Abstract:The source characteristics and origin of high-Ti (HT) and low-Ti (LT) magma types are the first-order geodynamic question for the Large Igneous Provinces (LIPs) and mantle plume, especially the Emeishan LIP (ELIP). In this study, we report LA-ICP-MS zircon U-Pb ages, as well as mineralogical, geochemical, and Sr-Nd isotopic data on the Late Permian basalts in the Xiaogaoshan, Yanyuan, Sichuan. The Xiaogaoshan basalts can be classified as LT/HT transitional type and sodic tholeiitic rock series. Clinopyroxene crystallization temperature and pressure are 1 061 to 1 180℃ and 190 to 352 MPa. The X_Mt of Fe-Ti oxides (0.24 to 0.38) indicates a relatively low oxygen fugacity environment and the Fenner trend of fractional crystallization (evolving to iron-enriched). The zircon U-Pb data yield age is 260.2±5.0 Ma, i.e., the peak magmatism of the ELIP. The chondrite-normal- ized rare earth elements (REE) patterns and the primitive mantle-normalized spidergrams show oceanic island basalt (OIB) affinity, with a trend to E-MORB (enriched Mid-Ocean Ridge Basalts). The rocks have low age-corrected (⁸⁷Sr/⁸⁶Sr)_i ratios (0.704 650 to 0.705 035) and positive εNd(t) values (+2.91 to +3.02). The geochemical and isotopic features suggest that the lavas have not undergone any significant crustal contamination, and the source is dominated by "plume" components. The Late Permian Xiaogaoshan basalts have a co-genetic relationship with the picritic porphyries in the Pingchuan iron oxide deposit via fractional crystallization. REEBOX PRO modeling of the adiabatic decompression melting for the Emeishan basalts indicate that the mantle sources of the Emeishan basalts are characterized by the primitive mantle (PM). Only HT basalts can be generated at elevated mantle potential temperatures (t_p=1 550℃ to 1 690℃) beneath a lithosphere that is 140 km thick. In contrast, expanded melting temperatures (t_p=1 400℃ to 1 690℃) and regime spread over LT and HT basalts beneath a considerably thinned lithosphere (50 km). Therefore, the origin of the Emeishan basalts, both LT and HT, is through a continuous melting process of the same source. The modelling suggests that the Xiaogaoshan basalts most likely formed under a thinner lithosphere (50 km), with melting temperature and pressure conditions of 1 403℃/2.38×10³ MPa to 1 557℃/3.55×10³ MPa.

Abstract:Many red chert blocks and some irregular stripped manganese-oxide aggregates and crusts are developed in the laterite on the top of the Santaishan peridotites, western Yunnan. Those cherts and manganese nodulars are unlike the marine facies ones in shape, chemical compositions and mineral assemblage. Those dark manganese-oxide aggregates and crusts can be classified as ferri-manganese and cobalt-manganese oxides. The energy spectrum analytical results show the ferri-manganese oxides are complicated and nonuniform in their chemical compositions, with main Mn and Fe and minor Al, Co, Ni, K and Ba elements. The separation degree between Mn and Fe elements is low with Mn/Fe ratios of 0.1~12.6. The cobalt-manganese oxides consist of main Mn, Co, Al, Ni and minor K, Ca and Si, showing high separation degree between Mn and Fe. X-ray powder diffraction analyses show that the ferri-manganese oxides occur as hollandite in crystal structure, and coexist with cryptocrystalline hematite, goethite and clay minerals, having capability of enrichment in Al, K, Ba, Co and Ni elements. The cobalt-manganese oxides is with lithiophorite crystal structure, and is associated with cryptocrystalline hematites and cherts, having capability of enrichment strongly in Co, Al and middle in Ni elements. Based on the methods of energy spectrum, microprobe, X-ray powder diffraction, and whole rock chemical analyses, we conclude that those manganese-oxide aggregates and crusts are generated in the supergene conditions of long-lasting leaching by atmospheric precipitation, acidification and redox on the peridotites, where Ca and Mg in the silicate minerals are lost and Si, Fe and Al are residual. Silicic acid was retained and altered to cherts due to poor drainage condition. Iron- and manganese-oxide gels were precipitated as aggregates and crusts under the alternation of wetting and drying climates. The supergenesis has transformed the peridotites to Fe, Al, Ni, Co, Cr, Mn, Sc and Y enriched laterite with potential economic values.

Abstract:The Shitouzui Cu-Fe deposit is one of the typical skarn deposits in the southeastern Hubei Province. Currently, its mineralization age and the evolution process of ore-forming fluids are not clear yet. Based on the field research and petrographic observation, three generations of garnets were identified in this deposit, and in situ EMPA, LA-ICP-MS trace element and U-Pb dating of garnets were conducted for a systematic study. The results indicate that Grt1 (Adr_61~68Grs_28~36) has small compositional variation, and formed by diffusion metasomatism; Grt2 (Adr_63~89Grs_7~33) with oscillatory zoning exhibits significant compositional variation and formed by infiltration metasomatism; the composition of Grt3 (Adr_82~89Grs_5~11) is uniform and it resulted from crystallization of residual fluid. Y/Ho values (19.24~32.13, averaging at 26.46) suggest that the garnets in the Shitouzui deposit have the same magmatic fluid source. Relatively LREE-enriched and HREE-depleted patterns reflect that all these garnets precipitated in weakly acidic fluid condition. The characteristics of δEu, Sn and REE concentration indicate that the ore-forming fluid changed from relative reduced to oxidized condition, the intensity of water/rock reaction showed an increase to decrease feature, respectively, during the formation from Grt1, Grt2 to Grt3. The LA-ICP-MS U-Pb dating result of Grt2, 138 ±1 Ma, accurately constrains the Cu-Fe mineralization age of the Shitouzui deposit and further confirms the close genetic relationship between the mineralization and the Tonglüshan quartz diorite. The mineralization of the Shitouzui Cu-Fe deposit is a response to the early Yanshanian magmatic activity in southeastern Hubei Province.

Abstract:The Lanxiagou molybdenum deposit, situated in northern Hebei Province within the western Yan-Liao Metallogenic Belt, primarily hosts molybdenite within granitic gneisses, with only sporadic mineralization in granitic intrusions. The influence of magmatic activity on molybdenum mineralization remains a key research focus. Zircon U-Pb dating reveals the granitic intrusion formed at 134.9±0.94 Ma (Early Cretaceous), coeval with regional magmatic events. Geochemically, the Lanxiagou granite exhibits high SiO₂ (75.41%~76.21%), alkalis (Na₂O+K₂O=8.04%~8.73%), and Al₂O₃ (12.19%~12.64%) with low CaO (0.44%~0.85%), classifying as high-K calc-alkaline, weakly peraluminous granite. It displays enrichment in LILEs (Rb, Th, U) and LREEs, depletion in HREEs and HFSEs (Nb, P, Ti), and moderate Eu anomalies (δEu=0.31~0.40). EPMA analyses indicate crust-derived ferromagnesian biotite (high Mg, Fe, K; low Ca, Na) and albite (high Al, Na; low K, Ca). Mineralogical and geochemical signatures suggest a differentiated I-type granite with crystallization differentiation of biotite, plagioclase, and apatite. Zircon εHf(t) values (-18.16 to -14.76) and t_DM2(Hf) ages (2 570~2 117 Ma) indicate derivation from Paleoproterozoic lower crustal melting. The biotite in the intrusion exhibits relatively high oxygen fugacity (above the NNO buffer), with crystallization temperatures of 599~776℃, consolidation pressures of 164~260 MPa, and emplacement depths of 6.23~9.90 km, indicating formation under temperature and oxygen fugacity conditions favorable for molybdenum mineralization and significant exploration potential.

Abstract:The red siliceous rocks of the Late Devonian Hongshanliang Formation in the Baogutu tectonic belt, Western Junggar, are extensively developed, comprising approximately 80% of the total stratigraphic thickness. Studying its geochemical characteristics can reveal the genesis of the rock and indicate the tectonic environment, and provide new sedimentary information for the study of the Late Devonian tectonic paleogeographic evolution in the area. The upper siliceous rocks are predominantly red to reddish-brown, with poorly developed bedding, and mainly occur in massive or banded forms. They are often associated with volcanic lava or within volcanic rock interlayers, but no sponge spicules have been observed. The middle siliceous rocks are red, display thin-bedded structures with well-developed stratification, and frequently exhibit sedimentary lamination with abundant sponge spicules. These rocks are interbedded with tuffaceous siltstone and tuffaceous argillaceous siltstone. The lower siliceous rocks, which are red or gray, show transitional lithological and petrographic features between the two aforementioned types. The upper and lower siliceous rocks are relatively low in SiO₂ (71.90%, 87.48%), CaO (1.45%, 1.28%), P₂O₅ (0.09%, 0.06%) and δEu, and high in TiO₂ (0.57%, 0.2%), Al₂O₃ (13.47%, 5.54%), MgO (1.80%, 0.94%), Na₂O (3.93%, 0.64%), K₂O (2.05%, 1.14%), Na₂O/K₂O (1.35, 0.40), Al₂O₃/(Al₂O₃ + ^TFe₂O₃) (0.74, 0.71) and Sc, V, Cr, Cu, Zn, Sr, Y, Zr, La, Ce, Nd, Yb, Lu, ΣREE, Th/Sc, Th/U. The content and corresponding ratio of the major elements in the siliceous rocks in the middle are just the opposite, with high SiO₂ (91%), CaO (2.14%), P₂O₅ (0.48%), low TiO₂ (0.07%), Al₂O₃ (1.05%), MgO (0.32%), Na₂O (0.14%), K₂O (0.14%), Al₂O₃/(Al₂O₃+^TFe₂O₃) (0.37), and significantly depleted in Sc, V, Cr and other elements that are relatively enriched in magmatism. The correlation ratios and graphic analysis show that the volcanism in Hongshanliang Formation had experienced a strong→weak→strong changing process from bottom to top. The upper and lower siliceous rocks are mainly volcanogenic silicon, which are formed in the back-arc basin margin area near the arc volcano, while the middle siliceous rocks are mainly biogenic, which are formed in the back-arc basin environment during the volcanic dormancy period.

Abstract:Titanite U-Pb dating is a significant way to investigate the geological processes such as metamorphism and partial melting. Here, we evaluate in situ titanite U-Pb dating method based on three well-known titanite standards (BLR-1, Ontario, Pakistan), using ThermoFisher Scientific iCapRQ quadrupole-inductively coupled plasma-mass spectrometer (Q-ICP-MS) coupled with 193 nm ArF excimer GeoLas HD laser-ablation system. After evaluating the influence of beam diameters, laser energy, and repetition rates on the U-Pb isotopic fractionation, the optimal instrumental conditions were confirmed at 5～8 J/cm²,5～8 Hz,44 μm. Besides, the titanite standards were accurately determined with ages of 1 047±6 Ma for BLR-1, 1 055±6 Ma for Ontario, 21.0±0.6 Ma for Pakistan. Further, we chose the granulitized eclogite and its partial melts from the central Himalaya for titanite U-Pb dating. Two types of titanite were recognized from the Himalayan granulitized eclogite and its partial melts, metamorphic type in eclogite and peritectic type in the leucosome. The metamorphic titanites in granulitized eclogites are characterized with lower Nb, Ta, Y but higher Nb/Ta. The U-Pb ages for three sets of metamorphic titanites are 14.1±1.6, 14.2±0.4 and 15.3±2.5 Ma. However, titanite commonly appears as the retrograded product and records the cooling age in eclogite, hence this study insists that granulitized eclogite from the central Himalaya has retrograded into granulite facies to high amphibolite facies at 15～14 Ma, combined with the Zr thermometer (700～850℃) of the titanite. The peritectic titanites with melt inclusions occurred are characterized with higher Th, Nb, Ta, REE and Th/U ratio but lower Nb/Ta ratio than the metamorphic type. Forty laser analyses for the peritectic titanite yield intercept ages of 12.1±1.7 Ma, consistent with the zircon rims (13.5±0.9 Ma) from the leucosome, but much younger than the zircon mantle (17.3±3.2 Ma), these results indicate eclogite from the central Himalaya has undergone decompression melting during the middle Miocene. Two different types of titanite U-Pb dating limit the retrograde metamorphism time of granulite facies to high amphibolite facies at 15～14 Ma and the partial melting age at about 12 Ma during the exhumation process.

Abstract:Supercritical geothermal resource is a kind of renewable and clean energy with great potential. Its formation and development process is accompanied by strong water-rock chemical reaction. By conducting dissolution experiments of potassium feldspar in pure water at 300~500℃ and 25~50 MPa, this study clarified the influence of temperature and pressure changes on the solubility of potassium feldspar under sub-critical to supercritical geothermal conditions, and revealed the evolution mechanism of its dissolution behavior. The results show that: ① Both temperature and pressure are important factors affecting the solubility of potassium feldspar under subcritical and supercritical geothermal conditions. ② At 400℃, the solubility of potassium feldspar is positively correlated with the pressure. When the pressure is 35 MPa, the solubility of potassium feldspar increases first, then decreases and then increases with the increase of temperature, showing a fluctuation phenomenon. ③ The variation characteristics of the solubility of potassium feldspar are related to the sharp changes in the properties of water (density, hydrogen bond, dielectric constant) under sub-critical and supercritical geothermal conditions. The results contribute to a better understanding of hydrogeochemical processes in supercritical geothermal systems.

Abstract:Traditional water-rock reaction experiments under high temperature high pressure (HTHP) conditions often result in precipitation or adsorption of the products during the subsequent cooling processes. This issue can be overcome by synthetic fluid inclusion, which enables in-situ entrapment of fluid samples under HTHP conditions, and analyses of fluid composition using a LA-ICP-MS. This study simulates the HTHP (200℃ and 10 MPa) water-rock reaction process between basin brine (NaCl/NaCl+CaCl₂) and basement rocks (Triassic diabase, lithic limestone, and Middle Triassic tuff) in Lanping Basin, Southwest China, and uses synthesis fluid inclusion in calcite to trap the fluid during reaction. By comparing the fluid composition before and after water rock interactions, we are able to explore the origin of ore-forming metals in the fluids, and their contributions to the formation of the Mississippi Valley-type (MVT) Zn-Pb deposits in the basin. Based on microthermometric analyses, the freezing temperature point of synthetic fluid inclusions trapping a 3 m NaCl + 0.15 m CaCl₂ fluid ranged between -13.6 and -11.4℃, while that trapping a 3 m NaCl fluid ranged between -11.8 and -10.7℃, indicating that the fluid composition trapped within these inclusions is consistent with the initial fluids loaded in our experiment. Furthermore, both microthermometric and LA-ICP-MS analyses demonstrated that this synthetic fluid inclusions method using calcite as the host mineral has a nice potential in simulating the relatively low-temperature fluid-rock interactions in nature.

Abstract:The paper is a systematic collection of 121 new minerals approved by the Commission on New Minerals,Nomenclature and Classification (CNMNC) of the International Mineralogical Association(IMA) in 2019, by listingmineral name, crystallochemical formula,crystal structuredata,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 121 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 discovering, researching and naming new minerals in China and promote the standardization of Chinese names of mineral species.

Abstract:Deep-sea rare earth element and yttrium (REY) resources are crucial to the development of modern industry. However, the overexploitation of terrestrial REY resources has led to a series of environmental and sustainability issues. The discovery of deep-sea REY resources offers new opportunities for global REY supply, but key scientific questions such as the sources of REY, the minerals hosting these elements, and the mechanisms of ore formation still require in-depth investigation. On the technical front, challenges include the high difficulty and cost of deep-sea mining, immature purification and smelting technologies, and insufficient environmental impact assessments. This paper systematically summarizes the "source-transformation" processes, the state of existence, the ore-forming mechanisms, and the current technical challenges and environmental issues faced by deep-sea rare earth resources. Moreover, this article emphasizes the needs to strengthen fundamental research, technological innovation, and international cooperation to promote the efficient and environmentally friendly development of deep-sea REY resources. Additionally, it calls for the establishment of comprehensive environmental impact assessment systems, the optimization of market forecasting models, and the rational utilization of these resources within the framework of international law to ensure national resource security and promote global sustainable development.

Abstract:Basalt is the most widely distributed extrusive rock in nature, with large reserves. Basalt ore, which meets industrial standards and has economic mining value, is widely used in various industrial fields because of its unique natural properties and excellent performance. Although China is rich in basalt mineral resources and widely distributed, there is less research on this deposit in the academic community. It is of great significance to summarize the distribution characteristics of basalt ore resources and the current situation of industrial development and utilization in China. This paper summarizes the domestic and foreign research, combs the distribution characteristics of basalt deposits in China, and summarizes the basalt ore, deposit types, industrial development and utilization status. The research shows that the total basalt volume in China is estimated to be about 2 trillion cubic meters, and the basalt ore mining volume has reached 91.5 million tons by the end of 2023, and is still increasing year by year. Basalt deposits can be divided into tholeiitic, calc alkaline and alkaline basalt deposits according to the difference of geochemical composition. From the perspective of ore types, there are mainly five types of basalt deposits for construction, cast stone, rock wool, veneer and cement mixture, among which basalt ore for construction and alkali basalt deposits are the most common. In terms of industrial development and utilization, basalt is mainly used in the field of construction and building materials. In addition, basalt can also be used as a solidification material for nuclear waste, carbon fixation material and agricultural fertilizer. With the development of the country, the mining and consumption of basalt ore in industry are increasing year by year with an average annual growth rate of 7%, and the compound annual growth rate of market scale is more than 10%. The market prospect is good. In the process of development and utilization, domestic basalt ore accounts for 98.5% of the consumption in the field of construction and building materials, while it only accounts for 1.5% in other fields. It is expected that in the future, basalt ore and its deep-processing products will expand their application in a broader field, which has become an inevitable trend.

Abstract:Hornblende is one of the widely distributed rock-forming minerals, and the contents of Mg²⁺ and Fe²⁺ are the basis for naming tremolite-ferroactinolite series, which is of great significance to the research of mineralogy, petrology and gemmology. In this paper, tremolite-ferroactinolite series samples from eight places of different origin were collected, and systematic Raman spectroscopy and electron probe quantitative analysis were carried out. It was found that the Raman spectrum peaks of hornblende series minerals varied regularly in the range of 3 600～3 700 cm^-1, and the peak area had a good linear correlation with the contents of magnesium and iron obtained by electron probe. The method of calculating Mg²⁺ and Fe²⁺ contents in tremolite-ferroactinolite by Raman peak area is concluded, which can be applied to rapid and non-destructive analysis for tremolite-ferroactinolite series minerals.

Abstract:Indium (In), a crucial metal, serves as a significant raw material in the domains of emerging industrial technologies as well as national defense and security. China is one of the most important countries of indium resources in the world, and southeast Yunnan plays the same role in our country. In this paper, the distribution and occurrence of indium in typical deposits such as Zhengcaidong and Laoyingwo in the Puxiong Pb-Zn metallogenic belt at the northern margin of Gejiu granite in Yunnan Province have been studied. LA-ICP-MS in situ trace element test of sphalerite shows that the indium content of sphalerite in Zhenngcaidong deposit ranges from 37.71×10^-6 to 403.88×10^-6, with an average of 157.44×10^-6. The indium content of sphalerite in Laoyingwo Pb-Zn deposit ranges from 378.58×10^-6 to 1 060.08×10^-6, with an average of 631.46×10^-6. The indium content in sphalerite is an order of magnitude higher than that in indium-rich deposits abroad. In addition, many Pb-Zn deposits (occurrences) occur in the Puxiong Pb-Zn metallogenic belt, and sphalerite is the dominate indium-bearing mineral in this region. Therefore, we suggest that the Puxiong Pb-Zn metallogenic belt is also an important indium metallogenic belt, which has important research and utilization values.