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In this work, a reliable and robust in situ non-matrix-matched calibration method is proposed for element composition determination in scheelite samples. With external calibration against the silicate glass standard reference material NIST SRM 610, the concentrations of both major elements (Ca and W) and trace elements (Si, Fe, Mo, Y, rare earth elements, etc.) in scheelite are determined using an ArF 193 nm excimer nanosecond laser ablation-inductively coupled plasma mass spectrometer (LA-ICP-MS). Here, the ablation was performed by hole drilling under a helium (He) environment using a laser spot size of 35 μm and a laser repetition of 5 Hz, and the aerosols were then transported to a quadrupole ICP-MS by a mixture of He and make-up gas argon (Ar) with a total gas flow rate of 1.6 L/min. Results showed that there was no apparent matrix effect between the NIST SRM 610 and scheelite by this proposed method. With internal standardization against W, the obtained concentrations of CaO and WO3 were found to yield an average matrix CaO/WO3 mass fraction ratio of 0.245 (2σ = 0.003, n = 19), which agreed well with the value of 0.243 (2σ = 0.002, n = 15) from electron probe microanalysis (EPMA). Furthermore, the accuracy of trace element analyses with this proposed non-matrix-matched calibration in situ method was evaluated by comparing the concentration results with those from bulk analysis by solution nebulizer ICP-MS (SN-ICP-MS). It was found that the quantification results from LA-ICP-MS and SN-ICP-MS were comparable, in particular showing a relative concentration bias of the total ∑REE+Y contents of less than 2%. This confirmed that scheelites can be accurately analyzed in situ by LA-ICP-MS without matrix-matched calibration standards. By using this developed in situ method, the element compositions in a series of scheelite samples from different W-associated deposits in China were successfully quantified, promising further genetic process investigation and associated geologic activities of the polymetallic resources.

The conducted study shows that apatite is one of the key accessory minerals in the ultramafic-mafic rocks of the Khudolaz differentiated complex in the Southern Urals, including late pegmatoid gabbro. Petrographic and mineralogical investigations determine apatite crystallizing simultaneously with hornblende in pegmatoid gabbro from the residual water-saturated melt after plagioclase crystallization at a temperature of 990–800 °C, a pressure of 1–3 kbar, oxygen fugacity from −13.9 to −10.7, and water content of 3.9–5.5 wt. %. Pegmatoid gabbro apatite (Appg) from the Severnyi Buskun composite massif differs from early ultramafic-mafic apatite having a fairly high potential for sulfide-platinum metal mineralization in low chlorine and high fluorine content. Low sulfur concentrations in Appg testify to the lack of sulfide-platinum metal mineralization potential of pegmatoid gabbro, but a scanty potential for rare-metal mineralization (e.g., REE) is possible. Appg is quite poor in REE despite the enrichment of pegmatoid gabbros in REE relative to early ultramafic-mafics, which indicates REE accumulation in the fluid. The ratios of cerium and europium anomalies characterize the Appg crystallization under conditions transitional from the magmatic to the hydrothermal stage. Generally, apatite is a good indicator of the difference in the conditions of formation of late pegmatoid gabbro and early ultramafic-mafic rocks, which determines the importance of this mineral in mineralogical and petrological studies. [ABSTRACT FROM AUTHOR]

The Perron deposit, located in the northern part of the Archean Abitibi belt, bears some of the highest gold-grade mineralization for orogenic-vein-type deposits worldwide (High-Grade Zone: HGZ). More than 13 gold-bearing zones with different sulfide assemblages, hydrothermal alterations, and gold grades have been recently outlined, and they range from volcanogenic to orogenic in origin. In addition, seven zones are hosted in a restricted volume of ~1 km3, which is called the Eastern Gold Zone. Pyrite, sphalerite, pyrrhotite, and chalcopyrite—each from a different gold-bearing zone—were analyzed with LA-ICP-MS to decipher their genetic links, mineralizing processes, and temperature of formation. The temperatures calculated with the sphalerite GGIMFis thermometer range from 348 to 398 °C. All gold-bearing zones recorded volcanogenic hydrothermal inputs at different intensities, manifested by pyrrhotite. Pyrite was late-metamorphic and related to the orogenic gold system induced by the contact metamorphism of amphibolite facies. The pyrrhotite grains had very homogeneous trace element signatures in all zones, which is a characteristic of metamorphic recrystallization, exhibiting a loss of mobile elements (Au, Te, Bi, Tl, Sn, W, In) but high concentrations of Ni, Co, and As. Conversely, the pyrite was systematically enriched with all elements depleted from pyrrhotite, bearing five specific signatures of element enrichments: W, Tl, Sn, In-Cd-Zn, and Bi-Te-Au. For gold-rich zones (e.g., the HGZ), gold was linked to the Bi-Te-Au signature of pyrite, with Bi enrichment occurring at up to 72,000 times the background level in Archean shale pyrite. It was concluded that gold was transported, at least in part, as Bi-Te melts in the previously documented non-aqueous orogenic fluids, hence accounting for the very-high-grade gold content of the HGZ. Genetically, the metamorphism of primary gold-bearing volcanogenic mineralizations was the main source of gold during the overprinting of amphibolite (600 °C) in a metamorphically induced orogenic mineralizing event. A strong volcanogenic pre-enrichment is considered the main factor accounting for the gold endowment of the Eastern Gold Zone. [ABSTRACT FROM AUTHOR]

In situ microanalysis of the sulfur (S) isotope composition and elemental distribution in sphalerite is important in geochemistry. A matrix-matched reference material is still lacking in situ microanalysis. In this study, a hydrothermal synthesis method combined with hot-press sintering processes was used to synthesize a sphalerite material Sph-LD. A large number of in situ microanalyses, including trace element concentrations and S isotope compositions, were performed on Sph-LD by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to assess the homogeneity. The LA-MC-ICP-MS results are highly consistent and yield a mean δ34S value of +17.11 ± 0.20‰ (2 SD, n = 560), which is analogous with that measured by IRMS. Microanalysis of element concentrations generally agrees with the data of ICP-MS within 10% for trace elements (relative standard deviation < 10%). These results indicate that Sph-LD is suitable to be a matrix-matched reference material available for quantitative analysis of element concentrations and S isotope measurement of sphalerite using LA-ICP-MS and LA-MC-ICP-MS. Meanwhile, the synthetic method introduces a novel concept for the development of standard materials. [ABSTRACT FROM AUTHOR]

The Bou Dahar Pb-Zn district, located in the Moroccan High Atlas, is a typical carbonate-hosted Pb-Zn ore district (>30 Mt at 4 wt.% Pb, 4 wt.% Zn). In situ trace element analysis was performed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on galena and cerussite from different ore types. The galena is generally enriched in Ag and Sb, secondarily enriched in Cu, with a trace amount of Cd and As, but extremely depleted in Bi and Tl. The main substitution mechanism in galena is (Ag, Cu)+ + Sb3+ ↔ 2Pb2+, and at high Sb concentrations, the further substitution of 2Sb3+ + □ ↔ 3Pb2+ (where □ represents a vacancy) took place. Micro-inclusions of Cu-Sb-bearing minerals (such as tetrahedrite) and Ag-bearing minerals (such as acanthite) may exist in some situations. The features of trace elements in galena show the existence of different coupled substitutions in vein-related ore, breccia-related ore, and strata-bound ore. This suggests that the Bou Dahar district experienced multistage mineralization. The MVT model alone cannot fully explain the ore-forming process. The cerussite replacing strata-bound galena is enriched in Sr, Ba, Ag, and Cu, with minor Sb, As, and Tl. Strontium and Ba are directly substituted with Pb in the cerussite lattice. Copper and Ag are likely present in cerussite as nano-inclusions, which differs from the coupled substitution mechanism of the original galena. High concentrations of Ag may occur due to minor electrum inclusions. The enrichment of Ag, Cu, and Au in cerussite during the oxidation process may guide the optimization of ore processing, especially in extracting valuable trace/minor elements. [ABSTRACT FROM AUTHOR]

Columbite-tantalite is predominantly found in rare-metal granites and pegmatites, alkaline and carbonatitic rocks, and columbite-tantalite-bearing peraluminous granites. It is recognized as a potentially valuable mineral for use in U-Pb isotopic dating. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) can be used in the U-Pb dating of columbite-tantalite. LA-ICP-MS requires matrixmatched reference materials for isotopic fractionation/mass bias correction. Some columbite-tantalite reference materials contain common Pb. However, columbite-tantalite reference materials with low contents of common Pb are scarce. Thus, in this study, we proposed a new potential reference material, OXF, with a low common Pb content for use in LA-ICP-MS U-Pb dating of columbite-tantalite. LA-ICPMS analysis revealed that the average U, Th, and Pb concentrations in OXF are 428 ± 156 ppm (2s), 6.3 ± 2.5 ppm (2s), and 20.0 ± 10.0 ppm (2s), respectively, with a total weight of 336.6 g. Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) revealed that the weighted mean 206Pb/238U age of OXF is 262.85 ± 0.64 Ma (MSWD = 1.8, 2s). The LA-ICP-MS U-Pb ages of the four laboratories in the China University of Geosciences (Wuhan) (CUGW), the China University of Geosciences (Beijing) (CUGB), Wuhan Sample Solution Analytical Technology Co. Ltd, China (WHSS), and the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS) were determined. The 206Pb/238U ages of the CUGW, the CUGB, WHSS, and the IGGCAS were 262.71 ± 0.33 Ma (2s, n = 151), 263.3 ± 2.3 Ma (2s, n = 46), 263.5 ± 1.3 Ma (2s, n = 42) and 264.3 ± 2.4 Ma (2s, n = 25), respectively. The weighted mean 206Pb/238U age of the four laboratories obtained using LA-ICP-MS and by combining the U-Pb data obtained from the laboratories was 262.83 ± 0.29 Ma (2s, n = 358), which aligns with its value obtained using CA-ID-TIMS after allowing for analytical uncertainties. OXF demonstrated homogeneous U-Pb ages with minimal Pb contributions, indicating its potential for serving as a primary reference material in LA-ICP-MS calibrations. [ABSTRACT FROM AUTHOR]

Gem-quality green vanadium grossular (var. tsavorite) is exclusively hosted in the Neoproterozoic Metamorphic Mozambique Belt (NMMB). The geochronology of tsavorite is limited until now, and the accurate crystallization age of the tsavorite in Kenya has remained unknown. Based on conventional gemological analyzing, by means of modern testing methods such as gemological analysis, UV-visible spectroscopy, Infrared spectroscopy, Raman spectroscopy, Electron probe, the spectral characteristics and chemical composition of tsavorite were determined, aiming to investigate the coloring elements of green garnets and trace the origin of tsavorite samples. The UV-Vis-NIR spectra and chemical composition analysis results show that vanadium and chromium are the main coloring elements in green tsavorite from Kenya. Combining the values of the δ18O (14.11‰) with the V/Cr ratio (around 4.4) of the tsavorite samples, the accuracy of the sample source has been identified. U–Pb dating of tsavorite from Kenya provides a concordant U-Pb age of 626.3 ± 4.6 Ma, in agreement with the weighted mean 206Pb /238U age of 625.9 ± 4.7 Ma (MSWD = 0.36), which indicated that Kenyan tsavorites were generated during the East African orogeny. Application of in situ laser U-Pb geochronology on gem-quality tsavorite to determine the mineralization time of Neoproterozoic Metamorphic Mozambique Belt of Kenya, which is the first step in characterizing the in situ dating analysis of gemstone tsavorite in Kenya mineral deposits [ABSTRACT FROM AUTHOR]

We have established a method for the simultaneous measurement of element abundances and boron isotopic compositions of bulk‐rock silicate samples by laser ablation coupled to two different ICP‐MS instruments. Fifteen silicate reference materials were prepared as micro‐particulate pressed powder pellets (MP) for analysis. Approximately 1/5th of the ablated material was transported to a single‐collector ICP‐MS for elemental measurement, while 4/5ths were sent to a multi‐collector ICP‐MS for boron isotope ratio measurement. Compositions of different milling materials (agate, zirconium oxide, tungsten carbide, sintered corundum and silicon nitride) were measured for the evaluation of potential contamination during sample preparation. Determined element mass fractions are in agreement with literature values within ±20%. For boron isotope ratios, the matrix‐dependent background elevation across the m/z from 9.9 to 11, and the effect of ablation mass was quantified. Measured δ11B values of most reference materials are consistent with literature values within ±1‰. The intermediate measurement precision is ±0.3‰ for JB‐2 with 30 μg g−1 B and ±0.4‰ for JA‐2 with 21 μg g−1 B. A publically available, web‐based streamlit app was developed for data processing (https://zenodo.org/doi/10.5281/zenodo.11150471). This paves the way for combined, accurate and precise elemental and boron isotope ratio measurements of geological materials. [ABSTRACT FROM AUTHOR]

The giant Changba-Lijiagou (Ch-L) Pb-Zn deposit is in the northeast part of the Xicheng ore cluster, Western Qinling Orogen. The ore genesis remains controversial; it could be either a sedimentary exhalative genetic type or an epigenetic hydrothermal genetic type. Here, in situ titanite U-Pb dating for the two kinds of titanite is presented, yielding ages of 212.8 ± 3.0 Ma in the mineralized skarn ore and 214.6 ± 5.1 Ma in the host rock. These ages conform to the previously reported magmatic zircon age (229–211 Ma) based on the in situ zircon U-Pb dating of plutons in this district and the time of large-scale magmatic–hydrothermal activities in Western Qinling Orogen (229–209 Ma). Titanites occurring in mineralized skarn and those that are calcite-hosted are similar to hydrothermal-origin titanites in major element characteristics. The Eu anomalies in the two types of titanite record oxidizing conditions during the mineralization process. A mineral assemblage of garnet, pyroxene, riebeckite, biotite, and potash feldspar, replacing the albite, is well-developed in the deposit. The mineralogical and geochronological characteristics indicate that the Ch-L Pb-Zn deposit is a distal skarn deposit and the result of intensive tectonomagmatic processes in the Xicheng ore cluster during the process of the Late Triassic orogeny. [ABSTRACT FROM AUTHOR]

BACKGROUND Compared with zircon U-Pb dating, monazite has more advantages in the dating of some metamorphic rocks or highly differentiated rocks. However, the U-Th-Pb isotopic dating of monazite has been limited, because of high Th concentration (commonly>7%), many mineral inclusions, and rare dating standard samples. Previous research on LA-ICP-MS U-Th-Pb dating of monazite mainly focused on laser parameters, and lacked attention on ICP-MS conditions. OBJECTIVES To find suitable experimental LA-ICP-MS monazite dating conditions. METHODS Using 193nm ArF excimer laser ablation system and Agilent 7500a inductively coupled plasma-mass spectrometer, laser parameters (laser beam spot diameter and laser frequency) and ICP-MS parameters(dwelling time of 232Th) were investigated. The laser beam spot diameter was set to 24μm, 16μm and 10μm, and the laser frequency was set to 3Hz, 4Hz and 5Hz. The dwelling time of 232Th was set to 10ms, 6ms, 3ms and 1ms for U-Th-Pb dating. Finally, the monazite sample RW-1 was used as the standard sample to calibrate the monazite sample Bananeira. RESULTS It was suitable for monazite dating when the beam spot diameter was 16μm, the dwelling time of 232Th was 3ms or 1ms, the energy density was 4J/cm2, the laser frequency was 5Hz, the carrier gas (He) flow rate was 0.35L/min, and the carrier gas (Ar) flow rate was 0.95L/min. Under these conditions, Bananeira's weighted average ages of 207Pb/235U were 510.7±8.6Ma (MSWD=0.87), and 513.8±5.7Ma (MSWD=0.38), which were consistent with the recommended age of 507.7±1.3Ma with respective errors of 0.59% and 1.20%. 208Pb/232Th weighted average ages were 496.9±8.6Ma (MSWD=0.596) and 499.8±5.6Ma (MSWD=0.37), which were consistent with the recommended age of 497.6±1.6Ma, with respective errors of 0.14% and 0.44%. The 207Pb/235U weighted average age of Huangshan sample HS-1 was 128.3±2.4Ma (MSWD=0.73), which were close to the zircon age of 127.0±2.1Ma (MSWD=0.93) in the Huangshan area. CONCLUSIONS The optimal laser and ICP-MS conditions are suitable for monazite U-Th-Pb isotopic age determination.