Laser Ablation Inductively Coupled Plasma Mass Spectrometry Research Articles

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.

Depositing &amp;gt;1.5 Mt of Tin Within &amp;lt;1 m.y. of Initial Granitic Intrusion in the San Rafael Tin (-Copper) Deposit, Southeastern Peru

Abstract The San Rafael Sn (-Cu) deposit, located in the Eastern Cordillera of southeast Peru, is one of the world’s largest cassiterite-bearing vein systems (&amp;gt;1 Mt Sn produced since 1969). The deposit consists of a quartz-cassiterite-chlorite-sulfide lode system spatially associated with an upper Oligocene (ca. 24 Ma) S-type granitic pluton. Based on a revised paragenetic sequence for the deposit, we interpret the temporal setting of both magmatic (biotite, K-feldspar) and hydrothermal (muscovite, adularia, cassiterite) minerals analyzed by 40Ar/39Ar step-heating and U-Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) geochronology. The least-disturbed biotite sample from the megacrystic monzogranite yielded a 40Ar/39Ar plateau age of 24.10 ± 0.26 Ma (2σ), which constrains the time of cooling of the upper part of the pluton to below 300°C. Greisen developed on top of the granitic cupola and its immediate metamorphic aureole dated at 24.24 ± 0.24 Ma (2σ; 40Ar/39Ar muscovite average plateau age) is interpreted to be contemporaneous with the emplacement of pre-ore quartz-tourmaline veins and breccias. In situ U-Pb dating of cassiterite, including both botryoidal cassiterite (“wood tin”) and coarse-grained cassiterite in quartz-chlorite veins and breccias, constrains the timing of the main Sn ore stage to between 24.10 ± 0.37 and 23.47 ± 0.53 Ma (2σ). Botryoidal and coarse-grained cassiterite are characterized by similar trace element compositions with fluctuating metal concentrations across growth banding, suggesting significant changes of physicochemical conditions of the hydrothermal system during cassiterite precipitation, likely caused by rapid and repeated mixing between magmatic fluids and meteoric groundwaters. Polymetallic sulfide-rich veins and quartz-carbonate veins are constrained to have formed between 22.72 ± 0.11 and 22.29 ± 0.24 Ma (2σ), based on adularia 40Ar/39Ar plateau ages. The latter overlap partially reset 40Ar/39Ar age spectra for K-feldspar megacrysts in the host granite and thus reflect pervasive alteration by hydrothermal fluids. Collectively, the results show the magmatic-hydrothermal system spanned at least 2 m.y. with the main Sn ore stage representing &amp;lt;1 m.y. in the lifetime of the deposit. The latest polymetallic stages postdate the main Sn ore stage by ca. 1 m.y. and reflect the waning of the hydrothermal system, accompanied by additional incursion of meteoric groundwaters. This study provides further evidence that the present-day exposed level of the San Rafael granite was a passive host for the Sn mineralization and only provided the structural focusing for the mineralizing fluids derived from a deeper part of the magmatic system.

Phase-A as boron carrier in the Earth's interior

The interest of the scientific community on the role of Dense Hydrous Magnesium Silicates (DHMSs) as geochemical reservoir is constantly increasing, particularly for boron (B) which is widely considered as one of the best proxies to understand geological processes involving serpentinized materials. In particular, the genesis of blue B-bearing diamonds in the lower mantle has been proposed to be related to the deep recycling of serpentinized materials through DHMSs. However, it is still unknown whether DHMSs are capable to incorporate and transport significant amounts of B to great depth. In this Letter, we attempt to fill this knowledge gap by providing the results of a pilot experiment aimed to investigate the B content in Phase-A, which is the first DHMS mineral replacing antigorite along a prograde cold subduction path. By using a Walker-type Multi Anvil module, we synthetized Phase-A at 700 °C and 7.0 GPa starting from a stoichiometric composition modelled in the MSH system (2 SiO2: 7 MgO) and adding 1000 ppm of B as ultrapure boric acid (H3BO3) in H2O plus trace of NH4OH. The experimental product has been characterized through electron microprobe, single-crystal X-ray diffraction, and laser ablation ICP-MS. Structural analyses confirmed the crystallization of the Phase-A and chemical analyses show B contents of ca. 200 ppm that are structurally incorporated in the Phase-A, thus suggesting its role as viable B source at depth. Our preliminary results extend the current knowledge of the B cycle and open new perspectives to better disclose the deep recycling of elements at the origin of the geochemical heterogeneity of the Earth's mantle.

Amphibole recycling and polybaric crystallization in rhyolitic lava domes from melt inclusion geochemistry at Cerro La Torta, Altiplano-Puna Volcanic Complex

La Torta is a rhyolitic lava dome located in the El Tatio volcanic complex, Región de Antofagasta (northern Chile), to the west of the Cerros de Tocorpuri volcanoes. La Torta is considered to be an important part of the central zone of the Altiplano Puna Magma Body (APMB) based on chemical and petrological signatures that distinguish it from other highly silicic volcanic systems in the area (i.e., Chao dacite). The petrological and geochemical characteristics, along with parental composition and magma evolution, were determined by analyzing amphibole and plagioclase-hosted melt inclusions using electron microprobe (EMP) and laser ablation ICP-MS (LA-ICP-MS). Our results show that La Torta dome was formed from a rhyolitic Ca- and K-rich, calc-alkaline magma, with an average SiO2 content of 76.8 wt % and H2O content of about 5.4 wt %, which was emplaced in the upper continental crust between 3.9 and 7.6 km below the paleosurface. The parental source of La Torta dome was a highly hydrous mush of andesitic composition, with plagioclase + amphibole ± quartz ± pyroxene crystal assemblage.Heating by an influx of magmas ascending from deeper sources to upper crustal depths (i.e., Altiplano-Puna Magma Body) caused the partial melting of amphibole and pyroxene in the source, evidenced by amphibole dissolution textures, enriching the melt in Cr, Ni, HFSE and HREE. As the system starts to cool and ascend, new amphibole crystallized from this mush, trapping the enriched residual melt as enriched melt inclusions in its cores, along with crystallization of biotite and plagioclase. We refer to this process as amphibole recycling. At the same time, the new melt drags the plagioclase and quartz inherited from the parental mush, forming the magma that emplaced at shallower levels in the crust to eventually erupt as La Torta.

Experimental Study and Thermodynamic Modelling of Equilibrium Distributions of Ni, Sn and Zn Between Slag and Black Copper for E-Scrap Recycling Applications

The recycling of waste electronic and electrical equipment (WEEE) and other secondary copper-containing materials through the "black copper" process relies on the selective distribution of metals among the gas, slag, and copper-rich liquid phase. This distribution is controlled by the effective oxidation/reduction potential, often expressed in terms of oxygen partial pressure. Separation of Ni and Sn presents a certain challenge in recycling though black copper route due to similar distribution coefficients over a wide range of oxygen partial pressures and possibly can be improved by optimizing the slag chemistry. This study provides experimental information on the distribution of Ni, Sn, and Zn between fayalite slags or calcium ferrite slags and copper-rich metal at 1250°C. The study uses high-temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA) techniques along with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for selected measurements of low concentrations. The oxygen partial pressure is controlled by the CO/CO2/Ar gas flow or by measuring the concentration of copper oxide in the slag. The effect of slag composition in terms of Fe/SiO2 or Fe/CaO ratio is studied by using different holding materials, such as silica (SiO2) ampoule, solid spinel (Fe3O4), wüstite (FeO), or dicalcium ferrite (Ca2Fe2O5). The experimental results are compared with literature data and used to optimize thermodynamic models for FactSage® software. The results demonstrate an opportunity for more effective separation of Ni and Sn using at oxidizing stage by using calcium ferrite slag promoting the formation of Sn4+.

U-Pb dating of pedogenic calcite near the Permian−Triassic boundary, Karoo Basin, South Africa

We report U-Pb age determinations of carbonate nodules from an in situ paleosol horizon in the Upper Permian Balfour Formation and from several horizons of pedogenic nodule conglomerate (PNC) in the Triassic Katberg Formation, Karoo Basin, South Africa, using laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS). The paleosol sample yields an age of 252 ± 3 Ma, which overlaps with a previous high-precision U-Pb zircon date from a volcanic ash deposit 2 m above the paleosol. This relationship demonstrates the reliability of using LA-ICP-MS dating techniques on terrestrial pedogenic calcite. Two PNC samples collected at the base of the Katberg Formation within the same sandstone unit yield ages of 255 ± 3 Ma and 251 ± 3 Ma. The age of 251 ± 3 Ma overlaps with the high-precision U-Pb zircon date below the PNC and is a maximum age estimate of deposition for the base of the Katberg Formation. Our results show that reworked nodules in the same concentrated conglomerate lag can be of different ages, but that similarly aged nodules are spatially associated. In addition, two PNC samples collected higher in the section yield ages of 249 ± 3 Ma and 241 ± 3 Ma, providing maximum depositional ages for the lower to middle Katberg Formation for the first time. We demonstrate that pedogenic carbonate nodules can be dated with meaningful precision, providing another mechanism for constraining the age of sedimentary sequences and studying events associated with the Permian−Triassic transition in the central Karoo Basin, even though the extinction boundary may not be preserved in this area.

Metallogenic Setting and Temporal Evolution of Porphyry Cu-Mo Mineralization and Alteration in the Delamerian Orogen, South Australia: Insights From Zircon U-Pb, Molybdenite Re-Os, and In Situ White Mica Rb-Sr Geochronology

Abstract Paleozoic porphyry-style hydrothermal alteration and mineralization has previously been recognized within the Delamerian orogen, South Australia, where porphyry prospects include Anabama Hill, Netley Hill, and Bendigo. However, limited exploration due in part to thick postmineralization cover hinders the understanding of the temporal context, metallogenic setting, and mineral potential of the porphyry systems along the Proterozoic continental margin of Australia. In this study, we have characterized the hydrothermal alteration and mineralization of these porphyry occurrences. Zircon U-Pb, molybdenite Re-Os, and white mica Rb-Sr ages have been determined to constrain the timing for emplacement of magmatic intrusions, precipitation of metal-bearing sulfides, and duration of hydrothermal alteration in the Delamerian orogenic belt. Zircon U-Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of nine granitoids reveal that the intrusive rocks were emplaced mostly between 485 and 465 Ma, whereas three intrusions at Bendigo have zircon U-Pb ages of 490 to 480 Ma. Molybdenite isotope dilution-negative thermal ion mass spectrometry (ID-NTIMS) Re-Os dating of the four prospects identifies two porphyry Cu-Mo mineralization events at 480 and 470 to 460 Ma, respectively. Nineteen white mica Rb-Sr LA-ICP-MS/MS (tandem mass spectrometers) analyses return an age range between 455 and 435 Ma for phyllic alteration at the Anabama Hill and Netley Hill prospects, whereas intense white mica-quartz-pyrite alteration at Bendigo prospect appears to have developed between 470 and 460 Ma. These geochronologic results indicate that the Delamerian porphyry systems postdated subduction-related magmatism in the region (514–490 Ma) but instead formed within an inverted back-arc regime, where mineralized magmas and fluids ascended along favorable lithospheric-scale structures, probably due to asthenospheric upwelling triggered by mafic delamination. Porphyritic stocks, dikes, and aplites with ages of 470 to 460 Ma are the most likely hosts to porphyry-style mineralization in the Delamerian orogen that appears to have formed simultaneously with the oldest known porphyry systems in the intraoceanic Macquarie arc (e.g., Marsden, E43, and Milly Milly; 467–455 Ma). These results emphasize the significance and potential of Early-Middle Ordovician intrusive systems to host such a type of magmatic-hydrothermal mineralization in the Delamerian orogen.