Laser Ablation Inductively Coupled Plasma Mass Spectrometry Research Articles

Effects of iron overload in human joint tissue explant cultures and animal models.

Osteoarthritis (OA) is a prevalent degenerative joint disease affecting over 530 million individuals worldwide. Recent studies suggest a potential link between iron overload, a condition characterised by the excessive accumulation of iron in the body, and the onset of OA. Iron is essential for various biological processes, and any disruption in its homeostasis can trigger significant health effects, including OA. This study aimed to elucidate the effects of excess iron on joint tissue and the underlying mechanisms associated with excess iron and OA development. Human articular cartilage (n = 6) and synovium (n = 4) were collected from patients who underwent total knee arthroplasty. Cartilage and synovium explants were incubated with a gradually increasing concentration of ferric ammonium citrate for 3days respectively. The effects of iron homeostasis in tissue explants were analysed using a Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). To further study the effects of iron excess on OA initiation and development, male 3-week-old Hfe-/- and 5-week-old Tfr2-/- mice, animal models of hereditary haemochromatosis were established. Littermate wild-type mice were fed a high-iron diet to induce dietary overload. All animals were sacrificed at 8weeks of age, and knee joints were harvested for histological analysis. The LA-ICP-MS analysis unveiled changes in the elemental composition related to iron metabolism, which included alterations in FTH1, FPN1, and HAMP within iron(III)-treated cartilage explants. While chondrocyte viability remained stable under different iron concentrations, ex vivo treatment with a high concentration of Fe3+ increased the catabolic gene expression of MMP13. Similar alterations were observed in the synovium, with added increases in GAG content and inflammation markers. In vivo studies further supported the role of iron overload in OA development as evidenced by spontaneous OA symptoms, proteoglycan loss, increased Mankin scores, synovial thickening, and enhanced immunohistochemical expression of MMP13, ADAMTS5, and P21 in Hfe-/-, Tfr2-/-, and diet-induced iron overload mouse models. Our findings elucidate the specific pathways through which excess iron accelerates OA progression and highlights potential targets for therapeutic intervention aimed at modulating iron levels to mitigate OA symptoms. KEY MESSAGES: Iron overload alters joint iron metabolism, increasing OA markers in cartilage and synovium. High iron levels in mice accelerate OA, highlighting genetic and dietary impacts. Excess iron prompts chondrocyte iron storage response, signalling potential OA pathways. Iron dysregulation linked to increased cartilage degradation and synovial inflammation. Our findings support targeted therapies for OA based on iron modulation strategies.

Laser ablation inductively coupled plasma mass spectrometry measurements for high-resolution chemical ice core analyses with a first application to an ice core from Skytrain Ice Rise (Antarctica)

Abstract. Conventional methods of inorganic impurity analysis do not provide high enough depth resolution for many scientific questions in ice core science. In this study, we present a setup of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for high-resolution glacier ice impurity analysis to the sub-millimetre scale. This setup enables ice core chemical impurity analysis to a depth resolution of ∼182 µm while consuming only very small amounts of ice. The system performs simultaneous analysis of sodium, magnesium and aluminium incorporated in the ice matrix. In this case study within the framework of the WACSWAIN (WArm Climate Stability of the West Antarctic Ice Sheet in the last INterglacial) project, our method is applied to a selection of samples from the Skytrain ice core (West Antarctica) over a total length of 6.7 m consisting of about 130 single samples. The main goal of this study is to use the new LA-ICP-MS method to extract meaningful climate signals on a depth resolution level beyond the limits of continuous-flow analysis (CFA). A comparison between low-resolution CFA data and the high-resolution LA-ICP-MS data reveals generally good agreement on the decimetre scale. Stacking of parallel laser measurements together with frequency analysis is used to analyse the high-resolution LA-ICP-MS data at millimetre resolution. Spectral analysis reveals that despite effects of impurity accumulation along ice crystal grain boundaries, periodic concentration changes in the Skytrain ice core on the millimetre scale can be identified in ice from 26.8 ka (kiloyears before present, i.e. 1950 CE). These findings open new possibilities for climate data interpretation with respect to fast changes in the last glacial period and beyond, for example within the Beyond EPICA oldest-ice project.

Morphogenetic varieties of iron oxyhydroxides in shimmering smokers-diffusers of the Rainbow hydrothermal field (36°13′ N, 33°54′ W, Mid-Atlantic Ridge): LA-ICP-MS data for the development of halmyrolysis theory

Research subject. Iron oxyhydroxides covering and replacing the chimneys of shimmering water smokers-diffusers of the Rainbow hydrothermal field (MAR). Aim. To identify features of the concentration and associations of chemical elements in varieties of iron oxyhydroxides to recognize patterns of geochemical differentiation under conditions of halmyrolysis of sulfide chimneys-diffusers. Materials and methods. Samples were collected during a dive to a depth of 2300 m using the manual manipulator of the Mir-2 manned vehicle (travel No. 50, research vessel Akademik Mstislav Keldysh, 2005). Varieties of iron ohyhydroxides were identified using electron microscopes (REMMA-202М with LZ-5 Link system, Tescan Vega 3 sbu with an Oxford Instruments X-act energy-dispersive analyzer, and Jeol Superprobe 733 with an EDA Oxford Instruments INCAx-sight) and a powder X-ray diffractometer (SHIMADZU XRD-6000, CuK-α radiation with monochromator). Further, a mass spectrometry with inductively coupled plasma and laser ablation (LA-ICP-MS) analysis was conducted at the South Urals Federal Scientific Center of Mineralogy and Geoecology, Ural Branch of the Russian Academy of Sciences. Results. Microlayered goethite aggregates containing admixtures of barite, calcite, aragonite, native sulfur, covellite, sphalerite, and an X-ray amophoric oxyhydroxide phase of iron cover the shimmering diffusers. Towards the inner parts of the chimney walls, they are replaced by pseudomorphs of lepidocrocite after pyrite and pyrrhotite, and then by radial and bacteriomorphic crustifications of lepidocrocite. The use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) showed that goethite varieties have the increased contents of Zn and Co associated with other elements of medium-temperature hydrothermal fluids (Cd, Mn, Ni, Ga, Sn, Pb and Sb) in the absence of significant concentrations of a high-temperature hydrothermal association (Se, Bi, Te). The role of elements of seawater association (Mg, Na, K, Sr, U, V, As, Mo, Ni, P, B, W, Cs, REE) decreases from the surface layered goethite aggregates to crustification varieties of lepidocrocite. Different scenarios of accumulation under conditions of sulfide halmyrolysis and precipitation on local reduction barriers are proposed for elements with different valences (U, V, Mo, As, Cr, Eu). It is assumed that some of the microelements (Sr, V, As, P, REE) found in goethite are products of sorption on iron hydroxides or are part of invisible Fe-Ca hydroxyphosphates. Conclusion. The influence of sulfide halmyrolysis on the differentiation of chemical elements has been revealed.

Occurrence and enrichment of critical metals in ferromanganese deposits in the western Pacific

Co-rich ferromanganese nodules and crusts are economically valuable deep-sea ferromanganese deposits widely distributed in the western Pacific Ocean and are rich in critical metals such as Co, Ni, Cu and rare earth elements (REEs). However, the lack of fine delineation and systematic comparisons of the distributions of these critical metals in these ferromanganese deposits limits the understanding of the occurrence states of Co, Ni, Cu and REEs and the metallogenesis of ferromanganese deposits. Therefore, the authors selected one nodule and one crust from the western Pacific Ocean, and utilized high-resolution methods such as micro-area X-ray fluorescence spectrometry (μ-XRF), laser-ablation inductively-coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS), and laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to depict elemental distribution and elemental profile.The results show that the ferromanganese deposits are predominantly composed of Fe-vernadite with low Mn/Fe ratios. Co, Ni and Cu exist primarily in the manganate octahedral layer of Fe-vernadite. REEs mostly exist in feroxyhite of Fe-vernadite, and manganate octahedral layer of Fe-vernadite also have high Ce content. Co, Ni and Cu contents of ferromanganese deposits are closely correlated with Mn/Fe ratios: Co, Ni and Cu contents increase with Mn/Fe ratios until the Mn/Fe ratios rises up to 4, and remain stable when Mn/Fe ratios > 6. The enrichment of Co, Ni and Cu in ferromanganese deposits is controlled by the redox conditions of seawater during accretion, whereas REEs enrichment is related to Mn and Fe fluxes in seawater during accretion. The coupling relationships between elemental distributions help to reveal the elemental occurrence state, and the geochemistry of ferromanganese deposits are analyzed to identify element enrichment mechanism.

New insights of emerald geographic origin determination based on the infrared spectroscopy of D2O and HDO molecules

Emerald geographic origin determination in laboratories typically relies on the microscopic features of inclusions, ultraviolet through visible and near-infrared (UV-Vis-NIR) spectroscopy, and trace element chemistry measured by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). Infrared (IR) spectroscopy, a non-destructive technique, has played a minor role in this process. This work conducts a systematic examination of emerald samples from twelve origins, encompassing spectroscopic, and trace element analyses. For the first time, IR absorptions related to D2O and HDO molecules within the 2600–2850cm–1 range for from multiple origins (333 emerald samples) were recorded, assigned, and classified. These IR absorptions, controlled by the concentrations of deuterium (D) and alkali metals (primarily sodium) within channels, reveal three distinct patterns and derived four groups that serve as strong evidence for origin determination. Emeralds from Zambia group display the most prevalent HDO-dominant IR-pattern I characterized by the pronounced absorption peak of Type II HDO at 2672cm–1; Panjshir (Afghanistan) and Swat (Pakistan) emeralds exhibit the transitional type IR-Pattern II with overall five peaks and obvious 2808cm–1 peak; D2O-dominant IR-Pattern III is featured by marked absorption band at 2740cm–1, and can be further subdivided into two subtypes (IIIa and IIIb). IR-Pattern IIIb is currently only found in Nigerian emeralds, characterized by strong broad band of Type I D2O due to enriched deuterium and obvious absorption of Type I HDO at 2685cm–1 due to depleted sodium. Furthermore, this research updates the classification of UV-Vis-NIR spectra, unveils the trace element features, and presents effective compositional diagrams. This contribution enriches and expands existing techniques and provides new insights for emerald origin determination.

Triple-oxygen isotopes of stony micrometeorites by secondary ion mass spectrometry (SIMS): Olivine, basaltic glass and iron oxide matrix effects for sensitive high-mass resolution ion microprobe-stable isotope (SHRIMP-SI).

Micrometeorites are extraterrestrial particles smaller than ~2mm in diameter, most of which melted during atmospheric entry and crystallised or quenched to form 'cosmic spherules'. Their parentage among meteorite groups can be inferred from triple-oxygen isotope compositions, for example, by secondary ion mass spectrometry (SIMS). This method uses sample efficiently, preserving spherules for other investigations. While SIMS precisions are improving steadily, application requires assumptions about instrumental mass fractionation, which is controlled by sample chemistry and mineralogy (matrix effects). We have developed a generic SIMS method using sensitive high-mass resolution ion micro probe-stable isotope (SHRIMP-SI) that can be applied to finely crystalline igneous textures as in cosmic spherules. We correct for oxygen isotope matrix effects using the bulk chemistry of samples obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and model bulk chemical compositions as three-component mixtures of olivine, basaltic glass and Fe-oxide (magnetite), finding a unique matrix correction for each target. Our first results for cosmic spherules from East Antarctica compare favourably with established micrometeorite groups defined by precise and accurate but consumptive bulk oxygen isotope methods. The Fe-oxide content of each spherule is the main control on magnitude of oxygen isotope ratio bias, with effects on δ18O up to ~6‰. Our main peak in compositions closely coincides with so-called 'Group 1' objects identified by consumptive methods. The magnitude of SIMS matrix effects we find is similar to the previous intraspherule variations, which are now the limiting factor in understanding their compositions. The matrix effect for each spherule should be assessed quantitatively and individually, especially addressing Fe-oxide content. We expect micrometeorite triple-oxygen isotope compositions obtained by SIMS to converge on the main clusters (Groups 1 to 4) after correction firstly for magnetite content and secondarily for other phases (e.g., basaltic glass) in each target.

Genetic relationship between W mineralization and granitic intrusion in Nanling Region, South China: Constraints from zircon and cassiterite u-pb age from new drill holes in Shangping deposit

The Nanling metallogenic belt is known for the widely development of typical quartz vein type W deposit. These quartz veins that contain wolframite are frequently located in close proximity to granitic intrusions. The genetic relationship between tungsten mineralization and the associated granitic rocks is still a subject of controversy. The Shangping deposit stands out as a historically significant W deposit with a quartz vein type in the region of Nanling. However, the specific time that W mineralization occurred remains enigmatic. Granitic intrusions are absent from the mine and only granite porphyry dike is exposed, so the link between tungsten mineralization and magmatic activity remains unclear. Fortunately, in recent years, a concealed granite intrusive has been exposed in drill holes in the southeastern of the Shangping W deposit. To comprehensively address the connection between granitic magma activity and W mineralization, it is vital to make up a relative deficiency of geochronological information on granite and ore mineral. Here, in order to get the first direct age constraints on the origin of the Shangping W deposit, we use a combination of different techniques, incorporating the Hf isotope geochemistry of zirconium and cassiterite U-Pb assessment using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Based on these robust data, we tentatively evaluated the connection between W mineralization and granitic intrusion.For the granite porphyry, the majority of representative U-Pb zircon assays establish a206Pb/238U age of 150.2 ± 0.5 Ma. An inferred emplacement age of ca. 151 Ma for the concealed granite in Kengweiwo is supported by a U-Pb isochron age from zircon. Combined with Hf isotopic characterization, it illuminates the mineralization potential of the Kengweiwo concealed granite. Cassiterite grains from hydrothermal quartz vein are subhedral to anhedral and have a lower intercept 206Pb/238U age of 153.9 ± 1.0 Ma. For the Shangping W deposit, all of these new geochronological dates provide well-constrained mineralization ages of 150–154 Ma. The dates of the concealed granite in the Kengweiwo area and the tungsten mineralization in the Shangping area are extremely concordant, indicating that they occurred roughly concurrently. The vein type tungsten mineralization in Shangping deposit may has a genetic link with crystallization of uncovered granite present at depth, which requires further investigation. These results emphasize the significance and potential of concealed granitic intrusion to host disseminated W mineralization in the deep part of Shangping deposit.

Effects of Thermal Annealing and Chemical Abrasion on In-situ U-Pb Dating of Complex Ancient Zircons by Laser Ablation ICP-MS

Effects of Thermal Annealing and Chemical Abrasion on In-situ U-Pb Dating of Complex Ancient Zircons by Laser Ablation ICP-MS

Geochronology and petrogenesis of Early Mesozoic Rb-mineralized granitic rocks from the Liuzhangshan Rb, West Qinling Orogen Belt, China

ABSTRACT The newly discovered Liuzhangshan (LZS) Rb deposit is a large granite-type deposit in the West Qinling Orogenic Belt (WQOB), spatially associated with biotite monzogranite. Previous research has focused on the geological characteristics and metallogenic conditions of the LZS Rb deposit; however, its geochronology and petrogenesis remain unclear. In this study, monazite U-Pb dating of biotite monzogranite in the LZS deposit yielded a U-Pb age of 200.8 ± 0.9 Ma via laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Combined with the age of magmatic rocks in the WQOB, we propose a potential mineralization event related to Rb around 200 Ma in the WQOB. The biotite monzogranite belongs to weakly peraluminous, high-K calc-alkaline serious, containing high SiO2, Na2O, K2O, and low FeO, MgO, CaO, and P2O5. Compared with primitive mantle and relatively unfractionated granodiorites found in the WQOB, the biotite monzogranite enriched in Rb, Th, U, and Pb, deleted in Ba, Sr, and Ti, and showed negative Eu anomalies, a high Rb/Sr ratio, and a low K/Rb ratio, an ∑REE of 31.3 ppm, an LREE/HREE ratio of 6.48, a LaN/YbN ratio of 2.59, an Mg# of 4.15, and a crystallization temperature of 760°C, the biotite monzogranite also had a high differentiation index (DI = 98.2), apparent tetrad effect (TE 1,3 = 1.12 ~ 1.15), characteristic of highly fractionated I-type granite. Monzoite from the biotite monzogranite in the LZS deposit has negative εNd(t) values ranging from −12.45 to −11.17, and TDM1 of 1569 ~ 2018 Ma, indicating that the LZS biotite monzogranite originated from the partial melting of a Mesoproterozoic ancient basement material, with a minor contribution from mantle-derived melts. Highly differentiated, low Sr and Yb contents, Sr/Yb ratios, and low crystallization temperature magma facilitated the enrichment of Rb.

Evidence of glass bead‐making in the early Islamic Iberian Peninsula

AbstractGlass beads from two Islamic archaeological sites in the Tagus valley in central Spain were selected and analysed by laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS), and a subset of samples (n = 6) was analysed for Pb isotopes by multicollector thermal ionization mass spectrometry (MC‐TIMS). The analytical and isotopic data of the beads from Ciudad de Vascos (Toledo) and Albalat (Cáceres) demonstrate beyond reasonable doubt that glass beads were produced in the Iberian Peninsula during the Islamic period using local Pb‐silica and soda‐rich plant‐ash glass. The bead workshops in al‐Andalus were evidently part of an efficient system of glass collection and recycling, and used only relatively simple bead‐making techniques such as winding and folding. At present it is unclear to what extent the Islamic bead‐makers in the Iberian Peninsula were involved in the international trade in glass beads or whether their products were mainly destined for a regional market. Despite local production, some samples show compositional and typological features that suggest the import of finished glass beads, perhaps from Central Asia.

2D geochemical imaging of biogenic marine carbonates using LA-TOF-ICP-MS at 1 and 2 μm pixel resolution

Many applications at the forefront of the study of the chemical composition of marine carbonates require in-situ micro-scale geochemical imaging. Such analyses are, however, challenging, requiring analytical techniques that are either expensive with limited accessibility (e.g. synchrotron X-Ray spectroscopy and secondary ion mass spectrometry), or time-consuming and able to only analyse a limited range of elements (e.g. electron microprobe). Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a tool for generating 2D images has grown in popularity, yet many analytical issues remain when generating high-spatial resolution geochemical images using this approach. Here we employ the imageGEO193 (ESL) fast wash-out laser ablation system coupled to the Nu Instruments Vitesse Time-of-Flight (TOF) ICP mass spectrometer, with its near-full mass spectra capabilities, to generate 2D geochemical images of a range of biogenic carbonates at ≤2 μm pixel resolution (pixel widths of either 1 or 2 μm) and at an unprecedented speed (200 pixels/s). We demonstrate sensitivity of ∼100 cps/μg g−1 at low mass rising to ∼1000 cps/μg g−1 at high mass based on analyses of reference materials JCp-1 (carbonate) and NIST SRM612 (silicate) with 1 μm wide square laser beams, and accuracy of ±7 % for elements present at concentrations >0.5 μg g−1 based on analyses of carbonate reference material JCt-1. By applying our quantitative method to a range of biogenic carbonates (coral skeletons, coralline algae, foraminifera), we demonstrate that considerable but coherent micron-scale compositional variability is the norm for nearly all quantified elements, including: Mg, Sr, Ba and U. This approach therefore has great potential to provide valuable insights into biomineralisation mechanisms and “vital effects”, ultimately facilitating more robust reconstructions of past environments.

Anomalous tellurium enrichment associated with gold mineralization: A mineralogical and isotopic study of the Yongxin Te-Au deposit, northeast China

The Yongxin tellurium-gold (Te-Au) deposit, a large epithermal deposit in the Duobaoshan polymetallic metallogenic belt (DPMB) within eastern section of the Central Asian Orogenic Belt (CAOB), is mainly hosted by syenogranite and mylonite. However, the Te-Au occurrence, precipitation mechanism and genesis in this deposit remain elusive. In this study, pyrite, the primary host of Te-Au mineralization, was studied utilizing multiparametric techniques such as scanning electron microscope (SEM), electron probe microanalysis (EPMA), in-situ laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) and femtosecond laser ablation coupled multi-collector inductively coupled plasma mass spectrometry (fs LA-MC-ICP-MS). The results show that there are three generations of pyrite termed here as Py1, Py2 and Py3. The coarse euhedral Py1 and fine vein Py2 contain negligible to low contents of Te and Au, whereas the anhedral aggregated Py3 with porosity and grain boundary (GB) shows the highest concentrations of Te and Au. Representative LA-ICP-MS profiles show that Te-Au occurs either as solid solution in the Py1 and Py2 or submicroscopic Au-Ag-Te-Bi inclusions, electrum and native gold in Py3. Thermodynamic data of telluride and sulfide show that the Te-Au was deposited under relatively oxidizing conditions with values of log f Te2 ranging from −15.2 to −11.2 and log f S2 from −16.7 to −12.1. at 200 °C. We infer that fluid mixing and fluid-rock interaction were the dominant mechanisms that triggered the precipitation of Te-Au in the Yongxin Te-Au deposit. Geochemical and geochronological data indicate that the likely source of Te is Te-rich oceanic sediments originating from the Western Pacific Plate. Pyrite and telluride from the gold deposits can be potential targets for Te exploration in the DPMB.

Multistage fluid mixing events induced Sn polymetallic super-enrichment at Dulong in Yunnan Province, South China

Dulong Sn polymetallic deposit is a world-class skarn tin deposit situated at the Youjiang basin with a reserve of 0.4 Mt Sn at 0.56 %, 5.0 Mt Zn at 5.12 %, together with 7 kt In. The deposit predominantly occurs within the Neoproterozoic Xinzhaiyan Formation and is controlled by NS-trending faults. Based on elaborate field and petrographic observations, the Dulong Sn polymetallic deposit was divided into four mineralization stages: stage 1 (prograde stage), stage 2 (retrograde stage), stage 3 (quartz-sulfide stage) and stage 4 (carbonate stage). Tin mineralization primarily occurs as cassiterite during stage 2, with additional cassiterite-stannite formation noted in stage 3. Analysis of fluid inclusions across these stages reveals the evolutionary history of the mineralizing fluids and the precipitation mechanisms at Dulong. During stage 1, diopside hosts both daughter-bearing multiphase inclusions and vapor-rich inclusions. The daughter-bearing multiphase inclusions exhibit homogenization temperatures ranging from 510 to 574 °C and salinities between 44.7 and 49.6 wt% NaCl equiv., whereas the vapor-rich inclusions display homogenization temperatures of 573–586 °C and salinities from 2.9 to 4.0 wt% NaCl equiv., indicating a boiling fluid process. Cassiterite (stage 2) features primarily liquid-rich two-phase inclusions, with homogenization temperatures of 351–410 °C and salinities of 6.3–9.6 wt% NaCl equiv. These inclusions document the mixing of magmatic fluid with meteoric water, which is likely the principal mechanism driving initial tin mineralization. Similarly, the same type of inclusions is also recorded in cassiterite of stage 3. The homogenization temperature of the inclusions in cassiterite is 290–334 °C and the salinities of the inclusions is 3.4–8.4 wt% NaCl equiv. Comparatively, the temperature continued to decrease in stage 3, indicating that fluid mixing may have persisted during this stage which could also explain the occurrence of cassiterite and stannite in this stage. In addition, redox reaction where CO2 and/or As (III) serve as oxidants may also be another mechanism to exact cassiterite from ore-forming fluid. Our Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data suggests that cassiterite of the Dulong deposit involves a variety of complex substitutional mechanism. Due to the differing geochemical properties of the elements and variations in their concentrations, there is an indication that two phases distinct mineralizing fluids may have been present. The varying geochemical properties and concentrations of elements such as Nb, Ta, Zr, Fe, In, and Ga align with microthermometric results, indicating a reduction in magmatic hydrothermal fluid contribution and/or a transition from high to low temperatures in the hydrothermal system. This variation is also likely attributable to fluid mixing processes.

Paleobotanical Evidence for Mediterranean Climates in the Western Canadian Paleoarctic During the Late Middle Eocene

AbstractPaleogene age deposits east of the Fifteenmile River, northwest of Dawson City, Yukon, Canada preserve a diverse high‐latitude fossil flora. Here, we provide new data on the age of the fossil site based on laser ablation–inductively coupled plasma–mass spectrometry (LA‐ICP‐MS) U‐Pb dating of tephra zircons, paleobotanical paleoclimate reconstructions, and growing season length estimates based on photoperiod. These new data indicate an age of the Fifteenmile River fossil locality as late middle Eocene and likely within the Middle Eocene Climatic Optimum episode. The paleoflora‐based paleoclimate reconstruction indicates the region was relatively wet and warm with non‐freezing winters, but also experienced seasonal dryness, with an approximate 7 months long growing season as suggested by photoperiod. We interpret this paleoclimate as summer dry and winter wet—a climate analogous to modern day warm Mediterranean climates in the Köppen‐Geiger climate classification system. These findings provide a new perspective on the past climate and environment of high‐latitude ecosystems during warm greenhouse intervals and contribute to our understanding of the Earth's climate history and its potential future changes.

INTRATEST TRACE ELEMENT VARIABILITY IN POLAR AND SUBPOLAR PLANKTIC FORAMINIFERA: INSIGHTS INTO VITAL EFFECTS, ONTOGENY, AND BIOMINERALIZATION PROCESSES

ABSTRACT To use planktic foraminiferal tests as paleoproxy substrates, it is necessary to delineate environmental versus biological controls on trace element incorporation. Here we utilize laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to explore interspecies, chamber-to-chamber, and intratest trace element (i.e., Mg, Na, Sr, Ba, Mn, Zn) variability in thickly-calcified specimens of the polar and subpolar planktic foraminifera Neogloboquadrina incompta, N. pachyderma, and Turborotalita quinqueloba collected from plankton tows in the Northern California Current. Among the study taxa, test Mg/Ca, Na/Ca, and Sr/Ca are likely dominantly controlled by depth habitat. The neogloboquadrinids record higher Ba/Ca and Mn/Ca and also show positive covariance between these elements, possibly due to calcifying in an oxygen-depleted marine snow microhabitat. Trace elements are found to be more enriched in the lamellar calcite than the outer chamber wall dominated by gametogenic crust. The data presented herein provide insight into potential vital effects, paleoproxy considerations, ontogeny, and biomineralization processes.

Variation in lifetime movements of an Ariidae species in an eastern Australian river revealed by otolith microchemistry

Ariids, or sea catfishes, inhabit marine, estuarine, and occasionally freshwater habitats circumtropically. They are most often locally abundant and are important in artisanal and commercial fisheries, particularly in developing countries. Detailed information on the ecology and habitat preferences of many of the genera within the family is lacking. We analysed the otolith of 57 blue catfish, Neoarius graeffei, collected from the lower reaches of the Clarence River, NSW, Australia with the aim of better understanding the species movement ecology, including its ability to respond to environmental change. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to quantify Sr:Ca, Ba:Ca and 87Sr:86Sr ratios in otoliths and infer lifetime movement patterns. Otolith microchemistry revealed inter-individual variation in the movement patterns of N. graeffei. A strong affinity for estuarine waters was evident among most individuals, with movement into upstream freshwater habitats for extended periods discernible in some individuals. Variation in movement patterns was identified by changes in Ba:Ca, Sr:Ca and 87Sr:86Sr otolith profiles, although Sr:Ca lacked clear patterns. Furthermore, both Ba:Ca and 87Sr:86Sr otolith transects revealed estuarine residence by juveniles, as well as multiple movements among chemically distinct areas throughout the lifetime of some individuals. Otolith microchemistry enabled elucidation of long-term movement patterns of N. graeffei in our study. Uncovering the variable movement patterns of a single species identifies the potential adaptable nature of other species within the Ariidae family and indicates N. graeffei is resilient to environmental changes and anthropogenic impacts.

Explainable extreme gradient boosting as a machine learning tool for discrimination of the geographical origin of chili peppers using laser ablation-inductively coupled plasma mass spectrometry, X-ray fluorescence, and near-infrared spectroscopy

The spectroscopic discrimination of chili pepper samples according to geographical origin was executed using analytical techniques coupled with machine learning. First, laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray fluorescence (XRF), and near-infrared (NIR) spectroscopy were chosen for simple and rapid sample measurements. Second, to secure discrimination accuracy, eXtreme Gradient Boosting (XGBoost), a tree-based ensemble technique, was adopted as a potential classifier. Also, for explainable machine learning modeling, SHaply Additive exPlanation (SHAP) values of employed variables were calculated to assess how they contribute to the discrimination. The use of XGBoost improved discrimination accuracies in all three measurements compared to k-nearest neighbor (k-NN), support vector machine (SVM), and partial least squares-discriminant analysis (PLS-DA). The accuracy was 96.2 % using the LA-ICP-MS data. When the XRF and NIR data were combined, the accuracy improved to 97.5 %. The accuracy improvement was attributed to the combination of complementary atomic and molecular spectroscopic signatures of the samples.

Climate-driven versus anthropogenic induced erosion of the last 3000 years from an ancient lake in the Southern Phokis Plain (Desfina), Greece

The timing and causes for erosional events at the Kastrouli (Greece) archeological site – a Late Myceneaen with reuse in later periods – are presented. Two borehole sediment cores (max 6 m depth), collected from the footsteps of the settlement hill plain, were studied. Sedimentary analysis and luminescence dating techniques investigate and identify periods of soil aggradation in this record. Moreover, optically stimulated luminescence (OSL) dating confirmed the concept of an ancient lake during Kastrouli settlement times. Macroscopic overview of the stratigraphic structure for each core, included lithological and textural evaluation of the core sediments, assessments of grain size, and determination of the geochemical and mineralogical composition of the sediments. X-ray powder diffraction (XRPD), X-ray fluorescence (XRF), and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) techniques were applied for the mineralogical and geochemical analysis. OSL ages from seven sediment horizons spanned from the Ottoman period to archaic times. All lithological findings correlate with the results of the electrical tomography survey conducted in same area. Extrapolation of the Logarithmic fitting of the data back in time of prehistoric Late Mycenaean era of Kastrouli verifies a lake deeper than 10 m, with a considerable enhancement in soil aggradation of 1.2 cm/year. Attempts to dry out the area are evidenced by the hydraulic works found in two engineering sinkholes. Sedimentation changes had occurred in the local environment over the last 2500 years, and soil aggradation underwent significant fluctuations in the two studied cores. The Roman period (a wet period) and the Byzantine period experienced high aggradation rates. By contrast, soil aggradation rates in southern Phokis (Kastrouli region) have remained exceedingly low from the Ottoman era (circa 13th century) to the present. In the context of the Phokis case study, it appears that the sedimentation rates, driven by climate, have strengthened anthropogenic activities.

Li enrichment in peridotites and chromitites tracks mantle-crust interaction

The ultramafic massifs of the Serranía de Ronda in southern Spain are the Earth's largest exposures of subcontinental lithospheric mantle (SCLM) peridotites (∼450 km2). These ultramafic massifs experienced asthenosphere melt percolation during their crustal emplacement. Mixing of these mafic melts with anatectic melts and fluids led to the formation of a world's unique Ni-arsenide-rich chromitite ores (hereafter CrNi ores) associated with orthopyroxenite and/or cordieritite (i.e., > 90 % volume of cordierite) hosted within the peridotites. This study uses laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to investigate the Li in rock-forming minerals of peridotite and CrNi ores to evaluate the role of Li as crustal tracer. Clinopyroxene crystallized from asthenospheric melts exhibits high Li contents (up to 8.5 ppm), exceeding the average values of the upper mantle (∼ 0.7 ppm), whereas orthopyroxene, olivine, and Cr-spinel from peridotite are mostly Li-depleted. In contrast, all rock-forming minerals of CrNi ores have abnormally high Li contents, displaying an overall Li enrichment trend toward the external parts of ultramafic massifs, on the way to the crustal rocks. This trend is evident in Cr-spinel from the CrNi ores, which display 6.9–7.9 ppm Li in the deepest portions of the massif (Arroyo de la Cala CrNi ore) up to 1.4–8.5 ppm in the shallowest part (La Gallega CrNi ore), as well as in orthopyroxenes that have 31.3–44.7 ppm Li in Arroyo de la Cala, and 45.1–51.4 ppm Li in La Gallega. Cordierite is present only in the CrNi ores situated in the external part of the ultramafic massifs, exhibiting 113.15–160.82 ppm Li in the Barranco de las Acedías CrNi ore and 36.5–60.5 ppm Li in La Gallega CrNi ore. Similarly to Li, LREE, fluid-mobile elements (K, Rb, Ba), and Sr in orthopyroxenes from the CrNi ores display enrichment from the inner to the outer parts of the ultramafic massif. These geochemical variations suggest that Li enrichment in CrNi ores and host peridotites was a twofold process: (1) asthenospheric melt percolation slightly increased Li abundances in the SCLM peridotites by modal and cryptic metasomatism involving clinopyroxene; (2) additional infiltration of Li-bearing crustally-derived fluids during the intracrustal emplacement of the mantle section boosted the Li contents of minerals in the CrNi ores. Our results highlight that Li may effectively track the interaction of the SCLM with crustal components.

Isotopic spike 190Os as internal standard and empirical coefficient LA-ICP-MS combined with Sb fire assay for the determination of ultra-trace platinum group elements in geochemical samples

In this work, a novel method of antimony fire assay (Sb-FA) enrichment combined with laser ablation ICP-MS (LA-ICP-MS) for the determination of ultra-trace platinum group elements (PGEs) in geological samples was established. The purification and recycling technology of ultra-clean and high-purity fire assay collector Sb2O3 was proposed, in addition, high-purity quartz crucible was developed to replace the usual clay crucible, then the blank values of PGEs were as low as 0.0007–0.0028 ng g−1 (for 20 g sample). 190Os isotopic diluent was used as internal standard (IS) and quantitatively added into the fire assay ingredients, and fully mixed and balanced with the PGEs in the real samples by means of high temperature melting, cupellation and horizontal rotation of crucible and dish. Both 190Os and PGEs in the real sample were pre-concentrated in microgram level Sb granules (100 mg) through Sb-remaining cupellation. After grinding and polishing, 195Pt, 105Pd, 101Ru, 103Rh, 193Ir, total 189Os and 190Os enriched in Sb slices were determined by LA-ICP-MS, 190Os in the internal standard was calculated by isotope dilution equations. The Certified Reference Materials (CRMs) for PGEs were treated by the same procedure to obtain completely matrix matched Sb slices to solve the problem of no internationally recognized uniform PGEs standard materials for LA-ICP-MS determination. Due to the similar distribution trends of different PGEs in Sb slices by LA-ICP-MS imaging, then matrix-matched internal standard calibration strategy was used to reduce the element fractionation effect and improve the determination precision and accuracy of LA-ICP-MS. The laser frequency, energy density, denudation diameter and dwell times were optimized. Under the optimal conditions, empirical coefficient method was used to fit the standard curve and excellent curve fitting of PGEs were obtained with the correlation coefficient between 0.9990 and 0.9999. The method detection limits (LODs) for PGEs ranged from 0.00042 to 0.010 ng g−1. The established method was successfully applied to analyze real geochemical samples and various matrix Certified Reference Materials (CRMs) domestic and international, the determined values were in good agreement with the results of Sb-FA ICP-MS and the certified values.