Laser Ablation Inductively Coupled Plasma Mass Spectrometry Research Articles

Mineralogy and Distribution of REE in Oxidised Ores of the Mount Weld Laterite Deposit, Western Australia

The Mount Weld rare earth element (REE) deposit, Western Australia, is one of the largest of its type on Earth. Current mining exploits the high-grade weathered goethite-bearing resource that lies above, and which represents the weathering product of a subjacent carbonatite. The mineralogy, petrography, deportment of lanthanides among the different components, and variation in mineral speciation, textures, and chemistry are examined. Microanalysis, involving scanning electron microscope (SEM) imaging, electron probe microanalysis (EPMA) and laser ablation inductively coupled-plasma mass spectrometry (LA-ICP-MS), was conducted on sized fractions of three crushed and ground laterite ore samples from current and planned production, and a representative sample from the underlying carbonatite. High-magnification imaging of particles in laterite samples show that individual REE-bearing phases are fine-grained and extend in size well below the micron-scale. Nanoscale inclusions of REE-phosphates are observed in apatite, Fe-(Mn)-(hydr)oxides, and quartz, among others. These have the appearance, particularly in fluorapatite, of pervasive, ultrafine dusty domains. Apart from the discrete REE minerals and abundant nano- to micron-scale inclusions in gangue, all ore components analysed by LA-ICP-MS contain trace to minor levels of REEs within their structures. This includes apatite, where low levels of REE are confirmed in preserved igneous apatite, but also Fe- and Mn-(hydr)oxides in which concentrations of hundreds, even thousands of ppm are measured. This is significant given that Fe-(Mn)-(hydr)oxides are the most abundant component of the laterite and points to extensive mobility and redistribution of REEs, and especially HREE, during progressive lateritisation. Late-formed minerals, notably tiny grains of cerianite, reflect a shift to oxidising conditions. REE-fluorocarbonates are the main host for REEs in carbonatite and are systematically replaced by hydrated, Ca-bearing REE-phosphates (largely rhabdophane). The latter displays varied compositions but is characteristically enriched in HREE relative to monazite in the same sample. Fine-grained, compositionally heterogeneous rhabdophane is accompanied by minor amounts of other paragenetically late, hydrated phosphates with enhanced MREE/HREE relative to LREE (although still LREE-dominant). Minor, relict xenotime and zircon are significant HREE carriers. Ilmenite and pyrochlore group members contain REE but contribute only negligibly to the overall REE budget. Although the proportions of individual mineral species differ, the chemistry of key ore components are similar in different laterite samples from the current resource. Mineral signatures are, however, subtly different in the lower grade southeastern part of the deposit, including higher concentrations of HREE relative to LREE in monazite, rhabdophane, florencite and Fe-(Mn)-(hydr)oxides.

Obsidian exchange networks and highland-lowland interaction in the Lesser Caucasus borderlands

Obsidian sourcing studies have a long history in the Near East, but relatively few have focused on obsidian exchange after the Early Bronze Age. Here, we present a multi-technique analysis of an assemblage of 111 obsidian artifacts from excavated Late Bronze and Early Iron Age (LBA-EIA; c. 15th-6th c BCE) contexts at Mtsvane Gora, southern Georgia. Because the site is situated in the lowland Kura Valley and the nearest obsidian sources are in the highlands to the south and west, obsidian provenance can serve as a proxy for mapping highland-lowland interactions. Chemical compositions analyzed via portable X-ray fluorescence spectrometry (pXRF), electron microprobe analysis (EMPA), and laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS), were compared with existing geological datasets of chemical analyses to identify the source of all but one of the artifacts analyzed. The results show that Chikiani, a source in the highlands of southern Georgia, was the geological origin of >90% of the objects analyzed. While acknowledging that obsidian exchange is just one aspect of highland-lowland interaction, this finding implies that Mtsvane Gora’s connections with the adjacent highlands were skewed towards greater engagement with some highland areas relative to others. More generally, the research suggests that geographic adjacency of highlands and lowlands does not necessarily mean that they were highly interconnected.

LA-ICP-MS analyses of trace elements in zoned sphalerite: A study from the Maoping carbonate-hosted Pb-Zn(-Ge) deposit, southwest China

In southwest China, many Pb-Zn deposits are described as low temperature carbonate-hosted deposits or Mississippi Valley-type (MVT) deposits. But trace element distribution and concentration in sphalerite between deposits may significantly vary and could possibly imply alternative deposit-types. An investigation was carried out on sphalerite (Sp-II) in the main ore stage of the Maoping carbonate-hosted Pb-Zn(-Ge) deposit (Southwest China), based on laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Here, Sp-II is divided into the dark red, yellow–brown, and light-yellow zones. Principal component analysis revealed element clusters distributed within distinct zoning types in Sp-II: the dark red zones are enriched in Mn, Fe, and Cd; the yellow–brown zones are enriched in Cu, Ge, Ag, and Sb; the light-yellow zones are enriched in Ga. Trace elements in Sp-II record temperature and sulfur fugacity (fS2) evolution of ore-forming fluid system, which tends to decrease from the dark red to yellow–brown to light-yellow zones. The formation of Sp-II may be an external process resulting from the varieties of temperature and fS2 in the ore-forming fluid, which may be driven by rock buffer. Here, Manganese, Fe, and Cd are preferentially incorporated in the relatively higher temperatures and fS2, whereas Ga is preferentially incorporated in the relatively lower those. Regardless of the zoning type, strong binary correlations between Ge and Cu as well as the high similarity of their concentration distribution in mapping images suggest coupled substitutions as Ge4+ + 2Cu+ ↔ 3Zn2+ and/or Ge2+ + 2Cu+ ↔ 2Zn2+ + vacancy. A trace element comparison of various Pb-Zn deposits in the world, including our new data from Maoping shows a distinctive signature for the Maoping deposit. Homogenization temperatures (217–430 ℃, mean 298 ℃) of the newly discovered ore body (No. VI) support that Maoping is a medium–high temperature carbonate-hosted deposit.

Ultraviolet-photoluminescence and trace element analyses in Ga-rich sphalerite from the Djebel Gustar Zn-Pb deposit, Algeria

The Djebel Gustar Zn-Pb deposit in northeastern Algeria is one of many carbonate-hosted base metal deposits in the Atlas metallogenic province of North Africa. The sphalerite in this deposit occurs in five distinct types that differ in texture, mineral assemblage, chemical composition, and UV photoluminescence signature. Detailed investigation of trace elements by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) showed that the sphalerite is significantly enriched in the critical metal Ga. The trace element concentrations of the different sphalerite types correlated well with their photoluminescence color; with Mn2+ (orange-yellow), Cu+ (green), and Ga3+ (red) being the dominant activators. We suggest that the Ga enrichment in the Djebel Gustar deposit is the result of formation conditions that include the mixing of a Cl-rich fluid carrying mainly Zn and Pb with a more reduced and Cl-poor fluid containing considerable organic matter and/or calcite with adsorbed Ga(OH)3. This Ga was subsequently incorporated into sphalerite, rather than forming a stoichiometric Ga phase. Furthermore, our study demonstrates that UV photoluminescence of low Fe sphalerite has the potential to become a simple and affordable tool for preliminary characterization of sphalerite ores in mining and exploration with respect to critical elements such as Ga.

Luminescence Characteristics of Green Grossular Garnets

Some light green grossular garnets exhibit orange-red luminescence under long-wave and short-wave ultraviolet light. To characterize their luminescence behavior, we studied seven grossular garnets with typical colors ranging from light yellowish-green to intense green by using photoluminescence (PL), ultraviolet–visible (UV–Vis) spectroscopy, electron paramagnetic resonance (EPR), Electron Probe Microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the PL spectra of these grossular garnets samples, a broad band exists at about 589 nm and three sharp peaks appear at 697, 702 and 716 nm. The three-dimensional fluorescence spectra reveal two luminescence emissions. They are (1) a broad band near 600 nm; and (2) a series of sharp peaks centered at 697, 702 and 716 nm. In the UV–Vis spectra, two prominent asymmetrical absorption bands near 430 and 605 nm are related to Cr3+ or Cr3+/V3+, and minor absorption peaks at 408 and 419/420 nm are related to Mn2+. EMPA and LA-ICP-MS analysis confirmed the existence of trace elements Ti, V, Cr and Mn. Furthermore, the EPR spectrum excluded the existence of V2+ and V4+ and confirmed the existence of Mn2+, Cr3+ and Fe3+. Regarding V, an interesting phenomenon was reported in which the intensity of luminescence could be suppressed in grossular garnets with higher concentrations of V. These results imply that chromium and manganese are the luminescence activators in grossular garnets, and vanadium is a powerful quencher.

Early Precambrian mafic dykes in western Shandong province, North China Craton: constraints on the chronology, genetic model and tectonic significance

AbstractIn the Late Neoarchaean, the lithosphere of the North China Craton (NCC) experienced a strong extensional event, which is of great significance for understanding the evolution of the continental crust in the Precambrian. In this study, a suite of mafic dykes from Shandong province in the northeastern NCC were investigated to determine the nature, timing and source of rift-related magma activities using zircon U–Pb data, whole-rock geochemistry and Nd–Hf isotopes. Zircon U–Pb dating of four dolerites by laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) yielded weighted mean 207Pb/206Pb ages in the range 2509 ± 6.1 to 2537 ± 6.2 Ma (2σ, 95 % confidence interval). The mafic dykes are classified as alkaline rocks based on their K2O + Na2O contents (6.78–7.21 wt %) and belong to the shoshonitic series according to their K2O contents (3.23–3.36 wt %). The dolerites show low concentrations of light rare earth elements ((La/Yb)N between 7.17 and 8.55), positive Eu anomalies (Eu/Eu* between 1.12 and 1.27), positive Ba, K, Pb, Sr, Eu, Dy and Lu anomalies, and depleted U, Nb, Pr, Ta, P, Nd and Ti anomalies. The dykes are characterized by low initial (87Sr/86Sr)i (∼0.6969), positive εNd(t) values (0.2–0.8) and εHf(t) values (0.5–8.6) and relatively old mean Nd and Hf model age (2.73 Ga). Collectively, the data suggest that the mafic dykes were derived from the partial melting (10–20 %) of an isotope-depleted garnet–lherzolite mantle source that was hybridized through interaction with subducted lower crustal material. The parental magmas of these dykes underwent a certain number of crustal contaminations during magma ascent. The mafic magmatism represented in the form of the dyke swarms is considered to be a response to widespread lithospheric extension which affected the NCC at c. 2.5 Ga during the Neoarchaean.

Trace elements of sulfides in the Dengjiashan Pb–Zn deposit from West Qinling, China: Implications for mineralization conditions and genesis

Dengjiashan is a large‐scale Pb–Zn deposit discovered in the western part of the Xicheng ore field within the West Qinling metallogenic belt. Information regarding the distribution and occurrence of trace elements in ore minerals and mineralization, as well as the genesis of this deposit, remains scarce. Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) analysis and elemental mapping were used to determine the distribution and occurrence of trace elements in the sulfide minerals of the Dengjiashan deposit, as well as delineate the process of its genesis. Our results showed that the trace elements enriched in the different sulfides were significantly different. Sphalerite is the main carrier mineral of the scattered elements Cd, Ge and Ga. Based on the trace element content and ratio, principal component analysis and colour of the sphalerite and pyrite, the deposit likely formed in a medium‐temperature environment. The comparative analysis of trace elements from multiple deposits of different origins, combined with the geological characteristics and distribution of sulfide trace elements, suggests that Dengjiashan is a sedimentary exhalative (SEDEX)‐type deposit. As the metallogenic process had a closer relationship to medium‐low temperature hot brine and later tectonic metamorphic hydrothermal fluid, than with magmatic hydrothermal fluid, the deposit is likely of non‐magmatic SEDEX–hot brine superimposed transition origin. This study provides additional insight on the distribution of trace elements in the sulfide minerals of the Dengjiashan deposit, as well as the processes that led to its formation, and may further facilitate ongoing and future key metal prospecting and exploration efforts.

Impact of Wood Ash and Sewage Sludge on Elemental Content in Hybrid Alder Clone

In this study, the focus was on evaluating the effects of the initial treatment of wood ash and sewage sludge on hybrid alder clones’ aboveground biomass and elemental content. To measure the element concentrations in the tree rings, laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) was utilized, which is a valuable tool for dendrochemistry research, albeit with some challenges in accurate quantification. One important aspect of the study was the development and comparison of different “in-house” matrix-matched standards for the precise quantification of element concentrations in tree rings. It was found that the commercially available reference materials, IAEA 413 (algae) and IAEA 392 (algae), were the best choices due to their homogeneity. The study also revealed that the use of sewage sludge and wood ash as soil improvers significantly benefited the increase in hybrid alder biomass. However, no significant increase in element content was found in the obtained wood mass, and for some elements, there was a decrease in concentration.

Disordered dolomite as an unusual biomineralization product found in the center of a natural Cassis pearl.

Natural pearls are produced without human intervention, mainly due to various irritations from the surrounding environment to their mantle tissues. Pearls usually possess similar mineral compositions to the host shells, which means they are also dominated by aragonite and calcite. In this study, we report a natural pearl from a Cassis species mollusk containing granular central structures. Raman spectroscopy, laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), energy dispersive X-ray spectroscopy (EDS) coupled with scanning electron microscope (SEM), and X-ray diffraction (XRD) analyses were carried out in order to characterize the mineral composition in the center region of this pearl. Our results showed that this pearl's center was made of mostly disordered dolomite (Ca0.53Mg0.47CO3) mixing with small amount of aragonite and high magnesium-calcite. To the best of our knowledge, this is the first time disordered dolomite was conclusively identified inside of a natural pearl and such information expanded our knowledge on internal growth structures and formation of natural pearls.

Precise U-Pb dating of incremental calcite slickenfiber growth: Evidence for far-field Eocene fold reactivation in Ireland

Abstract The Variscan orogen in southern Ireland and Britain is characterized by an intensely deformed, E-W–trending fold-and-thrust belt. Farther north in Ireland, the Carboniferous North Dublin Basin exhibits tight chevron folds and kinematically linked en echelon vein sets, along with bedding-parallel veins with slickenfibers. This deformation is assumed to be Variscan in age, despite lying 150 km north of the supposed Variscan “front.” The laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating of these calcite veins undertaken for this study showed that relict Variscan U-Pb ages are very poorly preserved. Instead, late Eocene ages were obtained from many calcite veins, including fold hinge breccias and bedding-parallel slickenfiber veins associated with N-S shortening (flexural slip). Also, U-Pb ages from one bedding-parallel vein showed protracted flexural slip over ~5 m.y. during late Eocene times. Detection of the growth domains within this vein was facilitated by the imaging approach to LA-ICP-MS U-Pb dating adopted in this study, which can identify age-homogeneous domains by integrating spatial U-Pb isotopic information with maps of petrogenetically diagnostic major and trace elements. The late Eocene fold reactivation phase was hitherto undetected on the Irish mainland, but regional Cenozoic N-directed shortening has been documented in Mesozoic–Cenozoic sequences of the southern Irish Sea, Celtic Sea, southern England, and the Paris Basin. We attribute late Eocene fold reactivation to far-field, N-directed shortening associated with the Alpine/Pyrenean orogenies. It is likely that many Variscan or Caledonian folds, particularly in southern onshore Ireland, were reactivated during Eocene–Oligocene shortening, which has not been recognized to date because of the lack of post-Variscan markers (e.g., dikes, Mesozoic–Cenozoic cover sequences).

Intra‐ and interspecific variation in trace element concentrations in feathers of north European trans‐African migrants

The knowledge of migratory connectivity is important for understanding the potential drivers of populations and it is thus important for conservation implications. Migratory connectivity of species can be studied using exogenous, such as rings and transmitters, or endogenous markers, such as stable isotopes and trace elements. The use of trace elements has been much less frequently studied compared to stable isotopes. Trace elements can be studied from the feathers of birds and this does not necessarily require trapping of individuals. Here we studied the variation of 18 different trace elements in feathers of two long‐distance trans‐African migrants, willow warblers Phylloscopus trochilus and barn swallows Hirundo rustica, using body feathers of museum specimens of birds from Finnish breeding grounds. The trace elements were measured using laser‐ablation inductively‐coupled‐plasma mass‐spectrometry (LA‐ICP‐MS). We show that trace element concentrations were relatively stable along the rachis within the same feather except in Ni and S, which showed a quadratic pattern. In general, variation within feathers of the same individuals was smaller than in feathers between individuals for most elements. Furthermore, concentrations of 11 trace elements showed significantly higher concentrations in willow warbler feathers collected in spring than in autumn, moulted in African wintering grounds and European breeding grounds, respectively. Last, concentrations of seven trace elements were significantly higher in the spring feathers of willow warblers compared to barn swallows. This suggests that trace elements could be used to separate moulting grounds of the birds on the larger scale within the same species, but also sampling design should be carefully considered.

The utility of otolith-based methods for discriminating stock structure of the fishery important monacanthid, Nelusetta ayraud, over an intermediate scale

Connectivity and population structure of exploited fish species are critical to understand for effective assessment and management at appropriate spatial scales. We provide a first look at connectivity and population structure of a fishery-important monacanthid, Nelusetta ayraud, using otolith-based methods to compare among three locations (220–540 km apart) along the coast of New South Wales (NSW), Australia. Otolith elemental signatures sampled with laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) revealed differences between two of the three locations during a recent period before capture, as well as differences between the two times examined, although spatial differences were consistent across these times. In contrast, elemental signatures in the juvenile core of the otolith did not differ among locations. Sr:Ca increased linearly with age, and Ba:Ca initially increased to age 1+ before declining in older age classes, consistent with previous observations of an ontogenetic movement into deeper offshore waters for N. ayraud. No differences in otolith shape were detected among locations using Elliptical Fourier Analysis. Our findings suggest there may be spatial structuring of the N. ayraud stock over an intermediate scale (100s km) within NSW, which will inform the design of a larger nation-wide investigation.

Late beryllium enrichment during dynamic growth of vesuvianite and scapolite from the Cuonadong Sn-W-Be skarn, Tibet

The genesis of beryllium (Be) mineralization associated with granitic tin (Sn)- tungsten (W) deposit has received little attention, especially the fluid Be concentration variation along with the developing of skarn. For revealing the less-known skarn Be enrichment characteristics, in-situ electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) along with element mapping were performed on the Be-bearing vesuvianite and scapolite grains from the Cuonadong Sn-W-Be skarn. As the main Be-bearing calc-silicate minerals, the vesuvianite (X19Y13Z18T0-5O68W10) and scapolite (M4T12O24A) incorporate Be element via occupying normally vacant T site and the Al-2(SiBe) substitution, respectively, and show outward increased Be content related to the varying solid-solution composition arising from the dynamic evolution of skarn. The homogeneous core enveloped by oscillatory mantle and rim under BSE or CL image and the increased liquid inclusion size towards the rim reflect both mineral’s staged growth under an elevated water–rock ratio. The increased Ca activity caused by enhanced interaction between fluid and Mn-containing carbonate may drive scapolite constituent change through (NaSi)-1(CaAl) substitution, creating more tetrahedral Al sites suitable for Be occupation and resulting in the increased Ca, CO32–, Be content and decreased Na content from core to rim. Precipitation of fluorite will lead to a reduce in hydrothermal Be solubility associated with a decreased fluorine activity, and favor Be to occupy the vacant T site by losing more hydrogen from the anion W site and finally form the Be-rich, Ca- and F-low vesuvianite rim. Significantly high Be, Sn, Mn and low Sr, LREE, U content at vesuvianite rim along with hydration alteration and mineralization suggest the onset of retrograde stage. Overall, the dynamic growth and epitaxially rising Be concentration of vesuvianite (∼97–1032 ppm) and scapolite (∼902–2928 ppm) recorded that the later pulsed fluid enriched Be as skarn developed, implying high grade Be mineralization tends to occur in the late magmatic-hydrothermal stage for F-rich peraluminous magmatic system.

Detrital zircon geochronology from the Nueva Segovia Schist, Nicaragua: evidence for the tectonic evolution of the Chortis Block?

Abstract The Chortis Block of Central America is a cratonic-type peri-Gondwanan terrane and is commonly included in Neoproterozoic–Paleozoic palaeogeographical reconstructions. At present, most research has focused on the Mesozoic evolution of the Chortis Block, however, its earlier history remains poorly constrained. As a result, there is considerable debate surrounding the internal complexities of the Chortis Block and its tectonothermal evolution has not been well established by geochronological and geochemical data. New field investigations from the Nueva Segovia Schist (Northern Nicaragua), considered one of the oldest exposed parts of the Chortis Block, reveal it is composed primarily of deformed sequences of greenschist facies marine clastic and chemical sediments in conformable contact with felsic volcanics. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) detrital zircon data from two samples taken from the Nueva Segovia Schist reveal a youngest age peak of c. 250 Ma with other significant peaks at c. 500 Ma, c. 1.0 Ga and c. 1.2 Ga. Taken together with field observations, these data suggest the Nueva Segovia Schist was likely deposited between c. 250 and 110 Ma proximal to Amazonia during the Late Paleozoic, and they support a Precambrian age for the basement of the East Chortis Terrane. Taken together the data support a Pangaean position of the Chortis Block, adjacent to Amazonia inboard of Oaxaquia.

Mapping bone microstructure trace element composition: Sr, Ba, Cu, and Pb in an early modern Danish skeleton.

A Geographical Information System (GIS) approach enhances the acquisition, management, and analysis of trace element data from cortical bone. A high-resolution spatial dimension expands the research potential of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) data from cortical bone cross-sections. The chemical characterization of hundreds of osteons, notably sequences of superimposed osteons, permits more exacting studies of individual life histories than is possible with analyses of bulk bone samples. A GIS procedure was used to estimate Sr, Ba, Pb, and Cu concentrations, originally generated through LA-ICP-MS, for bone microstructural features, notably fragmentary and intact osteons, in a human femoral cross-section. The skeleton is from Ribe, Denmark, and dates to the early modern period. Postmortem chemical alteration was limited to the bone's outer and inner margins. Two dietary indicators, Sr and Ba, and two socioeconomic indicators, Pb and Cu, measured for individual osteons were correlated with one another. Osteon sequences indicate concentrations of all four elements increased late in life for this individual. The application of GIS procedures expedites fine-grained analyses of variation in the distribution of trace elements in bone microstructure identifiable in cortical bone cross-sections. It provides an efficient means of extracting the most information possible from LA-ICP-MS data about the lives of people in the past. Combining the two procedures makes it easier to track exposure to elements such as Pb across the part of an individual's life represented by osteon sequences.

Characterisation of Three Sri Lankan Zircon Megacrysts as Potential Reference Materials for Microbeam U‐Pb Geochronology and Hf‐O‐Zr Isotope Measurements

In situ U‐Pb geochronology and hafnium, oxygen and zirconium isotope measurements in zircons using laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and ion microprobe techniques can provide essential isotopic data to constrain geological evolutionary histories. Developing reliable zircon reference materials is the cornerstone for in situ zircon chronology and isotopic studies. In this study, the homogeneity of U‐Pb ages and Hf‐O‐Zr isotope ratios in three Sri Lankan zircon megacrysts (SLZA, SLZB and SLZC) were investigated using multiple analytical methods. The obtained U, Th, Pb and Hf mass fractions of the SLZA zircon were 839 ± 56 μg g‐1 (1s), 151 ± 15 μg g‐1 (1s), 198 ± 28 μg g‐1 (1s) and 8635 ± 286 μg g‐1 (1s), respectively. The mass fractions of U, Th, Pb and Hf in the SLZB zircon were 1106 ± 106 μg g‐1 (1s), 331 ± 61 μg g‐1 (1s), 376 ± 57 μg g‐1 (1s) and 9673 ± 976 μg g‐1 (1s), respectively. The U, Th, Pb and Hf mass fractions determined in the SLZC zircon were 551 ± 35 μg g‐1 (1s), 111 ± 8 μg g‐1 (1s), 129 ± 18 μg g‐1 (1s) and 7881 ± 393 μg g‐1 (1s), respectively. The chemical abrasion isotope dilution thermal ionisation mass‐spectrometry (CA‐ID‐TIMS) method yielded a Th‐corrected weighted mean 206Pb/238U age of 556.94 ± 1.29 Ma (95% conf., n = 5) for the SLZA zircon, 552.90 ± 1.29 Ma (95% conf., n = 7) for the SLZB zircon and 560.83 ± 1.29 Ma (95% conf., n = 7) for the SLZC zircon. The obtained Hf isotopic compositions of the SLZA, SLZB and SLZC zircons determined with the solution MC‐ICP‐MS method were 0.281651 ± 0.000014 (2s, n = 10), 0.281704 ± 0.000008 (2s, n = 10) and 0.281676 ± 0.000006 (2s, n = 10), respectively. The obtained O isotopes of the SLZA and SLZB zircons measured with the laser fluorination method were 12.14 ± 0.56‰ (2s, n = 4) and 11.91 ± 0.30‰ (2s, n = 4), respectively. The Zr isotopes of the SLZA, SLZB and SLZC zircons determined with double spike TIMS analysis yielded mean δ94/90ZrSRM3169 values of ‐0.03 ± 0.06‰ (2s, n = 10), ‐0.03 ± 0.04‰ (2s, n = 10) and 0.00 ± 0.07‰ (2s, n = 8), respectively. The SLZA zircon can be used as a primary reference or quality control material for microbeam U‐Pb, Hf and Zr isotope measurements because of its slight heterogeneity. The U‐Pb, Hf and Zr isotopic compositions of the SLZB and SLZC megacrysts were homogeneous. The O isotopic compositions in the SLZA and SLZB zircon were slightly dispersed, indicating that these two megacrysts can only serve as secondary reference materials for microbeam O isotope measurements.

Distribution of Copper, Iron, and Zinc in the Retina, Hippocampus, and Cortex of the Transgenic APP/PS1 Mouse Model of Alzheimer's Disease.

A mis-metabolism of transition metals (i.e., copper, iron, and zinc) in the brain has been recognised as a precursor event for aggregation of Amyloid-β plaques, a pathological hallmark of Alzheimer's disease (AD). However, imaging cerebral transition metals in vivo can be extremely challenging. As the retina is a known accessible extension of the central nervous system, we examined whether changes in the hippocampus and cortex metal load are also mirrored in the retina. Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to visualise and quantify the anatomical distribution and load of Cu, Fe, and Zn in the hippocampus, cortex, and retina of 9-month-old Amyloid Precursor Protein/Presenilin 1 (APP/PS1, n = 10) and Wild Type (WT, n = 10) mice. Our results show a similar metal load trend between the retina and the brain, with the WT mice displaying significantly higher concentrations of Cu, Fe, and Zn in the hippocampus (p < 0.05, p < 0.0001, p < 0.01), cortex (p < 0.05, p = 0.18, p < 0.0001) and the retina (p < 0.001, p = 0.01, p < 0.01) compared with the APP/PS1 mice. Our findings demonstrate that dysfunction of the cerebral transition metals in AD is also extended to the retina. This could lay the groundwork for future studies on the assessment of transition metal load in the retina in the context of early AD.

Gold mineralized diorite beneath the Linglong ore field, North China craton: New insights into the origin of decratonization-related gold deposits

Gold deposits in Precambrian cratons were mostly generated during the formation and stabilization of the cratons, but the North China craton is unusual in that its gold deposits were mainly formed ∼1.7 b.y. after its stabilization. A magmatic-hydrothermal origin or mantle-derived fluid source has been proposed for the giant gold deposits of the Jiaodong District in the eastern North China craton, but direct evidence is sparse, and the mineralization processes remain controversial. Here, we present the results of a comprehensive geological, geochronological, and geochemical study of the gold mineralized Xiejia diorite beneath the Linglong ore field at Jiaodong to link the gold mineralization to underlying magmatism. Magmatic zircon and titanite grains from the Xiejia diorite have laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS) U-Pb ages of 121.3 ± 0.9 Ma to 120.8 ± 1.1 Ma and 121.7 ± 3.9 Ma, respectively, which are indistinguishable from the time of gold deposition throughout the Jiaodong District as constrained by previous studies. The diorite has a shoshonitic composition and is characterized by strong enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) along with significant depletion in high field strength elements (HFSEs) and heavy rare earth elements (HREEs). Samples of the diorite have high initial 87Sr/86Sr ratios, but low εNd(t) and ɛHf(t) values and low Pb isotope ratios. These geochemical characteristics are akin to those of contemporaneous mafic dikes in most gold mines at Jiaodong, indicating that the Xiejia diorite was most likely derived from an enriched lithospheric mantle source. The upper part of the diorite intrusion is pervasively altered and mineralized, containing an average of 0.32 g/t Au, but locally up to 7.59 g/t. Hydrothermal titanite from the mineralized diorite has a LA-ICP-MS U-Pb age of 122.3 ± 4.3 Ma, which is consistent with the gold-bearing pyrite Re-Os isochron age of 122.5 ± 6.7 Ma. Ore-related sericite aggregates from the Dongfeng gold deposit above the Xiejia diorite have a 40Ar/39Ar plateau age of 122.6 ± 1.3 Ma. Pyrite from the mineralized diorite yielded δ34SCDT values of 2.1‰−9.7‰, which are comparable with those of pyrite (δ34SCDT = 5.8‰−8.1‰, where CDT indicates the Canyon Diablo troilite standard) from gold ores of Dongfeng. Pyrite grains from both groups also have similar Pb isotope compositions. The S and Pb isotope data are consistent with values of mafic dikes that are spatially and temporally associated with gold veins in the Linglong ore field. The results presented here thus indicate a possible genetic link between gold mineralization in the Xiejia diorite and underlying magma presumably represented by the Xiejia diorite. The auriferous fluids exsolved from that magma and migrated upward along the Potouqing fault to form the Dongfeng gold deposit above the Xiejia diorite. The mineralized diorite thus links shallow gold mineralization to deep-seated mantle-derived magmatism generated during the extensive destruction of the North China craton induced by the rollback of the subducted paleo-Pacific plate.

Particulate Standard Establishment for Absolute Quantification of Nanoparticles by LA-ICP-MS.

The development of nanotechnology has transformed many cutting-edge studies related to single-molecule analysis into nanoparticle (NP) detection with a single-NP sensitivity and ultrahigh resolution. While laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been successful in quantifying and tracking NPs, its quantitative calibration remains a major challenge due to the lack of suitable standards and the uncertain matrix effects. Herein, we frame a new approach to prepare quantitative standards via precise synthesis of NPs, nanoscale characterization, on-demand NP distribution, and deep learning-assisted NP counting. Gold NP standards were prepared to cover the mass range from sub-femtogram to picogram levels with sufficient accuracy and precision, thus establishing an unambiguous relationship between the sampled NP number in each ablation and the corresponding mass spectral signal. Our strategy facilitated for the first time the study of the factors affecting particulate sample capture and signal transductions in LA-ICP-MS analysis and culminated in the development of an LA-ICP-MS-based method for absolute NP quantification with single-NP sensitivity and single-cell quantification capability. The achievements would herald the emergence of new frontiers cut across a spectrum of toxicological and diagnostic issues related to NP quantification.

Tracing timing of growth in cultured molluscs using strontium spiking

IntroductionGrowth experiments present a powerful tool for determining the effect of environmental parameters on growth and carbonate composition in biogenic calcifiers. For successful proxy calibration and biomineralization studies, it is vital to identify volumes of carbonate precipitated by these organisms at precise intervals during the experiment. Here, we investigate the use of strontium labelling in mollusc growth experiments.MethodsThree bivalve species (Cerastoderma edule, Mytilus edulis and Ostrea edulis) were grown under monitored field conditions. The bivalves were regularly exposed to seawater with elevated concentrations of dissolved strontium chloride (SrCl2). In addition, the size of their shells was determined at various stages during the experiment using calliper measurements and digital photography. Trace element profiles were measured in cross sections through the shells of these molluscs using laser ablation ICPMS and XRF techniques.ResultsOur results show that doses of dissolved strontium equivalent to 7-8 times the background marine value (~0.6 mmol/L) are sufficient to cause reproducible peaks in shell-incorporated strontium in C. edule and M. edulis shells. No negative effects were observed on shell calcification rates. Lower doses (3-5 times background values) resulted in less clearly identifiable peaks, especially in M. edulis. Strontium spiking labels in shells of O. edulis are more difficult to detect, likely due to their irregular growth.DiscussionStrontium spiking is a useful technique for creating time marks in cultured shells and a reproducible way to monitor shell size during the growing season while limiting physical disturbance of the animals. However, accurate reconstructions of growth rates at high temporal resolution require frequent spiking with high doses of strontium.