Search Results (119)

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these giant deposits remain poorly understood. Mafic microgranular enclaves (MMEs), mafic dikes, and multiple porphyries have been documented in the Saindak mining area. This work examines both the ore-rich and non-ore intrusions in the Saindak porphyry Cu-Au deposit, using methods like molybdenite Re-Os dating, U-Pb zircon ages, Hf isotopes, and bulk-rock geochemical data. Geochronological results indicate that ore-fertile and barren porphyries yield ages of 22.15 ± 0.22 Ma and 22.21 ± 0.33 Ma, respectively. Both MMEs and mafic dikes have zircons with nearly identical ²⁰⁶Pb/²³⁸U weighted mean ages (21.21 ± 0.18 Ma and 21.21 ± 0.16 Ma, respectively), corresponding to the age of the host rock. Geochemical and Sr–Nd–Hf isotopic evidence indicates that the Saindak adakites were generated by the subduction of the Arabian oceanic lithosphere under the Eurasian plate, rather than through continental collision. The adakites were mainly formed by the partial melting of a metasomatized mantle wedge, induced by fluids from the dehydrating subducting slab, with minor input from subducted sediments and later crust–mantle interactions during magma ascent. We conclude that shallow subduction of the Arabian plate during the Oligocene–Miocene may have increased the flow of subducted fluids into the sub-arc mantle source of the Chagai arc. This process may have facilitated the widespread deposition of porphyry copper and copper–gold mineralization in the region. Full article

The El Bola mafic–ultramafic intrusion (EBMU) in Egypt’s Northern Eastern Desert represents an example of Neoproterozoic post-collisional layered mafic–ultramafic magmatism in the Arabian–Nubian Shield (ANS). The intrusion is composed of pyroxenite, olivine gabbro, pyroxene gabbro, pyroxene–hornblende gabbro, and hornblende-gabbro, exhibiting adcumulate to heter-adcumulate textures. Mineralogical and geochemical analyses reveal a coherent trend of fractional crystallization. Compositions of whole rock and minerals indicate a parental magma of ferropicritic affinity, derived from partial melting of a hydrous, metasomatized spinel-bearing mantle source, likely modified by subduction-related fluids. Geothermobarometric calculations yield crystallization temperatures from ~1120 °C to ~800 °C and pressures from ~5.2 to ~3.1 kbar, while oxygen fugacity estimates suggest progressive oxidation (log fO₂ from −17.3 to −15.7) during differentiation. The EBMU displays Light Rare Earth element (LREE) enrichment, trace element patterns marked by Large Ion Lithophile Element (LILE) enrichment, Nb-Ta depletion and high LILE/HFSE (High Field Strength Elements) ratios, suggesting a mantle-derived source that remained largely unaffected by crustal contribution and was metasomatized by slab-derived fluids. Tectonic discrimination modeling suggests that EBMU magmatism was triggered by asthenospheric upwelling and slab break-off. Considering these findings alongside regional geologic features, we propose that the mafic–ultramafic intrusion from the ANS originated in a tectonic transition between subduction and collision (slab break-off) following the assembly of Gondwana. Full article

The Yanbian area of Jilin Province is situated in the eastern segment of the southern margin of the Xing-Meng Orogenic Belt, representing a region that has been superimposed and reworked by the Paleo-Asian Ocean and Circum-Pacific tectonic event. To determine the emplacement age and petrogenesis of the quartz diorite in the Fudong area of Yanbian, Jilin Province, and to investigate its tectonic setting, petrographic studies, zircon U-Pb geochronology, whole-rock Sr-Nd isotopic analysis, zircon Hf isotopic analysis, and detailed geochemical investigations of this intrusion were carried out. The results indicate that the Fudong quartz diorite has: (1) A weighted mean zircon U-Pb age of 186 ± 1.7 Ma, corresponding to the Late Early Jurassic; (2) geochemically high concentrations of Sr (average: 1146 ppm) and Ba (average: 1213 ppm), and enrichment of light rare earth elements (LREE), along with notably high Th/Yb and Rb/Y ratios; (3) geochemically, the quartz diorite is enriched in large-ion lithophile elements (LILEs; e.g., Ba, K) and light rare earth elements (LREEs), while being depleted in high-field-strength elements (HFSEs; e.g., Ta, Ti). These features are consistent with magma formed in a subduction-related setting. In summary, the Fudong quartz diorite formed within an active continental margin tectonic environment associated with the subduction of the Paleo-Pacific Plate. Its primary magma likely originated from an enriched lithospheric mantle that had been metasomatized by fluids released from the subducted slab. Full article

The Yana–Kolyma collision orogen, Eastern Siberia, is one of world-class gold economic belts, where large gold deposits are localized, mainly in the Upper Paleozoic and Lower Mesozoic clastic rocks. Dike-hosted orogenic gold deposits are found and to a lesser extent studied, but they are important for understanding the structural control of mineralization within the framework of the orogen. Orogenic gold deposits of the Vyun ore field are hosted in Kimmeridgian–Titonian mafic, intermediate and felsic dikes, but they have no genetic connection with dikes. The late formation of deposits led to the fact that previously reactivated polydeformed structures were subsequently mineralized. The study of the structural control of mineralization is also complicated by superimposed late tectonic events. Based on the analysis of collected field materials, this paper presents the results of the study of deformation structures of the Vyun ore field within the framework of the Mesozoic evolution history throughout the geological time of the eastern convergent margin of the Siberian Craton. Four stages of deformations are identified. The pre-mineralization deformations and metamorphic and magmatic events share a common NE-SW shortening (D1 phase), which is related to the subduction of the Oymyakon oceanic slab and collision of the Kolyma–Omolon superterrane from the eastern margin of the Siberian Craton. This first stage is characterized by the superposition of several tectonic events under conditions of compression and progressive deformations (D1/1 and D1/2). Ore mineralization was formed at the end of compression in the same stress field (D1/2). Its structural control is determined by reactivation of older dikes and faults. Dikes are areas of heterogeneous stress and heterogeneous strain, being favorable for the concentration of ore fluids. The metallogenic time of formation of the gold mineralization is synchronous with the tectonic event, which likely reflects the final stages of the Kolyma–Omolon microcontinent–Siberian Craton collision of the Valanginian during crustal thickening. The main impulse of the Au mineralization D1/2 phase coincided with a slowdown in convergence. The post-mineralization tectonic regime was related to the Aptian–Late Cretaceous tectonic transition from compression to transpression. Transpressional tectonics were determined accordingly by W-E (D2 phase) and N-S (D3 phase) stress fields caused by several accretion events in the Cretaceous on the northern and eastern margins of Siberia. D4 phase extensional structures were caused by the opening of the Eurasian Oceanic basin in the Arctic in the Paleocene. The obtained results have a first-order impact on the understanding of the structural control of orogenic gold deposits and their relationship to the evolution of the host orogen. The new findings improve the tectonic knowledge of an area of interest for ore deposit exploration targeting orogenic gold deposits in Phanerozoic terranes of craton margins. Full article

The Chinese Altay is located in the western segment of the Central Asian Orogenic Belt (CAOB) and preserves critical records of the Paleo-Asian Ocean (PAO) Plate evolution during the Paleozoic era. This region also hosts significant mineral deposits, making it a focal point for geological research. In this paper, field investigation, petrology, mineralogy, and petrography studies were conducted on volcanic rocks in the Fuyun–Qinghe area, southern margin of the Chinese Altay, and the paper provided new zircon LA-ICP-MS dating data, Lu-Hf isotope data, and whole-rock geochemical data of the basaltic to andesitic volcanic rocks. Thus, the formation age, petrogenesis, and tectonic setting of these rocks were discussed, which was of great significance to reveal the nature of the PAO Plate. The findings showed that the basaltic andesitic volcanic breccia was formed at 382.9 ± 3.4 Ma, the basalt was 401.7 ± 4.7 Ma, and the andesites were 405.1 ± 5.6 Ma and 404.8 ± 6.7 Ma, which indicated that the above rocks were formed in the Early–Middle Devonian. The volcanic rock assemblages were hawaiite, mugearite, potassic trachybasalt, basaltic andesite, andesite, benmoreite, etc., which contained labeled magmatic rocks such as adakite, sub-boninite, niobium-enriched arc basalt (NEAB), picrite, high-magnesium andesite (HMA), and magnesium andesite (MA). Comprehensive analysis indicated that magma probably mainly originated from three sources: (1) partial melting of the PAO slab, (2) partial melting of the overlying garnet–spinel lherzolite mantle peridotite metasomatized by subducting-related fluids (melts), and (3) a possible input of the asthenosphere. Comparative analysis with modern analogs (e.g., Chile Triple Junction) indicates that ridge subduction of the PAO had existed in the Fuyun–Qinghe area during the Early–Middle Devonian. Based on available evidence, we tentatively named the oceanic plates in this region the central Fuyun–Qinghe Ridge and the Junggar Ocean Plates, separated by the ridge on both sides. Although the ocean had a certain scale, it had entered the climax period of transition from ocean to continent. Full article

This study addresses the numerical simulation of non-isothermal two-phase water-oil flow in oil reservoirs. The problem of heavy oil recovery by reservoir heating (via heated fluid injection) is investigated, aiming to reduce oil viscosity and increase its mobility. The governing equations are formulated in terms of non-wetting phase pressure (oil), wetting phase saturation (water), and reservoir average temperature, without assuming local thermal equilibrium. Temperature-dependent relative permeabilities are considered. The Finite Volume Method is employed, and the resulting algebraic equations are linearized using the Picard method. The linearized discretized equations are solved sequentially for pressure, saturation, and average temperature, utilizing the Preconditioned Conjugate Gradient (pressure and average temperature) and Preconditioned Stabilized Biconjugate Gradient Method (saturation). After validating the numerical results, a sensitivity analysis is performed using a reservoir with slab geometry. The results demonstrate the positive impact of reservoir heating on heavy oil recovery. Full article

Ion-adsorption-type rare-earth element (iREE) deposits, a primary source of global heavy REE (HREE) ores, have attracted wide attention worldwide due to their concentrated distributions and irreplaceable role in the field of cutting-edge technologies. In recent years, iREE mineralization has been reported in the overlying weathering crust of the Mosuoying granites within the Dechang counties, Sichuan Province, Southwest China, suggesting great potential for the formation of iREE deposits. The Mosuoying granites, acting as the primary carrier of REE pre-enrichment, govern the contents and distribution patterns of REEs in their weathering crust. Therefore, investigating the sources and enrichment mechanisms of REEs in the parent rocks will provide a critical theoretical basis for the scientific exploitation and utilization of iREE deposits. In this study, we investigated the migration and enrichment of REEs in the Mosuoying granites (850–832 Ma) using petrography, geochronology, geochemical, and Sr-Nd-Hf isotopic data. The results reveal that the REE enrichment in the Mosuoying granites might be associated with both the melting of crustal felsic rocks and the magmatic-hydrothermal evolution. On the one hand, the granites exhibit different REE patterns. Compared to the light REE (LREE)-rich granites, the HREE-rich granites feature higher SiO₂ contents, higher differentiation index (DI), lower Nb/Ta and Zr/Hf ratios, and more significant negative Eu anomalies, indicating that the crystal fractionation of magmas governed the differentiation of REEs. Furthermore, the hydrothermal fluids further promoted the formation of the HREE-rich granites. On the other hand, the geochemical characteristics suggest that they are A-type granites. Regarding the isotopic characteristics, the Mosuoying granites exhibit negative whole-rock εNd(t) and zircon εHf(t) values, suggesting an evolved crustal source. Therefore, we suggest that the high REE contents in the Mosuoying A-type granites might originate from the partial melting of felsic rocks in a shallow crustal source under high-temperature and low-pressure conditions. Specifically, the high-temperature A-type granitic magmas caused the partial melting of the felsic crustal materials to release REEs; concurrently, these magmas enhanced the solubility of REEs in melt during magmatic evolution, inhibiting the separation of REE-bearing minerals from the melts. These increased the REE contents of the granites. The high-temperature heat source might be associated with the process where the asthenospheric mantle experienced upwelling along slab windows and heated continental crust in the Neoproterozoic extensional setting. Full article

The work reports preliminary results on the morphological changes that biomass particles experience at high heating rates in a heated strip reactor (HSR) at T = 1000–1600 °C under an inert atmosphere. Samples included a natural lignocellulosic biomass (pinewood) as well as biomass components: cellulose, hemicellulose (xylan) and lignin. On top of that, reference compounds have been investigated, namely naphthalene pitch, a paraffinic wax and glucose. During the heat-up phase, the investigated biomass mainly retains the original morphology and size, while the single components exhibit different behaviors. Hemicellulose undergoes a fluid stage and eventually forms millimetric spherical char particles. Cellulose does not become fully fluid but softens and forms millimetric char aggregates of different shapes. Lignin particles hardly soften and stick together in a curved slab. Comparison with model compounds allows us to infer that the degree of melting and the viscosity of the melt are responsible for the final particle shape. In fact, naphthalene pitch and glucose appear to be more viscous during pyrolysis and lead to the formation of three-dimensional columns a few millimeters high. Wax undergoes extensive melting, but the relatively low viscosity and the absence of crosslinking reactions eventually lead only to the formation of droplets. Full article

The petrology, geochemistry, and zircon U-Pb chronology of the Huoshaodian pluton in the Liuba area of the western part of the South Qinling tectonic belt are investigated in this study. The Huoshaodian pluton consists of gabbro, quartz diorite, and granodiorite, and the dominated rock type is quartz diorite. The results indicate that the Huoshaodian pluton belongs to the calc-alkaline series. In the chondrite-normalized REE, all of the samples showed similar patterns, with an enrichment of light REEs and depletion of heavy REEs, but they showed slight differences in the degrees of Eu anomalies. The primitive mantle-normalized trace element diagram reveals an enrichment of large-ion lithophile elements (LILEs) and light rare earth elements (LREEs), as well as depleted high field strength elements (HFSEs). The zircon U-Pb dating results reveal that the gabbro, quartz diorite, and granodiorite have crystallization ages of 214.9 ± 0.58 Ma, 215.0 ± 1.2 Ma, and 215.4 ± 1.9 Ma, respectively, indicating that the Huoshaodian pluton was emplaced during the late Triassic period (214.9–215.4 Ma). In terms of petrogenesis, the gabbro of the Huoshaodian pluton originates from a transitional lithospheric mantle that has undergone fluid metasomatism and partial melting. Specifically, it originated through 1%–2% garnet spinel peridotite undergoing partial melting. In addition, the gabbro underwent a slight degree of contamination by crustal materials during its ascent and intrusion, with some continental crust material being incorporated. The quartz diorite and granodiorite of the Huoshaodian pluton are formed through partial melting processes occurring within the normal lower crust. Combined with the previous studies on the early Mesozoic tectonic evolution of the South Qinling, this study proposes that the formation mechanism of the Huoshaodian pluton may be as follows: in the early Triassic, the Mianlue Ocean subducted northward beneath the Qinling microblock, resulting in a large-scale continental-continental collision between the North China Block and the Yangtze Block; when the oceanic crust subducted to a certain depth, the detachment of the subducting slab triggered the upwelling of mantle material. The heat from mantle-derived magma caused the partial melting of the mafic lower crust, while the mafic magma entered into the upper granitic magma chamber and began to mix. Due to the high viscosity contrast and temperature difference between the two end-member magmas, incomplete mixing led to the formation of a melt with distinct adakitic characteristics and a mafic melt representing mantle-derived material. Full article

The early Permian mafic–ultramafic intrusion-related Cu-Ni mineralization in Northern Tianshan offers valuable insights into the nature of the mantle beneath the Central Asian Orogenic Belt (CAOB) and enhances the understanding of magmatic sulfide mineralization processes in orogenic environments. The Yunhai intrusion, rich in Cu-Ni sulfides, marks a significant advancement for Cu-Ni exploration in the covered regions of the western Jueluotag orogenic belt in Northern Tianshan. This intrusion is well-differentiated, featuring a lithological assemblage of olivine pyroxenite, hornblende pyroxenite, gabbro, and diorite, and contains about 50 kilotons of sulfides with average grades of 0.44 wt% Ni and 0.62 wt% Cu. Sulfide mineralization occurs predominantly as concordant layers or lenses of sparsely and densely disseminated sulfides within the olivine pyroxenite and hornblende pyroxenite. In situ zircon U-Pb dating for the Yunhai intrusion indicates crystallization ages between 288 ± 1 and 284 ± 1 Ma, aligning with several Cu-Ni mineralization-associated mafic–ultramafic intrusions in Northern Tianshan. Samples from the Yunhai intrusion exhibit enrichment in light rare earth elements (LREE), distinct negative Nb and Ta anomalies, positive ε_Nd(t) values ranging from 2.75 to 6.56, low initial (⁸⁷Sr/⁸⁶Sr)_i ratios between 0.7034 and 0.7053, and positive ε_Hf(t) values from 9.27 to 15.9. These characteristics, coupled with low Ce/Pb (0.77–6.55) and Nb/U (5.47–12.0) ratios and high Ti/Zr values (38.7–102), suggest very restricted amounts (ca. 5%) of crustal assimilation. The high Rb/Y (0.35–4.27) and Th/Zr (0.01–0.03) ratios and low Sm/Yb (1.47–2.32) and La/Yb (3.10–7.52) ratios imply that the primary magma of the Yunhai intrusion likely originated from 2%–10% partial melting of weak slab fluids–metasomatized subcontinental lithospheric mantle (peridotite with 2% spinel and/or 1% garnet) in a post-collisional environment. The ΣPGE levels in the Yunhai rocks and sulfide-bearing ores range from 0.50 to 54.4 ppb, which are lower compared to PGE-undepleted Ni-Cu sulfide deposits. This PGE depletion in the Yunhai intrusion’s parental magma may have been caused by early sulfide segregation from the primary magma at depth due to the high Cu/Pd ratios (43.5 × 10³ to 2353 × 10³) of all samples. The fractional crystallization of minerals such as olivine and pyroxene might be a critical factor in provoking significant sulfide segregation at shallower levels, leading to the extensive disseminated Cu-Ni mineralization at Yunhai. These characteristics are similar to those of typical deposits in the eastern section of the Jueluotage orogenic belt (JLOB), which may indicate that the western and eastern sections of the belt have the same ore-forming potential. Full article

Rough surfaces known as stylolites are common geological features that are developed by pressure solution, especially in carbonate rocks, where they are used as strain markers and as stress gauges. As applications are developing in various geological settings, questions arise regarding the uncertainties associated with quantitative estimates of paleostress using stylolite roughness. This contribution reports for the first time a measurement of the temperature at which pressure solution was active by applying clumped isotopes thermometry to calcite cement found in jogs linking the tips of the stylolites. This authigenic calcite formed as a redistribution of the surrounding dissolved material by the same dissolution processes that formed the extensive stylolite network. We compare the depth derived from these temperatures to the depth calculated from the vertical stress inversion of a bedding parallel stylolite population documented on a slab of the Calcare Massiccio formation (early Jurassic) formerly collected in the Umbria-Marches Arcuate Ridge (Northern Apennines, Italy). We further validate the coevality between the jog development and the pressure solution by simulating the stress field around the stylolite tip. Calcite clumped isotopes constrain crystallization to temperatures between 35 and 40 °C from a common fluid with a δ¹⁸O signature around −1.3‰ SMOW. Additional δ¹⁸O isotopes on numerous jogs allows the range of precipitation temperature to be extended to from 25 to 53 °C, corresponding to a depth range of 650 to 1900 m. This may be directly compared to the results of stylolite roughness inversion for stress, which predict a range of vertical stress from 14 to 46 MPa, corresponding to depths from 400 to 2000 m. The overall correlation between these two independent depth estimates suggests that sedimentary stylolites can reliably be used as a depth gauge, independently of the thermal gradient. Beyond the method validation, our study also reveals some mechanisms of pressure solution and the associated p,T conditions favouring their development in carbonates. Full article

The Solonker-Xar Moron-Changchun-Yanji Suture Zone is the result of the final closure of the Paleo-Asian Ocean (PAO). However, the closure time of the PAO in Northeast China remains controversial. The Hunchun area is located in the easternmost part of the Solonker-Xar Moron-Changchun-Yanji Suture Zone. Tectonism and magmatism in the Hunchun area can provide important information for understanding the late-stage evolution of the PAO. In this study, our zircon U-Pb ages show that the granodiorites and diorites in the Hunchun were formed at 282.3–251.4 Ma. This geochronological evidence suggests prolonged Permian magmatism in the Hunchun area. Whole-rock geochemistry, zircon trace, and Lu-Hf isotope data show that all the intrusive rocks are mainly calc-alkaline series to arc tholeiite series. Granodiorites are I-type granites formed by the partial melting of juvenile lower crust derived from the mantle. Diorites show similar characteristics to the sanukitic high-Mg diorite and are formed by the partial melting of the depleted mantle metasomatized by subduction sediments and/or slab-derived fluids. These results indicate that the Permian diorites and granodiorites in the Hunchun area formed in an active continental margin setting related to the subduction of the PAO plate. Significantly, sudden changes in the whole-rock Sr/Y and (La/Yb)_N ratios and zircon ε_Hf(t) values are observed in the Late Permian-Early Triassic igneous rocks in the eastern Central Asian Orogenic Belt (CAOB). This indicates that the final closure of the PAO in Northeast China likely occurred in the Late Permian-Early Triassic. Full article

The descaling roll is a critical component in a hot-rolling production line. The operating conditions are significantly impacted by water with high-pressure and dynamic shocks caused by high-temperature steel slab descaling. Roll surfaces often experience wear and corrosion failures. This is attributed to a combination of high temperatures, intense wear, and repeated thermal, mechanical, and fluid stresses. Production costs and efficiency are significantly affected by the replacement of descaling rolls. Practice shows that the use of plasma cladding technology forms high-performance coatings. Conventional metal surface properties can be significantly improved. In this study, a Ni-WC composite coating was prepared on the descaling roll surface by plasma-transferred arc welding (PTAW) technology. The microstructure and phase composition of the welding overlay were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that the WC hard phase added to the molten pool dissolves, and subsequently M₇C₃ and W₂C phases are formed. To further explore the morphological evolution mechanism of the hard phase, numerical simulations were performed using a phase-field method to model M₇C₃ phase precipitation. The evolution from nucleation, rod-like growth, to eutectic structure formation was revealed. Experimental and simulation results show high consistency, validating the established phase-field model. In this study, a theoretical foundation for designing and preparing high-performance coatings is provided. Full article

The Kalatag mineralization belt is an important metallogenic belt of polymetallic mineral deposits in the northern part of eastern Tianshan, and its age and tectonic setting are still controversial. We identified a set of Devonian volcanic rocks hosted in the Early Palaeozoic package of dominantly marine sediments with a small amount of terrestrial rocks. This study presents petrological, U–Pb geochronology, and geochemical data for the volcanic rocks. The ages of the rhyolite (407.2 ± 1.9 Ma) and basaltic andesite (380.4 ± 2.8 Ma) suggests that the Kalatag belt is a Devonian volcanic succession. These rocks consist mainly of marine calc–alkaline lava, tuff, pyroclastic rocks, and minor terrestrial basaltic andesite. The lavas are characterized by the enrichment of light rare earth elements and strongly depleted in Nb and Ta, typical of island arc magmatic rocks. The volcanic rocks probably originated from the partial melting of the mafic lower crust which was modified by subducted slab-related fluids. During their ascent through the crust, these volcanic rocks underwent variable extents of fractional crystallization (rhyolites) and crustal contamination (basaltic andesites). Combined with the results of previous studies, we suggest that the Devonian rocks formed in an island arc related to the northward subduction of the Northern Tianshan Ocean with a crustal thickness of ~35–40 km. Full article

Serpentinites make up one of the most significant rock units associated with primary suture zones throughout the ophiolite sequence of the Arabian–Nubian Shield. Wadi Sodmein serpentinites (WSSs) represent dismembered parts of the oceanic supra-subduction system in the central Eastern Desert of Egypt. In this context, we present whole-rock major, trace, and rare earth elements (REE) analyses, as well as mineral chemical data, to constrain the petrogenesis and geotectonic setting of WSS. Antigorite represents the main serpentine mineral with minor amounts of chrysotile. The predominance of antigorite implies the formation of WSS under prograde metamorphism, similar to typical metamorphic peridotites of harzburgitic protolith compositions. The chemistry of serpentinites points to their refractory composition with notably low Al₂O₃, CaO contents, and high Mg# (90–92), indicating their origin from depleted supra-subduction zone harzburgites that likely formed in a forearc mantle wedge setting due to high degrees of hydrous partial melting and emplaced owing to the collision of the intra–oceanic arc with Meatiq Gneisses. Spinels of WSS generally exhibit pristine compositions that resemble those of residual mantle peridotites and their Cr# (0.625–0.71) and TiO₂ contents (<0.05 wt%) similar to forearc peridotite spinels. Moreover, WSS demonstrates a significant excess of fluid mobile elements (e.g., Th, U, Pb), compared to high-field strength elements (e.g., Ti, Zr, Nb, Ta), implying an interaction between mantle peridotites and fluids derived from the oceanic subducted-slab. The distinct U-shaped REE patterns coupled with high Cr# of spinel from WSS reflect their evolution from mantle wedge harzburgite protolith that underwent extensive melt extraction and re-fertilized locally. Full article