Permian–Triassic granitoids are widely distributed along the Jinshajiang suture belt, eastern Tibet, and are regarded as the result of the tectonic-magmatic activity associated with the evolution of Paleo-Tethys Ocean. This paper focuses on the high-K calc-alkaline I-type Rennong (~235 Ma) and Jiaduoling (~232 Ma) granitoid plutons, eastern Tibet, which are enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), but depleted in high field strength elements (HFSEs) with moderate-weak negative Eu anomalies (0.61–0.90). The Rennong granites are characterized by uniform zircon ε_Hf(t) values (-7.3 to -3.5) and negative ε_Nd(t) values (-7.6 to -5.7), with old two-stage Nd model ages (T_DM2 = 1.51–1.46 Ga) and were likely formed by partial melting of the basement rocks, whereas the Jiaduoling rock samples have variable zircon ε_Hf(t) values (-5.7 to +5.5) but negative ε_Nd(t) values (-7.6 to -7.7) and are proposed to be formed by hybridization of mantle-derived mafic magma, Rennong felsic magma and sediments. Mafic microgranular enclaves (MMEs) in the Jiaduoling granitic rocks, have similar zircon U-Pb ages (~237 Ma) and zircon ε_Hf(t) values (-4.4 to +6.3) to the host rocks, indicating that zircons in the MMEs were actually xenocrysts that formed at an early stage in the granitic magma chamber. These results reveal that the break-off of the Jinshajiang oceanic slab beneath Changdu (Qamdo)-Simao Block was in a post-collisional setting, resulted in the upwelling of asthenosphere in the Late Triassic, and then, generated the wide-spread intermediate-felsic magmatism along the Jinshajing belt, including the Rennong and Jiaduoling plutons.

The Irtysh tectonic belt lies on the southern margin of the Chinese Altai Orogen. Several secondary shear zones with NW-SE strikes have developed in this tectonic belt, and the deformation processes are of great significance to understanding the tectonic regime of the Altai Orogen in the Late Paleozoic. The Tuerhongshate ductile shear zone is located in the eastern Irtysh tectonic belt with obvious deformed structures. The felsic rocks are strongly mylonitized, exhibiting S-C fabrics, asymmetric rotational porphyroclasts, and bookshelf structures of the plagioclases, indicating a sinistral shear sense. The deformation mechanisms, lattice preferred orientations (LPOs) of quartz, and opening angles of quartz c-axis suggest that the deformation temperatures range from 400 to 500 ℃, consistent with higher-greenschist to lower-amphibolite facies conditions. The calculated kinematic vorticity values (W_k) of the studied samples range from 0.53 to 0.89 and indicate general shear to simple shear, based on rotational rigid porphyroclast method and oblique grain-shaped/quartz c-axis fabric method. The U-Pb ages of magmatic zircons in felsic mylonites indicate that the sinistral shear occurred after 296.7 ± 3.0 Ma (Early Permian) in the Tuerhongshate shear zone and persisted for approximately 13 Ma. Combined with the tectonic setting and the observed sinistral strike-slip shear indicators in the mylonite zone, these features demonstrate that the Irtysh tectonic belt was in a post-orogenic and strike-slip environment following the closure of the Irtysh Ocean.

The Ordovician-Silurian transition was marked by extensive volcanic activity globally. In South China, intensive volcanism was documented by abundant ash layers in strata, but the origins and tectonic settings of these ashes remain controversial. This study presents the stratigraphic distribution of volcanic ash layers, zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf, providing insights into the tectonic setting and the origin of the parent magmas. The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen, with a mixed source from mantle and crust. The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.

It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature. Combined with the large size of certain garnet porphyroblast, this allows investigating variations in metamorphic conditions such as pressure, temperature, deviatoric stress, and fluid composition, which occur during subduction-related metamorphism. Here, one garnet porphyroblast of 6 cm diameter was sampled from the Yardoi schists of Tibet, and the major-, trace-, and Li-Mg isotopic compositions of distinct growth zones were determined in situ. The δ⁷Li values range from +6.0‰ to +4.1‰ and follow 'S-shaped' patterns on both sides of the garnet's core, revealing a two-stage growth process corresponding to the fluid-assisted sequential recrystallization of chlorite and micas during prograde metamorphism. By contrast, once corrected for the overprinting by retrograde metamorphism, the δ²⁶Mg values vary monotonically from -1.73‰ in the core to -1.32‰ in the outer rim, reflecting a single-step process interpreted to result from increasing temperature and the solid-state recrystallization of chlorite-biotite during prograde metamorphism. This different behavior of Li and Mg isotopes is interpreted to result from the fact that Li is more fluid-mobile than the major element Mg.

Eastern Myanmar is the key position linking between SW Yunnan and northern Thailand for better understanding of Tethyan evolution. However, the actual location and evolution of the Tethyan suture zone are still unclear in eastern Myanmar. The present study focuses on the geochronological, geochemical and zircon Lu-Hf isotopic study on the plutonic rocks, including granite, diorite and gabbroic rocks, from the Tachileik area, eastern Myanmar. These plutonic rocks yielded zircon U-Pb weighted mean ages of ca. 353–355 Ma, suggesting the Early Carboniferous emplacement. The Tachileik granites are high-K calc-alkaline, weakly peraluminous and have low P₂O₅ contents, which are typical features of Ⅰ-type granites. They have positive zircon ε_Hf(t) values (+4.5– +7.4) with T_DM2 ages of 981–825 Ma, indicating a juvenile mafic lower crust source. The Tachileik gabbros and diorites show high Al₂O₃ contents and Mg^#, but low TiO₂ and K₂O contents, belonging to tholeiitic and calc-alkaline basalt series. They are characterized by enrichments in large ion lithophile elements (LILEs, e.g., Rb, Ba and Sr), depletions in high field strength elements (HFSEs) and distinctly negative Nb and Ta anomalies, similar to the volcanic arc basalt. The zircon Hf isotopic (+4.7– +7.1) and whole-rock geochemical data imply that the Tachileik gabros and diorites probably resulted from partial melting of lithospheric mantle in the spinel stability field within an arc-related setting. The magmatic rocks can be grouped to the Late Devonian–Early Carboniferous magmatic rock and pyroclastic rock zone from SW Yunnan to northern Thailand based on their age and geochemical characters. The zone was formed in the post-collisional extension-related tectonic setting of the Proto-Tethys. This study provides important evidences for the evolution of the Proto-Tethys in Southwest Yunnan and Southeast Asia.

Zircon U-Pb ages, major and trace elements and Sr-Nd-Hf isotope data of the diabase in the Zhangjiakou District were studied to investigate its derivation and tectonic implications. Zircon U-Pb ages indicate that the diabase was emplaced at ~130 Ma or younger, and captured zircons cluster at ~147, ~240, ~430 and ~465 Ma. The diabase is characterized by minor variations in SiO₂ (49.35 wt.%–52.10 wt.%), TiO₂ (1.65 wt.%–1.77 wt.%), Al₂O₃ (17.00 wt.%–18.26 wt.%), MgO (4.28 wt.%–4.93 wt.%), CaO (6.69 wt.%–7.90 wt.%) and Mg^# (48–54). It has no significant Eu anomaly and displays enrichment in large ion lithophile elements (Rb, Ba and Sr) and depletion in high field strength elements (Nb, Ta, P and Ti). The diabase exhibits homogeneous Sr ((⁸⁷Sr/⁸⁶Sr)_i = 0.706 06–0.707 01) and Nd (ε_Nd(t) = -13.6 to -13.2) isotopic compositions. These features suggest that the parental magma was derived from partial melting of the ancient lower crust, relating to mantle upwelling that was triggered by the stagnant slabs or lithospheric detachment associated with the westward subduction of the Paleo-Pacific Plate. The Early Paleozoic inherited igneous zircons in the diabase suggest that the northern margin of the North China Craton (NCC) likely underwent southward subduction of the Paleo-Asian Ocean.

The Chinese Altai, a key component of the Central Asian Orogenic Belt (CAOB), represents a significant Phanerozoic accretionary orogenic belt. The oceanic-continental subduction processes spanning the Cambrian to Carboniferous and subsequent intracontinental extension since the Triassic have been well documented in the Chinese Altai, the southwestern segment of the CAOB. Deciphering the petrogenetic evolution of this region during the Permian is thus crucial for advancing our understanding of its tectonic transitions. However, the Permian tectonic setting of the Chinese Altai remains contentious. To address this knowledge gap, this study presents new geochronological and geochemical data for the Jiangjunshan pluton in the southern Chinese Altai. Zircon U-Pb geochronology reveals that the gabbro and two-mica alkali feldspar granite—which collectively constitute the primary lithology of the Jiangjunshan pluton—were emplaced at ~272 ± 3.5 and ~272 ± 1.6 Ma, respectively. Geochemically, the gabbro exhibits pronounced light rare-earth element (LREE) depletion, low Nb/Yb (0.39–0.46) and Ti/V (23.7–25.3) ratios, and trace-element signatures akin to normal mid-ocean ridge basalts (N-MORB). However, its conspicuous Nb-Ta depletion parallels that of island arc basalts. Depleted Hf-Nd isotopic compositions (ε_Hf(t) = +0.60 to +4.63, ε_Nd(t) = +6.32 to +7.80) in the gabbro, coupled with negligible correlation between ε_Nd(t) and SiO₂ contents imply limited crustal assimilation during magma evolution. Petrological modeling, based on Sm/Yb and La concentrations, suggests the gabbroic melt derived from ~8%–20% spinel lherzolte mantle melting. Analogously depleted Hf-Nd isotopes (ε_Hf(t) = +6.81 to +9.10, ε_Nd(t) = +0.79 to +1.45) in the granite, together with petrographic evidence lacking mafic-ultramafic xenoliths, point to a juvenile lower-crustal source. Integrating the gabbro's N-MORB-like affinity with arc-specific features, regional ultrahigh-temperature metamorphism in southern Chinese Altai, and Permian tectonics, we propose a ridge-subduction regime as the likely petrogenetic setting for the Jiangjunshan magmas. During ridge subduction, upwelling of asthenospheric mantle beneath the ridge induced partial melting of the lithospheric mantle, giving rise to the parental magma of the Jiangjunshan gabbro. This mafic magma underplating subsequently heated the juvenile lower crust, triggering its partial melting and generating the parental magma of the two-mica alkali feldspar granite. Our model indicates that ridge-subduction-related magmatism persisted in the Chinese Altai until the Middle Permian, followed by a tectonic shift from oceanic-continental subduction to intracontinental extension.

Um Solimate emerald deposit is a unique example for the well-known beryl-related schist type. Where, the Be-mineralization is restricted to NNE-trending quartz veins/lenses and as disseminated emerald grains within the altered-metasomatic zones of phlogopite- and graphite-schists. The study of fluid inclusions for the mineralized quartz vein revealed three major groups: (ⅰ) aqueous (H₂O-NaCl), (ⅱ) aqueous-carbonic (H₂O-CO₂-[CH₄]-NaCl), and (ⅲ) aqueous-hydrocarbonic (H₂O-CH₄) FIs. They have been further classified into five types (namely: types 1, 2, 3, 4 and 5) according to number of phases at the room temperature (20 ℃) as well as microthermometric measurements. Based upon the study of fluid inclusions, the initial-ore forming fluid was supposed to be of magmatic nature, characterized by a relatively high temperature of homogenization (T_{h, tot}: 269–485 ℃) and higher salinity (8.4 wt.%–9.6 wt.% NaCl equiv.), followed by development of aqueous-carbonic inclusions at lower temperature (T_{h, tot}: 241–355 ℃) and lower salinity (3.3 wt.%–4.9 wt.% NaCl equiv.) through metamorphic dehydration/decarbonation. Methane-rich FIs were suggested to be formed as a result of local re-equilibration of graphite in reduced environment at the contact aureole of the felsic intrusion. The P-T conditions of ore formation were estimated as modal temperature between (330–370 ℃) and fluid pressures of about 200 MPa, corresponding to an estimated depth ranges from 7 to10 km. The formation of emerald is closely associated with multiple events through the ore evolution, the deposition is ascribed to destabilization process of continuous metasomatic interactions and elemental substitutions between felsic-derived Be-bearing fluids with the adjacent mafic-ultramafic rocks at the zone of mineralization.

The giant Pulang porphyry copper deposit, located in the southern Yidun arc segment of southeastern Tibetan Plateau, represents one of the region's largest mineral systems. This study employs numerical simulation to unravel its metallogenic processes. By integrating field-based geological observations with mineralogical and geochemical data, we developed a coupled model encompassing five key stages of ore formation. The simulation successfully reproduced thermal anomalies and accurately predicted the spatial distribution of mineralization zones at Pulang. Coupling dynamic modeling results with chalcopyrite precipitation rates and average Cu grades enabled quantitative estimation of deposit formation duration (0.99–1.22 Ma). Compared with conventional geochronological approaches, this process-constrained modeling framework provides unprecedented insights into the thermodynamic mechanisms controlling porphyry copper system evolution, offering valuable implications for regional exploration strategies.

Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand. The 509 Daobanxi Li pegmatite deposit, located in the West Kunlun orogenic belt of northwestern China, represents a significant example of an LCT-type (Li-Cs-Ta) pegmatite system. This study investigates the paragenetic sequence of lithium (Li) minerals and the factors controlling their crystallization, providing new insights into the magmatic-hydrothermal evolution of rare-element pegmatites. Pegmatite dikes exhibit distinct zonation, comprising a wall rock zone, a border zone (aplitic layer), and a core zone (pegmatitic layer), with Li mineralization concentrated in the pegmatitic and aplitic layers. The primary Li minerals include spodumene (Spd), montebrasite (Mbs), eucryptite (Ecr), elbaite (Elb), and lepidolite (Lpd), which crystallize in the order of spodumene → montebrasite → elbaite → lepidolite. Spodumene, the dominant Li-bearing mineral, crystallizes from a Li-saturated melt during the magmatic stage. Montebrasite, a Li-phosphate mineral, forms in P-rich environments, coexisting with spodumene and columbite-group minerals (CGM). During the magmatic-hydrothermal transition, elbaite crystallizes from a B-rich melt, exhibiting skeletal and patchy zoning due to undercooling and disequilibrium crystallization. Hydrothermal alteration leads to the breakdown of spodumene and the formation of secondary minerals such as eucryptite and lepidolite, with lepidolite being the final Li-bearing phase, enriched in fluorine. The coupled dissolution-precipitation processes during the magmatic-hydrothermal transition play a critical role in the remobilization and enrichment of rare elements such as Li, Nb, Ta, and Sn. This deposit, characterized by spodumene crystallization in the Spd + Quartz stability field (≥300 MPa, ≤725 ℃) and subsequent alteration to Ecr + quartz assemblages (270 ℃, 160 MPa), exhibits broader temperature-pressure conditions exceeding typical global pegmatites like Tanco, with no petalite formation observed due to its persistent exclusion from petalite stability fields throughout mineralization. The shear zone controls the pegmatite emplacement and lithium enrichment in the 509 Daobanxi lithium deposit, and its deformation-fluid coupling mechanism provides new insights for the exploration of LCT pegmatite deposits. The present study highlights the importance of understanding both magmatic and hydrothermal processes in the formation of LCT-type pegmatites and provides valuable insights for the exploration of critical metal resources in similar geological settings.

Water-soluble organic acid anions (WSOAA) in subsurface water have been intensively studied during past several decades. They are used as natural gas precursor, tracer for the movement of underground fluid, indicator for porosity improvement, and detecter of deep subsurface life on the Earth. However, little is known about the distributions and origins of organic acids at deep-ultradeep depth underground. Herein, we collected twenty-nine source rock samples covering a wide maturity range from the Ordos, Qinshui, Junggar, Minhe, and Southern North China basins, as well as six subsurface water samples with depth between 6 544 and 8 396 m from industrial gas producing wells in the Tarim Basin, China. We carried out pyrolysis experiments at various temperatures (250–450 ℃) to investigate the role of water on the generation of organic acids. Results show that there are considerable amounts of WSOAA detected in both high-over mature source rocks and deep-ultradeep subsurface water. WSOAA mainly consists of monocarboxylates, predominately formate and acetate. High-TOC oil-generating source rock has low production rate of organic acids due to lack of hydrogen. Different source rocks have distinct ratios of formate to acetate concentration, expressed as c(formate)/c(acetate), which is due to significant differences in both initial molecular structure and metabolite. This indicates that c(formate)/c(acetate) can be used to distinguish types of organic matters (OMs). Concentrations of WSOAA show a "sharp decrease-slight increase-slow decrease" evolution trend with progressive maturity. Moreover, there are higher production rates of organic acids under hydrous pyrolysis experiments at ≥400 ℃. All geochemical signatures indicate that at both deep-ultradeep depth and high-over mature stages, the formation of organic acids is attributed to the thermochemical oxidation of organic components by mainly hydroxyl radicals, challenging the traditional model of organic acid evolution. This work suggests that petroleum exploration can be extended to great depths in sedimentary basins, when formation temperatures are not exceeding 230 ℃.

The 128.6-m-thick, shale-dominated Klimoli, Wulalike and Lashizhong formations exposed at the Hatuke Creek Section in the Zhuozishan area of Inner Monglia, North China, have been investigated for conodonts. Detailed stratigraphical collections of conodonts preserved on bedding planes from graptolitic shales, supplemented by additional discrete conodonts acid-leached from limestones, enable a refinement of the conodont biostratigraphic scheme at this section. Four successive conodont biozones, ranging in age from mid Darriwilian to late Sandbian (Stage slices Dw2–Sa2), are identified: the Dzikodus tablepointensis Biozone, the Eoplacognathus suecicus Biozone, the Pygodus serra Biozone, and the Pygodus anserinus Biozone, in ascending order. New sub-biozones, based on morphotypes of the biozonal index species, are proposed for the Pygodus serra and Pygodus anserinus biozones, providing alternatives when the traditional sub-biozones are unrecognizable. The biozonation is clearly correlated with the coeval Baltoscandian, South American and South China reference standard successions. The diverse preservation states of conodont bedding plane assemblages suggest that the alteration of conodonts in graptolitic shales represents a diagenetic process, challenging the prevailing hypothesis of pre-diagenetic dissolution. This study highlights the crucial role of previously overlooked conodont bedding plane assemblages in correlating Ordovician slope/basin facies shales, which holds great potential for marine shale gas exploration.

Carbonates present complex pore systems that strongly influence the physical properties and their interrelationships. This study proposes a new approach to establish pore-type mixing-based permeability transforms by integrating well-log and core data. We investigate the influence of pore-structure heterogeneity on permeability and velocity through the rock-frame flexibility factors (γ and γ_µ), derivable using standard sonic and density logs. We derive permeability transforms, with correlation coefficients, R of 0.8 to 0.9, from core measurements and pore-structure variations-dependent physical parameters, namely the porosity exponent (m), Poisson's ratio (σ), velocity deviation log (VDL), and velocity ratio (VR). Through extrapolation using log-data, the m- and VDL-based correlations provide significantly better permeability estimates, with the highest accuracy attained with the m-based correlation, whereas the VR- and σ-based correlations lead to permeability overestimation for high porosities. We plotted log-derived porosity vs. permeability, obtained applying the m-based correlation, to generate consistent porosity-permeability relationships, which account for pore-structure heterogeneity, by sorting the scattering points into distinct groups/trends by considering the variations of pore-structure types and abundance of a specific porosity. For the studied oilfield, three porosity-permeability relationships are identified, with correlation coefficients approaching 0.9, thus validating the approach and supporting its application in petrophysically similar reservoirs.