a skeptical explanation under this situation. In this work, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to determine trace elements concentrations in hematite from the uraniferous Lower Yaojia Formation (Hailijin ore field, SW Songliao Basin, NE China), aiming to fingerprint this proposed U pre-concentration in details. Some trace elements contents, such as Mo, Ge, Ca, P, Y, Pb, Th, Sn, and W, are positively correlated with U content in hematite. Given that uraniferous oxygenated groundwater with a near-neutral pH is unable to efficiently dissolve detrital phosphate (i.e., apatite and monazite) in the Lower Yaojia Formation, phosphorous must have been released from these P-rich phases before late diagenesis. Such a conclusion is supported by our observations that monazite from the reduced sandstone has a corrosive morphology, and exhibits a corresponding U enrichment in the corrosive rim. The dissolved P and U can be adsorbed by porous titania up to several thousand ppm during early diagenesis, providing a pre-concentrated metal source for remobilization during late diagenesis. It can not only account for a trace-element signature derived from monazite (i.e., Ca, P, Y, Pb, and Th) in hematite geochemistry, but also fingerprint Mo and Ge migrations resulted from oxidation of pyrite and organic matter, respectively. In addition to U, tungsten and Sn would be re-equilibrated with infiltrated oxidized fluid during the recrystallization of porous titania, and partially incorporated into simultaneously formed hematite grains due to high compatibility. The remobilization of pre-concentrated U induced by oxygenated fluid incursion led to U accumulation in a redox front during late diagenesis, forming uraninite nanoaggregates with relatively high concentrations of P, Y and Ti. Our work has verified that trace-element signature in hematite from sandstone is a reliable fingerprint to reveal ore-forming processes, and we propose for the first time that titania and phosphate play a crucial role for U pre-concentration in sandstone-hosted U deposits.

Detrital zircon U–Pb and Hf isotopic dataset for the Central Asian Orogenic Belt, northern China

AbstractThe Central Asian Orogenic Belt (CAOB) is one of the biggest accretionary orogens in the world. With the development of laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS), large data of detrital zircon U–Pb and Hf isotopes have been published for decades, which leads to better understanding of the tectonic evolution and geodynamics of the CAOB. We compiled the data about the information of articles, samples and their analytical methods and results, then checked and corrected. These data are available to support future research activities in the CAOB, northern China, for example, the provenance analysis, climate changes and paleogeographic reconstruction.

Screening for elevated blood lead levels using single hair strands: Accounting for external contamination

Hair has long been explored as a potential biomarker of lead exposure since lead is readily adsorbed into hair's keratinous matrix; however, the utility of hair as a biomarker for lead exposure is hampered by its susceptibility to external contamination: lead particles attach to the exposed hair surface, confounding estimates of endogenous concentrations. This study describes the development of a hair screening tool, in which the confounding influence of external contamination are mitigated by focusing on the unexposed hair root, to predict elevated blood lead levels (BLLs). This tool requires a single strand of scalp hair, which is analyzed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Forty-four (44) workers with high potential for lead exposure, and 63 reference individuals (with no known lead exposure) volunteered for the study. Hair lead level (HLL) thresholds were developed using methods from clinical assessment to screen exceedances of BLL thresholds at 10 and 15 µg/dL. Hair from both groups showed significantly lower lead concentrations in below-scalp portions compared to above the scalp (above-scalp was 11.2 times higher in workers, and 3.7 times higher in reference group). Hair lead concentrations below the scalp in workers significantly predicted BLLs. HLL thresholds for screening BLLs were 0.60 mg/kg and 0.75 mg/kg for BLLs of 10 µg/dL and 15 µg/dL, respectively. These HLL thresholds yielded high sensitivity (>85%), and slightly lower specificity (67% and 33%, for BLL thresholds of 10 µg/dL and 15 µg/dL, respectively). This study provides reference HLLs in non-contaminated portions of hair (<0.097 mg/kg), shows the significance of external contamination on exposed portions of hair even in a reference population, and assesses the effectiveness of below-scalp hair as a biomarker of elevated lead exposure. This hair screening tool effectively predicted BLL exceedances and could be considered as a non-invasive alternative to blood sampling.

How old is the Ordovician–Silurian boundary at Dob’s Linn, Scotland? Integrating LA-ICP-MS and CA-ID-TIMS U-Pb zircon dates

AbstractSedimentary rocks exposed at Dob’s Linn, Scotland, have significantly influenced our understanding of how life evolved over the Ordovician to Early Silurian. The current interpreted chronostratigraphic boundary between the Ordovician and Silurian periods is a Global Boundary Stratotype Section and Point (GSSP), calibrated to 443.8 ± 1.5 Ma (Hirnatian–Rhuddanian age), based on biostratigraphic markers, radioisotopic dates and statistical modelling. However, challenges arise due to tectonic disturbances, complex correlation issues and the lack of systematic dating in Ordovician–Silurian stratigraphic sections. Here, hundreds of zircon grains from three metabentonite ash horizons were dated using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). A subset of the grains were re-analyzed using Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS). We present a high-precision CA-ID-TIMS 238U-206Pb weighted mean date of 440.44 ± 0.55/0.56/0.72 Ma (±analytical/with tracer/with U-decay constant) for the Coronagraptus cyphus biozone. However, the study reports younger, and in certain cases, older LA-ICP-MS zircon dates within the Coronagraptus cyphus, Akidograptus ascensus and Dicellograptus anceps zones, suspected as being influenced by Pb loss and LA-ICP-MS matrix mismatch. The study reports concerns about the suitability of Dob’s Linn as a GSSP section and examines various LA-ICP-MS maximum depositional age (MDA) approaches, suggesting the use of the TuffZirc date and the youngest mode weighted mean (YMWM) as suitable MDA calculations consistent with CA-ID-TIMS results.

Close relationship between potassium accumulation in internodes and translocation of non-structural carbohydrate to grains in rice cultivars with different yields

Potassium (K) is an important macronutrient together with nitrogen and phosphorous. Potassium mostly accumulates in the internodes of rice plants during ripening stage. Since internodes are responsible for translocation of carbohydrates to the grains during ripening, the involvement of internode K in grain yield has been suggested, however, the precise mechanism remains unclear. This study aims to examine the relationship between rice grain yield in different cultivars and the dynamics of K and non-structural carbohydrates (NSC) in the internodes during the ripening period. Field experiments were conducted to investigate the differences in the dynamics of K and NSCs in internodes from heading to maturation in 10 cultivars with different yields and three mutants with different grain numbers. To reveal the localization of K in internode tissues, we conducted laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis. During the early ripening period from heading to 14 days after heading (14 DAH), the decrease in NSC contents in lower internodes was higher in the high-yielding indica cultivars than in japonica cultivars. In the late ripening period from 14 DAH to maturing, re-accumulation of NSC in lower internodes was higher in the japonica than in the indica. In contrast, the increase in K contents in the internodes was larger in the indica than in the japonica throughout the ripening stage. In the internodes of low-yielding whole crop silage (WCS) cultivar, the NSC contents were maintained at high levels during ripening, while K contents were consistently low. Similar results were observed in the mutant with low grain numbers. The mutant had lower K contents and higher NSC contents than the wild type (WT). Correlation analysis of different cultivars indicated that the change in K content in whole internodes from heading to maturing was negatively correlated with the change in NSC content. LA-ICP-MS analysis of internode tissues of the indica cultivar revealed that K accumulated more in the parenchyma cells than in large vascular bundles. These results suggest that K accumulation in the internodes is positively correlated with NSC translocation from internodes to grains, which could be through indirect effect of K accumulation in parenchyma on enhancement of long distance transport of NSC from internodes to the grains. This study provides new insights into the mechanism underlying the role of K in grain filling, which would help improving usage of K fertilizer for optimum plant growth and yields.