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Breast cancer (BC) is the leading cause of cancer death among women worldwide, making the discovery and quantification of new biomarkers essential for improving diagnostic and preventive strategies to limit dissemination and improve prognosis. Essential trace metals such as Fe, Cu, and Zn may play critical roles in the pathophysiology of both benign and malignant breast tumors. However, due to the high metabolic activity and reduced element selectivity of cancer cells, also non-essential elements may be taken up and may even be implicated with disease progression. This study investigates the spatial distribution and concentrations of both essential and non-essential elements in breast tissues, assessing their potential for diagnostic applications. Laser ablation (LA)–inductively coupled plasma–mass spectrometry (ICP-MS) with a time-of-flight (ToF) mass analyzer (LA-ICP-ToF–MS) was used to inquire the distribution of almost all elements across the periodic table and their abundance in metastatic (n = 11), non-metastatic (n = 7), and healthy (n = 4) breast tissues. Quantification was achieved using gelatine-based standards for external calibration to quantitatively map various elements. Overall, the Fe, Cu, Zn, Sr, and Ba levels were significantly increased in tumor samples with Sr and Ba showing strong correlation, likely due to their similar chemistry. Comparison of calibrated LA-ICP-ToF–MS data with a histologic staining demonstrated the possibility to clearly differentiate between various tissue types and structures in breast tissues such as tumor niche and stroma. The levels of the studied elements were significantly higher in the tumor niche areas compared to the stroma, and for Fe, a significant accumulation was observed in the tumor niche areas from the metastatic patient group relative to the levels found in the same areas of the non-metastatic group. LA-ICP-ToF–MS was used to quantitatively map the biodistribution of essential and non-essential elements in metastatic and non-metastatic breast cancer tissues. [ABSTRACT FROM AUTHOR]

Studies on emeralds from Habachtal (Austria) are scarce and non-exhaustive. However, they represent a significant interest to the community, as they have been assumed to be present in historical pieces of jewelry. Along with Egypt, Habachtal is suggested to be one of the main sources of gem-quality emeralds of archaeological significance. In this regard and due to their similar macroscopic look and geological context, it has always been challenging to distinguish Austrian and Egyptian emeralds set in historic jewelry. In this paper, a first comprehensive study of several Habchtal emeralds is presented based on a combination of classic gemology, chemistry and spectroscopy, using non-destructive to micro-destructive methods. Spectroscopic analyses, such as via Raman, FTIR and UV-Vis–NIR spectroscopies, showed that emeralds from Habachtal (Austria) contain Type II H2O molecules with alkalis and they are colored by chromium and iron, similarly to emeralds from Egypt. Under an optical microscope (and identified by Raman spectroscopy), actinolite needle-like inclusions are frequently observed in Austrian emeralds. Other inclusions, such as quartz, plagioclase, albite, phlogopite and pyrite, can also be observed in Austrian samples. Chemical analysis of Austrian emeralds' trace elements by LA–ICP–MS show similar results to those from Egypt, with the exception of V, K and Rb, which show a lesser content in Austrian emeralds. Thanks to the determination of inclusions combined with a careful examination of specific chemistry, this study shows that Austrian emeralds can be distinguished from their Egyptian counterpart. [ABSTRACT FROM AUTHOR]

The Xiong'ershan district is situated on the southern margin of the North China Craton (NCC) and located within the Qinling–Dabieshan Orogen's orogenic zone. It is adjacent to the XiaoQinling mining district and exhibits very favorable geological conditions for mineralization, as the district contains numerous gold deposits, positioning it as one of the key gold-producing areas of China. The Miaoling gold deposit is a hydrothermal deposit and is controlled by the Mesozoic nearly NS-trending fault. The ore bodies are hosted in the Mesoproterozoic Xiong'er Group of the Changcheng System of volcanic rocks, with reserves reaching large-scale levels. Pyrite is the main gold-bearing mineral and can be classified into four generations: early-stage fine- to medium-grained euhedral to subhedral cubic pyrite (Py1); medium- to coarse-grained euhedral to subhedral cubic granular pyrite in quartz veins (Py2a); fine-grained subhedral to anhedral disseminated pyrite in altered rocks (Py2b); and late-stage anhedral granular and fine-veinlet pyrite in later quartz veins (Py3). Through in situ trace element analysis of the pyrite using LA-ICP-MS, a positive correlation between Au and As was observed during the main mineralization stage; gold mainly exists as a solid solution within the pyrite lattice, and the ablation signal curve reflecting the intensity of trace element signals showed that gold also occurs as micron-scale mineral inclusions. The trace element content suggested a gradual increase in oxygen fugacity from Stage 1 to Stage 2, followed by a decrease from Stage 2 to Stage 3. The Co/Ni values in the pyrite (0.56 to 62.02, with an average of 12.34) exhibited characteristics of magmatic hydrothermal pyrite. The in situ sulfur isotope analysis of the pyrite using LA-MC-ICP-MS showed δ34S values of 4.24‰ for Stage 1, −6.63‰ to −13.79‰ for Stage 2, and −4.31‰ to −5.15‰ for Stage 3. Considering sulfur isotope fractionation, the δ34S value of the hydrothermal fluid during the main mineralization stage was calculated to be between 0.31‰ and 2.68‰. [ABSTRACT FROM AUTHOR]

The unconformity-related uranium (URU) deposits in the Proterozoic Athabasca Basin are one of the most important U resources in the world. This type of U deposit can be divided into monometallic (U) and polymetallic (U-Ni-Co-As) subtypes. While it is generally agreed that the URU deposits formed from reaction between oxidizing, basinal brines carrying U and/or Ni-Co-As with reducing basement fluids or lithologies, it is debatable whether the polymetallic deposits formed from co-enrichment of U-Ni-Co-As or enrichment of U superimposed by a separate Ni-Co-As mineralization event. This study addresses this problem through mineralogical, geochemical and fluid inclusion investigation of the Midwest U-Ni-Co-As deposit. Petrographic studies indicate that the sequence of ore precipitation started with uraninite, followed by Ni-Co arsenides and sulfoarsenides and then Cu-Pb-Fe sulfides, and this sequence was repeated episodically. This observation suggests that the deposit did not form from two separate U and Ni-Co-As mineralization events, but rather multiple episodes of U-Ni-Co-As mineralization. Linear correlations between chemical ages and Si-Ca-Fe contents of the most pristine uraninite U1 suggest a maximum primary mineralization of ca. 1600 Ma, which is consistent with the inferred primary U mineralization age in the Athabasca Basin. Microthermometric and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of fluid inclusions in syn-mineralization drusy quartz indicate that the composition of the ore-forming fluids is characterized by the H2O-NaCl-CaCl2-KCl-MgCl2 system and comparable to those from both monometallic and polymetallic URU deposits. The relationship between U and Ni + Co in the fluid inclusions and its comparison with other URU deposits support a model in which U and Ni-Co were co-enriched in a unified mineralization process. The development of breccia structures in the ores and the dramatic fluid pressure fluctuation revealed by fluid inclusions suggest that the deposit formed from multiple episodes of fluid flow related to repeated reactivation of basement-rooted faults. [ABSTRACT FROM AUTHOR]

Chemical fingerprinting and spectrophotometry were combined to conduct a provenance analysis of radiolarite artefacts from three Moravian (Czech Republic) Aurignacian sites of Tvarožná I, Nová Dědina I and Milovice I. Of the different methods used, laser ablation with inductively coupled plasma mass spectrometry (LA-ICP-MS) was the best suited to distinguish the different areas containing radiolarite outcrops. Based on their chemical fingerprint, Moravian Aurignacian radiolarite artefacts were most likely imported from the western Slovak part of the Pieniny Klippen Belt. The abundant radiolarite outcrops in the Vienna region were apparently ignored, with the possible exception of two radiolarite artefacts from the Milovice I site. However, these could also have been manufactured from gravel radiolarites found around the site. Upon assigning other lithologies from Aurignacian sites in Moravia to their areas of provenience, it transpired those imports derived primarily from non-south-western regions. A similar situation was previously observed in the Moravian Szeletian, possibly indicating information exchange between the two Upper Palaeolithic cultures. Although the subsequent Gravettian culture relied more on long-distance imports, north-eastern − south-western movements and transfers were predominant up until the end of the Moravian Upper Palaeolithic, largely due to the communication corridor of the Moravian Gate. Upper Palaeolithic Moravia was an important source of raw materials and a hub for gathering other materials and information from concrete supply zones, while others were neglected. [ABSTRACT FROM AUTHOR]

Magmatic hydrothermal deposits are important sources of many bulk, precious, and rare metals, and have attracted interest from both academic and industrial communities. However, it is still unclear if the major enrichment of the ore-forming metals occurs in the parental magma source region, during the magma evolution, or after the fluid exsolution. Fluid inclusions trapped in hydrothermal minerals crystallized in the early, high-temperature stage before metal precipitation record information close to that of the initially exsolved magmatic fluids, which are helpful in revealing whether the metals have been already significantly enriched prior to the hydrothermal stage. In this study, available compositional data of such early-stage fluid inclusions from magmatic hydrothermal systems globally have been compiled. The results indicate that the concentrations of Cu, Sn, and W respectively from the Cu-, Sn-, and W-mineralized fluids are significantly higher than the hydrothermal systems that do not produce ores with the corresponding metals. This suggests that Cu, Sn, and W could have already been enriched in the magma source and/or magma evolution stage. The Mo concentrations show no difference between Mo-mineralized and Mobarren fluid systems, indicating no significant pre-enrichment in the source region or during the magma evolution. This also implies that an efficient collection of Mo from a large volume of magmas is required to account for the formation of a large Mo deposit. Almost all the hydrothermal fluids contain high concentrations of Fe and Zn-Pb, but only a few of them eventually form Fe or Zn-Pb deposits, reflecting an important role of the hydrothermal evolution process on the selective metal mineralization. The above results indicate that different metals are enriched in different stages of a magmatic hydrothermal system, and that the major roles played in the formation of a deposit vary with the metal types. In addition to the metal concentrations in the ore-related magmas and fluids, other factors (including but not limited to the intrusion shapes, emplacement depths, structural pathways, and wallrock properties) are also critical in determining the fertility and mineralization diversity of a magmatic hydrothermal system. [ABSTRACT FROM AUTHOR]

The Muzidian gneiss complex (MGC) in the Northern Dabie Orogen is the oldest exposed rock formation in the South China block. However, there is still a lack of research on its metamorphic age and tectonic implications. LA-ICP-MS in situ U-Pb dating and trace element analysis of monazite were carried out on two gneiss samples from the MGC. The results show that most monazite grains exhibit homogeneous features with no zoning, evident depletion of HREEs and negative Eu anomalies, suggesting that they may be of metamorphic origin. The monazite U-Pb ages of the two gneiss samples are 129±1Ma and 130±1Ma, respectively, which represent the time of metamorphism of the MGC. These ages are broadly consistent with the emplacement age of the early Cretaceous granitoids in the Muzidian area, as well as the large amount of exposed migmatites in the Northern Dabie Orogen. Our study shows that the extensional collapse of the thickened continental crust and the delamination of the orogenic crustal root during the early Cretaceous of the Dabie Orogen caused contemporaneous metamorphism, migmatation, and magmatism, which constrained the tectonic regime switch time of the Northern Dabie Orogen from compression to extension to ~130Ma. [ABSTRACT FROM AUTHOR]

The tea-dust glaze ancient porcelain is one of the earliest crystalline glazes, which is rarely studied deeply because of its rarity. In this study, the mineral crystals in tea-dust glaze made in the Ding Kiln of the Northern Song Dynasty were analyzed by optical microscope (OM), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), scanning electron microscopy coupled with an X-ray energy dispersive spectrometer (SEM-EDS), laser confocal Raman spectrometer (LRS), and high-resolution time of flight-secondary ion mass spectrometry (ToF-SIMS). The results show that the main crystal phase in the glaze is the same as that of the Longquanwu Kiln in the Liao and Jin Dynasty, which is anorthite and augite. The overall performance of the glaze is that the sauce-black glaze matrix is rich in iron (Fe2O3 mean 9.73%) and the mineral crystal is rich in iron (Fe2O3 mean 11.33%). In addition to α-Fe2O3 crystals, Fe3O4 crystals and other recrystallized minerals after melting, the glaze also has pleonaste, residual kaolinite and other unmelted minerals from raw glaze materials. The residual kaolinite shows that the firing temperature of the samples in this study was most likely below 1200℃. [ABSTRACT FROM AUTHOR]

Eclogite‐facies rocks provide important constraints on the behaviour of convergent plate boundaries and the geometries of tectonic reconstructions due to the high to ultrahigh pressure conditions at which they form. Many eclogite occurrences are documented near the suture zone of active collisional settings where they are interpreted to mark the approximate location of former ocean basin subduction. Such observations influence tectonic interpretations for older eclogites within more deeply eroded and/or less well‐exposed terranes. The eclogitic Glenelg inlier in northwest Scotland is one such example, with c. 1 Ga eclogites having previously been interpreted as marking the trace of a Grenville‐aged collisional suture zone that defines a third 'arm' to the Grenville orogen alongside well‐defined sutures in North America and Scandinavia. Here we use a combination of geochronology, phase equilibrium modelling and accessory‐phase thermometry to show that the eclogite‐facies assemblages were produced at ∼$$ \sim $$18–19 kbar and 700°C–750°C from c. 1.1 to 1.0 Ga. Accounting for the foreland basin setting of equivalent‐aged sedimentary rocks in the region and demonstrating the thermal viability of this setting, we show that eclogite formation occurred in deforming foreland crust adjacent to the Grenville orogen, in a setting broadly analogous to fault‐bounded basement uplifts in the forelands of active deformation belts, such as the Himalayas and Andes. Our results demonstrate that eclogite‐facies rocks can form in a greater range of tectonic settings than are sometimes considered, with implications for tectonic reconstructions of collisional zones. In this instance, our results remove the need for a third 'arm' of the Grenville orogen by placing Glenelg in a foreland setting, reconciling the absence of plentiful Grenville‐aged metamorphic rocks in northwest Scotland, the sedimentological record and paleomagnetic data in the wider region. [ABSTRACT FROM AUTHOR]

Trace element analysis of otoliths from core to edge was used to reveal differences in habitats of larvae and early juveniles of Japanese jack mackerel (Trachurus japonicus) caught in the East China Sea (ECS), Pacific Ocean, and Sea of Japan. Multi‐element signatures (Sr:Ca, Mg:Ca, Na:Ca, K:Ca, and Ba:Ca) were analyzed with multivariate statistics to determine whether these element signatures provide insight into regional population structure. The median values of elements: Ca ratios in otolith core region differed significantly among areas, with most elements between the ECS and the Pacific Ocean or Sea of Japan showing significant differences. The Sr:Ca ratios exhibited a V‐shaped trend from the otolith core to the edge, which was likely related to the vertical habitat layer shift of larvae and early juveniles of T. japonicus. Canonical analysis of principal coordinates using the element: Ca ratios and the hatching day were re‐classified according to the sampling area with higher accuracy in the ECS (88–95%) and the Sea of Japan (76–83%) compared to the Pacific Ocean (69–72%). These results indicate that the proportion of eggs, larvae, and early juveniles transported by the Kuroshio Current from the southern ECS—the main spawning ground—to the Pacific Ocean or the Sea of Japan is low and that juveniles distributed in the coastal waters off southwestern Japan may have originated from local spawners. These results suggest that determining the elemental composition of larvae and juveniles of T. japonicus is effective in determining the habitat differences of this species in the three regions. These findings will help to understand population structure and recruitment process of this species around Japan. [ABSTRACT FROM AUTHOR]

Context: The effectiveness of using shell microchemistry methods for reconstructing the pelagic dispersal of shell-forming marine organisms relies on the existence of sufficient spatial variability and temporal stability in the microchemical composition of coastal waters. Aims: This study aimed to determine whether shell microchemistry methods can reliably infer pelagic dispersal of green-lipped mussel (Perna canaliculus) across a large and well-mixed embayment in New Zealand. Methods: Isotopes of 12 chemical elements (7Li, 27Al, 59Co, 60Ni, 63Cu, 66Zn, 88Sr, 138Ba, 139La, 140Ce, 208Pb and 238U) were assessed from juvenile mussel shells grown in situ from 22 sites for two consecutive periods of ~5 weeks. Key results: There was sufficient spatial variability in measured shell element concentrations to support microchemical atlases that are capable of distinguishing among regions within this large embayment, with 73% assignment accuracy. However, the temporal variability in the microchemical signatures is such that they would need to be sampled contemporaneously with animal samples to be effective for distinguishing pelagic dispersal of mussels in the embayment. Conclusions: The shell microchemistry shows sufficient spatio-temporal resolution for reliably inferring pelagic dispersal of this economically and ecologically important mussel species over a large embayment. Sufficient resolution at such large scale may come from unique hydro-geological inputs. Implications: This study confirms the feasibility of shell microchemistry method in tracking pelagic dispersal of marine organisms across a large well-mixed embayment, offering insights to improve accuracy and reduce costs for future research. The feasibility of using microchemical methods to study the dispersal of an important aquaculture species, the green-lipped mussel (Perna canaliculus), in a large bay in northern New Zealand, where knowledge of the dispersal of wild seed mussels is urgently needed to improve seed-collection efforts. [ABSTRACT FROM AUTHOR]

Discovered within the North Himalayan Metallogenic Belt (NHMB), the Zhaxikang Pb–Zn–Ag–Sb deposit stands as the sole super-large scale ore deposit in the region. This deposit holds significant quantities of Pb and Zn (2.066 million tons at 6.38% average grade), Ag (2661 tons at an average of 101.64 g/t), and Sb (0.235 million tons at 1.14% average grade), making it one of China's foremost Sb–polymetallic deposits. Stibnite represents the main carrier of Sb in this deposit and has been of great attention since its initial discovery. However, the trace element composition of stibnite in the Zhaxikang deposit has not yet been determined. This study carried out an analysis of the distribution patterns and substitution processes of trace elements within stibnite gathered from the Zhaxikang deposit, aiming to provide crucial information on ore-forming processes. Utilizing high-precision laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we discovered that the studied stibnite is notably enriched in arsenic (~100 ppm) and lead (~10 ppm). Furthermore, the notably consistent time-resolved profiles suggest that elements such as Fe, Cu, As, In, Sn, Hg, and Pb predominantly exist as solid solutions within stibnite. Consequently, it is probable that the enrichment of Cu, Pb, and Sn in stibnite is due to isomorphic substitution reactions, including 3Pb2+↔2Sb3+, Cu+ + Pb2+↔Sb3+, and In3+ + Sn3+↔2Sb3+. Apart from that, Mn, Pb, and Hg with the spiky signals indicate their existence within stibnite as micro-inclusions. Overall, we found that the trace element substitutions in stibnite from the Zhaxikang Pb–Zn–Ag–Sb deposit are complicated. Incorporations of trace elements such as Pb, Cu, and In into stibnite are largely influenced by a variety of factors. The simple lattice structure and constant trace elements in studied stibnite indicate a low-temperature hydrothermal system and a relatively stable process for stibnite formation. [ABSTRACT FROM AUTHOR]

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 effects of different regional tectonic events on the Neoproterozoic basement rocks of the Arabian–Nubian Shield in Sinai, as well as the Egyptian unstable and stable shelves, remain uncertain. Coupling fission-track thermochronometry findings with the modeling of the time–temperature history has proved to be an effective method for tackling these issues. The obtained zircon fission-track ages were differentiated into two groups from the Ediacaran–Cambrian and the Ordovician–Carboniferous periods, while the apatite fission-track data revealed two separate groups of cooling ages of the Carboniferous–Triassic and Late Cretaceous ages. The integration of these cooling ages and modeling of the time–temperature history revealed four discrete cooling pulses during the Neoproterozoic, Devonian–Carboniferous, Cretaceous, and Oligocene–Miocene eras. After integrating our findings with the regional tectonic historical and sedimentological records, these could be identified as cooling/exhumation pulses activated in response to the post-accretional event of erosion, Variscan tectonism, the disintegration of Gondwana, and the Gulf of Suez rifting, respectively. Furthermore, the southern border of the Egyptian unstable shelf was found to extend southward to South Sinai and south of the Bahariya depression. [ABSTRACT FROM AUTHOR]

Garnet U‐Pb dating by laser ablation‐inductively coupled plasma‐mass spectrometry requires the development of matrix‐matched reference materials of variable chemistry and U mass fraction for accurate analysis. Additional calibration of existing primary reference materials is also justified based on the relatively poor calibration of some of the widely available primary reference materials that are currently utilised by the geoscience community. We present a micro sampling workflow combined with a refined ID‐TIMS methodology for the generation of high precision (~ 0.1%) U‐Pb dates from domains within garnet single crystals. Using this workflow, we calibrated two new natural andradite reference materials, the Jumbo andradite (And99; 110.34 ± 0.03 (0.04) [0.13] Ma, n = 7, MSWD = 1.21) and the Tiptop andradite (And87; 209.57 ± 0.11 (0.13) [0.26] Ma, n = 6, MSWD = 1.39). We also present additional calibration of the widely utilised Willsboro‐Lewis andradite primary reference material (And90; 1024.7 ± 9.5 (9.6) [9.6] Ma (2s; overdispersed), n = 6). Wafers of the Jumbo and Tiptop andradite reference materials are available from the authors upon request. [ABSTRACT FROM AUTHOR]

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 learningbased 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. [ABSTRACT FROM AUTHOR]

The metaturbidite‐hosted, ∼380 Ma Dufferin gold deposit, Meguma terrane, northeastern Appalachian Orogen (Nova Scotia, Canada) is an orogenic gold deposit with mineralized saddle reef‐type quartz veins hosted by metasandstones and black slates in a tightly folded anticline. Together with native gold inclusions, genetically related hydrothermal carbonaceous material (CM) in veins occurs as pyrobitumen in cavities and along fractures/grain boundaries proximal to vein contacts and wallrock fragments. Integrating several microanalytical methods we document the precipitation of gold via coupled fluid‐fO2 reduction (via interaction with CM) and pH increase. These changes in fluid chemistry destabilized gold bisulfide complexes, leading to efficient Au precipitation from a gold‐undersaturated (0.045 ± 0.024 ppm Au; 1σ; n = 58 fluid inclusions) aqueous‐carbonic fluid (H2O‐NaCl‐CO2 ± N2 ± CH4). The proposed mineralization mechanism is supported by: (a) a complementary decrease in Au and redox‐sensitive semimetals (As, Sb), and increase in wall rock‐derived elements (i.e., Mg, K, Ca, Sr, Fe) concentrations in fluid inclusions with time; (b) a corresponding decrease in the XCO2, consistent with CO2 removal via reduction/respeciation and late carbonate precipitation; and (c) gold embedding in, or on, the surface of CM inside mineralized cavities and fractures. Despite mineralizing fluids transporting low concentrations of Au far from saturation, precipitation of gold was locally evidently high where such fluids interacted with CM, contributing to the overall gold endowment of Meguma deposits. This work re‐emphasizes CM as a potential prerequisite for efficient gold precipitation within the overall genetic model for similar orogenic metasedimentary settings globally where the presence and/or role of CM has been documented. Plain Language Summary: The Dufferin gold deposit in Nova Scotia, Canada, formed ∼380 million years ago within metamorphosed sedimentary rocks called the Meguma Group. The deposit contains gold‐bearing quartz veins sandwiched between layers of tightly folded rocks. This study focused on unraveling the mechanisms behind some of the gold deposition within this deposit, specifically where associated with carbonaceous matter (CM). We found a close association between gold and CM, which represents organic matter preserved in the rocks. CM is abundant within small cavities throughout the quartz veins that also contain appreciable gold occurring as microscopic particles in the CM. By using a variety of analytical techniques, we determined that efficient gold mineralization occurred in response to specific chemical changes to the gold‐carrying fluid, including a decrease in the oxidation potential and a decrease in the acidity of the fluid through interaction with the CM‐rich rocks. Such changes to the fluid caused gold to become insoluble and form particles that were deposited in the rocks and vein material. Importantly, despite the fluid having a low concentration of dissolved gold, it exhibited a remarkable ability to deposit significant quantities of the precious metal, underscoring the important role of CM in facilitating efficient gold precipitation from fluids. Key Points: First fluid gold concentrations (0.045 ± 0.024 μg/g) measured from an economic, Meguma‐type metasediment‐hosted gold depositFluid Au, S, As, W, and B concentrations comparable to Alpine and Variscan metamorphic fluids hosted in uneconomic, Au‐poor vein systemsGold and carbonaceous matter are coeval and co‐distributed in flysch wallrocks and vein laminae [ABSTRACT FROM AUTHOR]

The Xiaoqinling gold province, located in the southern margin of the North China Craton (NCC), is the second largest gold-enriched region in China. In this region, the Mesozoic Huashan (HS) and Wenyu (WY) plutons are the major magmatic intrusions coeval with gold mineralization, although they show contrasting characteristics in the distribution of gold. In this study, we use geochemical features of titanite determined by LA-ICP-MS and EPMA analyses and elemental mapping to decipher the mechanisms that led to the difference in gold enrichment related to the two plutons. Titanite from the Wenyu granitic pluton exhibits significantly higher (La/Sm)N, (La/Yb)N, ΣLREE/ΣHREE ratios, and ΣREE concentration and slightly higher (Gd/Yb)N values than those of the Huashan Pluton, suggesting that the Wenyu pluton might have experienced more complex magmatic evolution, widespread hydrothermal alteration, and higher silica activity in the melt than the Huashan pluton. The titanite grains from the Huashan pluton show higher (Nb/Ta)N and (Lu/Hf)N values and significantly lower Zr concentration than those of the Wenyu pluton. The titanite grains from the Wenyu pluton show higher vanadium and gallium concentrations and Fe/Al ratio than those of the Huashan pluton, indicating comparatively higher f o 2 . Furthermore, the titanite grains from Wenyu pluton indicate higher water content in the magma. In addition, magma mingling and magmatic hydrothermal fluids derived from the crust/mantle are critical sources for ore-forming materials. These results suggest that the Wenyu pluton is more conducive to gold migration and enrichment than the Huashan pluton. [ABSTRACT FROM AUTHOR]

Baddeleyite is an important U‐Pb geochronometer and Hf isotope tracer that commonly occurs as an accessory phase in silica‐undersaturated igneous rocks of terrestrial and extra‐terrestrial origin. Currently, very few well‐characterised, large sized reference materials are available for baddeleyite U‐Pb geochronology and Hf isotope measurement. In this study, we document a baddeleyite reference material (SK10‐3) of Cenozoic age. SK10‐3 is inclusion‐free and does not contain secondary alteration minerals. The baddeleyite has uniform U‐Pb ages and Hf isotope ratios, within analytical uncertainty, as demonstrated by multiple LA‐ICP‐MS spot analyses (weighted mean 206Pb/238U age: 31.59 ± 0.11 Ma, MSWD = 0.7, n = 197) and LA‐MC‐ICP‐MS analyses (arithmetic mean 176Hf/177Hf ratio: 0.282741 ± 59, 2s, n = 188). Seven ID‐TIMS analyses yielded a weighted mean 206Pb/238U age of 31.592 ± 0.020/0.022/0.040 Ma (n = 7, 2s, MSWD = 2.2). Nine aliquots of MC‐ICP‐MS analyses yielded an arithmetic mean 176Hf/177Hf ratio of 0.282742 ± 8 (2s). We further demonstrate that the method of shallow‐pit (~ 2 μm depth) ablation substantially improves the precision and accuracy of baddeleyite U‐Pb ages. SK10‐3 has a relatively high 176Yb/177Hf ratio (~ 0.007) compared with most other baddeleyites, allowing the precise measurement of βYb and may be useful in generating the βYb‐βHf relationship during LA‐MC‐ICP‐MS Hf isotope measurement. SK10‐3 may be a useful addition to previously distributed baddeleyite reference materials for microbeam‐based U‐Pb geochronology and Hf isotope measurements. [ABSTRACT FROM AUTHOR]