Search Results (375)

The subduction polarity of the Mongol–Okhotsk Ocean (MOO) during the Mesozoic remains contentious, with competing models advocating for southward, northward, or bidirectional subduction. The Xifengshan area in the northern Great Xing’an Range, located south of the Mongol–Okhotsk suture, preserves Early–Middle Jurassic calc-alkaline intrusions, which provides important constraints on this debate. We present zircon U–Pb ages, whole-rock geochemistry, and Lu–Hf isotopes for diorite, granodiorite, and monzogranite from this area. Zircon U–Pb dating yields ages of 178–173 Ma, defining a short-lived magmatic pulse. The suite is calc-alkaline, enriched in LILE and depleted in Nb–Ta–Ti, typical of arc magmas. The diorite represents the most mantle-proximal preserved end-member of the system and records substantial mantle input from a slab-modified mantle wedge. Geochemical trends (increasing Rb/Th, decreasing Sr with differentiation) reflect plagioclase-dominated fractional crystallization with minor AFC. Local adakitic-like signatures are better interpreted as differentiation-related effects than as direct evidence for slab melting. Zircon εHf(t) values (+1.62 to +11.55) and T_DM1 ages (363–772 Ma) are greater than the crystallization ages, indicating substantial juvenile input together with the variable involvement of previously accreted crustal components. We suggest that mantle wedge-derived magmas modified by slab-related components triggered the partial melting of the arc crust, whereas subsequent intracrustal differentiation produced the observed intrusive sequence. The continental arc system provides robust evidence for the southeastward subduction of the MOO during the Early–Middle Jurassic, resolving the long-standing polarity controversy. Full article

The urea cycle (UC) is usually described as the hepatic metabolic pathway responsible for ammonia detoxification, but its role extends far beyond nitrogen (N) elimination to include cellular biosynthesis and metabolic signalling. In cancer cells, the UC is reconfigured/reorchestrated to support high anabolic demand, often involving the dysregulation of key enzymes such as ASS1, ASL, OTC and CPS1. While these changes support biomass production and stress resistance, they also generate measurable biochemical signatures through kinetic and thermodynamic isotope effects (¹⁴N/¹⁵N). In this review, we summarise UC biochemistry and recall key enzymatic mechanisms. Together, these elements provide a mechanistic framework to interpret changes in ¹⁵N abundance observed in tumour tissues and cells. We discuss how the redirection of N flux toward nucleotide and polyamine synthesis, coupled with partial excretion of ¹⁵N-depleted urea, may shape the isotopic composition of cancer cells. By integrating molecular oncology with stable isotope analysis, this review highlights the potential of natural isotope abundance as a functional readout of tumour metabolism and supports further investigation of its translational relevance in cancer phenotyping and monitoring. Full article

The northwestern Amazonian Craton exposed in eastern Colombia preserves a complex Proterozoic tectonothermal history. In this study, we present new zircon and apatite U–Pb geochronological data from orthogneisses of the Guaviare Complex (Termales Gneiss unit) to constrain the timing of crust formation, metamorphism, and subsequent thermal events. Zircon U–Pb data define a dominant concordant population at ca. 1.30 Ga, interpreted as the crystallization age of an igneous protolith. This age is consistent with Mesoproterozoic A-type magmatism previously recognized in the region and consistent with emplacement under intracratonic extensional conditions, as suggested by previous studies. A limited number of discordant zircon analyses indicate Pb loss and/or partial isotopic resetting between ~1.0 and 0.6 Ga, although no well-defined metamorphic zircon population is identified. Meanwhile, apatite U–Pb analyses from key samples yield consistent lower intercept ages between 633 ± 16 Ma and 543 ± 8 Ma, indicating a widespread Ediacaran thermal disturbance that may have affected the Guaviare Complex, temporally overlapping with alkaline magmatism in the northwestern Amazonian Craton, including the San José del Guaviare Nepheline Syenite. However, alternative mechanisms such as fluid-assisted Pb mobility, regional reheating, or prolonged cooling cannot be excluded. Finally, the combined zircon–apatite dataset highlights the value of multi-chronometer approaches for resolving complex thermal histories in cratonic domains. Full article

This study investigates the origin and Nb–Ta enrichment mechanisms of the Middle Triassic Nare Alkaline Rocks in Gerze, central Tibet, using petrological, geochemical, and geochronological data. U–Pb zircon dating constrains the trachyte formation to the Middle Triassic, identifying NaOI as the oldest known seamount fragment in the zone and providing a key age for the early Meso-Tethyan Ocean. Whole-rock geochemistry data show the basalts possess typical OIB signatures, derived from a depleted mantle source modified by a mantle plume. The trachyte originated via a multi-stage process: Middle Triassic basaltic magmas underplated to form a deep-seated magma chamber, underwent high-pressure fractional crystallization, and the resulting crystal mush was later reheated and partially melted by subsequent magmas to generate trachytic melt. This model is supported by Hf isotopes and mineral chemistry. The rocks formed in a mature, thick-lithosphere intra-oceanic plate setting. Niobium occurs primarily as ilmenorutile with high Nb₂O₅ content, but its low modal abundance and very fine grain size imply low beneficiation recovery and limited current economic potential. However, the NaOI formed in an intra-oceanic island setting and hosts an early-stage Nb–Ta metallogenic system linked to alkaline magma differentiation, highlighting their potential for rare-metal exploration. Full article

Variscan two-mica granites are widespread in the Trás-os-Montes region (NE Portugal), yet their emplacement ages, petrogenesis, and relationship with Variscan deformation phases remain poorly constrained. This study integrates U–Pb zircon geochronology, whole-rock geochemistry, and oxygen isotope data to characterise four peraluminous two-mica granites in the Trás-os-Montes area (Fornos, Carviçais, Fonte Santa, and Bruçó) and to refine their tectonomagmatic context within the Central Iberian Zone. All granites are S-type, ilmenite-series, and derived from reduced magmas, as indicated by their strongly peraluminous compositions, mineral assemblages (muscovite ± biotite), absence of magnetite and presence of ilmenite, and high δ¹⁸O values (>11‰), consistent with partial melting of metasedimentary crust. U–Pb ages reveal two distinct magmatic pulses: an older event at ~340 Ma (Fornos and Fonte Santa granites), predating the onset of C3 deformation and likely associated with late C1 crustal thickening to early C2 tectonics, and a younger pulse at ~320–318 Ma (Carviçais and Bruçó granites). These magmatic pulses are linked to contrasting structural controls, with the older granites emplaced within regional-scale antiforms and the younger intrusions localised along structures related to C3 deformation. Together, these results document two discrete crustal melting events separated by ~20 Ma and record a progressive shift from fold-controlled to strike-slip-dominated granite emplacement during Variscan orogenic evolution. Moreover, the study highlights that tungsten mineralisation is preferentially associated with reduced, crust-derived granites emplaced during specific tectonic regimes, providing new constraints for metallogenic models in NW Iberia. Full article

The hydrothermal-filling-type tremolite jade (nephrite) deposit in sanchakou, Qinghai Province is hosted in marine dolomite, and its ore-forming fluid sources and metallogenic mechanisms remain poorly constrained. Here, we conducted an integrated study involving field geological mapping, petrographic observations, and geochemical analyses (major and trace elements, REEs, Sr isotopes) to constrain material sources, fluid physicochemical features and mineralization processes of the deposit. Results show that the ore-forming fluids were derived from deep crust, with homogeneous initial ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.70949 to 0.70959, distinctly higher than the host dolomite (~0.707683), indicating intensive water–rock interaction with Sr-radiogenic lithologies during fluid upwelling. The host dolomite provided the main Ca and Mg, while Si and partial Mg were sourced from deep Si-Mg rich hydrothermal fluids, with negligible contribution from coeval gabbro. The ore-forming fluids were rich in Si, Mg, large-ion lithophile elements and volatiles (e.g., F⁻), characterized by medium-high to medium-low temperature evolution and fluctuating oxidation states. Mineralization can be divided into four stages: deep fluid generation and migration, infiltration metasomatism and silicification, tremolite crystallization at peak oxidation, and open-space filling and jade precipitation. High-quality tremolite jade mainly formed via pulsed hydrothermal injection and direct crystallization in tectonic fractures. This study establishes a genetic model for hydrothermal-filling-type nephrite, enriching relevant metallogenic theories and supporting subsequent exploration. Full article

Pegmatites with miarolitic cavities have not previously been reported from the Larsemann Hills, East Antarctica, and their age and origin remain poorly constrained. We report the first geochemical and geochronological data for fluorapatite from a newly discovered pegmatite with miarolitic cavities in the Larsemann Hills. Large Fe-rich fluorapatite crystals (up to 5 cm) contain abundant oriented monazite-(Ce) inclusions and display elevated REE (1397–7966 ppm), relatively high Y (945–4192 ppm), and low Sr (52.2–83.5 ppm). Their trace-element signatures plot within the fields of partial melts, high-grade metamorphic rocks, and evolved fluid-rich magmatic systems. U–Pb dating of fluorapatite yields concordant ages of 519 ± 4 Ma (ID-TIMS) and 521 ± 31 Ma (LA-ICP-MS), indicating crystallization during the D₄ stage of the Pan-African orogeny. The isotopic equilibrium between apatite and monazite inclusions suggests synchronous formation and late-stage fluid overprinting. Combined geological, geochemical, and isotopic evidence shows that the pegmatite formed in situ as a product of anatexis of the Broknes paragneisses and evolved within a volatile-rich magmatic–hydrothermal system. These results provide the first direct age constraints on pegmatites with miarolitic cavities in Antarctica and shed new light on the final stages of East Gondwana assembly. Full article

Accurately tracing the geographical origin of Zanthoxylum schinifolium Sieb. et Zucc. is important for brand authentication, quality control, and food safety assurance. In this study, the stable isotope ratios (δ¹³C, δ¹⁵N, δ²H, δ¹⁸O) and the contents of 20 elements were analyzed in samples from three major production regions. Significant differences (p < 0.05) were observed in δ¹³C, δ²H, δ¹⁸O and most elemental profiles across origins. Chemometric methods—including principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and linear discriminant analysis (LDA)—were applied to classify samples by geographical origin. OPLS-DA identified key discriminators (VIP > 1) such as Ca, δ¹³C, Mg, δ²H, B, δ¹⁸O, Cr, Ni, Na, Pb, As, Co, Se, and Zn, achieving a classification accuracy of 96.8%. LDA based on the combined isotope and element datasets showed even higher performance, with an original discrimination rate of 98.4% and a cross-validated rate of 92.8%. The results demonstrate that integrating stable isotope and multi-element fingerprints with supervised classification models provides a reliable and effective approach for verifying the geographical origin of Zanthoxylum schinifolium, supporting its use in traceability systems and fair trade practices. Full article

Late Early Jurassic continental arc magmatism in the northern Greater Khingan Range enables the investigation of complicated tectonic processes associated with the subduction and closure of the Mongol–Okhotsk Ocean. To further clarify the timing, genesis, and geodynamic mechanisms driving the magmatic activity during this period, the present study addresses these critical questions by integrating zircon U–Pb geochronological, geochemical, and isotopic analyses of a wide variety of igneous rocks, including gabbro, gabbro-diorite, granodiorite, porphyritic monzogranite, and biotite-bearing monzogranite from the Fushan region. Zircon U–Pb geochronology constrains the timing of magmatic activity to 184–179 Ma, coinciding with active subduction phases. Geochemical data reveal arc-like signatures characterized by enrichment in light rare-earth elements (LREEs) and large-ion lithophile elements (LILEs), together with pronounced depletion in high field strength elements (HFSEs). A comprehensive analysis of geochemical and Sr–Nd–Hf isotopic signatures suggests that the mafic rocks originated from an enriched lithospheric mantle modified by subduction-related fluids and sediment-derived melts. By contrast, the granodiorite and porphyritic monzonite exhibit adakitic characteristics, indicating partial melting of the thickened Mesoproterozoic lower crust with contributions from mantle-derived or newly formed crustal material. The biotite-bearing monzogranite, with its pronounced Eu anomaly and lower zircon saturation temperatures, reflects advanced magmatic differentiation from a shallower source. These findings indicate extensive crust–mantle interactions during the southward subduction of the Mongol–Okhotsk Ocean, driven by high-angle subduction and slab rollback. Full article

Monitoring the hydrochemistry of groundwater and the H-O isotopes in the Jingpo Lake volcanic area, China, is fundamental to studying the mechanisms of volcanic and seismic events, as well as the associated hazards. To study the hydrogeochemistry of fluids in the Jingpo Lake volcanic area, water samples from seven sites were tested for hydrogeochemistry, H-O isotopes, and radon (Rn) content. The genesis and evolution of the groundwater system were elucidated through an integrated approach employing Gibbs diagrams, ionic ratio analyses, reservoir temperature estimation (silica–enthalpy method), and inverse geochemical modeling with PHREEQC. The results showed that the dominant water chemistry type was HCO₃⁻, primarily influenced by volcanic rock weathering and deep hydrothermal activity. Spring and well water were influenced by cation exchange, adsorption, and rock weathering dissolution. The H-O isotope composition and radon content indicate that atmospheric precipitation is the main source of supply, while well water is influenced by deep fluids. According to the Na-K-Mg triangle diagram, most of the groundwater was shallow and immature, whereas the well water was partially balanced. The temperature of the geothermal water was controlled by the geothermal gradient, depending on its occurrence and circulation depth. Additionally, the equilibrium temperature of the thermal reservoir was calculated using the silica–enthalpy equation method, with the concentrations of dissolved components in the water taken into account. The temperature of the thermal reservoir of the well water and the depth of groundwater circulation were estimated. The original reservoir temperature in the study area was calculated to range from 108 °C to 156 °C, with a geothermal water-to-shallow groundwater mixing ratio of between 71% and 85%. The estimated shallow temperature ranged from 64.9 °C to 74.9 °C. These hydrogeochemical signatures reflect active water–rock interactions and the contribution of deep-seated geothermal fluids, providing robust evidence for ongoing geothermal activity in the Jingpo Lake volcanic system. The findings enhance our understanding of the recent geological evolution and present-day hydrothermal processes of this potentially active volcanic field, which establishes a crucial hydrogeochemical baseline for future monitoring and hazard assessment studies. Full article

The Dengshang Mo deposit is a recently recognized porphyry-type system within the Yanliao Mo metallogenic belt of northern Hebei Province. However, its ore-hosting rhyolitic porphyry emplacement age and petrogenesis remain insufficiently understood. This study integrates petrography, zircon U–Pb geochronology, Lu–Hf isotope analysis, zircon trace element geochemistry, and whole-rock major- and trace element data to investigate the petrogenesis of the Dengshang rhyolitic porphyry and its genetic relationship with Mo mineralization. The ore-hosting porphyry is predominantly composed of quartz and plagioclase phenocrysts. LA-ICP-MS zircon U–Pb dating yields an emplacement age of 168.3 ± 1.2 Ma, indicating that the rhyolitic porphyry was emplaced during a Middle Jurassic magmatic episode. Petrological and geochemical characteristics classify the Dengshang rhyolitic porphyry as an I-type granite. Zircon ε_Hf(t) values range from −0.93 to −7.29, corresponding to two-stage model ages (T_DM²) of 1.27–1.67 Ga, which suggests derivation from partial melting of the Mesoproterozoic lower crust. Zircon trace elements display significant positive Ce anomalies (δCe = 10.14–332.85), and calculated oxygen fugacities (ΔFMQ = −0.65 to +2.77; median = +0.51) indicate moderately oxidized magmatic conditions conducive to Mo enrichment. These results collectively imply that the Dengshang rhyolitic porphyry was emplaced at ~168 Ma associated with paleo-Pacific plate subduction. This geodynamic setting triggered partial melting of Mesoproterozoic lower crust, producing oxidized magmas that experienced fractional crystallization prior to shallow emplacement. Our findings elucidate the petrogenesis of the Dengshang rhyolitic porphyry and its control on Mo mineralization, and contribute new insight for understanding porphyry Mo genesis within the complex tectonic evolution of the Yanliao Mo Belt. Full article

The Tawenchahanxi mining area, situated in the southeastern Qimantagh region of the East Kunlun Orogenic Belt, hosts a skarn-type Fe–polymetallic deposit associated with acidic granitic intrusions. Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating yields ages of 233.3 ± 1.2 to 234.3 ± 1.1 Ma for a granodiorite and 397.7 ± 1.4 Ma for a quartz porphyry, indicating two magmatic intrusive events during the Early Devonian and Late Triassic. The Early Devonian quartz porphyry is characterized by high ${\mathrm{S}\mathrm{i}\mathrm{O}}_2$ (72.39%–74.04%), high total alkalis (7.81%–7.83%), high TFeO (>1.0%) and high crystallization temperatures (~865 °C), together with low CaO (1.64%–1.70%) and MgO (0.61–0.65%), which are all consistent with A-type granite affinity. The granodiorite exhibits aluminum saturation index (A/CNK) values of 0.67–1.07 (metaluminous to weakly peraluminous) and belongs to the high-K calc-alkaline series. It exhibits moderate negative Eu anomalies (δEu = 0.71–0.83), and zircon saturation temperatures of ~748 °C, collectively indicative of I-type granite affinity. Both rock suites display depletion in Nb, Ta, and Sr and enrichment in Rb and LREEs. Zircon Hf isotopic data show εHf(t) values of −0.64 to 0.57 for the quartz porphyry and −4.37 to −1.06 for the granodiorite, indicating derivation primarily from partial melting of ancient crust with variable mantle contributions. These intrusions formed during post-collisional extensional (Early Paleozoic) and collisional to post-collisional (Late Paleozoic–Early Mesozoic) stages, respectively, associated with mantle magma underplating and crust–mantle mixing. Such processes formed the material basis for the polymetallic mineralization in the Tawenchahanxi district by providing Fe–Cu–Pb–Zn and other ore-forming elements from deeper crust. Full article

Mafic microgranular enclaves (MMEs) are widespread in granitic plutons and provide valuable insights into mush–magma mixing processes in crustal magma reservoirs. In this study, we characterize chemical zoning and Sr isotopic compositions of plagioclase in the MMEs, gabbro and host monzogranite from the Late Triassic Xiuyan pluton in East China, to constrain the origin of MMEs and the role of crystal mushes in magma mixing. The MMEs in the Xiuyan pluton are angular and range from centimeters to several meters in size. They exhibit sharp contacts with the host monzogranite and show diverse disequilibrium textures. Plagioclase in MMEs occurs as fine-grained antecryst with normal zoning (An_46–66 in the core and An_17–29 in the rim). The cores are commonly characterized by coarse sieve textures, patchy zoning, and resorption surfaces at core–rim boundaries. In situ Sr isotopic compositions show subtle but systematic core–rim variations, with (⁸⁷Sr/⁸⁶Sr)_i increasing slightly from cores (~0.70639) to rims (~0.70664), and rim values overlapping the whole-rock (⁸⁷Sr/⁸⁶Sr)_i of MMEs. These features suggest that the rim was crystallized from locally hybridized melts produced by interaction between interstitial melts in a basaltic mush and granitic magma. Plagioclase in the gabbro occurs as medium-grained phenocryst with normal zoning (An_46–65 in the core and An_18–27 in the rim) but shows nearly homogeneous (⁸⁷Sr/⁸⁶Sr)_i across individual grains (0.70612–0.70637), comparable to whole-rock gabbro values of 0.70623. The plagioclase cores in gabbro also show coarse sieve texture and patchy zoning with the resorption surface in the margin of the core and rim. We interpret the sieve textures in plagioclase cores from both MMEs and gabbro to record partial dissolution during rapid ascent and decompression of an initially H₂O-undersaturated, crystal-bearing basaltic magma, during which increased effective water activity reduced plagioclase stability prior to the growth of the rim. Plagioclase in the host monzogranite is medium- to coarse-grained, compositionally homogeneous, and characterized by low An contents (An_12–24) and elevated (⁸⁷Sr/⁸⁶Sr)_i of ~0.70828. We propose that MMEs in the Xiuyan pluton formed when semi-consolidated mafic mush was mechanically disaggregated into angular fragments and subsequently entrained into coexisting granitic melt. This study reveals that MMEs formed by mechanical disaggregation of a semi-consolidated mafic mush into angular fragments, followed by their entrainment into the granitic melts. Full article

Determining the age and origin of the “Huoshan Sandstone” holds significant geological implications for the stratigraphic division and correlation of Precambrian sequences in the North China Craton, provenance analysis, reconstruction of tectonic–sedimentary patterns, and paleogeographic settings restoration. This paper investigates the petrology, zircon U-Pb dating, Hf isotopes analysis, and zircon microzonation geochemistry of the “Huoshan Sandstone”. The “Huoshan Sandstone” is grayish-white, light gray, light yellow, purplish-red quartzitic sandstone and quartz sandstone, with a quartz content ranging from 85.5% to 97.8%. The quartz grains exhibit relatively straight contact edges, characteristic of low-grade metamorphosed quartzite. The protolith of the “Huoshan Sandstone” is a medium-grained quartz sandstone with dominant grain sizes of 0.30~0.50 mm, exhibiting well-rounded to subrounded grains and highly developed siliceous cementation characterized by secondary overgrowth. The zircon Th/U ratio confirms that the zircons in the “Huoshan Sandston” are mainly magmatic zircons. Most zircons exhibit extreme HREE enrichment and left-sloping REE patterns, and show significant positive Ce anomalies (Ce/Ce* of 1.06~290.68) and negative Eu anomalies (Eu/Eu* of 0.065~0.61). The age range of zircon ²⁰⁷Pb/²⁰⁶Pb is 1770 ± 20~2732 ± 16 Ma, and there are two obvious peaks at 1800 and 2500 Ma in the U-Pb age frequency histogram, the age of the intersection point on the concordia line is 2521 ± 31 Ma, and the age of the intersection point on the lower part of the line is 1829 ± 22 Ma. These two ages correspond to the timing of Neoarchean TTG gneiss formation through oceanic crust partial melting in the central North China Craton, and the ~1.85 Ga Paleoproterozoic thermal metamorphic event recorded in the Zhongtiao Group of the same region, respectively. The maximum depositional age of the “Huoshan Sandstone”, constrained by the youngest detrital zircon U-Pb ages at 1770 ± 20 Ma, indicates that its sedimentation occurred after 1770 ± 20 Ma (Late Late Paleoproterozoic). Furthermore, as it underlies the red shales of the Cambrian Mantou Formation as a distinct tectonic layer, it must have formed prior to the deposition of the Cambrian Mantou Formation. In addition, in situ Lu-Hf isotopic analyses of these zircons yielded two-stage model ages, mainly between 2.5 and 2.8 Ga, suggesting the provenance to be the Precambrian basement of the Zhongtiao Mountain region in the central North China Craton. It is inferred that the Precambrian strata in the Zhongtiao Mountain area were involved in the process of subduction, collage, and collision of the two continental blocks of the eastern and western parts of the North China Craton, and further confirmation is provided that the final collision of the two continental blocks to form the central orogenic belt occurred in the late Palaeoproterozoic. Full article

The Seulawah Agam volcano, located in Aceh, hosts one of Indonesia’s largest unexploited geothermal resources that is included in the Indonesian Green Energy Program. Previous studies of the Seulawah geothermal system (SGS) have used partial data and methods without developing a comprehensive conceptual model of the reservoir and its fluid flow and heat transfer patterns. This study aims to characterize the groundwater flow and heat transfer patterns of the SGS through numerical modeling based on integrated geological, geophysical, and geochemical data. Numerical modeling was conducted along two representative transects: Ie Seum, Ie Jue, and Kawah van Heutsz manifestations. MODFLOW 6 was used to model groundwater flow and heat transfer using a new conceptual model derived from magnetotelluric data, chemical composition and physical properties of the fluid, isotopic data, and mineragraphic data. The low resistivity anomalies are closely related to fluid discharges beneath the Ie Seum and Ie Jue areas. The depth of the Ie Seum reservoir is around 1.0–2.5 km, with estimated temperatures of 120–242 °C, while the depth of the Ie Jue and Kawah van Heutsz reservoirs is between 0.8 and 2.5 km, with estimated temperatures of 150–316 °C. The modeling suggests that the Ie Seum and the Ie Jue–Kawah van Heutsz systems represent regional groundwater and intermediate-local flow regimes, respectively. It is suggested that drilling be conducted around the local Ie Jue hydrothermal system, which is more economical given the shallower reservoir and higher temperature. Full article