Although previous researchers have conducted numerous studies on the early Paleozoic tectonic evolution of the Proto-Tethys in the Western Kunlun Mountains, there are still different opinions in understanding the closure timing of the Proto-Tethys Ocean. In this article, we have conducted geological, petrological, geochemical, and isotopic geochronological studies of the Middle Ordovician volcanic rocks and monzogranite of the intrusive accretion complex in the Mailun area of the eastern Kudi. The results show that rhyolite samples have SiO₂ contents ranging from 75.83% to 76.24%, K₂O contents ranging from 4.68% to 5.35%, Na₂O contents ranging from 3.09% to 4.22%, and A/CNK values ranging from 1.00 to 1.05, indicating that the rhyolite is a weak peraluminous rock and belongs to the high potassium alkaline series. The rhyolite samples have∑REE contents rangingfrom 161.95×10^–6 to 238.53×10^–6, (La/Yb)_N values ranging from 10.11 to 10.97, (Gd/Yb)_N values varying from 1.26 to 1.33, and δEu values ranging from 0.24 to 0.26. The monzogranite samples have SiO₂ contents ranging from 69.39% to 74.81%, K₂O contents ranging from 4.01% to 5.41%, Na₂O contents ranging from 3.62% to 3.99%, and A/CNK values ranging from 1.01 to 1.20, indicating that they belong to the weak to to strong peraluminous rocks and/or belong to the high potassium alkaline - shoshonitic series. The monzogranite samples have ∑REE contents ranging from 233.08×10^–6 to 754.92×10^–6, (La/Yb)_N values ranging from 12.04 to 34.84, (Gd/Yb)_N values ranging from 1.60 to 5.26, and δEu values varying from 0.54 to 0.7. The rhyolite in the Middle Ordovician volcanic strata in the Eastern Kudi area has the LA-ICP-MS zircon U–Pb age of (473.4±4.8) Ma. It is believed that the rhyolite was formed in the early Middle Ordovician Epoch in the active continental marginal environment based on its zircon age and geochenical characteristics. The monzogranite has the LA-ICP-MS zircon U–Pb age of (459.3±1.1) Ma, indicating that it was formed in the late Middle Ordovician Epoch. It belongs to the strong peraluminous S-type granite with its magma sourced from the metamorphosed sedimentary rock. The monzogranite was formed at the beginning of the post-collision stage, indicating that the closure of the Proto-Tethys Ocean in the Eastern Kudi area was in the late Middle Ordovician Epoch. Results of previous researches and this study have shown that the Proto-Tethys Ocean in the Western Kunlun Mountains is characterized by many islands. The development of Kudi Ophiolite and Kangxiwa-Subashi Ophiolite indicates that the Proto-Tethys Oceanic plate was subducted sequentially from north to south.

The dissolution of silicate minerals is of great importance to many geochemical processes. In order to better comprehend the dissolution properties of muscovite, the dissolution process of cations, and the changes of structure and microstructure of muscovite in aqueous interfacial reaction with oxalic acid and sulfuric acid solutions have been studied in this paper. The changes of composition, structure and morphology of muscovite in the process of its interfacial reaction with acidic solutions have been characterized by using ICP-OES, XRD, SEM and AFM methods. The results show that the dissolution rates of cations from muscovite in sulfuric acid solution are relatively high, due to the relatively large concentration of H⁺ in sulfuric acid solution at the initial stage of the reaction. With the progress of the reaction, oxalic acid solution resulted in a rapid dissolution of Si⁴⁺, Al³⁺ and K⁺ from moscovite. This can be attributed to the weakening of bond energy of moscovite and reduction of the H⁺ repulsion on the surface of muscovite caused by the adsorption of oxalate anionic ligands on the surface of muscovite. In the reaction process of muscovite with oxalic acid and sulfuric acid solutions, the dissolution rate of K⁺ is higher than those of Al³⁺ and Si⁴⁺, which is related to the binding force between ions. After the reaction of muscovite with oxalic acid solution, the concentration ratio of dissolved Al³⁺ and Si⁴⁺ (Al/Si value) is increased gradually with the extension of reaction time. However, after the reaction of muscovite with sulfuric acid solution, the Al/Si value is changed in an opposite trend. This difference is due to the fact that the complexation of Al³⁺ by oxalate anion ligands resulted in the accelerated dissolution of Al³⁺ in structure of muscovite, while the complexation of Si⁴⁺ by oxalate anion ligands resulted in weak influence on the dissolution of Si⁴⁺ in structure of muscovite. After the reactions of muscovite with oxalic acid and sulfuric acid solutions, banded corrosion pits appeared on the surface of muscovite, which was related to the preferential dissolution of the defect site of muscovite. The formation of the corrosion pits resulted in the attack of proton and ligand on the exposed new edge surface (hk0), then caused the increase of size of corrosion pit more than the increase of depth.

Beryllium is a key strategic metal, which is of great significance to the development of science, technology and industry in China. There will be a large shortage of demanded beryllium supply by 2030. Previous researches have shown that there is relatively high exploration potential of beryllium resource in the Himalayan area. However, the high altitude of the Himalayan area has severely restricted the effectiveness of traditional geological prospecting methods. Hyperspectral remote sensing technology is characterized by the wide detection area and non-invasive measurement. If it can directly identify beryllium-containing minerals, it will provide important technical support for the exploration of beryllium resources in high altitude areas. Beryl is the most typical ore mineral in beryllium deposits in China. In this paper, the spectra of beryllium-bearing beryls were measured by using the visible-shortwave infrared spectroscopy and thermal infrared spectroscopy. Meanwhile, based on the simulation of main mineral characteristics of pegmatitic beryls, some mixed mineral samples with different percentages of beryls have been prepared for undertaking their short-wave infrared spectral quantitative study. The experimental results show that beryl has absorption characteristics at 850 nm, 1150 nm, 1400 nm, 1900 nm, 2055 nm, 2155 nm and 2200 nm in visible-shortwave infrared spectra, and reflection characteristics at 960 cm^–1(～10417 nm) in thermal infrared spectra. At the same time, the absorption peak depths and first derivatives at 850 nm and 1400 nm are increased with the increase of beryl contents in the mixed samples. By comparing with previous remote sensing spectral features of ground objects, it is found that the direct identification of beryl in pegmatitic beryllium ore by using the thermal infrared hyperspectral remote sensing is highly feasible. The visible-shortwave infrared remote sensing technique using the sun light as light source will be affected by the atmosphere, and its feasibility for directly identifying beryl is relatively low. However, by using artificial light as light source, feasibility for directly identifying beryl in a short distance is relatively high. Additionally, the content of beryl in pegmatite ores can be retrieved according to the absorption peak depth and other indicators.

The Nanyangtian W deposit, located in the Laojunshan ore concentration district, is the largest W deposit in the southeastern Yunnan, China. The latest chronological studies revealed that there are two-periods (Late Triassic and Early Cretaceous) skarnization in this deposit. Skarns are represented by the layered garnet–diopside skarn and quartz–garnet–vesuvianite–scheelite veined one, respectively. In this study, based on the field and microscopic mineralogical observations, we have identified three types of garnets including the layered type (Stage 1), massive and quartz vein type (period 2) garnets. The in situ analytical results of major and trace elements of garnets and vesuvianites of different stages indicate that all garnets of two periods belong to the grossularite-almandine solid solution series with slight compositional variation from Gro₉₅Alm₅ to Gro₈₅Alm₁₄, and the vesuvianite is characterized with enriched Al. The BSE images show that there is no growth zonation in both garnet and vesuvianite minerals indicating that they were formed in a relatively closed and stable hydrothermal fluid environment. The existence of REE in garnet is mainly controlled by two substitution mechanisms of [REE³⁺]^VII+[Y²⁺]^VI→[X²⁺]^VII+[Y³⁺]^VI and [REE³⁺]^VII+[Z³⁺]^IV→[X²⁺]^VII+[Si⁴⁺]^IV. The certain positive correlation between Na and REE in vesuvianite indicate that the REE substitution mechanism could be 2Ca²⁺ ↔ REE³⁺+Na⁺. The layered garnets are obviously depleted in HREE, with positive Eu anomalies, and relatively high contents of U and HFSE, indicating that the early-period skarn was formed under a relatively reduced, acidic and low Water–Rock ratio fluid condition. The quartz-vein type garnets are obviously depleted in LREE but enriched in HREE, with negative Eu anomalies, and relatively low contents of U and HFSE, and vesuvianite of the same stage has dramatic negative Ce anomalies, indicating that the late-period skarn was formed under a relatively oxidized, neutral to weak alkaline and high Water–Rock ratio fluid condition. The reduced and acidic fluid environment during the Late Triassic period is not conducive to the precipitation of scheelite, leading to that W occurred mainly in skarn minerals in form of the isomorphic substitution. During the Early Cretaceous period, the weakly alkaline, strongly oxidized, and high Water-Rock ratio characterized late-stage W-rich magmatic hydrothermal fluid is conducive to the precipitation of scheelite which is finally resulted in the the large-scale W mineralization.

With the increasing demand for lithium resources, the development technology of clay-based lithium ore has become the focus of attention in the industry. This paper takes a clay-type lithium deposit in Yunnan as a case study. For example, the utilization of lithium resources in clay-type lithium ore is realized through thermal-chemical activation roasting and water leaching of lithium. In this paper, the hot chemical activation roasting of clay lithium ore is studied.The effects of additives, calcination temperature and time on the extraction of lithium were investigated. The effects of leaching temperature, time and liquid-solid ratio on the activated product water were investigated.The process of dissolution and diffusion of soluble substances in water leaching was analyzed. The amount of sodium sulfate is 30%, the roasting temperature is 700 ℃, and the roasting time is 60 min.Under the conditions of 60 min, leaching temperature and leaching time were 30 ℃ and 1 min respectively, and the liquid-solid ratio was 1 mL/g, the leaching rate of lithium was 89%. The XRD, XPS and TOF-SIMS analytical results of the calcined samples show that the clay-type lithium ore had reacted with lithium chlorite, kaolinite and montmorillonite to have produced sillimanite and albite through the action of sodium sulfate, and the lithium in the ore has been converted into the soluble lithium sulfate. Based on the time-of-flight ion mass spectrometry and XPS analytical results, the extraction mechanism of lithium from the ore has been explored. The thermochemical action of the clay-type lithium ore led to the collapse and defects of structures of silica-aluminum minerals, then resulted in the formation of soluble lithium sulfate through the reaction of free lithium on the surface from the structure of mineral, and the additive of sodium sulfate. The green and efficient extraction of lithium has been realized through the dissolution-diffusion of lithium into the solution in the water leaching process of the clay-type lithium ore.

The Mengjiagou iron deposit is located at the northern end of the Mengjiagou-Beitun-Caiyuan synclinorium fold belt in the western ore belt of the northern Qian′an iron orefield in the eastern Hebei. Its orebodys ocurred in form of the gentle and open syncline in the metamorphic rocks of the Santunying Formation of the Archan Qianxi Group. In recent years, with the improvement of exploration level, a second layer of iron ore body has been discovered in the deep part of the Mengjiagou iron deposit. This leads to the opening up of a new space for prospecting iron ore in the Qian′an area of the eastern Hebei. However, the relatively low research level of iron orebodies in depth of the area restricted the understanding of regional mineralization theory. This article aims to explore the similarities and differences between the deep and shallow orebodies of the Mengjiagou iron deposit, to distinguish the sources of ore-forming materials and their ore-forming environment through the analysis of geological and geochemical characteristics of those two layering orebodies. The results show that ores of both the deep and shallow orebodies in the Mengjiagou iron deposit are mainly pyroxene magnetite quartzite ore, with a small amount of dipyroxene magnetite quartzite ore. They have insignificantly different contents of magnetite and basically same texture and structure. However, the dipyroxne magnetite quartzite ore in the shallow layer contains slightly high content of magnetite relative to the deep layer. The lithology of wallrocks of the shallow layering orebodies is relatively consistent, while that of the deep layering orebodies is relatively complicated. Ores of the deep and shallow layering orebodies contain main chemical composition of TFe₂O₃ and SiO₂, with relatively low contents of Al₂O₃ and TiO₂, and extremely low contents of high field strength elements (Hf, Sc, Rb, Th), indicating that no continental debris material was added in the sedimentation process. Ores of both the deep and shallow layering orebodies have left-declined REE distribution patterns, with La and Y positive anomalies and Eu positive anomalies. The ratios of various elements indicate that both layers of orebodies in the Mengjiagou iron deposit are characterized with the dual superposition of seawater and hydrothermal fluids. The lack of negative Ce anomalies indicates that the Mengjiagou iron deposit was formed in an anoxic environment. Results of the comparative analysis of geochemical characteristics of various BIF iron deposits hosted in different metamorphic rocks in the eastern Hebei show that they have consistant source of ore-forming materials.

To unify the classification and naming of rocks is conducive to the academic exchange and guidance of resource development. The national standard for the classification and nomenclature of phosphatic rocks adopts the textural-genetic classification as the primary criterion. Consequently, any advancements of researches on the genesis of phosphatic rocks will directly influence the classification and nomenclature scheme of phosphatic rocks. Based on the microscopic observations of typical phosphatic rocks in Guizhou, Yunnan, Sichuan, Hunan, and Hubei provinces, combined with comprehensive analysis of previous research achievements, this paper proposes a new textural-genetic classification scheme for phosphatic rocks by referencing the research methodology of carbonate microfacies. (1) The new textural-genetic classification pointed out that phosphatic rocks can be categorized into the allochthonous, autochthonous, recrystallized, mud-cracked, and silicified ones for reflecting their dynamic formation history. (2) A type of medium-grained clastic phosphatic rock is refined and supplemented, with clasts including intraclasts, bioclasts, coated grains, peloids, and lumps. Especially, the bioclast was regarded as granular component and was emphasized to have participated into the formation of phosphatic rock as its critical component. (3) The type of autochthonous phosphatic rock has been sub-classified to sub-types such as the stromatolitic, laminar, and clotted phosphatic rocks for reflecting different morphologies of algae, and a sub-type of continental sedimentary phosphite. 以These revised contents of the above proposed textural-genetic classification serve as foundational material for establishing a new edition of the national standard for the classification and nomenclature of phosphatic rocks.

A series of high Ba-Sr granitoids, developed in the Taihang Mountains region, are associated with a large amount of metal mineralization. To analyze their genesis is of great significance for studying the crust-mantle interaction and the evolution of its corresponding magmatic mineralization system in the destruction process of the North China Craton. This study takes the Guanyintang intrusion in the central section of the Taihang Mountains as an example to conduct zircon U–Pb geochronological, lithogeochemical, and genetic mineralogical researches of its different rocks. The research results show that main components of the Guanyintang intrusion are quartz monzonite, granodiorite, with minor diorite as the marginal phase of the intrusion. The compositions of dikes associated with the intrusion are consistent with those of main components of the Guanyintang intrusion. The diorite was formed at 125.2 Ma. Three measured ages for porphyritic quartz monzonite, granodiorite, and porphyritic granodiorite are 124.6 Ma,129.9 Ma, and 130.33 Ma, respectively. The Lu-Hf isotopic characteristics of zircons indicate that the Guanyintang intrusion was formed by the mixture of acidic magma produced by the partial melting of ancient crust and basic magma produced by the partial melting of lithospheric mantle. Characteristics of the zoning texture of orthoclase indicate that the Guanyintang high Ba-Sr granitoid was formed by the mixture of the granitic magma in the magma chamber and the mantle derived magma which were intruded into the acidic magma chamber in multiple pulsations.

Bridgmanite (Mg-Pv), as the most abundant mineral in the lower mantle, has been discussed by many scholars in recent years regarding to the different substitution mechanisms of structural water in Bridgmanite and their important scientific significance for the content of structural water in the lower mantle. The core–mantle boundary of the Earth is a key area bearing the processes of plate subduction and Mantle convection. To explore the relative stabilities among different occurrence mechanisms of structural water in Bridgmanite in this area will help us to understand the content, distribution, migration and circulation rules of water in the deep Earth. In this study, we have systematically studied the relative stabilities of three different substitution mechanisms of structural water in Bridgmanite including the V_Mg2H(V^′′_Mg+2OH^·), V_Si4H(V^′′′′_Si+4OH^·) and Al_SiH(Al^′_si+OH^·) under temperature and pressure conditions at the core–mantle boundary of the Earth through the first principles molecular dynamics simulation. The research results indicate that among the three substitution mechanisms under high pressure, the stability of the Al_SiH(Al^′_si+OH^·) substitution mechanism was significantly affected by the temperature, and it was increased with the increase of temperature. On the other hand, the researches on the relative stabilities of the V_Si4H(V^′′′′_Si+4OH^·) and V_Mg2H(V^′′_Mg+2OH^·) mechanisms show that under the condition of core–mantle boundary of the Earth, structural water may be more favourable to enter the lattice of Bridgmanite with the V_Si4H(V^′′′′_Si+4OH^·) substitution mechanism, that is, to occupy the Si site in the lattice of Bridgmanite. However, if the concentration of Si vacancy in Bridgmanite at the core–mantle boundary of the Earth is very low, the capability of structural water entering into the lattice of Bridgmanite through the dissolution of cation vacancy defects will also be very limited. In contrast, the relatively high stability of the Al_SiH(Al^′_si+OH^·) substitution mechanism under high temperature and high pressure suggests that the Al rich region at the core–mantle boundary of the Earth could have considerable water content, possibly as high as about 0.5 wt.%. In addition, the molecular hydrogen in the interstitial sites of the lattice of Bridgmanite may also have a certain degree of stability under high temperature and high pressure conditions at the bottom of the lower mantle. These provide some new insights into the occurrence state and source of structural water within the interior of the Earth.

Tetragonal germanium dioxide has excellent electrical and optical properties and holds significant application value in fields such as electronic components and others. However, its large-scale preparation faces several challenges. Most of the existing methods for converting hexagonal germanium dioxide to tetragonal germanium dioxide require medium-to-high temperature conditions, high-pressure environments, and catalyst assistance, and generally have problems such as long reaction cycles and easy introduction of impurities. In this study, we developed a novel method for preparing pure tetragonal germanium dioxide under the relatively low temperature condition and have thoroughly investigated effects of temperature, pressure, and oxygen fugacity on the product formation. The research results indicate that hexagonal germanium oxide can be completely converted to tetragonal germanium oxide by adding gaseous water under conditions of temperatures ranging from 200 °C to 450 °C, and low pressure of 1.30×10³ kPa. Raman spectroscopy and X-ray diffraction analyses confirmed that the experimental product possesses a high-purity tetragonal structure with no detectable impurities. Comparative experiments using different oxygen fugacity buffer pairs (Ni-NiO, Fe₃O₄-Fe₂O₃, MoO₂-MoO₃) demonstrated that the tetragonal germanium oxides which were produced under the oxygen fugacity conditions of over 1.05×10^–28 kPa have good thermodynamic stability. Compared to previously reported preparation methods of the tetragonal germanium dioxide, this synthesis route has three main advantages including the easily achievable reaction conditions, no catalyst requirement, and a straightforward process flow. By increasing the reaction vessel capacity, the batch conversion from hexagonal germanium oxide to tetragonal germanium dioxide can be accomplished. This novel preparation method offers a viable solution for the large-scale production of high-quality tetragonal germanium oxide, which is conducive to promoting applications of the tetragonal germanium oxide in the fields of new electronics and optoelectronics. This study optimized the preparation process of tetragonal germanium oxide, greatly enhancing the application potential of tetragonal germanium oxide in high-tech sectors and providing crucial support for the development of related industries.