Laser Ablation Inductively Coupled Plasma Mass Spectrometry Research Articles

The glass from the arrabal of Arrixaca (Murcia, 12th-13th centuries)

This article presents an assemblage of 36 glass samples excavated in the urban site of San Esteban, part of the arrabal of Arrixaca (Murcia) (in al-Andalus, an arrabal was a relatively dense urbanised area outside the city walls) in contexts securely dated to the 12th and early 13th century, spanning the rule of Ibn Mardanīš, and the early period of Almohad domination in the city. The samples were analysed by electron microprobe (EMPA) for major and minor elements and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for trace elements. The results are examined within the context of glass production, circulation, and consumption in al-Andalus and the Islamicate Mediterranean more broadly. The results show that some of the glasses found in San Esteban-Arrixaca may have been imported from other Islamicate regions (Egypt and Mesopotamia), but that the vast majority can be related to previously recognised compositional Iberian glass groups. At the same time, the identification of several fragments of production waste and raw glass suggest that some glass-working facility may have existed in the vicinity of San Esteban-Arrixaca. The compositional evidence also indicates that recycling (including of imported glass objects) may have been a fairly common practice in Andalusi glassmaking, but it is suggested that some of the usual chemical markers of recycling may, in the case of al-Andalus and perhaps also elsewhere in the medieval Mediterranean, be the result of the cross-breeding of glass- and glaze-making activities.

Dendrochemical Analysis as a Method to Identify Mineralized Zones: Insights from the Marathon Cu-PGE Deposit

The Marathon Cu-platinum-group element (PGE) deposit is located within the Eastern Gabbro Series of the Proterozoic Coldwell Alkalic Complex, 10 km north of Marathon, Ontario. The Cu-PGE mineralization occurs within the Two Duck Lake Gabbro, an olivine gabbro intrusion. This geochemical orientation study tested the trace element analysis of tree cores as a method of identifying mineralized versus background areas in the Marathon deposit, focusing on copper (Cu), sulfur (S), palladium (Pd), and silver (Ag). Tree core samples (n=25) were collected with an increment borer from black spruce (Picea mariana) trees and dated by counting growth rings. Fifteen cores, 12 near/overtop the deposit and three distal control samples, were analysed with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) over a 10-year interval (1992-2002). Data normalization to 88Sr like in other dendrochemical studies corrected for tree health and growth effects. 32S, 63Cu, and 105Pd were found to have the highest concentrations at 94.198, 2.224, and 0.055 ppm, respectively, in control sample 23KPA2-3004. This tree is located beside the Pic River and receives large amounts of run-off from the entire Eastern Gabbro Series, possibly enhancing the chemical composition of the tree core. Excluding this anomalous sample, significant concentrations of Cu and Ag were found moving SSW along the deposit, aligning with the direction of movement of the Pleistocene Laurentide Ice Sheet. While this study did not clearly identify mineralized zones in the Marathon deposit, it has identified the possibility of mineralized run-off in the Pic River affecting nearshore tree chemical composition. The influence of local terrain and glacial till must be also considered when using this method. Future research will continue to study the factors influencing the uptake of elements in trees and refine methods for detecting mineralization through tree core analysis.

Paleoproterozoic ultrahigh-temperature metamorphism in the Helanshan complex, North China Craton: New constraints from chloritized sapphirine-bearing pelitic granulites

Identifying ultrahigh-temperature (UHT) metamorphism in granulite-facies metamorphic terrains and determining its pressure-temperature-time (P-T-t) paths are crucial steps toward elucidating the anomalously hot geodynamic evolution process. This study presents the inaugural identification of chloritized sapphirine-bearing granulites in the Helanshan Complex, located in the western segment of the Khondalite Belt, North China Craton. Three stages of metamorphic evolution were identified based on petrographic analyses, mineral chemistry, and phase equilibrium modelling: the pre-Tmax stage involves the presence of rutile-stable phase assemblage, wherein rutile is partially substituted by ilmenite; the Tmax stage involves the assemblage of garnet + plagioclase + K-feldspar + sillimanite + spinel ± sapphirine + quartz + ilmenite + melt, as evidenced by microscale (<5 μm) blebs of variably chloritized sapphirine within spinel; and the retrograde cooling stage features the solidus assemblage of garnet + plagioclase + biotite + K-feldspar + sillimanite + cordierite + quartz + ilmenite + melt. Phase equilibrium modelling indicates Tmax conditions of 958–1055 °C and 6.4–7.8 kbar, suggesting UHT conditions accompanied by a high geothermal gradient of approximately 150 °C/kbar. Furthermore, a clockwise P-T trajectory was established, involving pre-Tmax decompression and post-Tmax near-isobaric cooling. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon and monazite UPb dating of UHT pelitic granulites produced ages clustering around 1.91 Ga, marking the era of UHT metamorphism within the Helanshan Complex. This discovery broadens the scope of UHT metamorphism and indicates that the entire Khondalite Belt experienced a regional UHT metamorphic event during 1.93–1.91 Ga, which was likely induced by an initial radiogenic heating synergy followed by an augmented mantle heat flux.

Germanium distribution in Mississippi Valley-Type systems from sulfide deposition to oxidative weathering: A perspective from Fule Pb-Zn(-Ge) deposit, South China

Abstract Germanium (Ge) is a critical raw material for emerging high-tech and green industries, resulting in considerable recent interest in understanding its distribution and geochemical behavior in ore deposits. In this contribution, the distribution of Ge and related trace elements in the Fule Pb-Zn(-Ge) deposit, South China, is investigated to reveal the distribution of Ge in the hydrothermal ores and during sulfide weathering, using multiple microanalytical techniques, including scanning electron microscopy, electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the Fule MVT deposit, sphalerite (ZnS) is the most significant Ge-carrier relative to other sulfides, though the five recognized textural types of sphalerite display progressive depletion in Ge from the first sphalerite generation to the late one. In the early stage, sphalerite with fine-grained chalcopyrite inclusions has the highest Ge concentrations, probably accounting for a significant proportion of the total Ge. We interpret that high Ge concentrations in the early sphalerite may be attributable to high Cu activity in the mineralizing fluids. During oxidative weathering, Ge was redistributed from its original host, sphalerite, to the weathering product willemite (Zn2SiO4) rather than smithsonite (ZnCO3), with high levels of Ge (up to 448 μg/g) present in the willemite. The formation of abundant willemite largely prevents the dispersion of Ge during weathering. In principle, willemite-hosted Ge should be fully recoverable, and the Zn-silicate ores may, therefore, be a potential target to meet future demand. This study provides new information on how Ge behaves from sulfide- to weathering-stage in MVT systems, which directly impacts Ge mobility and deportment changes and the development of metal-lurgical strategies for Ge recovery.

Ages and geochemistry of garnet reveal multi-types of iron-copper mineralization in the Eastern Tianshan, NW China

The Aqishan-Yamansu Fe-Cu-Au metallogenic belt in the Eastern Tianshan, NW China, hosts numerous Fe and Fe-Cu deposits that may have different genetic models, such as volcanic-hosted and skarn/IOCG types. These variations in genetic models are attributed to whether the mineralization is associated with hydrothermal activity related to volcanic or intrusive rocks. This study primarily focuses on garnets formed during the early skarn alteration in the Shuanglong Fe-Cu and Shaquanzi Fe deposits within this belt. Garnets from the Shuanglong deposit can be divided into two types and exhibit general homogeneity, with SL-Grt1 being Fe-rich and subsequently replaced by the Fe-poor SL-Grt2. Garnets from the Shaquanzi deposit display complex zonation patterns, SQZ-Grt1 show core–oscillatory zoned rim and SQZ-Grt2 show core–mantle–oscillatory zoned rim. Laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) dating of SL-Grt1 and SL-Grt2 produced lower intercept 206Pb/238U ages ranging from 318.0 ± 6.4 Ma to 303.7 ± 16.4 Ma, coinciding with the multi-stage granite occurrence. In contrast, SQZ-Grt1 and SQZ-Grt2 yielded ages between 328.0 ± 2.6 Ma and 320.4 ± 1.7 Ma, corresponding to the timing of the hosted rhyolite. SL-Grt1 show light rare earth element (LREE) enrichment, and low concentrations of high field strength elements (HFSE), such as V and Zr, and appears to have formed rapidly within an open system. Conversely, SL-Grt2 is characterized by heavy rare earth element (HREE) enrichment and elevated HFSE contents, which could be formed slowly in a closed system. The variable composition in the SQZ-Grt1 and SQZ-Grt2 record cyclical changes in fluid kinetics (vigorous fluid flow vs. fluid stagnation). The cyclical zones in SQZ-Grt2 with HREE and HFSE concentrations below the detection limit indicate multiple inputs of external seawater. The distinct characteristics between Shuanglong and Shaquanzi garnets may reflect the difference between the single magma intrusion and complex volcanic activity. Combining previously published chronological data, this study elucidates a transition from the Middle Carboniferous volcanic-hosted Fe deposits (335–320 Ma) to the Late Carboniferous intrusion-related skarn or IOCG type Fe-Cu deposits (310–300 Ma) in the Aqishan-Yamansu belt.

Detecting element migration from ore systems: an LA-ICP-MS method for the in situ measurement of element contents and 207 Pb/ 206 Pb values on rough fracture coatings

In situ elemental content and 207 Pb/ 206 Pb values in three rough fracture coatings within drill cores from the McArthur River unconformity-related uranium deposit, Athabasca Basin, Canada, were measured using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) image mapping. Fracture-coating samples were located proximal and distal to the ore deposit. Samples required minimal preparation in this method, with areas ( c . 500 × 500 μ m) targeted in a cell-spaced grid pattern using a 50 μ m spot, spaced 200 μ m on the x -axis with an offset of 100 μ m on the y -axis, to overcome sample surface topography. A 5 s acquisition time was applied to elemental content measurements and a 2 s acquisition time was applied to 207 Pb/ 206 Pb measurements. These parameters increased the spatial resolution and analytical sensitivity and minimized the contribution of the host rock underlying the fracture surface to the geochemical signal in comparison to extended acquisition times. In addition, laser ablation temporal profiles allow for the interpretation of the timing of element/isotope migration and fixation on the rough fracture coating. Rasterized maps generated in Iolite™ v.4 demonstrate the chemical distribution of elements and 207 Pb/ 206 Pb values on the rough fracture coatings, allowing for the identification of mineral phases hosting pathfinder elements, pathfinder element associations and the generation of bulk in situ or specific mineralogy geochemical values. Bulk in situ values calculated using an integration of the 2D image data and targeting the c . 500 × 500 μ m surface of the fracture coating compared to previous bulk geochemical methods obtained by sampling the fracture coating with a microdrill (i.e. modified aqua regia (HCl: HNO 3 : H 2 O) and weak acid leach (2% HNO 3 )) highlights that in situ analysis greatly improved detection of pathfinder elements on the fracture surface. This study is the first application of in situ LA-ICP-MS for measuring element contents and 207 Pb/ 206 Pb values on rough fracture coatings and demonstrates its importance as a new geochemical tool to the mining industry for future mineral exploration.

The Study of Olivine Inclusions in Diamonds from Liaoning, China and the Evaluation of Related Thermometers

Olivine is the most abundant mineral in mantle peridotite and a typical inclusion in diamonds, providing essential evidence for the characterization of the diamondiferous lithospheric mantle. Three olivine inclusions in diamonds (OlDia) from Liaoning in the North China Craton (NCC) were exposed for in situ measurements, and the compositional data of 62 other OlDia from Liaoning were collected based on previous reports. The enrichment of TiO2 (&gt;0.1 wt.%) with high Cr# (&gt;50; Cr# = 100Cr/(Cr + Al) by atom) was revealed, despite the predominance of depleted TiO2 contents and high Mg# (92.8–93.2; Mg# =100Mg/(Mg + Fe) by atom) for OlDia. Silica fluid accompanying olivine still trapped in the host diamond was recognized using Raman spectroscopy. Three thermometers were applied to the OlDia, based on the data from Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and Electron Probe Micro-Analysis (EPMA), and a temperature range (TLA and TEPMA) of 1080–1380 °C was yielded. With respect to the TLA, Al-in-olivine thermometers were preferred, although there was a smaller deviation between TEPMA and TLA when using the Cr-in-olivine thermometer. The results of these thermometers show a high correlation with TEPMA, enabling their application based on EPMA data. Projections onto 39–42 mW/m2 model geotherms underline a diamondiferous base of the lithospheric mantle beneath the NCC. The lithospheric mantle is characterized by refractory and depleted sections, where enrichment metasomatism may have occurred at the lower roots (161–178 km).

Effects of phosphatization on the mineralogical and geochemical composition of marine ferromanganese crusts from the JiaXie Guyot in the Western Pacific: Constraints from high resolution analysis

The marine crusts comprise ferromanganese sediments formed through the precipitation of dissolved elements in seawater. These crusts serve as a record elements signal from paleo-ocean and are extensively utilized in paleo-oceanography. Previous researches have examined the chemical composition of the phosphatized crust layers using powder chemistry and leaching experiments. However, there exist divergent viewpoints regarding the influence of phosphatization on element behavior. In this study, we employed a combination of analytical techniques including scanning electron microscope (SEM), powder X-ray diffractometer (XRD), TESCAN Integrated Mineral Analyzer (TIMA), laser ablation and inductively coupled plasma time of flight mass spectrometry combined system (LA-ICP-TOF), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). These methods were utilized to achieve mineral phase quantification, precise depiction of element distribution, and in-situ profile analysis of elements within the phosphatized crust layers from the JiaXie Guyot in the Western Pacific. The mineral phase analysis shows enormous carbonate fluorapatite (CFA) precipitate, which replace calcite in the old phosphatized layer. Additionally, vernadite experiences partial dissolution. Furthermore, a small amount of hematite, goethite, todorokite, zeolite, barite, as well as trace amounts chalcopyrite, sphalerite, galena, ilmenite, and pyrite are formed. The element distributions suggest potential outward migration of Fe, V, Zr, Zn and Cu, while Ce and Pb are locally enriched. In the phosphatized crust, some elements exhibit depletion in the old crust layer compared to the young crust layer, with Fe > Si > V>Zn > Ti ≥ Pb, while others are enriched in the order crust layer, such as Y>Pd > Ce > Pt. The study proposes that FeOOH·nH2O and associated adsorbed elements like Si, Ce, Y, V, Zn, Ti and Pb dissolve in vernadite and migrate outward during phosphatization, with weak phosphatization influence on Mn oxide. In addition, the phosphate-rich seawater might contribute additional elements such as Y, Ce and Pd to the crust layers. Thus, this study highlights the elemental distributions, migration patterns observed, and significance of presence for critical metals between old and young crust layers from the influence of phosphatization based on high resolution analysis. Particularly, it acknowledges the contribution of phosphate-rich seawater to the elemental composition of crust layers.

Zircon U-Pb geochronology, major, trace elemental, and Sr-Nd-Pb isotopic geochemistry: constraints on the age and magmatic origin of Mesozoic mafic dykes in the Guangxi Zhuang Autonomous Region, South China

ABSTRACT As a direct product of lithospheric extension, the mafic dyke group have become an ideal object for studying the formation, evolution and dynamics of both the crust and continental orogenic belts. Given the scientific significance of mafic dykes and their utility in addressing outstanding questions concerning the origin and development mafic dyke swarms Mesozoic age with-in the South China Plate, in this study, 54 representative mafic dykes within the Guangxi Zhuang Autonomous Region, South China, were examined. Research methods include laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb age-dating, whole rock geochemistry, and the Sr-Nd-Pb isotope geochemistry of the studied mafic dykes. The results indicate that these rocks formed between 139 Ma and 113 Ma and have typical doleritic and lamellar textures. They fall into the alkaline and shoshonitic series, are characterized by enrichment of light rare earth elements, some large ion lithophile elements (Rb, Ba, and Sr), Th, U, and Pb, and have depleted Nb, Ta, Hf, and Ti. Moreover, the mafic dykes studied have high initial87Sr/86Sr ratios (0.7055–0.7057), negative εNd(t) values (from −15.2 to −11.4), and relatively constant initial Pb isotopic ratios (that are Enriched Mantle-1 (EM I)-like; 206Pb/204Pb = 16.765–16.816, 207Pb/204Pb = 15.429–15.476, and208Pb/204Pb = 36.882–37.144). The above results indicate that the group of dolerites and lamprophyres studied herein were likely derived from magma generated via low-degree partial melting (1.0%–10%) of an EM1-like garnet-lherzolite mantle source. The parental magmas to these fractionated olivine-, clinopyroxene-, plagioclase, and Ti-bearing phases, with negligible crustal contamination during ascent and dyke emplacement. On the basis of existing research and evidence from this study, we propose a reasonable model for the origin of the mafic dykes: the ancient Pacific Plate subducting below the South China plate led to extension of the lithosphere, an upsurge of the asthenosphere, which triggered partial melting of the lower mantle lithosphere in the Early Cretaceous, and the formation of the parent magma to the Mesozoic mafic dykes in the Guangxi Zhuang Autonomous Region study area. The involvement of slab-derived fluids from the subduction of the ancient Pacific Plate was responsible for metasomatism of the mantle source to these mafic magmas.

Insights on the formation of layered ferromanganese precipitates from the southern Mariana Arc, West Pacific, from micron-scale major, minor, and trace element variations

A combined laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy dispersive X-ray spectroscopy (EDS) study was used to map 49 elements in four FeMn precipitates produced from three different genetic processes (hydrogenetic, hydrothermal, and mixed-type hydrogenetic-hydrothermal) in samples obtained from the southern Mariana Arc. Results show Mn-oxide minerals are consistently found to be associated with Ba, Mo, Sb, V, Zn, and the rare earth elements and yttrium (REY), excluding Ce, whereas Fe-oxyhydroxide minerals are primarily associated with Ti, Co, Cr, Cu, Nb, and Pb. Element distributions in FeMn precipitates from the southern Mariana Arc differ from deposits formed in other environments; notably, there is a decoupling of As and Sb, and redox-sensitive elements are more variable than non-redox-sensitive elements. Samples previously classified as either hydrogenetic or hydrothermal in origin, based on bulk geochemical data, show characteristics of both at higher resolution. Combining high resolution in-situ data with genetic classification discrimination diagrams reveals more ambiguity in metal and metalloid origin than previously thought. Mariana Arc FeMn precipitates can be separated into two formation sub-types (hydrothermal or mixed hydrothermal/hydrogenetic) based on textural and compositional differences, e.g., differences in Ce/Ce and Y/Ho values and relative variations in (Zr + Y + Ce) versus (Co + Ni) versus (Mn + Fe). Improved classification and knowledge of how fast-growing hydrothermal FeMn precipitates form may help us identify a relatively renewable critical metal resource.

Exploring emerald global geochemical provenance through fingerprinting and machine learning methods

Emeralds – the green colored variety of beryl – occur as gem-quality specimens in over fifty deposits globally. While digital traceability methods for emerald have limitations, sample-based approaches offer robust alternatives, particularly for determining the geographic origin of emerald. Three factors make emerald suitable for provenance studies and hence for developing models for origin determination. First, the diverse elemental chemistry of emerald at minor (<1 wt%) and trace levels (<1 to 100’s ppmw) exhibits unique inter-element fractionations between global deposits. Second, minimally destructive techniques, including laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), enable measurement of these diagnostic elemental signatures. Third, when applied to extensive datasets, machine learning (ML) techniques enable the creation of predictive models and statistical discrimination with adequate characterization of the deposits. This study employs a carefully selected dataset comprising more than 1000 LA-ICP-MS analyses of gem-quality emeralds, enriched with new analyses. This dataset represents the largest available for global emerald deposits. We conducted unsupervised exploratory analysis using Principal Component Analysis (PCA). For machine learning-based classification, we employed Support Vector Machine Classification (SVM-C), achieving an initial accuracy rate of 79%. This was enhanced to 96.8% through the use of hierarchical SVM-C with PCA filters as our modeling approach. The ML models were trained using the concentrations of eight statistically significant elements (Li, V, Cr, Fe, Sc, Ga, Rb, Cs). By leveraging high-quality LA-ICP-MS data and ML techniques, accurate identification of the geographical origin of emerald becomes possible. These models are important for accurate provenance of emerald, and from a geochemical perspective, for understanding the formation environments of beryl-bearing pegmatites and shales.

Tracking quartz and zircon provenance in sedimentary rocks using Ti distributions: Unlocking the volcanic-plutonic connection in old igneous systems

Although the relationship between silicic volcanic and plutonic rocks has been extensively studied, it remains controversial whether most plutons have volcanic counterparts and how the volcanic-to-plutonic ratio has evolved through time. This stems primarily from the scarcity of geologic examples with both volcanic and plutonic counterparts, especially in ancient terranes where volcanic deposits have likely been eroded. Here, we introduce a novel approach to identify remnant volcanic crystals in proximal siliciclastic/detrital rock formations. As most erupted crystals stop their growth before reaching the solidus, in contrast to plutonic crystals, the distribution of Ti (a proxy for temperature of crystallisation and/or magma evolution) in (weathering-resistant) quartz and zircon can help in identifying volcanic crystals in sedimentary rocks derived from supracrustal sources that have been completely eroded. Laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of quartz and zircon from volcanic and plutonic units that are known to be spatially and temporally related (from Southern Rocky Mountain Volcanic Field, Colorado, and Taupo Volcanic Zone, New Zealand) reveal that volcanic crystals have generally distinct distributions of, and on average higher Ti contents than, plutonic crystals. To further develop and test this methodology, we analysed samples from the 1.075 Ga Pikes Peak granite (CO, USA) and from the associated series of intra-granite sedimentary dikes that form part of the Cryogenian Period Tava sandstone. Blue band cathodoluminescence (CL) images can be used as a proxy for Ti-in-quartz. Our CL-screening method provides a statistically representative distribution of Ti contents in quartz crystals from individual thin sections. The Tava sandstone contains a higher concentration of high-Ti (and hence high-temperature) quartz and zircon grains than the average Pikes Peak batholith, interpreted as grains eroded from a no longer exposed, volcanic counterpart of the Pikes Peak magmatic system. Our study illustrates a means to test whether magmatic reservoirs that are now represented by crystallised ancient plutons once fed volcanic eruptions, and identifies a strategy for reconstructing volcanic-plutonic relationships, even when parts of the geological association have been eroded.

Source and U-Pb Chronology of Diagenetic Fluids in the Permian Maokou Formation Dolomite Reservoir, Eastern Sichuan Basin, China

The hydrothermal dolomitization, facilitated by basement fault activities, had an important impact on the Permian Maokou Formation dolomite in the Sichuan Basin, which experienced complex diagenesis and presented strong reservoir heterogeneity. The source and age of diagenetic fluids in this succession remain controversial. In this study, various analyses were implemented on samples collected from outcrops and wells near the No. 15 fault in the eastern Sichuan Basin to reconstruct the multi-stage fluid activity and analyze the impact on reservoir development, including petrology, micro-domain isotopes, rare earth elements, homogenization temperature of fluid inclusions, and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb dating. The homogenization temperature of primary brine inclusions in fine-grained matrix dolomite and saddle dolomite is concentrated between 100 and 150 °C, which indicates that the impacts of abnormally high temperatures of other geological bodies. The δ13C and δ18O value and low 87Sr/86Sr value indicate that the diagenetic fluid of fine-grained matrix dolomite is mainly Permian seawater. The U-Pb ages of fine-grained matrix dolomite are ~260 Ma, which coincides with the age of the main magmatism of Emeishan Large Igneous Province (ELIP), and hydrothermal fluid provided a favorable high-temperature environment in the penecontemporaneous stage. While highly radiogenic 87Sr/86Sr compositions suggests those of saddle dolomite, the high-temperature Sr-rich formation fluid. The U-Pb ages of saddle dolomite are 245–250 Ma, which coincides with the age of the 255~251 Ma magmatism of ELIP. This indicates that those should be the diagenetic products of the ELIP hydrothermal fluid in the shallow burial stage. The U-Pb age of coarse-grained calcite is 190–220 Ma, and it should be the diagenetic product of the deep burial stage. Brine inclusions associated with primary methane inclusions were developed in coarse-grained calcite, with a homogenization temperature range of 140.8–199.8 °C, which indicates that the formation fluid activities were related to hydrocarbon charging. The Permian Maokou Formation dolomite was firstly formed in the penecontemporaneous shallow burial stage, and then it was subjected to further hydrothermal dolomitization due to the basement faulting and the abnormally high heat flow during the active period of ELIP. Hydrothermal dolomitization contributed to the formation and maintenance of intercrystalline and dissolution pores, whereas it also formed saddle dolomite to fill the pores, and reduce the pore space. The influence of deep fluid activities on reservoir evolution is further distinguished.

The leaky chronometer: Evidence for systematic cryptic Pb loss in laser ablation U‐Pb dating of zircon relative to CA‐TIMS

AbstractU–Pb dating of zircon via laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) has become a primary method for determining the age of crystalline rocks and the provenance and maximum depositional age of (meta)sedimentary rocks. Although chemical abrasion has become a standard approach for mitigating Pb loss in zircon dated via high‐resolution thermal ionization mass spectrometry (CA‐TIMS), laser ablation dating is rarely accompanied by chemical abrasion. We evaluate the accuracy of U–Pb dates acquired via LA‐ICP‐MS relative to CA‐TIMS through analysis of a large database of paired analyses from the same zircon crystals. We show that laser ablation 206Pb/238U dates are systematically younger than their CA‐TIMS counterparts, with a greater shift in detrital zircon (−2.0%) versus igneous or metamorphic zircon (−0.9%). Although systematic biases related to “matrix effects” may be a contributing factor, our analysis suggests that unmitigated cryptic Pb loss is likely widespread in laser ablation U–Pb datasets.

Yampi Peninsula felsic Hart Dolerite: re-evaluating the Nellie Tonalite using evidence from whole rock, petrography and geochronology

The Nellie Tonalite forms a discontinuous 20 km elongate northwest-trending felsic intrusion at the far-western end of the Western Zone of the Lamboo Province, in the Wunaamin Miliwundi Orogen, Western Australia. This intrusion is poorly understood with previous interpretations assigning it to the ca 1860 Ma Paperbark Supersuite. We present the first geochronological results for the Nellie Tonalite, which have a weighted mean laser ablation, inductively coupled plasma, mass spectrometry (LA-ICP-MS) U–Pb zircon age of 1794 ± 4 Ma. This date is coincident with the age for felsic granophyres of the Hart Dolerite, which have previously been described from the Kimberley Basin overlying the Halls Creek Orogen and central parts of the Wunaamin Miliwundi Orogen. Other similarities of the Nellie Tonalite with the felsic Hart Dolerite are micrographic and granophyric intergrowths of quartz and K-feldspar, and a distinct geochemical depletion of V. This V depletion is interpreted to be the result of closed-system, in situ fractional crystallisation of titanomagnetite from a basaltic composition. The fractional residue from this process can be found at several locations across the Halls Creek Orogen and Wunaamin Miliwundi Orogen and at Speewah Dome in the east Kimberley where magnetite gabbros within the Hart Dolerite also host a large Ti–V mineral resource. It is proposed that the Nellie Tonalite is a western correlate of the felsic Hart Dolerite. This demonstrates that the magmatic processes required for Speewah-style Ti–V mineralisation are extensive across the entire Lamboo Province. Additionally, the scale, constancy of the composition, texture and age of the felsic Hart Dolerite encompassing the entire inland margin of the Kimberley Region, and the rapid emplacement time of <3 m.y., support the interpretation of a mantle plume model for the emplacement of the Hart Dolerite.

Assessing spatial distribution of bioindicator elements in various cutaneous tumors using correlative imaging with laser-ablation-based analytical methods

Correlative imaging of cutaneous tumors provides additional information to the standard histopathologic examination. However, the joint progress in the establishment of analytical techniques, such as Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) in clinical practice is still limited. Their combination provides complementary information as it is also shown in our study in terms of major biotic (Ca, Mg, and P) and trace (Cu and Zn) elements. To elucidate changes in the elemental composition in tumors, we have compiled a set of malignant tumors (Squamous Cell Carcinoma, Basal Cell Carcinoma, Malignant Melanoma, and Epithelioid Angiosarcoma), one benign tumor (Pigmented Nevus) and one healthy-skin sample. The data processing was based on a methodological pipeline involving binary image registration and affine transformation. Thus, our paper brings a feasibility study of a practical methodological concept that enables us to compare LIBS and LA-ICP-MS results despite the mutual spatial distortion of original elemental images. Moreover, we also show that LIBS could be a sufficient pre-screening method even for a larger number of samples according to the speed and reproducibility of the analyses. Whereas LA-ICP-MS could serve as a ground truth and reference technique for preselected samples.

P-based referencing for correcting tissue artifacts in laser ablation-inductively coupled plasma-mass spectrometry imaging of cancer samples.

A referencing strategy based on the element P is presented to compensate for cryosectioning tissue artifacts in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data. The study examines how the gadolinium-based contrast agent Gadofosveset is distributed in murine cancer tissue, and illustrates how referenced images can compensate for tissue artifacts like folds, overlaps, and density variations. Compared to non-referenced images that provide information on the absolute distribution of the analyte, referenced images allow for the representation of the analyte distribution relative to the amount of material introduced into the instrument, which in this case is correlated to the P signal. Tissue artifacts were corrected in referenced images for both Gadofosveset and endogenous elements, such as Fe and Zn. Additionally, the referencing approach provides valuable information on the Gd uptake relative to the tissue density in necrotic compared to vital tumor areas, which is not obtained from in vivo magnetic resonance imaging (MRI) data. However, validation of in vivo MRI and ex vivo LA-ICP-MS methods was possible by establishing a mean ratio of necrotic to vital tumor areas in the T1-weighted image post Gadofosveset injection and the non-referenced LA-ICP-MS image of Gd. In summary, P-based correction of LA-ICP-MS imaging data allows for a more accurate spatial representation of certain elements, including endogenous and exogenous elements such as injected contrast agents.

Xenolith Petrochronology (San Luis Potosi, Mexico) Constrains Heat Sources for Cenozoic Ultrahigh‐Temperature Metamorphism in the Lower Crust

AbstractUltrahigh‐temperature (UHT; &gt;900°C) metamorphism drives crustal differentiation and is widely recognized in the rock record, but its geodynamic causes are debated. Previous work on granulite‐facies metapelite xenoliths from San Luis Potosí, Mexico suggests the lower crust experienced a protracted UHT metamorphic event that coincided with the onset of regional extension. To determine the duration, conditions, and heat sources of UHT metamorphism recorded by these xenoliths, this study characterizes the major‐element, trace‐element, and U‐Pb isotopic systematics of quartz, rutile, feldspar, garnet, and zircon by in situ electron microprobe (EPMA) and laser‐ablation inductively coupled‐plasma mass spectrometry (LA‐ICP‐MS), and augments these data with detailed petrography, thermobarometry, phase equilibria modeling, and diffusion modeling. Thermobarometry and phase equilibria modeling suggest peak metamorphic conditions exceeded 0.7 GPa and 900°C. Zircon petrochronology confirms &gt;15 Myr of UHT conditions since its onset at ∼30 Ma. A small population of zircon record elevated temperatures following transition from backarc compression to extension during the waning stages of orogenesis (60–37 Ma). Garnet preserves trace‐element zoning and mineral inclusions consistent with suprasolidus garnet growth and subsequent compositional modification by intracrystalline rare‐earth element diffusion during protracted heating, with diffusion chronometry timescales in agreement with zircon data, followed by fluid‐driven remobilization of trace elements along now‐healed fractures within ∼1 Myr of eruption. In sum, these data are most compatible with lithospheric mantle attenuation or removal as the dominant heat transport mechanism driving synextensional UHT metamorphism and crustal melting, which has bearing on models for crustal differentiation and formation of modern and ancient granulite terranes globally.

Tracking Childhood Lead Exposure in Early Industrial Romanians

Childhood lead exposure has been linked to severe adverse health outcomes throughout life. Measurements of lead in teeth have established that individuals living in contaminated environments show higher levels compared to individuals living further away, although less is known about when individuals are most susceptible to these exposures. We examined lead (Pb208) concentrations (ppm) in teeth over the first 2.5 years of life in 16 children born in the late 19th to early 20th century throughout Romania. This period of intense industrialization was characterized by increases in mining, coal burning, and oil refining—activities that contaminate air, water, and food with Pb. We hypothesized the distance from an operational mine or oil refinery, or being born in a city, would be positively associated with cumulative dentine Pb exposure (CDPE). We also predicted that Pb exposures would peak in the first six months of life when gastrointestinal (GI) absorption of Pb is likely highest. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of sectioned tooth dentine followed by Bayesian statistical analyses revealed that living 30 km or more from a mine or oil refinery did not explain CDPE. However, being born in a city explained 42% of CDPE. All individuals showed maximum Pb exposures after six months of age, likely due to contaminated solid food and/or non-milk liquids. This research demonstrates how tooth formation can be coupled with comprehensive elemental mapping to analyse the context and timing of early-life neurotoxicant exposures, which may be extended to well-preserved teeth from clinical and historic populations.

LA-ICPMS for In Situ U-Th Dating of Holocene Stalagmites.

Here, we present an in situ U-Th dating approach of carbonate speleothems using laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) with a detection efficiency of 1-2%. By online addition of a 229Th-233U-236U isotope triple spike to the laser-generated aerosol, instrumental mass discrimination and U/Th elemental fractionation could be monitored and corrected. With this approach, the 234U/238U and 230Th/238U activity ratios of a flowstone sample in secular equilibrium could be accurately reproduced as unity with two-sigma uncertainties ±0.053 and ±0.050, respectively. The method was used for the determination of the formation ages of individual layers in natural stalagmites ranging between 210 and 1 thousand years ago (ka). The determined ages corresponded well with those obtained using conventional solution multi collector-ICPMS techniques after isotope separation. Particularly, Holocene stalagmites, as young as 1 ka, could be accurately dated with 2 standard error of ±76 years. This developed microdomain U-Th dating approach thus can be applicable for diverse research areas, such as paleoclimatology, oceanography, geomagnetism, and archeology.