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The Sonkul and adjacent Kokturpak multiphase plutons are situated along the 'Major Structural Line of Tien Shan' (known also as the 'Nikolaev Line') that extends for over 500 km and divides the terranes of the Middle and Northern Tien Shan. The plutons comprise a broad variety of high-potassic igneous rocks including the early olivine gabbro, intermediate monzonite to quartz monzonite, and later granodiorite, monzogranite, and leucogranite-alaskite, in turn followed by the late mafic dikes. U-Pb dating of zircon grains yields ages of 299 ± 2 Ma (olivine gabbro), 300 ± 3 Ma to 298 ± 3 Ma (monzonite to quartz monzonite), 299 ± 3 Ma to 298 ± 4 Ma to 297 ± 4 Ma (granodiorite), and 289 ± 4 Ma to 285 ± 2 Ma (monzogranite). These consecutive intrusive phases appear to have been produced by partial re-melting of a partially crystallized (mush) magma batch at deeper levels, which is evident by the presence of zircon antecrysts dated at some 306–311 Ma (up to 323 Ma?). Geochemical signatures of the igneous rocks correspond to high-K calc-alkaline to shoshonitic series intrusions emplaced in a transitional subduction-related to post-collisional setting. A low-degree partial melting of the metasomatically enriched upper mantle can be envisioned as the leading process of shoshonitic magma generation; this was followed by amphibole fractionation in a deep (lower crustal ?) magma chamber and possibly a mantle-induced generation of granitic magmas in the crustal protolith. Further mixing/mingling of the mafic magma and crustal granitic magma was followed by the magma fractionation and emplacement at shallow crustal levels. Assimilation of the old continental crust is consistent with the presence of ancient xenocrystic zircons (dated at ca. 1.5 to 2.5 Ga) in the studied rocks. The Late Carboniferous to Early Permian age and high-K calc-alkaline to shoshonitic composition are similar to those of highly mineralized intrusions of the other segments of the Middle Tien Shan. In this regard, several magmatic pulses of high-potassic intrusions and corresponding metallogenic pulses can be suggested in this region. Whereas the early (ca. 337 to 315 Ma) igneous suites accompanied by dominantly porphyry Cu-Au-Mo mineralization, the later (ca. 305 to 285 Ma) suites including the Sonkul and Kokturpak plutons are accompanied by W- and/or Au-dominant mineralization. This mineralization appears to pre-date more substantial intrusion-related to orogenic-type Au mineralization. [ABSTRACT FROM AUTHOR]

Due to the escalating demand for conventional potassium sources, and their unavailability in many African countries, there is a growing interest in hydrothermally treated igneous rocks as viable alternatives. These materials exhibit promising potential in enhancing potassium release, comparable to traditional sources like muriate of potash (M.O.P.). However, it remains uncertain whether they can adequately fulfill the nutrient requirements of plants. In this study, we evaluated nutrient balance in ryegrass (Lolium multiflorum) using raw and hydrothermally treated K-bearing silicate rocks as fertilizers. The Compositional Nutrient Diagnostic (CND) approach was used to assess the plants' nutrient status, involving identification of high-yield subpopulations, and setting a yield cutoff. We derived a theoretical threshold for nutrient imbalance (CNDr2) using statistical methods like the chi-square distribution function and low-yield subpopulation proportion. CNDr2 was validated via Cate–Nelson partition and sum of squared individual nutrient indexes. Results showed a yield cutoff of 37.759 kg ha−1, distinguishing low-yield and high-yield subpopulations based on cumulative variance ratio functions from survey data. The theoretical threshold derived using the chi-square function was 10.1, subsequently validated by the Cate–Nelson method. Critical CND nutrient indices were symmetrical around zero, but their sum indicated foliar nutrient imbalance, notably zinc, potassium, and copper excess, attributed to 20 interactions identified (4 synergetic and 16 antagonistic). This study underscores hydrothermal treatment's efficacy in improving nutrient availability and achieving a balanced nutrient profile compared to raw materials. It offers a promising solution for enhancing agricultural productivity, especially in tropical regions like Africa, where traditional sources are scarce. [ABSTRACT FROM AUTHOR]

Monazite is a LREE-rich accessory mineral in various igneous and metamorphic rocks; therefore, monazite geochronology has the potential to answer a range of important geological questions. We demonstrate the feasibility of in situ Lu–Hf dating by LA-ICP-MS/MS applied to monazite for the first time. Eight monazite samples were investigated, with ages of 2.65–0.27 Ga and Lu contents of 19–180 μg g−1. Although the isobaric interferences of 176Lu and 176Yb occur at extremely low reaction rates (reacted/unreacted fractions) for higher mass reaction products (+82 a.m.u), isobaric interference corrections are still needed for the monazite samples due to their high Lu/Hf and Yb/Hf ratios (mean 175Lu/177Hf = ∼24 000; mean 172Yb/177Hf = ∼52 000) when using an iCap TQ instrument. The RW-1, ELK, 44 069, and Maine 1 monazites yield relatively low common Hf contents, whereas the Vermillion, Namaqualand, 117 531, and Maine 2 monazites have high and variable common Hf contents. The results show that in situ monazite Lu–Hf dating by LA-ICP-MS/MS is feasible and can yield precise (0.40–2.96%, 2 relative standard error) and accurate (−0.40 to +1.99%, 2 relative deviation) ages that are comparable to those from the U–Th–Pb system. There are no systematic Lu–Hf age biases with respect of the U–Th–Pb ages and Lu and Hf contents. We report a data reduction scheme (DRS) and Visual Lu–Hf age plugin for Iolite software to process in situ Lu–Hf age data. Lu–Hf geochronology could provide independent age constraints for the monazite, which has previously been successfully dated using the U–Th–Pb system. [ABSTRACT FROM AUTHOR]

The article discusses Canadian mineral artist Roger H. Mitchell, a professor emeritus at Lakehead University, who combines his passion for geology with art to create digitally-worked abstract artworks using petrological images. Mitchell's art is inspired by his extensive research on rare igneous rocks and his fascination with the textures and colors of minerals observed under cross-polarized light. His artwork, part of the Steinbilder series, showcases the hidden beauty of rocks and minerals through vibrant colors and unique compositions, with some pieces resembling stained-glass windows. Mitchell's work has been exhibited in Thunder Bay, Ontario, and he plans to share his collection on the Almaz Press website. [Extracted from the article]

Olivine, typically occurring as a forsterite-fayalite solid solution, is a major rock-forming mineral in mafic and ultramafic igneous rocks, and it is important for understanding the genesis, evolution, and alteration of its host rocks. In this study, both GGA and GGA + U methods were employed to calculate the reduced partition function ratios of Fe, Mg, O, and Si isotopes for the forsterite-fayalite solid solution, aiming to elucidate the impacts of Fe content and Hubbard U correction on the isotope fractionation signatures of Fe, Mg, O, and Si in olivine. On the whole, the β Fe -factor, β Mg -factor, β O -factor, and β Si -factor decrease with increasing Fe content. The linear correlations between β -factors and bond lengths obtained from GGA + U are better compared to those from GGA. The Hubbard U correction can increase the β Fe -factor. When Fe/(Fe + Mg) ≤ 1/8, ≤ 1/2, and ≤ 1/2, the effect of Hubbard U correction on β Mg -factor, β O -factor, and β Si -factor can be considered negligible, respectively, suggesting that the β Mg -factor, β O -factor, and β Si -factor of Fe-bearing olivine calculated using GGA + U and those of Fe-free minerals calculated using GGA can be combined to derive 103ln α and trace geological processes. Furthermore, equilibrium fractionation of Fe, Mg, O, and Si isotopes between olivine and other minerals, including troilite, clinopyroxene, and garnet, were also calculated. Our results are helpful in interpreting the observed data regarding Fe, Mg, O, and Si isotopic compositions of olivine, leading to a comprehensive understanding of relevant geological processes. [ABSTRACT FROM AUTHOR]

Nb and Ta are geochemical twins, yet their ratio varies considerably in igneous rocks. It is generally supposed that felsic melts coexisting with residual rutile will have elevated Nb/Ta ratios relative to their basalt precursors, which is pivotal to our understanding of deep crustal melting and continent formation throughout Earth's history. This study reports petrological, bulk-rock and mineral geochemical, and Sr-Nd-Mo-Hf isotopic data on Eocene adakitic rocks in central Tibet. These rocks can be petrologically and geochemically divided into an amphibole-bearing high-Nb/Ta and an orthopyroxene-bearing low-Nb/Ta group, which were formed by partially molten eclogitized lower crust based on the geochemistry of their early-crystallized minerals. The two groups have similar Sr–Nd–Hf isotope compositions and abundances of strong incompatible elements, suggesting that their source protoliths share identical compositions. Besides, the values of TiO 2 , Ba, Zr/Sm, and La/Yb are comparable between the two groups of rocks, eliminating the possibility of variations in Nb/Ta-sensitive minerals (e.g., rutile, amphibole, biotite, and titanite) in the source as the cause of their Nb/Ta variation. The contrasting mineral assemblages of the two group rocks, along with the higher Ce/Mo ratios and lower δ98/95Mo values in the low-Nb/Ta group, indicate the source of the low-Nb/Ta contains less water than that of the high-Nb/Ta group. These findings, combined with experimental results and trace element partial melting modeling, lead us to propose that the D rutile Nb/Ta responsible formation of the low-Nb/Ta group is higher than that of the high-Nb/Ta group, due to the decreased water content in the source. Thus, the central Tibetan adakitic rocks provide the first natural example demonstrating that the Nb/Ta ratios in felsic rocks derived from rutile-bearing eclogite depend on the physical conditions of source melting, which are not always higher than the protolith. Our study also highlights the potential of employing Mo isotopes in adakitic rocks to test this hypothesis for those that are not petrologically distinguishable. [ABSTRACT FROM AUTHOR]

Crustal growth is closely associated with the oceanic subduction process, although the precise mechanism involved remains poorly constrained. Northeast (NE) China is an important component of the largest accretive orogenic belt worldwide – Central Asian orogenic belt. Its accretionary process was dominated by the Paleo-Asian and Paleo-Pacific Oceans; thus, NE China can provide a promising insight to explore this complex mechanism. We report new geochronological, geochemical and Hf isotopic compositions of the igneous rocks found in the Central Jilin Province, NE China. The geochronological results reveal that these igneous rocks were formed during 174.7 − 167.7 Ma (i.e. Early−Middle Jurassic). The quartz diorite and monzogranites from the northeastern margin of the North China Craton have high Sr (314 − 757 ppm) content, (La/Yb)N (7.11 − 29.9) and Sr/Y (41.50 − 157) ratios, low Y (2.03 − 12.97 ppm) and Yb (0.30 − 1.34 ppm) contents, exhibiting adakitic features. Coupling with their significant negative εHf(t) values (−32.51 to − 5.45), we propose that these igneous rocks were originated from the partial melting of an ancient thickened lower crust. In contrary, the syenogranite, granite porphyry, and porphyritic monzogranite from the Zhangguangcai and Jiamusi blocks are characterized by high K calc-alkaline, low MgO (0.03 − 0.88 wt.%), Zr + Nb + Ce + Y (141 − 462 ppm) contents and Sr/Y (0.93 − 17.40) ratios, indicating an affinity of I−type granite. In view of their positive εHf(t) values (5.41 to 9.47), we suggest that they were originated from the partial melting of a juvenile lower mafic crust. Despite they have different magma sources, all the Jurassic igneous rocks exhibit typical geochemical signatures associated with subduction, such as enriched in large ion lithophile elements and depleted in high field strength elements. Considering the spatial-temporal distribution of coeval igneous rocks within the region, we propose that the Early Jurassic is the early subduction of the Paleo-Pacific Ocean. The Jurassic igneous rocks can be divided into two categories, one with high Sr/Y ratios and negative Hf isotope, and the others with low Sr/Y ratios and positive Hf isotope, which may indicate that crustal architecture in subduction zone has a significant effect on continental crustal growth and reworking in NE China. [ABSTRACT FROM AUTHOR]

We report the δ142/140Ce values for thirty‐three widely available geological reference materials (RMs), including igneous rocks, metamorphic rocks, sediments and soils. The Ce isotope ratios of twenty‐two Chinese RMs are reported for the first time. After chemical purification using TODGA resin (50–100 μm, Eichrom, USA), Ce isotope measurements of these RMs were conducted by multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) with a combined standard‐sample bracketing (SSB) and Sm‐doping technique. The data quality of the Ce isotope results was assessed by repeated measurement of pure Ce reference solutions (NIST SRM 3110, JMC304, CDUT‐Ce) and well‐characterised geological RMs (BHVO‐2, BCR‐2, Nod‐A‐1, Nod‐P‐1, etc.). Our results are in excellent agreement with previously reported values within intermediate measurement precision (±0.04‰, 2s). The igneous rock and soil RMs showed limited variations in δ142/140Ce values, which ranged from ‐0.036 ± 0.018‰ to 0.062 ± 0.046‰ and ‐0.015 ± 0.015‰ to 0.029 ± 0.009‰, respectively. The river/marine sediments and Mn nodules displayed variable Ce isotope ratios ranging from ‐0.005 ± 0.018‰ to 0.141 ± 0.023‰, suggesting detectable Ce isotopic fractionation during low‐temperature processes. [ABSTRACT FROM AUTHOR]

Columnar jointing occurs commonly in igneous rocks and rarely in sedimentary rocks. We report the results of combined field and petrological studies, Raman spectroscopy and column geometry analysis of columnar jointing in Paleoproterozoic carbon-bearing rocks, Eastern Fennoscandian Shield, NW Russia. The columnar rocks occur near the contact with the saucer-shaped dolerite sill emplaced in the unconsolidated organic rich sediments. Columnar jointing aureole (1 to 7 m) and column architecture strongly depends on the contact morphology. Columnar jointing is caused by the contraction of organic-rich sediments due to generation and further release of gas and oil rich fluid. The results of integrated studies indicate that fluidization driving the jointing is associated with not only the dehydration, but also with the mobilization of gas and oil rich fluid due to the thermal maturation of organic matter. Columnar jointing is associated with intensive fluid circulation and devolatilization evidenced by the numerous veins, globules, and vugs filled with migrated carbonaceous matter and secondary minerals in the columnar rocks as well as high vesicularity of dolerites near the contact. The redistribution of the mobile elements (K, Rb, LREE) along with the significant enrichment of S near the contact also indicates the intensive fluid circulation. The study contributes to understanding of mechanism of columnar jointing in sedimentary rocks and formation the fracture networks in organic-rich sediments. [ABSTRACT FROM AUTHOR]

The Adyrtor multiphase pluton is situated in the easternmost part of the 'Main Structural Line of Tien Shan', or the 'Nikolaev Line', and intrudes the Paleoproterozoic metamorphic sequence representing the oldest (1.8–2.5 Ga) continental basement fragment in the Tien Shan orogenic belt. The intrusions comprise mafic to intermediate (monzodiorite, monzonite, quartz syenite) and silicic (quartz monzonite, monzogranite, and leucogranite-alaskite) rocks. Geochemical signatures of the igneous rocks correspond to high-K calc-alkaline to shoshonitic series intrusions, with a strong A-type granite affinity, emplaced in post-collisional setting. Based on the isotopic U-Pb data, quartz syenite from the Adyrtor intrusions crystallized at 330.7 ± 4.3 Ma, and quartz monzonite – at 329.5 ± 5.8 Ma. Although the ages identified correspond to those of the subduction-related magmatism in the western part of the Middle Tien Shan, geochemical characteristics of the rocks support rather post-collisional setting of the plutons, principally due to a 'scissor-like' closure of the Turkestan paleoocean, starting from the east. Magmatic evolution included a generation of shoshonitic magma by low-degree partial melting of the metasomatically-enriched upper mantle, followed by amphibole fractionation in a deep (lower crustal ?) magma chamber. Then, under the influence of mantle-supplied fluids and heat, granitic magmas in the crustal protolith could have been generated, with further mixing/mingling of the mantle-derived mafic (shoshonitic) magma and mantle-induced crustal granitic magma, followed by the magma fractionation and emplacement at shallower crustal levels. Assimilation of an old continental crust is also envisioned, consistent with the presence of the xenocrystic zircons dated at ca. 1.6 Ga to 2.5 Ga and the A-type granitoid affinity of the igneous rocks. The associated skarn-porphyry W-Mo(-Cu-Au) mineralization is consistent with post-collisional setting of the productive intrusions. This mineralization complements the group of similar deposits and occurrences associated with high-K calc-alkaline to shoshonitic series intrusions in the Middle Tien Shan and globally. The high endowment in W and Mo can be explained by the fertilization of subduction-modified subcontinental lithospheric mantle in these metals, with its further involvement in the magma generation in post-collisional setting. Also, a stronger W-Mo mineralization can reflect a greater role of a crustal protolith in the magma generation, as revealed by the distinct A-type affinity of the igneous rocks. [ABSTRACT FROM AUTHOR]

The stable isotope compositions of sulphur (δ34S) and oxygen (δ18O) in barite are frequently used as proxies for microbial sulphate reduction (MSR) in diverse environments, such as in relation to anaerobic oxidation of methane in marine cold seeps. There, isotopically heavy barite is used as a marker for MSR from a sulphate pool that has undergone semi-closed system conditions. Closed-system MSR is also a commonly observed feature in igneous rock hosted fracture aquifers, as shown by extremely 34S-enriched pyrite. What is less well-constrained is whether δ34S in barite can be used as a proxy for MSR in such systems. Here we explore the microscale heterogeneity of δ34S and δ18O via secondary ion mass spectrometry and the trace element Sr via LA-ICP-MS maps in barite precipitated in granite-hosted boreholes during a 17-year experiment, at Äspö, Sweden. We compare it with δ18Osulfate, δ34Ssulfate, and δ34Ssulfide of the fracture fluids and with paragenetic pyrite with δ34S values reflecting closed system MSR. The δ18O values in barite (+9.4 to +16.9 ‰) represent two generations of barite, one with low values and one with high values. The latter are likely impacted by sulphur disproportionating or -oxidizing bacteria. The barite reflects a much smaller span in δ34S (+14.5 to +28.6 ‰) than the pyrite (−47.2 to +53.3 ‰). This lack of extremely high δ34Sbarite values is proposed to be due to that barite saturation only occurred in the early parts of the Rayleigh cycle. Additionally, fluid migration has affected the δ34S values to lower values, accompanied by higher Sr concentrations. Taken together, barite δ34S values cannot be regarded as a reliable independent proxy for MSR in deep sulphate-poor igneous rock hosted aquifers. However, the relation between the δ34S values of coeval barite and pyrite is regarded as a useful proxy for MSR-related fractionation during early stages of MSR. [ABSTRACT FROM AUTHOR]

How gabbro affects the generation and expulsion of hydrocarbons in muddy surrounding rocks is clarified by analyzing thin section, major and trace elements, total organic carbon (TOC), pyrolysis, extracts and vitrinite reflectance data from source rocks in the Chunxi area the Dongying Sag, Bohai Bay Basin, eastern China. The results show that a magma intrusion brings copious heat to the source rocks, which promotes abnormal maturation of organic matter (OM) and rapid hydrocarbon generation. The CH4 and H2 produced by gabbro alteration play a role in hydrocarbon generation of source rocks. The hydrothermal process during magma intrusion provides many different minerals to the source rock, resulting in carbonate‐rich surrounding mudstone. The carbonate and clay minerals produced by volcanic mineral alteration jointly catalyze the hydrocarbon generation of the source rock. The high‐temperature baking of the intrusion results in hydrothermal pressurization and hydrocarbon generation pressurization, causing many fractures in the surrounding rock. The generated oil and gas are discharged through the fractures under diffusion and pressure. Mantle‐derived CO2 is also conducive to the expulsion of hydrocarbons because of its strong enrichment capacity for hydrocarbons. [ABSTRACT FROM AUTHOR]

Upper Miocene volcanic and plutonic rocks on Kos island preserve a record of magmatic and tectonic events in the transition zone between the Aegean and Anatolian microplates. Their field setting, syn-intrusion deformation, mineralogy, and geochemistry were investigated. Volcanic rocks, including trachyandesite flows and trachyandesite to rhyolite domes, were extruded on a central E–W horst and directly overlie Alpine basement. Thick successions of trachytic flow tuffs are interbedded with fluvial and lacustrine basinal sediments to the south of this horst. Volcanism was synchronous with the emplacement of the Dikeos monzonite pluton, which is geochemically similar to some lithic clasts in the thick flow tuffs and is cut by mafic dykes including lamprophyres. Two main types of mafic magma were present: a K-rich lamprophyric magma that evolved to trachyandesite and more calc-alkaline magma similar to mafic enclaves in the monzonite. Syn-intrusion structures in the monzonite indicate emplacement during E–W sinistral strike-slip faulting that created local transtensional deformation, providing accommodation for a Dikeos magma reservoir. A change in the style of deformation in the Late Miocene led to NW-striking extension in the footwall, occupied by mafic dykes and mineralized veins, and extensional detachment of the hanging wall, resulting in unroofing of the monzonite. [ABSTRACT FROM AUTHOR]

Petrographic studies have been carried out on the Early Miocene Darnó Conglomerate Formation, which consists only of debris of ophiolitic mélange and is found today on Darnó Hill in SW Bükk, NE Hungary. The studied sediments are bounded by the Darnó line from Darnó Hill. The aim of this work was to show if it is possible to reconstruct the petrographic composition of the source area only from its debris. The rock types were determined in thin sections using a polarizing microscope, and a quantitative analysis of the different rock types was carried out using the grain counting method, the results of which were interpreted as volume ratios. The main rock types observed in the studied samples (textural varieties of basalt, dolerite/microgabbro, claystone, siltstone, and radiolarite) are similar to the rock types of the mélange assemblage of Darnó Hill. Based on the volume calculations of basaltic detrital grains with different textures characteristic for pillow basalts, it could be established that pillow basalts dominated the igneous rocks in the source area of the Darnó Conglomerate on Darnó Hill already in the Miocene. Thus, this work shows that the lithological composition of a source area can be precisely outlined by a detailed petrographic analysis of the debris eroded from the immediate vicinity. [ABSTRACT FROM AUTHOR]

For a long time, elucidating the tectonic setting of unknown rock samples has been a focal point for geologists. Traditional methodologies for this purpose have been scrutinized increasingly due to their inherent limitations. In response to these challenges, this paper applies modern machine learning techniques to analyze the geochemical data of igneous rocks and improve understanding of tectonic settings. By employing a variety of machine learning models, including Decision Trees, K-Nearest Neighbors, Support Vector Machines, Random Forests, Extreme Gradient Boosting, and Artificial Neural Networks, and training with 23 features comprising nine major elements (SiO2, TiO2, Al2O3, CaO, MgO, MnO, Na2O, K2O, and P2O5) along with 14 trace elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), the study successfully distinguished between seven different tectonic settings. Among these models, Random Forest, Extreme Gradient Boosting, and Artificial Neural Networks demonstrated superior classification accuracy and recall rates, with accuracies of 0.85, 0.87, and 0.86, respectively. This validates the effectiveness and potential of machine learning technologies in distinguishing the tectonic settings of igneous rocks through their geochemical elements. To enable geologists and researchers to more accurately understand and predict the origins of igneous rocks without the need to master machine learning knowledge, a user-friendly software, GeoTectAI, has been developed. [ABSTRACT FROM AUTHOR]

Sviatonossites are syenites with andradite garnet, a rare type of igneous rocks described by P. Eskola in 1913 on the Svyatoi Nos Peninsula (Lake Baikal). Due to the absence of zircon in the rocks, which makes it possible to date them reliably by the U‒Pb method, geochronological Sm–Nd studies of the bulk composition and minerals are carried out. As a result, two estimated periods of the formation of sviatonossites are obtained. According to the bulk composition and four minerals (garnet, pyroxene, potassium feldspar, and apatite), the age is 262 ± 21 Ma (RMSD = 1.6), and according to the bulk composition and garnet, it is 274 ± 25 Ma (RMSD = 0). The results obtained coincide with the timing of tectonic–metamorphic and igneous processes associated with the formation of the Eastern Transbaikalia segment of the Central Asian (Mongol–Okhotsk) folded belt. Sviatonossites in the complexes of mobile (folded) belts framed by the Siberian Craton are indicator rocks reflecting the manifestation of mantle–crustal interaction. [ABSTRACT FROM AUTHOR]

X-ray spectra are pivotal for understanding chemical bonding and atomic interactions in materials. Particularly, valence-to-core (VtC) electronic transitions and satellite peaks within X-ray spectra provide insights into valence states and chemical environments. This study focuses on the multi-vacancy satellite peaks, Si KβIII and KβIV, and their application in analyzing silicate minerals in igneous rocks. A wavelength dispersive X-ray fluorescence (WD-XRF) spectrometer, commonly employed for chemical analysis of geological samples, was utilized in this study. The Si KβIII and KβIV peaks were selected due to their VtC transitions and multi-vacancy origin, offering enhanced sensitivity to the chemical environment. We examined 41 certified reference materials (CRMs) of igneous rocks, demonstrating the capaβility of these satellite peaks to reveal detailed chemical and structural information. A strong correlation was found βetween the chemical composition of silicate minerals and the intensities along with chemical shifts of the Si KβIII and KβIV peaks. We developed a regression model to predict mineral concentrations, validating the method with CRMs. The results suggest that the spectral region of the Si KβIII and KβIV peaks serves as a distinctive fingerprint for identifying silicate minerals in igneous rocks. [ABSTRACT FROM AUTHOR]

Recent advances in subsurface microbiology have demonstrated the habitability of multi-million-year-old igneous rocks, despite the scarce energy supply from rock-water interactions. Given the minimal evolution coupled with exceedingly slow metabolic rates in subsurface ecosystems, spatiotemporally stable igneous rocks can sustain microbes over geological time scales. This study investigated a 2-billion-year-old mafic rock in the Bushveld Igneous Complex, South Africa, where ultradeep drilling is being executed by the International Continental Scientific Drilling Program (ICDP). New procedures were successfully developed to simultaneously detect indigenous and contaminant microbial cells in a drill core sample. Precision rock sectioning coupled with infrared, fluorescence, and electron microscopy imaging of the rock section with submicron resolution revealed microbial colonization in veins filled with clay minerals. The entry and exit of microbial cells in the veins are severely limited by tight packing with clay minerals, the formation of which supplies energy sources for long-term habitability. Further microbiological characterization of drilled rock cores from the Bushveld Igneous Complex will expand the understanding of microbial evolution in deep igneous rocks over 2 billion years. [ABSTRACT FROM AUTHOR]

This paper completes the examination of results of the study of lithogeochemical characteristics of a pilot collection of the Riphean–Vendian sandstones, siltstones, and claystones (last one based on the interpretation of results) in Belarus. Data on the age of detrital zircon published in recent years suggest that Upper Precambrian rocks of this region were sourced from the Osnitsk–Mikashevichi and the Trans-Scandinavian igneous belts, the Volyn–Brest large igneous province, rapakivi granites, as well as various rock associations of Sarmatia, Danopolonian orogen and Svecofennides. Based on the lithogeochemical characteristics, the distribution of data points of the studied clastic rocks on discriminant diagrams provides insight into the possible provenance, paleogeodynamic, paleogeographic, and paleoclimatic settings and suggests several conclusions. The considered Riphean–Vendian stratons in Belarus are composed mainly of erosion products of within-plate granitoids, as well as various island-arc and syncollisional felsic igneous rocks. The share of erosion products of mafic rocks among them generally does not exceed 30%. It is significant mainly in the Volyn Group rocks (erosion products of the Volyn–Brest large igneous province), as well as in some samples of the Nizov, Selyavy, and Kotlin formations (fragments of mafic rocks from other provenances?). The source-to-sink transport was accomplished mainly by large rivers. Paleogeodynamic settings varied from quite active to quite passive. The paleoclimate in catchment areas was most likely arid/semiarid in the Riphean. In the Vendian, it was humid and varied from subtropical in the Early Vendian (except the Glusk Formation) to tropical in the Late Vendian. The obtained results also make it possible to show some peculiarities of the known methods and techniques of paleoclimate reconstruction. [ABSTRACT FROM AUTHOR]

Earthquake recurrence intervals, surface-rupture extents, and interactions between faults provide insight into how faults behave and are critical for seismic hazard mitigation and earthquake forecasting. Investigating the paleoseismology of spatially related faults can reveal strain distribution and whether faults rupture as a system or independently. Summer Lake basin, a graben in the northwestern Basin and Range with four active faults (three of which have prior paleoseismic investigations), provides an opportunity to investigate fault interactions. To expand the paleoseismic record, two trenches were excavated across the previously undocumented Thousand Springs fault, exposing a normal fault zone that offsets a sequence of deep- to shallow-water lake sediments, sand dunes containing reworked Mazama ash, and other Cascades-sourced tephra. Tephra units were correlated to known units by their physical characteristics, stratigraphic sequence, glass chemistry, and two new radiocarbon dates from the uppermost lake sediments. Using trench exposures, measured vertical separations through auguring, colluvial wedges, and extrapolated offsets based on a constant sedimentation rate, we identified at least five surface-rupturing earthquakes with a total offset of 3.4 + 2/-1 m in the past ~65 ka. The oldest event (EH5) occurred at 63.8 ± 1.5 ka, event horizon 4 at 36.2 ± 12.7 ka (which could be more than one event), and event horizon 3 at 24.6 ± 0.3 ka. Event horizon 2, a warping event at our site, is likely more than one event and occurred between 7.5 and 10 ka; and the most recent event (EH1+), most likely more than one event, occurred between 3.3 and 7.7 ka. Several events correlate, within error, with events on other faults in the Summer Lake basin, suggesting that (1) the faults generally rupture together as a system, (2) the most recent earthquake may have ruptured all faults in the region, and (3) fault rupture is influenced by the rapid regression of Lake Chewaucan (~13 ka). [ABSTRACT FROM AUTHOR]

To study the oil and gas enrichment characteristics of the reservoir rocks in the second Member of the Nantun Formation (N2) of the F1 fault in the Beier Depression, this research focuses on the mechanism of shortening the sealing time of the regional mudstone cap due to faults and the factors influencing the sealing duration. The period during which the regional mudstone cap seal began is determined by analyzing the relationship between the diagenetic index of the regional mudstone cap and its underlying reservoir rocks and time. This relationship between the rock-formation index and time helps establish the onset of regional mudstone cap seal, and from this, the index of shortening time due to faults is derived. A research framework to study the sealing time shortening of regional mudstone cap seal caused by a fault was developed, which was further applied to analyze the relationship between the fault-induced shortening time of the seal in the lower of the first Member of the Damoguaihe Formation section ( D 1 x ) of the Beier Depression and hydrocarbon concentrations in the N2 Formation. The results show that the F1 fault at measurement points 1–4, 6, and 9–11 reduced the blocking time of the regional mudstone cap in  D 1 x  to 100%, hindering hydrocarbon accumulation and preservation in the N2. Conversely, the F1 fault at measurement points 5, 7, 8, and 12–15 reduces the blocking time of the regional mudstone cap in the  D 1 x  by 37–99%, which is more conducive to hydrocarbon accumulation and preservation in N2, resulting in positive oil and gas shows. Based on the test results, a discussion on the feasibility, applicability, and limitations of the new method is conducted, yielding the following conclusions: (1) The relationship between oil and gas indications in the reservoir rocks of the Nan'er Member confirms the feasibility of the new method. The research findings of the new method on the F1 fault align with current oil and gas exploration realities, indicating its potential use in studying the degree to which faults shorten the sealing time of regional mudstone caprocks. (2) The new method is primarily applicable to the study of the modification effects of tensile normal faults on regional mudstone caprocks and their impact on oil and gas sealing capacities. However, its application to other types of faults may have limitations. (3) The new method is mainly suitable for caprocks dominated by mudstone. When studying other types of caprocks, such as carbonate rocks, evaporites, igneous rocks, and metamorphic rocks, different research methods and technical means are required. These findings provide valuable insights for oil and gas exploration efforts near fault zones. [ABSTRACT FROM AUTHOR]

The distribution of zircon crystallisation ages in igneous rocks has been proposed to provide insights into the dynamics of underlying magma reservoirs. However, the ability to interpret magmatic processes from an age distribution is challenged by a complex interplay of factors such as sampling biases, analytical uncertainties and incorporation of extraneous zircon grains. Here, we used a compilation of magmatic zircon U-Pb ages measured by chemical abrasion isotope dilution thermal ionisation mass spectrometry (CA-ID-TIMS) to quantify the differences that exist among zircon U-Pb age distributions from different magmatic systems. The compiled dataset was rigorously filtered through a number of processing steps to isolate age distributions least impacted by sampling biases and analytical factors. We also filter the database using a new algorithm to systematically identify and remove old outliers from age distributions. We adopt the Wasserstein distance as a dissimilarity metric to quantify the difference between the shapes of age distributions. Principal component analysis of a dissimilarity matrix of pairwise Wasserstein distances of age distributions reveals a difference between zircon age distributions found in plutonic, porphyry and volcanic rocks. Volcanic and porphyry zircon populations exhibit a skew towards younger ages in their distributions, whereas plutonic age distributions skew towards older ages. Using a bootstrap sampling approach to generate synthetic age distributions, we show that this difference can be predominantly ascribed to truncation of zircon crystallisation during volcanic eruptions and porphyry dyke emplacement, which leads to a younger skew. We also find that higher magmatic flux can contribute to the younger skew of volcanic and porphyry zircon age distributions, though we emphasise that no difference in flux is required given the strong effect of truncation on zircon age distributions. Given the multitude of factors that influence zircon age distributions, we urge caution when quantifying the thermal evolution of crustal magma bodies using zircon age distributions integrated with numerical models. [ABSTRACT FROM AUTHOR]

ABSTRACT Subduction zones are the primary locations of material exchange between the crust and mantle, and thus, arc igneous rocks are extensively examined to explore crust–mantle interactions during oceanic subduction. In this study, the Sr‐Nd‐Hf isotopic compositions and elemental characteristics of the Yinwaxia mafic dykes from the Shibanshan–Huaniushan arc in the southern Beishan Orogen were investigated to determine their petrogenesis and explore crust–mantle interactions during the subduction of the Liuyuan Ocean. The dykes were subdivided into two groups based on their geochemical composition and spatial distribution. Group I dykes in the northern Yinwaxia area possess depleted light rare earth elements and slightly enriched large‐ion lithophile elements, indicated by relatively high ratios of Rb/Nb (1.4–82), Ba/Nb (6–408), and Cs/Nb (0.13–2.74), and low ratios of Th/Yb (0.03–0.39), Th/Nb (0.10–0.83), and (La/Yb)N (0.33–1.36). Further isotopic composition study revealed that low values of (87Sr/86Sr)i (0.7028–0.7052), and high values of εNd(t) (4.9–9.1) and εHf(t) (13.2–24.0), which suggests that the mantle source of Group I dykes was metasomatized by aqueous fluids. In Group II dykes located in the southern Yinwaxia area, enrichment of light rare‐earth elements and large‐ion lithophile elements was observed, featuring lower ratios of Rb/Nb (0.5–16.7), Ba/Nb (13–51), and Cs/Nb (0.15–1.56), but higher ratios of Th/Yb (0.25–2.64), Th/Nb (0.19–1.49), and (La/Yb)N (1.09–2.98) compared to Group I. Furthermore, Group II dykes exhibited higher values of (87Sr/86Sr)i (0.7051–0.7077) and lower εNd(t) (−1.7 to +3.8) and εHf(t) (3.7–9.4) isotopic compositions, which suggests that the slab fluids involved in their mantle source were dominated by sediment‐derived melts. The difference between the mafic dykes from Groups I and II suggests the addition of steadily increasing amounts of sediment‐derived melt in their mantle source; moreover, the increased (La/Yb)N ratio and decreased εNd(t) with increasing distance from the Liuyuan mélange are records of the spatial evolution of the composition of the slab fluids during the oceanic subduction of Liuyuan Ocean in the early Permian. [ABSTRACT FROM AUTHOR]

Amphibole is an important mineral during the differentiation of arc magmas but rarely as a phenocryst in arc lavas or eruptive pyroclastic rocks. The Sanggeda complex, intruded into the ophiolite of the Indus–Yarlung Zangbo Suture Zone (IYZSZ), Zedong, southern Tibet, mainly consists of amphibole-rich, fine-grained, and porphyritic gabbros. The complex provides an opportunity to study the differentiation of arc magmas through amphibole crystals. Four distinct amphibole crystal populations can be recognized according to petrographic observations, EMPA, and LA–ICP–MS analysis. The first ones (Type 1) are fined-grained and euhedral, are crystallized during ascent, and are the product of the shallow emplacement of host magma. The second ones (Type 2) are euhedral, with slight negative Eu and Sr anomalies, and crystallize from an evolved magma that previously experienced plagioclase fractionation. Type 3 amphiboles have similar morphological characteristics to Type 2 but are without Eu and Sr anomalies. Type 4 crystals are shown as pseudomorphs, formed by the reaction–replacement between the clinopyroxene and melt. Type 1 crystals are autocrysts. Other amphiboles within host magma, whether presented as phenocrysts or cumulate nodules, are antecrysts. Based on the amphibole crystal population developed in the complex, in this study, a trans-crustal magma plumbing system is proposed, containing at least three magma reservoirs located at different crust depths: the shallow emplaced crust (~4.8 km), the mid-crust (~12.9 km), and the lower crust (~21.8–24.9 km). Early amphibole crystallization is an effective process to generate silicic residual melts. Gravity could help in that sense. Precursor amphibole and clinopyroxene can efficiently delaminate back into the mantle and promote the generation of silicic continental crust. [ABSTRACT FROM AUTHOR]

The late Mesozoic igneous rocks along the coastal South China Block (SCB) exhibit complex parental sources involving a depleted mantle, subducted sediment-derived melt, and melted crust. This period aligns with the magmatic flare-up and lull in the SCB, debating with the compression or extension in coastal region. Our study employs numerical models to investigate the dynamics of the ascent of underplating magma along the Changle–Nan'ao Belt (CNB), simulating its intrusion and cooling processes while disregarding the formational background. The rheological structure of the lithospheric mantle significantly influences magma pathways, dictating the distribution of magmatism. This work reveals that the ascent of magma in the presence of faults is considerably faster than in the absence of faults, and contemporaneous magmatic melts could produce different cooling and diagenetic processes. Additionally, the influence of pre-existing magma accelerated the emplacement of underplating magma. The magma beneath the fault ascended rapidly, reaching the lower crust within 20 million years, with a cooling rate of approximately ∼ 35 °C Myr -1. Conversely, the thickened magma took 40–50 million years to ascend to the lower crust, cooling at a rate of ∼ 10 °C Myr -1. In contrast, magma without thickening and fault would take a considerably longer time to reach the lower crust. The ascent of magma formed a mush-like head, contributing to magmatic circulation beneath the crust and decreasing crustal thickness. Multiphase magmatism increases the geothermal gradient, reducing lithospheric viscosity and promoting underplating magma ascent, leading to magmatic flare-ups and lulls. Our findings suggest that the Cretaceous magmatism at different times in the coastal SCB may be associated with the effects of lithospheric faults under similar subduction conditions. Boundary compression forces delay magma ascent, while rising magma induces a significant circulation, decreasing the crustal thickness of the coastal SCB. This study provides new insights into the complex interplay of magmatic processes during subduction, emphasizing the role of lithospheric structure in shaping the temporal and spatial evolution of coastal magmatism. [ABSTRACT FROM AUTHOR]

The main ocean–continent transformation stage of the Qinling and Qilian conjunction zone happened in the Early Paleozoic with the occurrence of a lot of subduction–collision–related magmatic rocks. However, there is still considerable controversy over the duration of the subduction–collision orogeny process of the Proto-Tethys Ocean, here termed as the Wushan–Shangdan Ocean. We provide geochronological, geochemical, and Lu-Hf isotopic data for typical Early Devonian igneous rocks there, named Tailu pluton. The Tailu pluton at 410 Ma comprised K-rich, calc-alkaline, metaluminous A-type granite with low Y/Nb ratios (0.85 to 1.35) and A/CNK values (0.90 to 1.01); with high SiO2 contents (65.44 to 74.46 wt%), Mg# values (39.2 to 50.7), and zircon saturation temperatures (745 to 846 °C); and with negative εHf (t) values (−8.0 to −1.9); therefore, they resulted from the partial melting of the ancient felsic lower crust accompanied by the incorporation of mantle-derived material during the intraplate magmatism process. Research on Tailu pluton has provided more sufficient evidence for the evolution process of the Qinling–Qilian conjunction zone in the Early Paleozoic, associated with evolution of the Wushan–Shangdan Ocean, the northern part of the Proto-Tethys Ocean. [ABSTRACT FROM AUTHOR]

This study presents the chemical and mineralogical composition of clay deposits and associated rock types within the Ropp Complex in order to assess the influence of parent lithology on the kaolinization, genesis, and utility of the deposit. Representative kaolin samples from E horizons of the weathering profiles and their bedrocks were collected from six sites in the Ropp Complex. Clay mineralogy was determined via the XRD technique, while a geochemical analysis was conducted using XRF, SEM coupled with EDS, and ICP-MS. The results showed that all kaolins dominantly contain kaolinite with a content of 77%–98% except for the AS1 kaolin with only minor kaolinite (20%) but mainly illite (65%). The notably lower crystallinity of kaolinite (HI value of 0.53–1.1) as well as its markedly small grain size is consistent with the formation of kaolinite from intensive chemical weathering of igneous rocks. The AS1 kaolin was probably formed from hydrothermal alteration in the burial stage due to the heating of groundwater by the late volcanism. Mobile trace elements (Sr, Ba, and Eu) exhibited a depletion trend, while immobile elements (Hf, Ta, Th) showed enrichment. The relatively more zirconium in kaolins implies the formation of low-temperature kaolinization. The notably high kaolinite content, accompanied by reasonable levels of Fe2O3 and TiO2, signifies a medium-grade quality. Furthermore, chondrite-normalized rare earth element (REE) patterns exhibit congruent trends in rocks and kaolin samples, indicating a relative enrichment in light rare earth elements (LREEs) alongside a discernible negative Eu anomaly. The abundant kaolinite and silicon–aluminum composition make the kaolins suitable for refractories, pharmaceutics, cosmetics, and supplementary cementitious material (SCM). [ABSTRACT FROM AUTHOR]

Minerals with compositional zoning in volcanic products are widely used to decipher the history of magmatic evolution. However, structural information, which reflects physical conditions and crystallization equilibrium, has often been overlooked. This study presents the first report on the structural zoning of deep‐derived biotite phenocrysts through investigations of metaluminous rhyolite from Long Valley, CA. Biotite is enriched in Si, Mg, and K and depleted in Fe3+, Ti, and AlIV in core zones compared with rims. In situ structural analyses, including micro X‐ray diffraction, Raman spectroscopy, and transmission electron microscopy, were conducted to identify cores with perfect 2M1 polytype and disordered rims of biotite. The results demonstrate the effectiveness of these methods in revealing various (micro)polytypes of a single species, which occur at different crystallization temperatures, pressures, supersaturation levels, and oxygen fugacities. The concept of structural zoning is introduced here to describe the different structural features distributed systematically in various parts of minerals. By combining structural and chemical zoning, we illustrate a two‐step growth for samples: equilibrium crystallization of the highly ordered cores in a deep magma reservoir with high temperature and pressure, followed by rapid growth of disordered rims during magma mixing in a crystal mush. We further discuss the implications of these findings for reflecting the plumbing system structure and eruption history of rhyolitic magma over extended periods. Our study underscores the remarkable sensitivity of structural zoning in delineating the crystallization conditions of minerals and documenting the environmental changes within magma. Plain Language Summary: The chemical zoning of minerals has been widely applied to reconstruct the evolutionary history of igneous rocks. However, for samples with complex crystallization histories, relying solely on compositional data may lead to misinterpretations because of elemental mobility and inhomogeneity. Therefore, chemical results must be complemented with structural information, which is a more sensitive and intuitive indicator of environmental changes, the crystalline state, and the reaction equilibrium. This work represents the first comprehensive examination of the structural zoning of deep‐derived biotite phenocrysts. We conducted mineralogical studies on rhyolite from Long Valley, California, CA, considering it an active and representative crater related to large‐volume, silica‐rich systems. Our investigation focused on biotite exhibiting compositional zoning, while we also revealed structural differences between the core and rim portions of the biotite. By correlating structural zoning with chemical features, we elucidated different magmatic stages, including storage, upwelling, activation, and eruption. This research enables us to trace volcanic evolution via mineralogical studies—from minerals in deep magma reservoirs to shallow short‐term crystalline meshes where they experience repeated thermal replenishment and basaltic injection and finally erupt to the surface. Key Points: Through investigations of Long Valley metaluminous rhyolite, we reveal, and introduce the concept of structural zoning of mineralsDisplaying an ordered 2M1‐polytype core and a disordered rim, the structural zoning of biotite records two distinct stages of crystallizationTwo‐step crystallization of phenocrysts provides valuable evidence for reconstruction of the plumbing system and the magmatic evolution [ABSTRACT FROM AUTHOR]

Knowing accurate values of rock engineering parameters in hard rock condition is the key in estimating and adjusting TBM performance. In this study, TBM penetration per revolution (Pr) as driving parameter, TBM operational parameters including cutterhead torque (Tq), field penetration index (FPI), thrust force (Th), cutter load (Fn), cutterhead rotational speed revolution per minute (RPM), and also cutterhead diameter as a mechanical machine specification are used to predict geomechanical parameters including rock quality designation (RQD) and unconfined compressive strength (UCS) based on reverse analysis in three types of strong rocks (Tuff, Andesite, Diorite) along the Southern lot of Kerman water transfer tunnel; KrWCT. A soft computing method called least squares-support vector machine (Ls-SVM), is trained using operating and driving data as well as rock engineering parameters gathered from the KrWCT project which is excavated in hard rock condition using double shield TBM. Due to the lack of access to the excavation face in mechanized tunneling, the collection of geomechanical data on the rock mass is possible only through the examination of excavated material and limited inspections during cutterhead repairs. Therefore, this paper has tried to predict and classify the rock engineering factors using some indicators related to machine performance, mechanical specification, and TBM operational parameters. Among the data collected during the pre-construction and construction phases of the project, the dataset was classified into 42 zones, and the reasonable distribution intervals of the main tunneling factors corresponding to each zone were defined. New empirical equations are developed to estimate the properties of igneous rocks based on linear and non-linear multivariable regression (MR). Several loss functions were used to assess the performance and precision of the applied methods. The results of the proposed models indicate an acceptable and reliable accuracy. Highlights: TBM data predicts rock engineering properties in complex geological condition. Forecasting RQD and UCS in deep tunnels through strong rocks using reverse analysis. Developing empirical models for calculating UCS and RQD based on statistical analysis. Detailed analysis of Ls-SVM supervised network for rock geomechanical prediction. Examining model accuracy with various statistical indices and loss functions. [ABSTRACT FROM AUTHOR]

The issue of the age of rare-metal granites of the Zashikhinskoye field is discussed. To obtain U–Pb (ID TIMS) geochronological data, a modified "chemical abrasion" technique with preliminary high-temperature annealing was used for metamictic zircon. Estimates of the age of alkaline leucogranites and albitites coincide and correspond to the age of formation of rare-metal granites of the Zashikhinskoye field 267 ± 1 Ma. Within East Sayan, igneous rocks with close ages are not yet known. The closest area of magmatic activity of this time was the large zonal Khangai magmatic range, which arose under the influence of the mantle plume and is characterized by widespread development in its peripheral part of alkaline and bimodal associations, including rare-metal magmatic ones. The Zashikhinskoye field is more than 350 km from the edge of its range. Nevertheless, on the basis of geochronological and geochemical data, it was assumed that this field was associated with the activity of the Khangai plume. [ABSTRACT FROM AUTHOR]

The petrogenesis of extremely fractionated igneous rocks is closely linked to the evolution of the continental crust and the formation of rare metal mineralization. Extremely fractionated magmas evolve via fractional crystallization, hydrothermal evolution, and volatile-rich fluid–melt interaction, but the specific effects of these magmatic and magmatic–hydrothermal processes remain unclear. To understand the mechanisms by which extremely fractionated granitic magmas evolve, we characterized the geochemical and Fe isotope signatures of a suite of granites and pegmatites from the Baishitouquan (BST) granitic pluton in northwest China. The BST granitic system evolved from a high SiO 2 and volatile-poor system to a low SiO 2 and volatile-rich system as it transitioned from an evolutionary stage dominated by magmatic processes to one dominated by magmatic–hydrothermal processes. This transition is supported by changes in the degree of melt polymerization (NBO/T) and other geochemical indicators of fluid activity (e.g., TE 1,3 (REE tetrad effect), Zr/Hf, Nb/Ta, and F/Cl ratios), suggesting that extremely fractionated granites form as a result of a combination of fractional crystallization and volatile-rich fluid–melt interactions. The bulk-rock samples of the BST pluton exhibit significant Fe isotope variability, with δ56Fe values ranging from 0.40 ± 0.02‰ in the least evolved leucogranite (Zone-a) to 0.65 ± 0.02‰ in the most evolved topaz albite granite (Zone-e). Notably, the increase in bulk-rock δ56Fe values during magma evolution is accompanied by a decrease in SiO 2 contents, which is opposite to the general trend during granitic magma evolution. Given the correlations between δ56Fe values and indicators of magmatic differentiation (e.g., Fe 2 O 3T , Rb, (Na + K)/(Mg + Ca), and (La/Lu) N), the variability in bulk-rock Fe isotope composition of granites is likely due to changes in magma composition, with garnet removal being the most likely mechanism fractionating Fe isotopes. Rhyolite-MELTS modeling, coupled with geochemical and petrographic characterization, indicate that the high concentrations of F and H 2 O in felsic magmas likely play critical roles in structurally modifying granitic melts by dramatically reducing their viscosity and enhancing fluid flow. The distinct geochemical–isotopic features of granites can, therefore, be used as tracers for identifying magmatic–hydrothermal processes and, potentially, rare metal mineralization. [ABSTRACT FROM AUTHOR]

New U–Pb zircon geochronology identifies a latest Triassic (ca 214–201 Ma) igneous suite of tuff, hypabyssal dikes, and a pluton on the southern Kenai Peninsula, Alaska. The igneous suite was emplaced within Upper Triassic sedimentary rocks along the southern margin of Western Wrangellia, the western-most fragment of the Wrangellia composite terrane. The igneous rocks range from mafic (50.6% SiO2) to felsic (78.3% SiO2), characteristically have less than 1.55% K2O, and generally have low trace element abundances. The tonalitic and trondhjemitic magmas were largely sourced in mafic-rich lower crust and incompletely assimilated quartz and other mineral xenocrysts are common. Fractionation involving plagioclase and amphibole is indicated for some magmas and composite intrusions and igneous xenoliths indicate magma mixing was possible. Paleozoic and Precambrian inherited zircons and initial 87Sr/86Sr (0.704103–0.705609) and 143Nd/144Nd (0.512396–0.512777) ratios indicate that the Western Wrangellia crustal sources are heterogeneous and contain sialic components. The latest Triassic magmatism reflects processes that preceded Early Jurassic subduction along the Wrangellia composite terrane and Pacific Ocean plate boundary. These processes involved heating and melting of mantle lithosphere and lower crust as mantle instabilities accompanied the breaking of the plate boundary linkages. The Late Triassic transition to subduction along the Wrangellia composite terrane margin coincided with the transition to subduction cessation in the Late Triassic arcs of the western Intermontane terranes of Canada. The shift to subduction along the outboard Wrangellia composite terrane margin marks the beginning of the Pacific Ocean–Cordillera plate interactions that came to dominate the tectonic evolution of the northern Cordillera from the Early Jurassic to today. [ABSTRACT FROM AUTHOR]

Xilinhot City is a significant pastoral city in China where groundwater serves as the primary water source for the cold and arid pastoral regions. The formation and evolution of material components in groundwater, as well as groundwater quality, are directly linked to the health of pastoral residents. This study is based on the physical and chemical test results of 22 groundwater samples collected from the Xilinhot River Basin in Inner Mongolia. Various statistical analyses, including Piper and Chadha diagrams, as well as hydrogeochemical simulation methods, were employed to assess the hydrogeochemical characteristics and material composition sources of groundwater, evaluate groundwater quality and non-carcinogenic risks, and comprehensively discuss the impact of macro- and microelements on human health. The findings indicate that igneous rocks containing minerals such as potassium feldspar, plagioclase, and pyroxene contribute Na+, Cl−, and K+ to the groundwater, while sedimentary rocks containing minerals like dolomite and calcite supply ions such as Ca2+, Mg2+, and HCO3−. The groundwater quality is primarily classified as Class II–V, with F− and NO3− exhibiting varying hazard quotients for children and adults in the study area, though they do not pose a non-carcinogenic risk. Additionally, the enrichment of hardness, Ca2+, Mg2+, Na+, SO42−, and other indicators in localized areas exceeds the recommended values for drinking water, potentially impacting the digestive and urinary systems of the human body. There is a risk of excessive fluoride in areas where F levels exceed 1 mg/L. Furthermore, the content of beneficial micronutrients such as selenium (Se), zinc (Zn), boron (B), and germanium (Ge) is relatively low. Based on the elemental abundance characteristics and a comparative analysis of the chemical properties of groundwater across five regions of China, this comparison facilitates a discussion on the definition of healthy groundwater, particularly in relation to safe consumption in cold and arid regions. This study aims to highlight the health issues associated with drinking groundwater in the cold and arid regions of Mongolia. The findings serve as a valuable reference for efforts aimed at reducing the incidence of endemic diseases and enhancing human lifespan. [ABSTRACT FROM AUTHOR]

In this study, the effect of using waste granodiorite powder (WGP) as a cement replacement material in percentages ranging from 1 to 9% on various physical and mechanical properties of ordinary concrete was investigated. The resistance of produced concretes with WGP to the high temperature effects on the 28 days compressive strength were studied as well. Granodiorite is one of the well-known igneous rocks that have been used in previous research as a replacement for coarse or fine aggregates due to the hardness of its grains. However, rare studies have investigated its powder as a partial cement replacement material. Results showed the ability of investigated WGP with high surface area to act as a supplementary cementitious material that contributed to enhance the results of mechanical and physical properties of concrete. At traditional room temperature, the optimal replacement percentage was 7%, where the 28 days compressive and tensile strengths were improved by 28.3% and 17.3%, respectively. The optimal replacement ratio varied between 7 and 9% in the case of high temperatures, according to exposure time and temperature degree. Statistical and sensitivity analysis was conducted on 66 available compressive strength value represents all variables before and after elevated temperature exposure. While the regression equation showed good R2 value of 85.3%, sensitivity analysis indicated that compressive strength value is most sensitive to temperature, followed by WGP ratio and exposure time, with importance values of 56, 26, and 18 %, respectively. Results showed also that the setting times and consistency was decreased with increasing the replacement ratio with WGP, while the workability was slightly improved up to 5% replacement ratio. Furthermore, microstructure analysis showed that WGP can help to densify the concrete matrix due to its small size and ability to fill the interstitial voids in the concrete matrix. [ABSTRACT FROM AUTHOR]

This study examined hydrogeological factors, including specific capacity, transmissivity and hydraulic conductivity, in the Geumgang River region of South Korea. A total of 4,329 well data (3,337 from bedrock aquifers and 992 from alluvial and weathered soil/rock aquifers) were collected from the basic groundwater survey reports and validated. To analyze geology-related ground-water productivity in this study, specific capacity and transmissivity data of nine geological units were considered. Alluvial and weathered soil/rock aquifer wells exhibited average specific capacity and transmissivity values of 147 m3/day/m and 84.1 m2/day, respectively. Meanwhile, bedrock aquifer wells showed average specific capacity and transmissivity values of 13.4 m3/day/m and 13.0 m2/day, respectively. Notably, in terms of specific capacity and transmissivity, alluvial and weathered soil/rock aquifer wells were more productive than bedrock aquifer wells. In case of bedrock aquifers, non-porous volcanic rocks and Cretaceous igneous intrusive rocks showed relatively low productive features and meta-sedimentary rocks showed higher productivity than other geological units. Box plot analysis for logarithmic specific capacity values was used to decide the criteria for groundwater productivity of wells. For bedrock aquifer wells, this study suggested that the lower whisker (−0.413), 1/4 quartile (0.457), 3/4 quartile (1.05), and upper whisker (1.94) can be used as the criteria for very low, low, moderate, high, and very high productivity. Spatial statistical analyses using kernel density and optimized hot spot methods identified several potential sites for large-capacity groundwater development with high probability. These hot spots are located in crystalline gneisses at Gongju-Sejong area, in Triassic-Jurassic intrusive igneous rocks at Gimje-Jeongeup and Boeun areas, and in meta-sedimentary rocks at Nonsan-Geumsan, Yeongdong, Boeun and Hongseong areas. Specifically, the Okcheon meta-sedimentary rocks aquifer, which is a significant bedrock aquifer in the Geumgang River region and widely distributed throughout the Okcheon Belt, was suggested as a prime candidate for groundwater development. Major aquifers in Okcheon meta-sedimentary rocks are closely associated with intercalated thin beds of brittle quartzite or carbonate rocks with dissolved cavities. The Jurassic granites aquifer can also be served as another important bedrock and/or alluvial and weathered soil/rock aquifers in the Geumgang River region, owing to its widespread distribution and moderate groundwater-yielding productivity. This aquifer type is related to the development of a stratiform fissured layer and an upper saprolite part due to weathering processes. [ABSTRACT FROM AUTHOR]

The sandstone uranium deposits in the Kelulun Depression are the first commercially viable uranium deposits discovered in the Hailar Basin and the ore-bearing strata corresponding to the Lower Cretaceous Yimin Formation. However, the source of sedimentary matter, uranium source conditions, and uranium mineralization processes in the region have not been characterized. Accordingly, we analyzed the lithology, whole-rock geochemistry, zircon U-Pb ages, and trace elements of the Yimin Formation sandstones. The Yimin Formation sandstones were primarily composed of detrital grains with low compositional maturity. A geochemical analysis indicated that the parent rocks are felsic igneous rocks formed at an active continental margin with a moderately high degree of weathering. The detrital zircon U-Pb ages of the Yimin Formation 215–287 Ma with a peak at 230–260 Ma. Based on chronological, geochemical, and lithological data, we conclude that the Yimin Formation matter is derived from the Adunchulu Uplift on the western side of the Kelulun Depression and its parent rocks are Triassic granites. The Adunchulu uplift since the late Early Cretaceous and weathering and denudation of its uranium-rich granites provided ample matter and uranium. Therefore, the Kelulun Depression is a promising area for the exploration of sandstone uranium deposits. [ABSTRACT FROM AUTHOR]

This paper presents a complete map of the Mesozoic volcanic-plutonic complexes in the Taiwan Strait and its adjacent areas in terms of seismic profiles, ages, geochemistry, isotopic systematics, and published data. Two periods of igneous activity in the Taiwan Strait can be distinguished by seismic profiles: Jurassic (200.4–148.2 Ma); and Latest Jurassic/Cretaceous to Maastrichtian (144–66 Ma), of which the Cretaceous is the best preserved and could possibly be the most widespread. Mesozoic magmatic activity with the NE-striking distribution was migrating southeastward (oceanward). LA-MC-ICPMS zircon U – Pb dating yields the age data of 109.5 ± 0.4 Ma for PTDH1 granodiorite and 92.6 ± 0.4 Ma for PTDH4 rhyolite in the Taiwan Strait, respectively. The 581.66-m-thick Upper Jurassic volcanic rocks of the Chuan2 well are the thickest Mesozoic igneous rocks in the Taiwan Strait. The petrogenetic discrimination diagram of the Cretaceous volcanic-plutonic complexes along the coast of South China and the Taiwan Strait generally is belonging to volcanic arc or intraplate type calc-alkaline rock series. The high potassium calc-alkaline rock series of the Cretaceous volcanic-plutonic complexes that is most widely distributed in the coastal areas of South China and the Taiwan Strait. They are controlled by the subduction of the Palaeo-Pacific domain. [ABSTRACT FROM AUTHOR]

The West Kunlun orogenic belt located in the northwestern margin of the Qinghai-Tibet Plateau is an important record of the formation and northward extension of the plateau, but the current research mainly focuses on the tectonic activities of the Cenozoic era, and there is still considerable controversy regarding the formation and evolutionary history of pre-Cenozoic orogenic belts. This study focuses on Cretaceous sandstone samples from the Kedong region in the piedmont belt of the West Kunlun orogenic belt. U-Pb geochronological analysis was performed on 200 detrital zircon grains from the core samples. Combined with stratigraphic data and previous research, the main provenance direction was investigated to constrain the tectonic evolutionary history of the orogenic belt's peripheral regions. The results show that the detrital zircons are aged from 290 to 208 Ma, 520-310 Ma, 810-580 Ma, 1,400-880 Ma and 2,548-1,730 Ma, reflecting the complexity of provenance in this area. Based on a comprehensive analysis of the characteristics of igneous rocks, zircon age composition and stratigraphic conditions in potential source areas, it is concluded that the primary source regions include the East Kunlun orogenic belt and the North and South Kunlun terranes, with a low likelihood of contributions from within the Tarim Basin. The evolution of the West Kunlun orogenic belt can generally be divided into two opening and two closing phases. The detrital zircon ages predominantly exhibit two peak values at 259 Ma and 459 Ma, respectively representing the ages of transition from oceanic crust subduction to continentcontinent collision for the Paleo-Tethys Ocean and the Proto-Tethys Ocean. Additionally, there is a temporal gap between the evolution of the Proto-Tethys Ocean and the Paleo-Tethys Ocean. The Triassic period marks a transitional phase in tectonic evolution, shifting into an intracontinental evolutionary stage. This study provides new geochronological evidence for the early developmental history of the West Kunlun orogenic belt. [ABSTRACT FROM AUTHOR]

Devonian successions in the Calliope and Yarrol provinces of the northern New England Orogen in central to northern Queensland have a lithological assemblage and depositional environments indicative of a close association with a subduction-related volcanic arc. These rocks have been interpreted as related to island arc and backarc settings based on geochemical characteristics of magmatic rocks. We present new detrital zircon ages from the Devonian to lower Carboniferous successions of the Calliope and Yarrol province successions. Most samples have no or relatively few zircon grains extracted except for samples of quartz-rich sandstone in the Middle Devonian Erebus beds of Hunter Island, located 160 km north-northwest of Rockhampton and another sample in the Rockhampton district. The samples with abundant zircon, and some with less common zircon, have prominent peaks of mid Cambrian to Ordovician ages and are consistent with derivation from the northern Thomson Orogen where igneous rocks of this age are documented in the Charters Towers Province. These data indicate a connection between the Devonian arc-flank deposits of the northern New England Orogen and the Thomson Orogen, which had previously been well established for Carboniferous deep-marine sandstones of the subduction complex (e.g. Shoalwater Formation). These results favour an east-facing continental margin arc setting in the Devonian contra to intra-oceanic island arc settings previously proposed. Detrital zircon age spectra from sampled early Carboniferous units of northern New England Orogen association indicate a pulse of felsic magmatism of that age. KEY POINTS: Devonian quartz-rich sandstones from the northern New England Orogen have abundant detrital zircon ages of mid Cambrian to Ordovician indicating a provenance connection with the Charters Towers Province of the northern Thomson Orogen. These results confirm a provenance linkage to Gondwana and imply that the Devonian tectonic setting was a continental margin arc and associated forearc basinal infill. Geochemical comparisons suggesting an island arc setting have overly influenced previous tectonic interpretations. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of rock magnetic studies and relative paleointensity determinations from sediments of Lake Shira, Khakassia. Carrier minerals of natural remanent magnetization (NRM) were identified through hysteresis loop parameter measurements, thermomagnetic and X-ray diffraction (XRD) analyses. The sediment age was determined by radiocarbon dating; according to age estimates, the studied sediment sequence covers approximately the past 9100 years. To obtain high-quality relative paleointensity results, the determinations were made on linear segments of the pseudo-Arai‒Nagata diagrams. The quality was assessed by the criteria of the number of points in the calculations of slope, quality criterion (q), NRM fraction destroyed in the paleointensity determination interval, and relative paleointensity determination error (σ). According to the rock magnetic studies and XRD analysis, the magnetic carriers are mainly single-domain (SD) and pseudo-single-domain (PSD) magnetite and hematite. The comparison of the obtained relative paleointensity data with model paleointensities calculated for the Shira coordinates from the various models (CALS10K.1b (Korte et al., 2011), PFM9k.1 (Nilsson et al., 2014), HFM.OL1.AL1, CALS10k.2 ARCH10k.1 (Constable et al., 2016)), with absolute paleointensities and with the collection of results from the studies of sedimentary and igneous rocks and archaeomagnetic objects has shown that these data are in good agreement and share common trends. This provides grounds for applying this approach to paleointensity determination from bottom sediments of modern lakes using the pseudo-Thellier method. [ABSTRACT FROM AUTHOR]

Abstract—A collection of igneous rocks of the Ukrainian Shield sampled from the Korsun-Novomyrhorod pluton (age interval 1760–1735 Ma, Ingul Domain) and from the Korosten pluton (age 1760–1750 Ma, North-Western Domain) is studied. The magnetic and thermomagnetic properties of samples were studied and X-ray diffraction analyses were carried out to obtain reliable determinations of paleointensity (Banc), It is shown that the carriers of the characteristic component of natural remanent magnetization are single- and small pseudo-single-domain magnetite grains. Banc was determined by two methods: through the Thellier‒Coe procedure with pTRM checks and by Wilson method. Paleointensity determinations are obtained from five sites and shown to meet quality criteria. For all sites, Banc and the virtual dipole moment (VDM) values are extremely low, varying within the ranges 3.6–9.76 μT and (0.92–2.43) × 1022 Am2, respectively. The analysis of the data from the paleointensity world database (WDB) indicates that the geodynamo operation mode in the Proterozoic can be characterized by an alternation of strong and weak dipole regimes, but the validity of this conclusion entirely depends on the reliability of data reported in the literature and presented in the WDB. [ABSTRACT FROM AUTHOR]

Post‐collisional potassic‐ultrapotassic rocks can provide key clues to the change of the recycled material type and/or tectonic transition in subduction‐related zones. Despite continental materials widely recognized in their sources, it remains unclear whether such continental materials were contributed by former oceanic subduction or recent continental subduction. Here we address this issue by systematically investigating previously reported and our new chemical and Sr–Nd–Pb isotopic compositions of the post‐collisional K‐rich rocks in Southeast Tibet. Kink‐like compositional variations provide solid evidence for a primary control of fractional crystallization on the evolution of these K‐rich magmas. Their primary melts are demonstrated to have been produced by partial melting of phlogopite‐bearing peridotites in subcontinental lithospheric mantle (SCLM). The trace element and Sr–Nd–Pb isotopic signatures argue against involvement of the deeply subducted Indian continent but suggest a great contribution from sediments in oceanic slabs. A thinned (∼70–100 km) and hot (∼55–70 mW/m2) lithosphere is also unraveled beneath Southeast Tibet during the potassic‐ultrapotassic magmatism. Together with geophysical data, here we suggest a two‐stage geodynamic model for post‐collisional potassic‐ultrapotassic magmatism in Southeast Tibet: (a) Before the Indian‐Asia continental collision, phlogopite/K‐richterite‐bearing SCLM sources were formed through oceanic subduction‐related metasomatism; (b) After the Indian‐Asia continental collision, asthenosphere upwelling induced by post‐collisional tectonic extension or deep subduction of the Indian continental slab caused lithospheric thinning, partial melting of pre‐existing phlogopite/K‐richterite‐rich SCLM and thus K‐rich magmatism. This study provides new insights into the role of oceanic subduction and continental collision in post‐collisional potassic‐ultrapotassic magmatism. Plain Language Summary: Potassic‐ultrapotassic rocks, a special group of K‐rich igneous rocks with K2O > 3.0 wt.% and K2O/Na2O > 1, have been widely recognized in post‐collisional settings. A large part of them also has low SiO2 (<56 wt.%), high MgO (>6.0 wt.%) and Mg# (>0.65; molar Mg/(Mg + Fe)), suggesting derivation from the mantle depths. Post‐collisional K‐rich rocks are widely distributed within the Himalaya‐Tibet Orogen. Over the last decades, numerous studies have focused on these K‐rich rocks because of their potentially great importance for understanding plateau uplift, continental subduction and Cu‐Mo‐Au mineralization. Although there is an increasingly clear consensus on the relevance of the deeply subducted Indian continent in the formation of the post‐collisional (<25 Ma) K‐rich rocks in Southwest Tibet, there remain considerable uncertainties about the mechanism of the potassic‐ultrapotassic magmatism in Southeast Tibet. Based on the systematic investigation of previously reported and our new chemical and Sr‐Nd‐Pb isotopic data of the post‐collisional K‐rich rocks in Southeast Tibet, here we unravel phlogopite‐bearing peridotite lithospheric mantle sources for these K‐rich rocks. This study highlights that the potassic‐ultrapotassic magmatism in Southeast Tibet was a combined result of pre‐collisional oceanic subduction‐related metasomatism and post‐collisional lithospheric thinning, a mechanism distinct from that in Southwest Tibet. Key Points: A primary control of fractional crystallization on magmatic evolution of post‐collisional potassic‐ultrapotassic rocks in Southeast TibetSubducting sediments within oceanic slabs rather than the deeply subducted Indian continent provided K‐rich materials in the sourcesA critical role of post‐collisional lithospheric thinning in the post‐collisional potassic‐ultrapotassic magmatism in Southeast Tibet [ABSTRACT FROM AUTHOR]

Some rock and soil samples exhibit significant loss of magnetic susceptibility (χ) with increasing applied field amplitude even at relatively low (10–100s of A/m) fields, a behavior which remains unexplained. Exceptionally strong negative field‐dependence of susceptibility (χHD) is present in sandstones and altered intermediate‐felsic igneous rocks in several cores from the northeastern Oklahoma subsurface. These same rocks also show elevated frequency‐dependence of susceptibility (χFD), with reasonable correlation of χHD to χFD, and frequency‐dependent χHD. Results from multiple characterization methods indicate that strongly negative χHD in these rocks is linked to a yet‐unidentified phase which begins the approach to magnetic saturation in low fields (<1 mT/800 A/m), shows elevated χFD to low temperatures, is unstable at high temperatures, possesses significant anisotropy of magnetic susceptibility, and becomes paramagnetic above ∼83°C. Clear associations with fluid alteration features indicate that this material may be highly relevant to rock alteration, diagenetic, and environmental studies. Plain Language Summary: Magnetic susceptibility is usually measured using weak magnetic fields, and in many geological materials the value depends on the strength of the field used. In the low‐field range, this usually results in slightly higher susceptibility values as field strength increases. In some rocks and soils, however, susceptibility decreases with increasing applied field, which has not been explained. The lowermost sandstones and uppermost igneous rocks in the northeastern Oklahoma subsurface have been found to provide prominent examples of this "negative field‐dependence" of susceptibility. When susceptibility of the same rocks is measured using an alternating‐current field, the results are also highly dependent on the frequency of that field. The strength of these behaviors is correlated, and both are found to be associated with a yet‐unidentified magnetization carrier with an apparent Curie temperature of ∼83°C. Through direct‐current measurements, it is apparent that the negative field‐dependence is due to this mineral approaching magnetic saturation at unusually low fields relative to most natural materials. The magnetic behavior is associated with other evidence of water‐rock interaction, which may prove to be a useful indicator of chemical conditions of alteration, diagenesis, and weathering. Key Points: Negative field‐dependence of magnetic susceptibility is poorly understood and occurs in rocks near the basement unconformity of NE OklahomaThis behavior is due to low‐field magnetic saturation of an unknown magnetic carrier with a magnetic ordering temperature near 80°CThe carrier is associated with frequency‐dependence of susceptibility and fluid alteration and may complicate environmental studies [ABSTRACT FROM AUTHOR]

Image-based automatic fracture extraction methods have many practical applications in geological and engineering. Fracture identification and quantitative characterization require the means of interpreting and statistically analyzing image data. In comparison to traditional digital image processing methods, supervised semantic segmentation methods based on Convolutional Neural Networks (CNN) offer distinct advantages in extracting fractures from CT images. The study analyzes the characteristics of fracture areas in CT images and compares the results obtained through traditional threshold segmentation methods with those achieved using deep learning techniques. An integrated approach combining interactive image segmentation was proposed in this study to extract the fractures, in which deep learning methods were to determine the fracture areas, as well as morphological operation and threshold segmentation methods were adopted to extract the fractures from the small target areas. The implementation of this method significantly enhances the efficiency of extraction results compared to manual fracture extractions. This study selected CT images of igneous rock with a resolution of 0.7 um as the research object. DeepLab V3 + and UNet3 + network models in the PaddleSeg framework were used for the deep learning process. Highlights: The characteristics of fracture morphology, opening degree and gray level in CT images of rock are analyzed. The effects of traditional segmentation algorithm and deep learning algorithm in fracture extraction were compared. A new method combining deep learning and threshold segmentation is proposed to extract fractures. [ABSTRACT FROM AUTHOR]

The article presents the results of hydrochemical studies of the Nizhne-Shchapinsky (Kipely) carbon dioxide thermal (39°C) springs in 2021. The springs are discharged within the Shchapinsky graben near the active Kizimen volcano. The results include macro- and microcomponent composition, isotopic composition of source water, some free gas components, and dissolved strontium. The results are discussed using previously published and archive data, taking into account the geological and structural position of the area, water–rock interaction, as well as using simple thermochemical calculations in order to explain the rare, but characteristic of the chemical composition of some carbon dioxide waters, predominance of magnesium over calcium. It has been shown that the waters of the Nizhne-Shchapinsky springs are formed as a result of mixing of two components: deeper and more heated sodium chloride water and more surface, less heated water with the composition Mg–Ca– , formed due to interaction with carbonate-bearing rocks and CO2 of igneous origin. [ABSTRACT FROM AUTHOR]

Zircon, with a chemical formula of ZrSiO4, is a widely used mineral for determining the crystallization age of igneous rocks. It is also used to constrain the timing of metamorphic events from its overgrowth or recrystallized domains. Furthermore, detrital zircon grains can provide information on the sedimentary provenance. Due to the trace amounts of uranium (parent) which decays into its daughter element (Pb), it is a prime geochronometer for the majority of magmatic and metamorphic rocks. With high-precision analytical instruments, such as TIMS, SIMS, and LA-ICP-MS, huge amounts of geochronological and trace element data from zircon have been generated around the globe to date. Target domains within zircon grains are analyzed to extract geochemical and geochronological records using spatially resolved techniques such as ion probes or laser ablation coupled with mass spectrometry. Before any such analysis, the zircon grains are examined for internal structures, growth zoning, and the presence of tiny inclusions. However, many researchers analyze multiple domains within single zircon grains for U-Pb isotope analysis with little regard for their internal structures, particularly crystallographic orientations. Hence, they may obtain mixed ages with variable discordance, leading to imprecise interpretation especially when the growth domains are not well-identified. Particularly, zircon grains that contain multi-growth domains or have local internal deformations within a single grain may not produce geologically meaningful age results if the analyses are conducted on mixed domains. This study presents a brief review on zircon geochronology, how to identify and visualize micro-deformations in metamorphic zircons through the EBSD analysis, and the effects of micro-deformation on age results. Examples from a case study conducted on zircons hosted in the Himalayan high-pressure eclogites are presented that show intra-grain plastically deformed domains and their effects on the corresponding age results. [ABSTRACT FROM AUTHOR]

The Molo‐Sarychat multiphase pluton is situated along the fault systems of the 'Main Structural Line of Tien Shan' (known also as the 'Nikolaev Line'). It comprises mafic to intermediate (monzodiorite, monzonite) and silicic (quartz monzonite, monzogranite and leucogranite‐alaskite) rocks, followed by the late mafic (monzodiorite‐porphyry to lamprophyre) dikes. Isotopic U‐Pb zircon dating of quartz monzonite and monzogranite indicates their Early Permian age (ca. 293 to 286 Ma). The rocks appear to have been produced by remelting of a partially crystallized (mush) magma batch at deeper levels, which is evident by the presence of zircon antecrysts dated at some 306 to 320 Ma. These geochronological data are consistent with a post‐collisional setting of the pluton that occurred after the cessation of subduction, which affected the Middle Tien Shan in the Late Palaeozoic. Geochemical signatures of the igneous rocks from the Molo‐Sarychat pluton correspond to high‐K calc‐alkaline to shoshonitic series intrusions emplaced in a post‐collisional setting. An initial shoshonitic magma was produced by a low‐degree partial melting of the metasomatically enriched upper mantle, with amphibole fractionation in a deep (lower crustal) magma chamber. In this evolution, a generation, under the influence of mantle‐supplied fluids and heat, granitic magmas in the crustal protolith can be suggested, with further mixing/mingling of the mantle‐derived mafic (shoshonitic) magma and mantle‐induced crustal granitic magma, followed by the magma fractionation and emplacement at shallower crustal levels. The skarn‐porphyry Mo‐Cu‐W(‐Au) mineralization associated with the Molo‐Sarychat pluton complements the group of similar deposits associated with high‐K calc‐alkaline to shoshonitic series intrusions in the Middle Tien Shan and globally. The characteristic Mo‐W‐Cu‐Au metal assemblage and the high endowment in W and particularly Mo can be related to the fertilization of subduction‐modified subcontinental mantle in these metals, and its subsequent involvement in the magma generation in post‐collisional setting. A certain role of crustal magma sources in the strong Mo endowment can be considered that would be consistent with some A‐type granitoid affinity of the igneous rocks. The Early Permian age of these high‐potassic intrusions supporting their post‐collisional emplacement is remarkably similar to the age of hydrothermal alteration assemblages, previously reported for the super‐large Kumtor Au deposit situated in a similar post‐collisional setting nearby. [ABSTRACT FROM AUTHOR]

The Mesozoic subduction zone over the Dongsha Waters (DSWs) of the South China Sea (SCS) is a part of the westward subduction of the ancient Pacific plate. Based on the comprehensive interpretation of deep reflection seismic profile data and polar magnetic anomaly data, and the zircon dating results of igneous rocks drilled from well LF35-1-1, the Mesozoic subduction zone in the northeast SCS is accurately identified, and a Mesozoic subduction model is proposed. The accretion wedges, trenches, and igneous rock zones together form the Mesozoic subduction zone. The evolution of the Mesozoic subduction zone can be divided into two stages: continental subduction during the Late Jurassic and continental collision during the late Cretaceous. The Mesozoic subduction zone controlled the structural pattern and evolution of the Chaoshan depression (CSD) during the Mesozoic and Neogene eras. The gas source of the hydrate comes from thermogenic gas, which is accompanied by mud diapir activity and migrates along the fault. The gas accumulates to form gas hydrates at the bottom of the stable domain; BSR can be seen above the mud diapir structure; that is, hydrate deposits are formed under the influence of mud diapir structures, belonging to a typical leakage type genesis model. [ABSTRACT FROM AUTHOR]

Developments in ultradeep azimuthal resistivity (UDAR) technology has recently progressed from their application in high-angle and horizontal wells to low-angle and vertical wells. This has presented the opportunity to assess their suitability as derisking tools because of their ability to look ahead of the bit, up to c. 100 ft (c. 30.5 m). Dominated by a complex interplay of structure, sedimentation, and volcanic activity, the NE Atlantic Margin presents a challenging environment to plan and drill wells safely and within planned budget, with many wells drilled within the Faroe–Shetland Basin (FSB) currently the most expensive to-date within the United Kingdom continental shelf (UKCS). The limited number of wells drilled in the FSB and their geographical sparsity relative to those of other areas of the UKCS, make offset analysis and derisking a challenge. The often-unpredictable distribution of igneous rocks throughout the basin presents significant challenges in the planning and drilling of oil and gas wells. Up to 88% of igneous intrusions within the FSB are estimated to be below seismic resolution, which alongside variation in composition, presents significant issues related to drilling safely, efficiently and successfully. Within this paper, we investigate the use of UDAR technology and how they could be deployed in areas of complex volcanic geology such as the West of Shetland (WoS). This paper reviews the nature of the drilling experiences within the FSB to date, the impact it has on exploration, and how improvements in drilling technology could help decrease nonproductive time (NPT). [ABSTRACT FROM AUTHOR]