Abstract:The Tongka microcontinent block, situated in the eastern segment of the Bangong-Nujiang suture zone in the central Tibetan Plateau, preserves key evidence of the Early Jurassic tectonic evolution of the Tethyan Ocean through its metamorphic and magmatic records. Pelitic high-pressure granulites occur as interlayers within dominant felsic gneisses and are accompanied by leucosomes of varying scales. These granulites are primarily composed of garnet, kyanite, biotite, K-feldspar, quartz, with minor accounts of plagioclase, muscovite, sillimanite, and rutile. Integrated analyses—petrography, mineral chemistry, geochronology, and phase equilibrium modeling—reveal a clockwise metamorphic p-T-t path that can be divided into three distinct stages: ① Near-isobaric heating prograde metamorphic stage: this stage is characterized by prograde conditions of 0.70～0.88 GPa and 655～680℃, constrained by the compositions of garnet cores and associated biotite inclusions; ② Peak metamorphic stage: the peak mineral assemblage—garnet + kyanite + biotite + K-feldspar + quartz + rutile + melt ±plagioclase—formed under conditions of 0.98～1.06 GPa and 770～790℃, as indicated by phase stability fields and the compositions of garnet mantles and matrix biotite. Zircon U-Pb dating yields a metamorphic age of 175 Ma, representing the timing of high-pressure granulite-facies metamorphism; ③ Cooling and decompression retrograde stage: The retrograde assemblage of biotite + plagioclase + sillimanite + muscovite reflects post-peak conditions of 0.32～0.68 GPa and 600～725℃. This clockwise p-T-t path reflects crustal thickening associated with the collision between the Tongka microcontinent block and the Qiangtang terrane. The near-isobaric heating stage likely records prolonged thermal input from upwelling asthenosphere into the thickened lower crust of the microcontinent.

Abstract:The oceanic subduction zones and collision orogenic belts are critical regions for the evolution and maturation of continental crust. However, the specific mechanisms driving crustal reworking and maturation remain subjects of considerable controversy. In this study, we employ an integrated approach that combines petrography, geochemistry,zircon U-Pb geochronology, and zircon Lu-Hf isotopic analyses to analyze the felsic gneisses and their internal leucosomes, basic gneisses, and diorites within the Guaijiaoliang-Shuangkoushan arc-related rock unit, in order to investigate the key mechanisms driving continental crust evolution in this region. Whole-rock geochemical analysis reveals that the felsic gneisses, basic gneisses, and diorites are enriched in large ion lithophile elements and light rare earth elements, while being depleted in high field strength elements, characteristic of typical arc magmatic geochemical signatures. The basic and felsic gneisses exhibit a continuous evolution in major element composition, suggesting that the protolith of felsic gneisses originated from the crystallization differentiation of basic magmas. The leucosomes within the felsic gneisses exhibit high SiO₂, Al₂O₃, and Na₂O contents but low K₂O, CaO, Rb/Sr, and Th/U ratios, characteristic of the geochemical features of trondhjemite, consistent with fluid-present melting. Zircon U-Pb geochronology reveals that the protolith of basic gneiss and diorites formed at 470.9±6.5 Ma and 441.6±3.0 Ma, respectively. Hf isotopic analysis reveals that the zircon εHf(t) values of the basic gneisses range from +6.74 to +11.26, whereas the εHf(t) values of the diorites vary from +5.13 to +8.06. The leucosomes in the felsic gneisses crystallized at 441.6±3.5 Ma, and their zircon εHf(t) values range from +7.24 to +12.27, which is consistent with those of the basic gneisses. Comprehensive analysis indicates that the Guaijiaoliang-Shuangkoushan arc magmatic-metamorphic unit records two phases of arc magmatic activity and one phase of metamorphic-anatexis. During the ~470 Ma oceanic crust subduction phase, subducted fluids facilitated partial melting of the mantle wedge, leading to the formation of the first phase of arc magmatism, i.e., the protoliths of the basic gneisses and felsic gneisses. During the transition from oceanic subduction to continental collision at ~440 Ma, the upwelling of the asthenosphere triggered partial melting of a hydrated mantle, resulting in the formation of diorites. The emplacement and crystallization of the diorites released heat and fluids, inducing hydrous partial melting of the felsic gneiss protolith. Both phases of arc magmatic activity and the subsequent anatexis events promoted the transformation of the continental crust from basic to acidic within the North Qaidam subduction-collision mélange belt. This suggests that arc magmatism and anatexis processes during the transition from oceanic subduction to continental collision were key factors driving the reworking and maturation of the continental crust.

Abstract:The Jiao-Liao-Ji Belt is the most representative Paleoproterozoic orogenic belt in the North China Craton. It not only hosts massive Paleoproterozoic continental crustal sediments but also contains abundant Paleoproterozoic graphite deposits, making it an ideal natural laboratory for investigating the genesis of Early Precambrian graphite and early Earth's climatic conditions. We conducted detailed petrographic, geochemical, Raman spectroscopic, carbon isotopic, and zircon geochronological studies on the Nanshu graphite deposit in the Jiaobei area, southern Jiao-Liao-Ji Orogenic Belt. The results show that the ore-bearing rocks in the Nanshu deposit are primarily graphite-bearing diopside quartz gneiss, graphite-bearing garnet felsic gneiss, and graphite-bearing two-pyroxene granulite. Their carbon isotopic compositions (δ¹³C_VPDB) range from -13.42‰ to -10.17‰, -21.00‰ to -17.28‰, and -12.99‰ to -12.65‰, respectively. Graphite occurs as flaky or granular crystals uniformly distributed within these rocks. Geochemical characteristics indicate that the protoliths of the graphite-bearing rocks are mainly sandstone and shale that did not undergo long-distance transportation, and are products of an active continental margin. Raman carbon thermometry yields peak metamorphic temperatures of 693~796℃, corresponding to the high-amphibolite to granulite facies. We propose that the carbon source of the Nanshu graphite deposit was primarily organic matter mixed with minor inorganic carbon. Decarbonation (CH₄) during burial metamorphosis contributed significantly to the positive shift in graphite carbon isotopes. Additionally, in the protolith of diopside-quartz gneiss, inorganic carbon released through the metamorphic reaction CaMg(CO₃)₂+SiO₂=CaMgSi₂O₆+2 CO₂, also contributed to the enrichment of heavy carbon isotopes. Zircon U-Pb dating of graphite-bearing diopside quartz gneiss yielded detrital zircon ages ranging from 3.617 to 2.054 Ga, with a dominant peak at 2.46 Ga, and metamorphic zircon ages of 1.82 Ga. Integrating previous data from the Jingshan Group, we constrain the depositional age of the deposit to 2.1~1.9 Ga and the metamorphic-mineralization age to 1.82 Ga. We conclude that during 2.1 ~1.9 Ga, substantial organic matter was rapidly deposited together with terrigenous clastics in a back-arc basin along an active continental margin. This organic material was subsequently transformed into graphite and concentrated into economic deposits during graphitization associated with the arc-continent collision orogeny.

Abstract:Cretaceous magmatic rocks are widely distributed in the northern the Lhasa Terrane, and the recorded magmatic-metamorphic events are of great significance for studying the petrogenesis and tectonic setting of Cretaceous magmatic rocks in the Lhasa Terrane. This paper reports the petrology, geochemical results and zircon U-Pb age of the Early Cretaceous granodiorite exposed in the Kongma area located in the northern Lhasa Terrane. The results show that the LA-ICP-MS zircon U-Pb age of granodiorite in the study area is 113.2±1.3 Ma, which belong to the late Early Cretaceous magmatism. These rocks are belong to the high potassium calc-alkaline series, with aluminum saturation index(A/CNK=1.05~1.12) and medium negative Eu anomaly, relatively enriched large ion lithophile elements Rb, Th, U, K, and deficient high field strength elements Ti, P, Ta, which is a peraluminous S-type granite. Geochemical characteristics of the rocks shows that they were originated from the partial melting of the ancient crust with the mixing of mantle materials. Combined with the regional data, it is believed that the granodiorite in the Kongma area was formed in the tectonic environment of the southward subduction collision of the Bangonghu-Nujiang oceanic crust in the late Early Cretaceous, which may be related to the asthenosphere material upsurge caused by the slab break-off under gravity drag.

Abstract:This paper takes a certain cassiterite polymetallic sulfide ore deposit in Inner Mongolia as its research object, using methods such as the third-generation automatic quantitative analysis for mineral parameters (AMICS), a systematic process mineralogical study was conducted on the chemical composition, mineral composition, and grain size distribution of the ore, as well as the grain size, liberation characteristics, and occurrence characteristics of the main minerals, and the occurrence state of the primary target elements. The results indicate that the primary valuable elements in the ore are Cu, Ag, and Sn. Cu is primarily present as sulfide copper minerals such as chalcopyrite and tetrahedrite, Ag is mainly distributed in tetrahedrite in a solid solution form, and Sn is primarily present as cassiterite. Under coarse grinding conditions, although the liberation degree of individual sulfide minerals is less than 70%, the liberation degree of sulfide mineral aggregates reaches 80%. Considering the brittle and fragile nature of cassiterite and its tendency to occur in association with sulfide minerals, it is recommended that under coarse grinding conditions, mixed flotation be first used to recover the copper-silver sulfide mineral aggregates, followed by gravity separation to recover cassiterite. This provides a reference for the development and utilization of similar cassiterite polymetallic sulfide ores in Inner Mongolia.

Abstract:Thallium (Tl), a strategically critical metal, holds significant application value in high-tech industries. The Nanhua As-Tl deposit in Yunnan Province represents one of the few independent thallium deposits worldwide, with ore bodies occurring as stratiform layers within thin-bedded dolomite of the Upper Jurassic Series. This study systematically investigates the deposit's mineral assemblages, textural characteristics, thallium occurrence modes, and enrichment mechanisms through comprehensive field surveys, petrographic observations, and analytical techni- ques including scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The results demonstrate that realgar and orpiment dominate the ore minerals, with hydrothermal mineralization divisible into two stages: Stage Ⅰ comprises realgar-orpiment-pyrrhotite-pyrite-(thallium minerals-chalcopyrite-galena) assemblages, while Stage Ⅱ is characterized by realgar-orpiment-thallium mineral assemblages. Stage Ⅰ realgar (Rlg1) appears as orange-yellow fine veins, contrasting with Stage Ⅱ realgar (Rlg2) exhibiting coarser orange-red veins. EPMA analyses reveal thallium primarily exists in two forms: discrete mineral phases and isomorphism. Beyond discrete thallium minerals, realgar, orpiment, pyrite, and pyrrhotite display anomalously high Tl concentrations, serving as principal carrier minerals. Pyrrhotite contains the highest Tl content (0.47%～1.89%, average 1.06%), showing strong positive correlation with As and negative correlation with Fe, suggesting coupled substitution of Fe by As³⁺+Tl⁺+Tl³⁺?2 Fe²⁺+Fe³⁺. Pyrite exhibits Tl concentrations of 0.04%～0.18% (average 0.10%) with similar elemental correlations, indicating direct Tl⁺ substitution for Fe²⁺ via 2 Tl⁺?□+Fe²⁺ (□ representing vacancy). Realgar contains slightly higher Tl (≤0.59%, average 0.13%) than orpiment (≤0.17%, average 0.07%), both likely incorporating Tl through isomorphism. Integrated studies suggest differential Tl enrichment correlates strongly with Tl-rich ore-forming fluids under low sulfur fugacity and reduced low-temperature conditions, identifying pyrrhotite as a key prospecting indicator for Tl-rich resources.

Abstract:Mineral replacement reactions play an important role in the rare earth mineralization process of carbonatites, which reflect changes in the environmental conditions or fluid composition during the evolution of the system. Due to the close ionic size range of rare earth element ions and calcium ions, calcite can be transformed into rare earth carbonates under the action of hydrothermal solution containing rare earth element. Under the combined action of Ce³⁺ and H₂O, calcite can be gradually transformed into lanthanite [Ce₂(CO₃)₃·8 H₂O] (room temperature)→ calcioancylite [CaCe(CO₃)₂(OH)·H₂O] (70~110℃) →hydrobastnäsite (150~165℃) →cerianite (CeO₂) (200~250℃). The different binding forms of water in rare earth carbonate minerals can effectively reflect the ambient temperature. The co-participation of F^-, Ce³⁺ and H₂O can accelerate calcite to transform to rare earth minerals. Calcite can be converted into stable bastnäsite phase at room temperature, but fluorine is not easy to replace the hydroxy occupation in calcioancylite for further transformation into bastnäsite. F^-, OH^- and CO^2-₃ are important ligands responsible for the binding of rare earth elements, and play an important role in the migration, transformation and fixation of REEs in hydrothermal environment.

Abstract:The Bohai Bay Basin is one of the important hydrocarbon-bearing basins in eastern China,and its complex reservoir-forming characteristics are closely related to modification by deep CO₂ injection and CO₂-rich hydrothermal activity. A comprehensive analysis of the correlations among CO₂ content, δ¹³C_CO2, and R/Ra indicates that the CO₂ in the basin is primarily derived from CO₂ released by deep mantle-derived magmatic activity. Statistical analysis of CO₂-bearing fluid inclusion data reveals a bimodal pattern in homogenization temperatures, suggesting that the study area reservoirs have undergone multiple episodes of hydrothermal modification. Additionally, this study summarizes various lines of evidence from petrology-mineralogy and geochemistry regarding the impact of hydrothermal activity on reservoirs. Petrological-mineralogical evidence includes typical hydrothermal minerals such as ankerite, pyrite, chlorite, and dawsonite. In regions like the Bozhong Depression, Jiyang Depression, calcite in reservoirs exhibits lower oxygen isotope values and positive Eu anomalies in rare earth elements,indicating a hydro- thermal origin. The modification of reservoirs by deep hydrothermal fluids shows significant spatial differences. Near areas of deep hydrothermal activity, CO₂-rich hydrothermal fluids significantly improve reservoir porosity and permeability through dissolution and thermal baking effects, with the peak of dissolution-induced improvement occurring at the leading edge of hydrothermal activity. In contrast, in areas far from deep hydrothermal activity, precipitation and cementation of authigenic minerals (e.g., dolomite, calcite, quartz) lead to reduced porosity and permeability.

Abstract:In this study, to address the reservoir injury problem triggered by montmorillonite hydration and expansion in high-temperature sour reservoirs (60℃, pH=6.5) in Shengli Oilfield, high-temperature-resistant silicate mixing bacterium was isolated from in-situ formation water and named as SSB-Mnt, to investigate the coupling mechanism of the modification of the mineral structure of montmorillonite. Through multi-scale characterization by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy spectroscopy (SEM-EDS) and inductively coupled plasma-optical emission spectrometer (ICP-OES) combined with dynamic analysis of the elemental content of the system, it was found that SSB-Mnt synergized with electron transfer through the metabolic production of acid (pH value reduction from 6.6 to 5.5), the reduction of 43.8%～49.7% structural Fe³⁺ in montmorillonite was achieved within 30 days (average Fe²⁺ concentration 0.402 mmol/L). Mineralogical evidence suggests that microbial action resulted in montmorillonite interlayer collapse with a reduction in layer spacing from 1.49 to 1.22 nm, depolymerization of the silica-oxygen skeleton (reduction in the intensity of the Si—O—Si absorption peaks), and the formation of secondary minerals associated with elements Fe, Ca, Ti, and P. In this study, we explored the model of synergistic modification of high-temperature-resistant bacteria and minerals under reservoir conditions, and formulated the formulated medium, which provided a theoretical basis for the microbial anti-expansion technology in unconventional oil and gas reservoirs.

Abstract:Anaerobic digestate from organic waste typically exhibits high concentrations of chemical oxygen demand (COD), phosphate and ammonia nitrogen, classifying it as recalcitrant high-strength organic wastewater. This study proposes supplementing digestate with sulfate as an electron acceptor for sulfate-reducing bacteria, aiming to rapidly degrade organic matter while inducing biomineralization to fix carbon, nitrogen, and phosphorus. To investigate the influence of magnesium and calcium ions on COD removal, biomineralization products, and carbon fixation in anaerobic digestate, batch biomineralization experiments were conducted using anaerobic systems with varying magnesium and calcium ion concentrations. The results show that under a total salinity of 10 g/L and a Mg²⁺/Ca²⁺ molar ratio ranging from 0.5 to 10, increasing the Mg²⁺ concentration from 0.12 g/L to 2.4 g/L boosted total organic carbon (TOC) degradation rates initially, but then caused them to decline. The optimal degradation rate was achieved at a Mg²⁺/Ca²⁺ molar ratio of 5, corresponding to 1.2 g/L of Mg²⁺. Furthermore, when the Mg²⁺/Ca²⁺ molar ratio was less than 1, calcite and struvite were the primary mineralization products, whereas monohydrocalcite and struvite prevailed for ratios above 1. These findings suggest that Ca²⁺ mainly facilitates carbon capture, while Mg²⁺ is crucial for immobilizing nitrogen and phosphorus. Consequently, the Mg²⁺/Ca²⁺ molar ratio serves as a key regulator of controlling both the types and proportions of carbonate and phosphate phases.

Abstract:Electron Backscatter Diffraction (EBSD) technology has emerged as one of the pivotal analytical tech-niques in structural geology, particularly in the fields of microstructural analysis and rheological studies. Over the past two decades, this technology has made significant advancements, with sample scanning speeds multiplying, identification accuracy greatly improving, and data processing methods becoming increasingly diverse. Consequently, EBSD’s capability for microstructural analyses of geological samples has been increasingly enhanced, and its application in geological research has become more profound and widespread. Traditional EBSD technology can provide basic crystallographic information such as grain size, crystal orientation, and grain boundary distribution. With the rapid development of high-resolution EBSD technology, it has been widely applied to identify intragranular strain in crystals and to efficiently obtain additional key parameters on a large scale, such as Kikuchi band contrast and so on. The realization of three-dimensional expression of EBSD data, along with the integration of data together with other analyses methods, has significantly expanded the application prospects of this technology in geological studies. Since its establishment, the EBSD facility at the Key Laboratory of Continental Dynamics of Ministry of Natural Resources, has accumulated extensive testing experience, sample preparation techniques, and data processing methods over more than two decades. Based on this foundation, combined with previous research, this paper systematically reviews the latest advancements in the testing principles, technical developments, sample preparation techniques, data acquisition, and processing methods of EBSD. In addition, it highlights several typical cases of EBSD applications in geological research in recent years to more intuitively showcase the advancement of EBSD technology. It not only constructed a methodological system for multi-scale structural analysis, but also provided crucial experimental evidence for revealing the stratification of continental rheology, the mechanism of deep deformation and the process of tectonic evolution.

Abstract:The paper is a systematic collection of 75 new minerals approved by the Commission on New Minerals,Nomenclature and Classification (CNMNC) of the International Mineralogical Association(IMA) in 2010, by listing mineral name, crystallochemical formula,crystal structure data,physical and optical properties, locality of origin and occurrence, relationship with other minerals, source of mineral names, chemical reaction and spectroscopic characteristics. It's very meaningful that Chinese names of 75 new minerals have been examined and revised under the authority of Chinese Commission of New Minerals and Mineral Names. As a part of the comprehensive introduction to discovery and research of new minerals in the world, this paper will provide reference for the work of discover- ing, researching and naming new minerals in China and promote the standardization of Chinese names of mineral species.