The Tarim Large Igneous Province constitutes the most significant tectono-thermal event in the evolution of the Tarim Craton, forming mafic-ultramafic layered intrusions (e.g., the Wajilitag complex) that host vanadium-titanium magnetite deposits. However, intermediate rocks identified at the margin of the Wajilitag intrusion have been largely overlooked. Thus, the magmatic evolution and deep-seated geodynamic processes of the Tarim Large Igneous Province have been incompletely understood. This study presents a comprehensive investigation of the Wajilitag biotite monzodiorite, integrating detailed petrographic, geochronological, and geochemical analyses. The biotite monzodiorite is primarily composed of plagioclase, orthoclase, biotite, hornblende and augite. LA-ICP-MS zircon U-Pb dating yields an age of 277.9±1.5 Ma (MSWD = 0.85), constraining the emplacement of the biotite monzodiorite in the Early Permian. This age is slightly younger than that of the Wajilitag mafic-ultramafic layered intrusion. The biotite monzodiorite is characterized by relatively low silica (SiO₂content is 52.14%–53.50%) and high alkali contents (Na₂O+K₂O content is 7.26%–7.60%), classifying it as shoshonitic series. The chondrite-normalized REE pattern displays a right-sloping trend with LREE enrichment and HREE depletion. It is enriched in large-ion lithophile elements (LILEs; e.g. Ba and Pb) and possesses high concentrations of high-field-strength elements (HFSEs; e.g. Nb, Ta, Zr, Hf), without Nb-Ta negative anomalies. These geochemical features are indicative of an OIB-like enriched mantle source, with negligible crustal contamination during ascent. The slightly enriched zircon Hf isotopic composition (εHf(t) value range from −1.8 to −4.4) of the Wajilitag biotite monzodiorite is similar to that of continental flood basalts from the Tarim Large Igneous Province. In the TiO₂-MnO-P₂O₅ and Hf-Th-Ta tectonic discrimination diagrams, the rocks exhibit an affinity consistent with within-plate basalts. Integrated studies suggest that the Wajilitag biotite monzodiorite was derived from partial melting of an enriched lithospheric mantle that had been modified by subducted oceanic crust, with eclogite as the residual phase in the source. The interaction between a mantle plume and the subducted slab played a significant role in its formation.

Xishenba mafic-ultramafic intrusion is located on the northern margin of the Yangtze Craton. It is a newly discovered magmatic Cu-Ni mineralized intrusion in Hannan, Shaanxi Province, with significant mineralization potential. The intrusion consists of lherzolite, olivine lherzolite, and gabbro. The ore bodies are predominantly hosted within the lherzolite unit, with sulfides mainly comprising pyrrhotite, pentlandite, and chalcopyrite. Zircon U-Pb concordant age of the Xishenba intrusion is （854±3）Ma, indicating that it was formed in the middle Neoproterozoic. Geochemically, gabbro exhibit right-inclined REE patterns characterized by light rare earth element (LREE) enrichment and heavy rare earth element (HREE) depletion. In contrast, olivine lherzolite and lherzolite display relatively flat REE patterns with slight LREE enrichment. All samples are enriched in large ion lithophile elements (Rb, K) and depleted in high field strength elements (Nb-Ta, Zr-Hf).These geochemical characteristics are similar to those of other Neoproterozoic mafic–ultramafic intrusions along the northern margin of the Yangtze Block and global island arc basalts, suggesting a plate convergence setting. Olivine crystals from the ore-bearing lherzolite have Fo value of 76.0～80.9 mol%, Ni content of <200×10⁻⁶ to 1445×10⁻⁶. The correlation between these parameters suggests that sulfide segregation occurred in the parental magma of the Xishenba intrusion. Zircon from the lherzolite yield ε_Hf(t) value of −6.82～4.84, indicative of a depleted mantle source. Modeling based on Hf isotopes and Th/Yb–Nb/Yb systematics suggests that the magma experienced 10%~30% crustal contamination during ascent, which was likely the key factor triggering sulfide segregation. Comparative analysis with magmatic deposits formed in convergent settings, such as those at Xiarihamu, Kalatongke, and Sibao, reveals that the Xishenba Cu–Ni deposit possesses significant mineralization potential. Consequently, similar types of mafic-ultramafic intrusions along the northern margin of the Yangtze Block should be prioritized as targets for future Cu–Ni exploration.

The Erlian basin, an essential sandstone-type uranium enrichment basin in northern China, is situated in the central segment of the Central Asian Orogenic Belt. In the basin, the Lower Cretaceous Saihan Formation constitutes the most significant uranium-bearing layer. Influenced by tectonic overturning and paleo-valley evolution, provenances experienced intensely spatial and temporal transition, and the precise depositional age of the Saihan Formation remains ambiguous. In this study, we conducted an integrated investigation of the Saihan Formation in the Naomugen Depression, employing petrographic analysis, LA-ICP-MS U-Pb geochronology and trace element geochemistry of detrital zircons. These methodologies are to determine the maximum depositional age, identify provenance characteristics of the uranium-bearing sandstones, and elucidate tectonic implications. Detrital zircon geochronological results reveal three predominant age clusters: 434 Ma (Caledonian), 265 Ma (Variscan), and 140 Ma (Yanshanian), indicating multiple magmatic sources spanning the Paleozoic to the Early Mesozoic. Notably, the youngest single-grain ages (125±3 Ma, 115±6 Ma, 122±2 Ma, 108±2 Ma) and weighted mean ages (113.3 Ma, 123 Ma) collectively constrain the maximum depositional age of the Saihan Formation to (108±2) Ma, corresponding to the Albian stage of the Early Cretaceous. Provenance analysis demonstrates that detrital materials were derived from: Cretaceous exposures in the central-western Sonid Uplift, Weijing intrusions in the Bayinbaolige Uplift, and Caledonian-Variscan complexes in the western Bainaimiao Arc. Integrating with volcanic records from the Tengger Formation, our findings confirm a rapid tectonic uplift event at ～110 Ma during the late Early Cretaceous. This tectonic episode created optimal metallogenic conditions through the formation of structural slopes and thick sandstone sequences, providing critical constraints for uranium exploration models in the region.

The sandstone uranium mineralisation found in the Santang Lake Basin is primarily located in the Hanshuiquan area, with the ore-endowed stratigraphy concentrated in the Neoproterozoic Changji River Group. In order to accurately and objectively evaluate the mineralisation conditions and prospects of the Hanshuiquan area in the Santang Lake Basin, the identification of interlayer oxidation zones and an understanding of the uranium mineralisation conditions are crucial. In this paper, the focus is on the Neoproterozoic Changji River Group. In order to identify the yellow sandstones, geochemical indexes of altered sandstones, constant and trace element analyses of rocks and ores, and physicochemical parameters of fluid action are employed. The grey-green, grey and grey-white sandstones containing minerals or anomalies are considered to be the transition zone, while the red sandstones and grey sandstones are the reductive zone. The grey-green, grey and grey-white sandstones are the result of oxidation, while the red sandstones and grey sandstones are the result of reduction. The oxidised red sandstones present in this area are the result of primary deposition under arid climatic conditions, while the yellow sandstones are interlayer oxidation zones formed by post-oxidation and control uranium mineralisation. It would be beneficial to trace the alteration front of the yellow sandstone in order to reduce the cost of exploration. Some of the geochemical indicators provide evidence that this red sandstone is a product of sedimentary diagenesis. This is evidenced by the higher organic carbon (Orgc), CaO, Cu/Al, Ni/Al and Cd/Al contents in the red sandstone than in the yellow sandstone, and the low temperature of fluid action at which it was formed. The in situ pyrite sulfur isotope signature of the microzone indicates an interstratified oxidized zone type of uranium deposit. The very restricted distribution of white and green sandstones suggests a weak but hydrocarbon-influenced influence. The analysis of tectonic, topographic, geomorphological and hydrological conditions, lithology, petrography and post-generation alteration conditions indicates that this area has certain conditions conducive to uranium mineralisation. However, there are some key deficiencies, including insufficient reductant capacity, weak oil and gas dissipation and the absence of uranium ore enrichment.

The sandstone-type uranium deposit in the Kelulun Depression is the first industrial uranium deposit discovered in the Hailar Basin. In order to preliminarily identify the types, occurrence characteristics, and mineralization significance of uranium minerals in the study area, this paper conducts a systematic study of the ore-bearing sandstone in the target layer by using polarized light microscopy combined with electron probe analysis on the basis of a field investigation. The results show that uranium mineralization in the study area occurs at the front edge of the braided river delta of the Yimin Formation. The rock type of the ore-bearing target layer is mainly medium-fine-grained feldspathic litharenite, with the overall development post-generation alteration. Uranium minerals are mainly coffinite, followed by uranium-titanium oxide. Coffinite is mainly distributed in colloidal or stellate forms in or around pyrite, and a few are filled in the edges of debris particles or dissolution pits in irregular granular form. Uranium-titanium oxides are mostly distributed in irregular granular forms in the biotite cleavage cracks. The coffinite and uranium-titanium oxide, as the first discovered independent uranium minerals in the study area, fill the gap left by the absence of uranium minerals in the Hailar Basin. In terms of uranium mineralization conditions, the Permian granite and intermediate-acidic volcanic rocks in the west of the study area provide sufficient uranium sources for the sandstone-type uranium mineralization in the area. Under the action of reducing media such as oil and gas, organic carbon, and sulfides in the area, U⁶⁺ in the ore-forming fluid is reduced to U⁴⁺ and precipitated into mineralization in the form of coffinite and uranium-titanium oxide.

Fluorite is an indispensable raw material in strategic emerging industries such as new energy and new materials. In recent years, significant breakthroughs have been achieved in fluorite exploration in the Altyn Tagh orogenic belt, with the discovery of world-class deposits such as Kaerqiaer, Piyazidaban, and Gajike. However, the nature of the ore-forming fluids and the genetic types of these deposits remain unclear. This study focuses on the Gajike fluorite deposit in the central and southern parts of the Altyn Tagh, conducting detailed geochemical research on trace elements in fluorite from different stages based on thorough geological characterization. The results indicate that fluorite from all stages is enriched in light rare earth elements, with rare earth element patterns showing a "right-leaning" type, and mineralization occurring during early hydrothermal activity. The Tb/La-Tb/Ca diagram suggests that fluorite is of hydrothermal origin, with hydrothermal fluids undergoing water-rock reaction with the surrounding rocks. The La/Ho-Y/Ho diagram reveals strong fractionation of Y and Ho, indicating that the fluorite exhibits homologous multi-stage characteristics, where early fluorite breccia underwent recrystallization while middle-stage fluorite cement precipitated during fluid migration. The δCe-δEu diagram shows strong negative Eu anomalies and positive Ce anomalies in fluorite, reflecting a medium-low temperature reduction environment with low oxygen fugacity and water-rock reaction effects. The high F content in the rock mass and the Ca-rich strata suggest that the F in fluorite originates from K-feldspar granite, while Ca comes from metamorphic strata and marble. Comprehensive analysis concludes that the Gajike fluorite deposit formed in a medium-low temperature reduction environment, and its genetic type is classified as a medium-low temperature hydrothermal deposit.

Early Paleozoic stratigraphic sequences are well exposed in the North Altyn ophiolitic mélange zone and its adjacent Central Altyn block, which documented the subduction and collision of the North Altyn Ocean. The Ordovician sequence within the North Altyn ophiolitic mélange zone is composed of clastic rocks, volcanic rocks and carbonates. Detrital zircon grains from the volcaniclastic sandstone samples determine a single age population at 420～440 Ma (peak at 470 Ma), with a maximum depositional age (YPP) of 456 Ma. Moreover, the detrital grains were predominantly derived from a juvenile crustal source (7.4＞ε_Hf(t)＞0). Coeval Ordovician Elantage Formation exposed in the northern margin of the Central Altyn block also displays a single age population, but at 510～450 Ma (peak at 470～465 Ma), with a YPP of 446 Ma. However, their Hf isotopes (−1.8～−8.4) indicate a source region dominated by crustal recycling. The zircon trace element signatures of both units argue for derivation from a granitic source. Field geology, detrital zircon age distribution patterns, along with zircon isotopic and geochemical compositions, suggest deposition in an active plate margin setting. This, together with regional geology and previous studies, favors the Elantage Formation as deposited in an Early Ordovician retro-continental arc basin related to the south directed subduction of the North Altyn Ocean, with detritus derived from the Cambrian-Ordovician continental margin arc type granitoids in the northern Central Altyn block. In contrast, the Ordovician sequence within the North Altyn ophiolitic mélange zone may have been deposited in a younger fore-arc basin, subsequent to retreat of oceanic subduction and the extension of the continental central Altyn block. The identified Ordovician continental arc margin basins argue for continuous subduction of the North Altyn Ocean from the Cambrian to the Ordovician period, which closed in late Ordovician.

The North China Craton underwent a prolonged and complex geological evolution during the Archean to Paleoproterozoic, with the magmatic and metamorphic processes remain as the research questions. This study focuses on the TTG (tonalite-trondhjemite-granodiorite) gneisses of the Taihua Group in the Xiong’ershan area along the southern margin of the North China Craton. The integrated field investigations, petrographic analysis under the microscope, geochemistry, zircon U-Pb dating and Hf isotopic studies are conducted to elucidate the Paleoproterozoic magmatic mechanisms and the tectonic evolution of this region. Zircon U-Pb dating constrains the magmatic crystallization age of the Taihua Group TTG gneisses in the Xiong’ershan area to approximately 2300 Ma, while the metamorphic ages range from 1984 Ma to 1940 Ma. The Taihua Group TTG gneisses exhibit a wide compositional range, with SiO₂ (59.35%～70.78%), Al₂O₃ (12.41%～17.93%), and relatively high CaO (1.40%～5.52%) and MgO (0.95%～2.56%) contents. It is enriched in light rare earth elements (LREE) and depleted in heavy rare earth elements (HREE), displaying strong fractionation between LREE and HREE. In composition, it resembles high-Al TTG gneisses. The samples are enriched in large-ion lithophile elements (LILEs) such as Rb, Ba, and Sr, but depleted in high-field-strength elements (HFSEs) like Nb, Ta, and Ti, which are similar to the features of island arc granites. Additionally, magmatic zircons display relatively high (¹⁷⁶Hf/¹⁷⁷Hf)ᵢ ratios (0.281282～0.281332), εHf(t) values (−2.98 ～ +0.20), and two-stage model ages (2844～2994 Ma), indicating that the magmatic source originated from the partial melting of Mesoarchean ancient crust. These findings suggest that the TTG gneisses in the Xiong’ershan area formed during the Paleoproterozoic subduction process between the eastern and western blocks of the North China Craton. The metamorphic age of 1984～1940 Ma records the collisional process along the Trans-North China Orogeny. This further constrains the timing of collision between the eastern and western continental blocks.

The genetic mechanism of serpentinized peridotite in Lüliangshan area of the North Qaidam UHPM belt is controversial. It was proposed as product of subducted slabs, refertilised lithospheric mantle or mantle wedge. In this paper, two types of peridotite (garnet lherzolite and dunite) were collected from Lüliangshan area, and the major and trace elements, and in-situ boron isotope of serpentine were analyzed. The two types of peridotite have experienced different types of serpentinization respectively. The dunite is dominated by the serpentinization of olivine, while the garnet lherzolite is dominated by the serpentinization of pyroxene. The serpentine produced by the serpentinization of olivine has higher content of MgO and As but lower content of Al₂O₃, Cr₂O₃, FeO, Li, Yb, Y, Ti, Sc and Zn; while the serpentine produced by the serpentinization of pyroxene is opposite. Serpentine in two types of peridotite showed significant differences in boron isotope. The boron content of serpentine in dunite is from 13.3×10^–6 to 38.5×10^–6, and its δ¹¹B value is from −9.5‰ to +5.0‰, which is close to or slight higher than the δ¹¹B value of the mantle. The boron content of serpentine in garnet lherzolite is from 10.5×10^–6 to 49.9×10^–6, and its δ¹¹B value is from 6.3‰ to 23.0‰, indicating that they are significantly enriched in heavy boron isotope. The difference of boron isotope composition of serpentines indicates that the Lüliangshan peridotite was formed in two different tectonic settings. The garnet lherzolite is formed in lithospheric mantle and has been altered by seawater, thus with enrichment of heavy boron isotope. While the dunite is of mantle-wedge origin and had undergone serpentinization interacted with subduction fluids, thus with enrichment of light boron isotope.

The marine carbonate rock series of the Ordovician Majiagou Formation in the central and eastern part of the Ordos Basin has great natural gas exploration potential. However, the hydrocarbon accumulation mechanism is complex. Studying the hydrocarbon accumulation stages and patterns of this formation series is of great significance for regional oil and gas exploration geological evaluation. In this paper, petrography of inclusions and homogenization temperature analysis were carried out on the carbonate rock samples of the Ordovician Majiagou Formation in the basin, and the PetroMod software was used to restore the thermal evolution history of the Ordovician. The results show that two phases of hydrocarbon fluid inclusions have developed in the carbonate rock series of the Majiagou Formation. The first phase is mainly hosted in the dissolution pores of calcite and dolomite, with a homogenization temperature of 110–130 ℃, and the corresponding natural gas charging period is 210–165 Ma (from the end of the Triassic to the end of the Middle Jurassic). The second phase is mainly hosted in the dolomite veins or late-stage calcite, with a homogenization temperature of 160–170 ℃, and the corresponding natural gas charging period is 123–97 Ma (the end of the Early Cretaceous). The Ordovician in the central and eastern part of the basin has experienced three thermal evolution stages: a slow heating stage before the Late Permian, a rapid heating stage from the end of the Late Permian to the end of the Early Cretaceous, and a cooling stage after the Early Cretaceous. The charging of natural gas in both phases occurred during the rapid heating stage, with an average heating rate of 0.86 ℃/Ma. The Ordovician carbonate rock reservoir is in direct contact with the coal-measure source rocks of the Upper Paleozoic in the upper part, and has a self-generation and self-reservoir input from the sub-salt marine source rocks in the lower part. The natural gas migrates along the pores and fractures and accumulates in the lithologic traps of dolomite. Since the Late Cretaceous, the basin has been uplifted and cooled, with an average cooling rate of 0.63 ℃/Ma, and the hydrocarbon generation of the source rocks has ceased.