Abstract:The Jinling skarn-type iron deposit, located in the Zibo area of the northern West Shandong Block, exhibits close genetic relationships with the Jinling high-Mg diorite intrusion. Through petrographic observations of diorite intrusions and skarns in the mining area, this study identifies three distinct types of apatite: magmatic Ap1 in diorite, early hydrothermal Ap2 in skarn, and late hydrothermal Ap3. Geochemical investigations of these apatite generations provide critical constraints on the evolution of ore-forming fluids and the controlling mechanisms of iron mineralization. The diorite-hosted Ap1 shows elevated Cl content, while the development of hydrous minerals (e.g., amphibole and biotite) indicates a water- and Cl-rich magmatic system. Such magma generated iron-enriched fluids through intense hydrothermal exsolution under decompression conditions, establishing the foundation for iron enrichment. Hydrothermal Ap2 displays higher ⁸⁷Sr/⁸⁶Sr ratios compared to Ap1, with values approaching those of Ordovician gypsum-bearing carbonate strata, suggesting evaporite-derived materials were incorporated into the mineralization system through fluid-wallrock interactions. From Ap1 to Ap2, the Eu anomaly transitions from negative to positive values, indicating that carbonate assimilation progressively increased oxygen fugacity in the hydrothermal system. This promoted oxidation of Fe²⁺ to Fe³⁺ and subsequent magnetite precipitation. The gradual depletion of Fe, Mn, and rare earth elements from Ap2 to Ap3 reflects significant consumption of these elements during late-stage fluid evolution, coinciding decrease and progressive mineralization processes.

Abstract:As one of the ubiquitous accessory mineral in granitoids, apatite can effectively monitor the variation of the parental magmatic melt and volatiles and serves as an important tool for tracing the petrogenesis of granitic intrusions and the related magmatic process. This paper conducts micro-area structure and in-situ major and trace element geochemical analysis of the apatite from the Haisigou monzogranite and granodiorite in the East Kunlun Mountains, and combines partial whole-rock geochemical studies to meticulously analyze the genetic types, magmatic physical and chemical conditions, and their evolutionary processes of granites. Furthermore, it explores the formation and evolution mechanisms of granitic intrusions. The results show that apatites in the monzogranite exhibit obvious oscillatory zonation, while apatites in the granodiorite lack any types of zonation. And all the apatites in the monzogranite and granodiorite show similar characteristics to rich-F apatites in composition. The apatite major and trace element compositions and whole-rock geochemical data reveal that the granodiorite has similar geochemical characteristics to I-type granites, while the monzogranite has compositions comparable to I-S transitional-type granites. The chemical variations of apatite zonations reveal that the magma reservoir of monzogranite was influenced by the melt component, heat and volatiles of mafic magmas, while the granodiorite magma reservoir is more likely to be affected by the heat and volatiles of the mafic magmas, and the participation of the mafic component is negligible. Combined with new regional studies, the Haisigou Triassic granitic intrusions might form accompanied with the slab break off at the late stage of the subduction of the Paleo-Tethys Ocea. In this context, the magmas in those reservoirs experienced crystal-melt segregations under the varying degrees of mafic magma recharge, and ultimately formed the monzogranite and granodiorite with cumulate affinities.

Abstract:In the Awati-Manjar transition zone of northern Tarim Basin, the Ordovician sedimentary sequence is characterized by the presence of extensive diabase intrusions. These igneous intrusions are not only key evidence for the magmatic activity process of the Tarim Large Igneous Province, but also closely related to oil and gas migration and accumulation, providing guidance for oil and gas exploration. Based on seismic profiles and drilling data analysis, combined with isotopic dating methods, this study systematically studies the diabase intrusions in the Awati-Manjar transition zone, revealing their formation time and spatial distribution characteristics, and discussing their emplacement mechanism. The results show that the diabase intrusions can be divided into two types: steeply dipping intrusions and layered intrusions. Steeply dipping intrusions generally unconformably intrude into the Sangtamu Formation and are concentrated in the YM, GL, and MS drilling areas, as well as the AM and AM north drilling areas. Layered intrusions intrude conformably into the top of the Yijianfang Formation, Tumuxiuke Formation, and Lianglitage Formation and are concentrated in the MS and FY drilling areas, with small-scale distribution in the YM west, GL, and AM north. Steeply dipping and layered diabase intrusions can exist independently, but in most cases, they are closely connected in three-dimensional space, forming symmetrical or asymmetrical disc-shaped intrusions. Zircon U-Pb isotopic dating results indicate that the diabase intrusions crystallized between 303～285 Ma, and can be further divided into two stages. The intrusions of first stage are limited in distribution. They occurred around 303 Ma, corresponding to the first phase of magmatism in the Tarim Large Igneous Province. The intrusions of second stage, as the majority of the diabase in the study area, occurred around 285 Ma, corresponding to the third phase of magmatism in the Tarim Large Igneous Province. The diabase intrusions are composed of feeding veins, internal beds, inclined veins, and external beds from bottom to top, which make up of a vertically related intrusive system. The top of the Middle and Lower Ordovician serves as an important structural transition surface and lithological interface, controlling the lateral intrusion and expansion of the magmas. Meanwhile, the planar distribution features are jointly controlled by the mantle plume activity, the regional stress field evolution and the basement structure feature.

Abstract:We reported zircon SIMS U-Pb ages, the whole rock geochemistry of the Shuanglang gabbro located in Longsheng County, North Guangxi from the western Jiangnan Orogen in this manuscript, to decipher their petrogenesis and tectonic setting. Samples comprised clinopyroxene and plagioclase with minor K-feldspar and Fe-Ti oxides. The Shuanglang gabbro with a zircon SIMS U-Pb age of 782±9 Ma. The bulk-rock have SiO₂ (50.05%~51.85%), Al₂O₃ (14.53%~15.42%) and CaO (6.95%~7.19%) contents, and MgO (8.97%~11.33%) and total FeO (10.63%~11.92%) contents. The samples display ocean island basalt (OIB)-like geochemical signatures, with the enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE) relative to heavy rare earth elements (HREE), with insignificantly negative Nb, Ta anomalies, and have high (⁸⁷Sr/⁸⁶Sr)_i (0.709 990~0.711 788) and negative εNd(t) (-2.4~-1.4) values resulted from the upper crust contamination. They are suggested to have originated from a small degree (3%~4%) of partial melting of the upwelling asthenospheric man-tle in an extensional setting of the garnet stability field. Based on the spatial distribution of the mafic-ultramafic rocks during 780~750 Ma in the western Jiangnan Orogen reported in both this study and previous publications and comprehensive analyses of them, we indicate that the subducted slab break-off triggered the partial melting of upwelling asthenosphere, which resulted into the formation of the OIB-like mafic-ultramafic rocks during 780~750 Ma in the western Jiangnan Orogen.

Abstract:The study of Paleoproterozoic meta-mafic-ultramafic rocks in the North Liaohe Group of the Liao-Ji orogenic belt in the North China Craton provides critical evidence for understanding regional tectonic evolution. Through detailed field investigations, petrographic observations, and systematic geochemical analyses, combined with previous research findings, this study yields new insights into the petrogenesis and tectonic setting of these rocks. It also presents a preliminary discussion on the intrinsic genetic relationship between the geodynamic mechanism of the Liao-Ji orogen and the source of Ni-Co elements. Based on previous data, the protoliths of the meta-mafic-ultramafic rocks have a peak emplacement age of ~2 152 Ma and underwent regional metamorphism at approximately 1 882 Ma. Geochemical results indicate that the meta-ultramafic rocks are hornblende-chlorite schists with a cumulate origin. Their LREE enrichment and Nb-Ta-Ti depletion characteristics suggest that the primary magma likely experienced metasomatism by subduction-related fluids. The protoliths of the meta-mafic rocks are all subalkaline tholeiitic basalts, which can be classified into two types. The first type exhibits geochemical features similar to MORB, originating from a depleted asthenospheric mantle source with limited fluid metasomatism. Zircon Hf isotopes from this type provide direct evidence for Paleoproterozoic juvenile crustal growth events in the Liao-Ji orogen. The second type of meta-mafic rock shows significant LREE enrichment and Nb-Ta-Ti negative anomalies, indicating that their primary magmas were derived from an enriched lithospheric mantle source that was intensely metasomatized by subduction fluids.Based on the petrogenetic mechanisms and source characteristics of the meta-mafic-ultramafic rocks, this study proposes that they formed in a back-arc basin tectonic setting. The two types of meta-mafic rocks respectively record the complete evolutionary process of the back-arc basin from initial extension (enriched component) to maximum spreading (depleted component). Ni-Co mineralization is closely related to this evolutionary process: back-arc extension facilitated mantle melting and extraction of Ni-Co elements; magmatic underplating and cumulate processes achieved pre-enrichment; the addition of crustal sulfur triggered sulfide melt segregation; and the final collisional orogeny led to the extraordinary enrichment and formation of the ore deposits.

Abstract:The Bashisuhong rare earth deposit is located at the northern margin of the Tarim Basin and the southern Tianshan region, at the junction between the Tarim Craton and the Central Asian Orogenic Belt. There has been ongoing debate regarding its formation age and tectonic attributes. To address these issues. this study focuses on the bimodal intrusive rocks discovered in the region and attempts to provide evidence to resolve the aforementioned problems. Through petrographic, zircon U-Pb geochronology, in situ Hf isotope analysis and geochemical studies of the rocks, the results show that the zircon U-Pb ages of the diabase and alkaline granite are 278.50±0.87 Ma and 275.89±0.94 Ma, respectively, indicating their formation in the Middle Permian. In terms of geochemical characteristics, both rocks have similar εHf(t) values (diabase average: 4.17, alkaline granite average: 3.42). The alkaline granite has high SiO₂, K₂O, Na₂O, and low MgO, CaO, with relatively high total rare earth element content, significant light/heavy rare earth element ractionation, and a distinct negative Eu anomaly, along with enrichment in high-field-strength- elements. The diabase has lower SiO₂, K₂O, higher MgO, CaO, relatively lower total rare earth element content, significant light/heavy rare earth element fractionation, a weak positive Eu anomaly, and elevated Ba content. In terms of rock genesis, the diabase originates from the asthenospheric mantle, undergoing low-degree partial melting; the alkaline granite magma originates from partial melting of lower-pressure, high-temperature crustal gabbro, displaying characteristics of A1-type granites. Combined with regional geological background analysis, it is concluded that the Bashisuhong alkaline intrusive complex formed in a non-orogenic intra-continental rift environment during the Middle Permian, driven by mantle plume activity, rather than in a post-collision orogenic extension tectonic background resulting from plate stress release. This provides new data for the study of the Late Paleozoic tectonic setting in the northern margin of Tarim.

Abstract:This study presents a comprehensive analysis of Late Neoarchean TTG (tonalite-trondhjemite-granodiorite) within the Longshan Complex, situated at the southwestern margin of the North China Craton (NCC), providing critical constraints on the tectonic evolution of this region. These TTG, located in the Guanshan area of the Long-shan Complex, were dated using zircon U-Pb isotopic analysis, yielding crystallization ages of 2 535~2 485 Ma (2 503±39 Ma, 2 535±39 Ma). The zircon εHf(t) values of the TTG are predominantly positive, and show two-stage Hf model ages ranging mainly from 3.1 Ga to 2.8 Ga. These data suggest that the TTG originated from partial melting of ancient crustal material with contributions from depleted mantle-derived components. Notably, one sample(23LS28) displays uniformly positive εHf(t) values, with some zircons closely approximating the isotopic composition of the coeval depleted mantle. The two-stage model ages for this sample fall within 2.8~2.5 Ga, indicating derivation from partial melting of juvenile crustal material. The TTG exhibit high SiO₂, Na₂O, and low K₂O. Most samples are characterized by flat heavy rare earth element (HREE) patterns, moderately elevated Y and Yb concentrations, low Sr/Y and (La/Yb)_N ratios, and minor to negligible Eu anomalies (δEu = 0.70~0.96). These characteristics suggest that the TTG were generated by partial melting of source rocks under low- to medium-pressure (LP-MP) conditions, with amphibole, plagioclase, and minor garnet as the residual phases. However, one sample (22LS30) exhibits distinct geochemical features, including lower Y and Yb concentrations, higher Sr/Y and (La/Yb)_N ratios, and a pronounced positive Eu anomaly (δEu = 2.47). These attributes indicate a deeper melting environment, corresponding to high-pressure (HP) conditions, with garnet, amphibole, and rutile as the dominant residual phases. The high Mg^#, Cr, and Ni contents observed in all TTG are consistent with geochemical signatures associated with melts derived from the subducted oceanic crust. According to the chronology, isotope geochemistry and petrogeochemistry, these Late Neoarchean TTG belong to the NCC, and may have been in a subduction-related setting at this time. With the increase of subduction depth, the subduction fluid/melt continuously reacts with the mantle wedge, and the mantle interaction continues to strengthen. In addition, this study obtained metamorphic ages of 1 871±26 Ma and 459~335 Ma. The former age is consistent with the metamorphic events dated at 1.97~1.80 Ga in the NCC, while the latter aligns with the Paleozoic metamorphic events in the North Qinling Orogenic Belt. It is concluded that the TTG subsequently experienced metamorphism during Late Paleoproterozoic thermo-tectonic event and were eventually incorporated into the Longshan Complex during the Paleozoic orogenic event.

Abstract:To explore the Paleozoic tectonic evolution characteristics of the southern margin of the Dunhuang block and constrain the activity trajectory of the southern side of the Central Asian orogenic belt, zircon U-Pb dating and petrological-geochemical analysis were conducted on the Haobula pluton. The LA-ICP-MS zircon U-Pb dating results indicate that the crystallization age of the Haobula pluton is 324.0±1.1 Ma, belonging to the Early Carboniferous period. Geochemical analysis of the rock reveals that the SiO₂ content of the Haobula pluton ranges from 65.31% to 75.50%, with an average total alkali (K₂O+Na₂O) content of 7.77%. The K₂O/Na₂O ratio varies from 0.90% to 1.35%. The Al₂O₃ content ranges from 13.41% to 16.05%. It belongs to the high-potassium calc-alkaline, peraluminous series. The pluton is relatively enriched in LREE and depleted in HREE (LREE/HREE=11.96~26.01), with a slight negative Eu anomaly (δEμ=0.70~1.01). It is relatively enriched in large-ion lithophile elements such as Rb, Ba, and K, as well as strong incompatible elements like Th, and depleted in high-field-strength elements like Nb, Ti, and P. Considering the regional tectonic features, it is believed that the southern margin of the Dunhuang massif was in the late stage of continental-continental collision (crustal thickening) during the Early Carboniferous.

Abstract:Tonalite and trondhjemite (plagiogranite) are typical granitoid rocks that contains abundant plagioclase. IUGS defines tonalite as the plutonic rocks that contains more than 20% quartz and plagioclase portion higher than 90% of the feldspar minerals. Meanwhile, the trondhjemite is defined as the light-coloured (mafic minerals, M<10%) tonalite. Tonalite and trondhjemite are the important constitute of Precambrian continental crust, and they also occurred in the plutonic assemblage of arc systems and in the ophiolite suites. The trondhjemites exposed within TTG suites exhibit high aluminous character, but many trondhjemites occurred in ophiolite suites have low aluminous content. Using the QAP classification results discriminated by the actual mineral modes as the benchmark, two chemical diagrams, i.e., SiO₂'-CaO/(CaO+K₂O) plot and 100×(Mg+Fe)/Si-SiO₂ plot are proposed as the tools to discriminate tonalite and trondhjemite from the other granitic rocks. Furthermore, the ACNK-Al/Si plot and ACNK-FeO^* plot are suggested to separate the low-aluminous trondhjemite (LAT) from the high-aluminous trondhjemite (HAT). The case studies indicate that the new chemical procedure performs well for discrimination of tonalite and trondhjemite occurred within the TTG suites as well as those occurred in the ophiolite suites. Avoiding the calculation of normative minerals, the new chemical procedure is accurate, fast, and user-friendly than the scheme base on normative An-Ab-Or diagram, which is commonly used as the key plot to identify tonalite and trondhjemite for many years.

Abstract:Bauxite is often associated with various critical metal elements such as gallium (Ga) and titanium (Ti). Studying the potential and comprehensive recovery and utilization of associated titanium resources in the accumulation-type bauxite in western Guangxi is conducive to the efficient utilization of mineral resources. This paper systematically collected the resource reserve data and ore quality characteristics of major accumulation-type bauxite deposits in western Guangxi, conducted a detailed survey on the current status of associated titanium resource utilization by major aluminum enterprises in the region, and focused on carrying out process mineralogy and ore beneficiation & metallurgical performance tests in the bauxite mining area on the periphery of Taiping, Pingguo City, Guangxi. On this basis, a comprehensive recovery and utilization process was proposed.The research shows that the associated titanium resources in the accumulation-type bauxite in western Guangxi are abundant, with the average content of titanium dioxide (TiO₂) ranging from 3% to 4%. The TiO₂ in the ore mainly exists in the form of anatase, which is difficult to be comprehensively recovered and utilized during the alumina production process. As a result, TiO₂ is further enriched in red mud, with its average content reaching approximately 6%. The comprehensive recovery and utilization of critical metal resources such as TiO₂ can be achieved through a process that first removes calcium and extracts iron from red mud, followed by extracting elements including titanium, scandium (Sc), and rare earths.

Abstract:Pull-apart basins are special extensional structures formed at the linkage zones of en echelon strike-slip fault systems. They preserve important records of tectonic activity and evolution within strike-slip fault systems, therefore, serving as key windows for studying strike-slip faulting. This study summarizes geometrical characteristics and tectonic evolution of pull-apart basins and concludes that the geometric evolution of a pull-apart basin is controlled by the geometry of the initial master strike-slip faults. Underlapping configuration of the initial master faults will undergo the complete evolutionary sequence (spindle-shaped, lazy Z/S-shaped, rhomboidal-shaped, elongated rhomboidal-shaped) whereas overlapping configuration directly forms rhomboidal or elongated rhomboidal basins. The main factors influencing the characteristics and tectonic evolution of a pull-apart basin include the number of initial strike-slip faults (two or multiple), initial strike-slip geometry (fault separation and fault overlap, underlapping or overlapping configuration), initial strike-slip kinematics (pure strike-slip, transtension, or transpression), basement characteristics (thickness of brittle crust, salt structures in the basement, etc.), and its evolution stages. This study also introduces crack propagation and basin development of pure strike-slip, transtensional, and composite pull-apart basins, presents typical natural examples such as the Dead Sea basin and pull-apart basins in the Marmara Sea, and provides a method to deduce the minimum strike-slip displacement and the starting age of active pull-apart basins and the corresponding strike-slip faults based on relative extension ε^*_x (strike-slip offset divided by fault separation) and slip rate of the strike-slip fault. Current understanding of basin depocenter evolution, rift shoulder uplift, and extinction mechanisms of pull-apart basins remains inadequate. Their roles in major earthquake nucleation and surface rupture propagation require further investigation. The integrated application of field investigations, compilation of field examples, physical modeling, and numerical simulations shows potential to address these problems.

Abstract:In 2024, a previously undocumented synthetic cubic zirconia product, traded as "heavy-zircon", emerged in the Wuzhou gem market (Guangxi, China). To address the lack of peer-reviewed data on its composition and identity, we performed a comprehensive mineralogical and gemological study using electron-probe microanalysis (EPMA), X-ray diffraction (XRD), fourier-transform infrared (FTIR), and micro-Raman spectroscopy. The material has a high relative density of approximately 7.40 and is primarily composed of Yb₂O₃ (51.08%~53.06%) and ZrO₂, with minor Y₂O₃. Its elevated density results from the incorporation of ytterbium (Yb), a heavy rare earth element. Single-crystal XRD confirms an isometric fluorite-type structure (space group Fm3m) with a lattice parameter a=5.134 8(18) Å and a unit-cell volume V=135.39(8) ų. The calculated chemical formulas are Zr_0.57Yb_0.40Y_0.03O_1.78□_0.22 or Zr_0.59Yb_0.41O_1.79□_0.21 (□ denotes oxygen vacancy). These results identify heavy-zircon as a high-density, ytterbium-rich variant of yttria-stabilized cubic zirconia. In accordance with gemological nomenclature, we propose "synthetic ytterbium-rich cubic zirconia" as its formal species name.

Abstract:The problems of low hydrophilicity and low specific surface area of natural zeolite lead to its poor humidity control performance, and its large-scale promotion and application are limited. In order to solve this problem, the natural clinoptilolite zeolite in the Weichang area, Chengde, was taken as the research object, and the HNO₃ solution and NaOH solution were used to study the effect of acid/alkali treatment on the structure and humidity regulation performance of natural zeolite and its mechanism. The composition and structure of the material was analyzed using XRF, XRD, TG, FT-IR, N₂ adsorption-desorption technique, and SEM-EDX, etc. The moisture absorption and moisture release properties of the materials were evaluated using different types of saturated salt solutions. The results showed that the acid/alkali treatment could effectively change the composition, structure and moisture controlling properties of natural clinoptilolite zeolite. After alkali treatment, natural clinoptilolite zeolite transformed into Na-P-rich zeolite, the silica-aluminum ratio was reduced from 5.4 to 1.5, the surface hydroxyl content was enhanced by 4.9 times, and the moisture absorption and moisture-release amounts increased by more than 2.64 times and 3.23 times, respectively. After acid treatment, the silica-aluminum ratio of natural clinoptilolite zeolite was raised from 5.4 to 20.5, the surface hydroxyl content increased by 3.5 times, and the moisture-absorption and moisture-release amounts increased more than 1.49 times and 1.46 times, respectively. The alkali-treated zeolite exhibits a broad application prospect in the field of humidity-controlling.

Abstract:Magnetic zirconium-iron oxide/palygorskite (MZIO/PG) as a low-cost adsorbent were produced by facile one-step co-precipitation technique and its properties for phosphorus adsorption were investigated by batch adsorption experiments. The adsorption kinetics characteristics and thermodynamic parameters were analyzed with a discussion on the adsorption mechanism. The results indicated that MZIO/PG composite adsorbent almost completely maintained the surface properties and structure of iron zirconium oxide, and the adsorption capacity of phosphorus can reach more than 90% of that of iron zirconium oxide. The adsorption kinetic data followed the pseudo-second-order model and Langmuir equation, Freundlich equation and D-R equation could all describe the adsorption equilibrium. The monolayer saturated adsorption capacity was 36.63 mg/g and the average adsorption energy is 19.4 kJ/mol. The increase in pH value impeded the adsorption and the ion strength has little effect on the adsorption. The adsorption had good selectivity and the adsorbent was easy to regenerate and effectively reused. The adsorption mechanism analysis found that ion exchange occurred between the surface hydroxyl of the adsorbent and phosphate groups, forming inner-sphere complexes.