Abstract:

Early Precambrian basement is well developed in western Shandong Province of the North China Craton. This paper shows a systematic study of the monzogranites from Culai Mountain,western Shandong, revealing the evolution history of Precambrian crust in the eastern part of North China Craton. LA-ICP-MS zircon U-Pb isotopic dating shows that the monzogranites from Culai Mountain were formed at about 2.48 Ga, which also restricts the time limit of metamorphism-anatexis in Culaishan area. The rocks have high Si, Na and K, low P, a A/CNK ratio of 0.94～1.10, and belong to the high-K calc-alkaline series. The monzogranites exhibit enriched light rare earth elements (LREEs) with no δEu anomalies, and are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr and Ba), and depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, P and Ti). Based on comprehensive analysis, it is believed that the monzogranite from Culai Mountain originated from partial remelting of the about 2.7 Ga thickened lower crust (tonalite TTG rocks). Formed in an extensional environment after collisional orogenesis, it marks that the completion of the collage of micro-land masses in western Shandong in the late Neoarchean, and together with other regions to formed a stable North China Archean Craton.

Abstract:

Beryl is an important Be-Al silicate mineral with high economic and industrial value. Laojunshan gneiss dome is located in the joint of South China block and Indosinian block, which has experienced multi-stage tectonic-magmatic action and developed Sn, Cu, Zn and other polymetallic deposits and emerald deposits. This study focuses on the detailed analysis of macro- and micro-structural characteristics of beryl and its symbiotic quartz veins in the region, and limits the temperature environment of formation and deformation through fluid inclusions and quartz EBSD fabric. The results show that beryl and quartz are rich in fluid inclusions, in which beryl has low temperature-high salinity two-phase and high temperature-low salinity three-phase fluid inclusions, and quartz has low temperature-low salinity two-phase fluid inclusions. The deformation characteristics of the quartz associated with beryl mainly develop rhombal <a> superimposed by secondary prim <c>, indicating low-temperture (350～400℃) deformation environment, superimposed by local high-temperture deformation. The magmatic fluid in the middle and late Yanshanian was accompanied by the uplift/exhumation of gneiss dome, which brought rich ore-forming elements, including the main Be elements of beryl mineralization. The exhumation process of regional gneiss dome from deep to shallow provides an important structural ore-bearing fluid channel for mineralization. With the occurrence of fluid immiscibility, the pH value of ore-forming fluid increases, thus promoting the occurrence and precipitation of ore-forming elements.

Abstract:

The Yangchang phosphate deposit is located within the shallow marine strata of the Meishucun Formation (∈₁ms) in the southwestern Yangtze block. Investigating the sedimentary environment evolution of the Meishucun Formation in this mining area holds significant implications for regional prospecting. This study conducts geochemical analyses of major and trace elements from the Meishucun Formation in the Yangchang phosphate mining area to explore the sedimentary evolution process and phosphate enrichment sites. The results indicate that the Meishucun Formation contains relatively high concentrations of CaO and MgO, with elevated loss on ignition. Notably, P₂O₅ is enriched in the upper part, while SiO₂ is enriched in the lower part. The first member of the Meishucun Formation (∈₁ms¹), formed during the early to mid-Cambrian transgression, exhibits multi-element enrichment characteristics. Specifically, the enrichment coefficients of U and Mo in the lower submember (∈₁ms^1-1) exceed 60 times the average crustal value, whereas those in the upper submember (∈₁ms^1-2) exceed 10 times the average crustal value. Significant differences in peak values of U and Mo enrichment are observed between the two submembers. The lower submember (∈₁ms^1-1) shows no Ce anomalies and weak negative Eu anomalies, while the upper submember (∈₁ms^1-2) displays weak negative anomalies for both Ce and Eu. These findings suggest that the first member of the Meishucun Formation was deposited in a subtidal low-energy environment, transitioning from a relatively anoxic environment in the lower submember (∈₁ms^1-1) to a relatively oxidized environment in the upper submember (∈₁ms^1-2). The second member of the Meishucun Formation (∈₁ms²), composed of endogenous sediments hosting phosphate ores, was formed in an intertidal or subtidal high-energy environment. Trace element characteristics suggest an anoxic environment, while negative Ce anomalies indicate an oxidized environment. This implies that the collophanite in the phosphorite of the second member crystallized and precipitated from supersaturated phosphorus-rich seawater above the subtidal oxidation-reduction interface under arid and hot conditions, subsequently depositing in a closed or semi-closed anoxic environment on the seafloor. The third member of the Meishucun Formation (∈₁ms³), consisting of endogenous sediments formed at the upper part of the supratidal or intertidal zone, inherits trace and rare earth element characteristics from the second member, indicating an oxidizing environment under dry and hot climatic conditions. In summary, the sedimentary environmental evolution of the Meishucun Formation can be divided into four stages: early transgression, middle transgression, late transgression, and regression, corresponding to climatic changes from arid or semi-arid and hot to warm and humid, then back to arid and hot. The seafloor also underwent four stages of sedimentary processes: reduction, oxidation, mainly focused on reduction, reduction and oxidation alternate with each other, and oxidation. We conclude that the Yangchang phosphate mining area was situated in the underwater intertidal or subtidal high-energy zones within the shallow shoals of the eastern Yunnan epicontinental sea, Yangtze Craton, where the formation and enrichment of collophanite are more favorable in relatively closed or semi-closed reducing environments or semi-reducing environments of seawater.

Abstract:

A thick layer of mirabilite was deposited in the lower part of the potassium-bearing strata of the Mahai Salt Lake in the Qaidam Basin. Unlike potassium salts, which usually formed in dry and hot climate, mirabilite is mostly formed under extremely cold conditions. Therefore, the study of the sedimentary characteristics and genesis of thick-layer mirabilite is of great significance for understanding the evolution of ancient environments and their impact on potassium salt mineralization. The article takes the stratigraphic profile of thick-layer mirabilite developed in the Mahai mining area of the Qaidam Basin as the research object, through systematic sampling, thin section identification, chemical composition, mineral type, and sulfur isotope analysis were carried out to study the changes in the chemical composition, mineral type, and sulfur isotope of the profile. The results show that the salt minerals in this section are main stone salt, gypsum, mirabilite, and glauberite, the maximum deposition age of the mirabilite layer is 275.3 ±47.9 ka BP, the research section shows the characteristic of evolution from thick-layer pure mirabilite to gypsum-bearing stone salt from bottom to top. The lower part is mirabilite layer, and glauberite appears in the middle and lower parts. The highest content of stone salt is in the middle and upper parts, while the content of stone salt in the upper part relatively decreases and the content of gypsum increases. Correspondingly, the content of potassium, magnesium, and calcium in the chemical composition of sediments steadily increases, while the overall content of sulfate ions and sodium decreases. During the period of thick-layer mirabilite deposition, Mahai Salt Lake was in a continuously dry and cold climate, which was beneficial to the continuous enrichment and increase of potassium and magnesium in the brine of the salt lake, which laid a foundation for the formation of solid potassium ore through local enrichment.

Abstract:

In order to determine the geochemical characteristics and paleosedimentary environment of the Lower Cretaceous Yixian Formation and Jiufotang Formation in the northern part of the Naiman sag, petrographic analysis was conducted on N10 and NA-2 wells located near the sedimentary center in the north. Samples of mudstone and evaporite were tested for major and trace elements, carbon and oxygen isotopes, organic carbon, pyrolysis, and group composition. The paleoredox conditions, paleosalinity, paleowater depth, paleoclimate, and lake water sealing characteristics of the study area were systematically analyzed. The study shows that they were volcanic facies in the early sedimentary period of Yixian Formation in the northern part of the Naiman sag, mainly fan delta-lacustrine depositional-lake facies sedimentary systems in the middle and late sedimentary period, and local shore-shallow lacustrine facies of different types of evaporites in the late sedimentary period. Sensitive elements or element ratios such as Cu/Zn, Sr/Ba, Sr/Cu, Rb/Sr, Fe₂O₃/MnO, Ga, Sr indicate that the climate of Yixian Formation changed from semi-humid-semi-arid to arid from the middle period to the end period, the water environment also changed from semi-closed-semi-open with partial oxidation to completely closed with weak oxidation-weak reduction, and the sedimentary geochemistry environment changed from freshwater-brackish deep lake to brackish shallow lake. The Jiufotang Formation is a semi-enclosed deep lake sedimentation of oxidized fresh water with a climate similar to that of the middle of the Yixian Formation. The sedimentary environment during the middle and late periods of the Yixian Formation and the Jiufotang Formation were suitable for biological reproduction, which were favorable for the development of argillaceous source rocks. And for the development of pores and intercrystalline pores of thick-layer evaporites, which can become good reservoir spaces, they are favorable for oil and gas enrichment.

Abstract:

The Ordovician weathered crust reservoir in the Ordos Basin is affected by calcites of different stages,so clarifying the genesis and influence of calcites can help to understand the mechanism of reservoir formation. Minera-logical,geochemical and isotope chronological results of calcites from the Ordovician weathered crusts in the Fuxian area of the Ordos Basin demonstrate that these calcites can be divided into white primary calcite, red secondary calcite and white secondary calcite. The white primary calcite filled in the pores and crevices of the paste mold,whereas the cleavage of calcite in the dissolved pores is much more developed than those in the dissolved seams. Geochemistry shows obvious negative Ce anomalies, a few calcites filled in the pores have positive Eu anomalies. They have red and orange-red cathodoluminescence, and their U-Pb ages are 333.3±3.3 Ma and 332.8±3.5 Ma, respectively, indicating that this type of calcite was formed in the early Carboniferous near surface environment. Gypsum was dissolved by atmospheric freshwater to form Ca²⁺, which reacted with atmospheric freshwater rich in CO^2-₃ at the gypsum mold pores and dissolution fractures. Red calcite is the secondary calcite of metasomatic dedolomitization, with dolomite crystal type mostly and orange-red cathodoluminescence. It is formed by metasomatic dolomite crystals in the atmospheric freshwater equimolarly from surface to near-surface environment, with high Mn,low Sr,high Sr isotopes and negative C and O isotopes. White secondary calcite is poikilitic,and medium-grained crystals,with developed cleavage, orange-red cathodoluminescence, high Sr concentration and high Sr isotopes, negative Ce and C anomalies, relatively stable O isotope,and U-Pb age of 212.0±19.0 Ma. The results indicate that this type of calcite was formed by the reaction of acidic fluids with Ca²⁺ during the Late Triassic hydrocarbon expulsion period. All kinds of calcite are the products of different diagenetic fluids in different diagenetic stages, which are easy to develop in the relative low-lying stagnant areas and result in the reduced rock porosity. Therefore, more attention should be paid to the high parts of paleo-karst geomorphology for effective reservoirs.

Abstract:

Magmatic sulfide and oxide deposits rarely commonly appear due to their different genetic mechanism, and the studies about their co-existence mechanism are important for understanding the mineralization of mantle-derived magmas. Chengde, Hebei Province is an important magmatic mineral resource rich area in China. Sulfides coexisting with magnetite appear in Habaqin iron deposit, and the magnetite has been studied, but few studies on sulfide are involved. We carried out the major and trace elements, and in situ S isotopes of sulfides as well as in situ Sr isotopes of amphibole and apatite on the basis of petrography of host hornblendite, to reveal the genesis of sulfides. The hornblendite shows cumulate texture and consists of amphibole (80%~85% by volume), magnetite (10%~15%), apatite (3%~5%), and minor sulfides (<5%). The magnetite appears as granular aggregates and sulfides as sparse disseminations (<5%). The sulfides are mainly pyrite with inclusions of magnetite and apatite, suggesting that sulfides crystallized at late stage. The contents of S and Fe in pyrites range from 52.0% to 53.0% and 45.4% to 46.5%, respectively, with higher concentration of Co (up to 1.68%), suggesting its formation is controlled by magmatic segregation, accompanied by slight magmatic hydrothermal process. The initial ⁸⁷Sr/⁸⁶Sr ratios of amphibole and apatite range from 0.705 82 to 0.708 30 and 0.706 16~0.708 09, respectively, and the δ³⁴S values of pyrites range from -2.8‰ to +1.3‰, suggesting that the hornblendite and its sulfur mainly originate from an enriched lithospheric mantle; sulfur saturation is primarily controlled by the fractional crystallization of the parental magma. The crystallization of magnetite leads to delayed sulfide saturation, and weak assimilation and contamination of crustal material results in weak sulfides separation compared to oxides.

Abstract:

In the early days of the porcelain industry in Jingdezhen, the porcelain capital, a single raw material—porcelain stone was used. During the developing process of porcelain industry, the ancestors of Jingdezhen porcelain invented the binary-compositions formulation: mixing porcelain stone and kaolin in a certain proportion to form porcelain raw materials, which greatly improved the quality and efficiency of porcelain production. However, we still do not know why ancient porcelain stones could become suitable raw materials for ancient porcelain making. For this purpose, this article conducted detailed microstructural studies and electron probe mineral composition analysis on porcelain stone samples taken from the rock walls of ancient mining pits in Gaoling Mountain. The results show that the porcelain stone from Gaoling Mountain is a special type of leucogranite, consisting of albite, K-feldspar, quartz, a small amount of biotite, and Fe-muscovite (?), and develops a micro fracture grid structure partially filled by chlorite. This composition and structural characteristics make porcelain stone an early excellent raw material for porcelain production that is easy to mine and process. Combined with the recently published experimental results of high-temperature crystallization of water rich acidic magma, we suggest that the Jingdezhen porcelain stone is a kind of leucogranite formed by dynamic crystallization of a water-saturated granite melt under the lower cooling-rate and lower undercooling degree conditions, with a mineral combination sequence of albite (+biotite) → K-feldspar+quartz →Fe-muscovite (?). Fe-muscovite (?) may be a new mineral, and further research is needed to determine its crystal structure and lattice parameters. The discovery of Fe-muscovite(?) in porcelain stones will help to understand the relationship between changes in the composition of ancient porcelain bodies and changes in porcelain-making formulas, and thus more reasonably infer the onset time of the emergence of binary formula technology.

Abstract:

Time is a basic physical parameter to describe a geological process or geological event. Each radionuclide has a particular half-life, hence, they are applied to investigate different time scales of geological processes according to their half-lives. The occurrence of geological events and the duration of geological processes can restrict their causes and mechanisms, which is the key to reconstruct the geological processes. Currently, many isotope decay systems have been developed to achieve high-precision isotope dating, however, U-Pb chronology system containing double decay system, which is the first tool that precisely restricted the exact age of the earth. From the early solution analysis method to the present in-situ U-Pb geochronology analysis by laser ablation analysis or secondary ion mass spectrometry, U-Pb system has developed vigorously. The only tool for the calibration of all in-situ U-Pb geochronology standards is the double-spike diluent method of thermal ionization mass spectrometry (ID-TIMS). Therefore, this study reviewed the development of high-precision ID-TIMS U-Pb geochronology in detail, where we focused on the milestone events in its development process. Finally, the potential applications of high precision geochronology for ore deposit research are discussed.

Abstract:

Carbonates play a crucial role in transporting surface carbon-bearing materials into the Earth's deep mantle through subduction. The recycling process of subducted carbonates is considered a pivotal process in the deep carbon cycle within subduction zones. During subduction, carbonates undergo decarbonation reactions to varying extents, releasing carbon-bearing fluids or melts into the mantle, thereby significantly impacting its composition and redox state. Today our comprehension of the carbonate recycling process in subduction zones largely stems from restricted investigations of (ultra) high-pressure metamorphic rocks, mantle xenoliths of different depths, experimental petrology and molecular dynamics conducted under conditions of high temperature and high pressure. A thorough understanding of the processes involved in subducting carbonate recycling is crucial for deciphering the geochemical and dynamic behavior of carbon in the deep Earth. This paper provides a comprehensive review of the subducting carbonate recycling process. It examines various decarbonization mechanisms, including metamorphic decarbonation, dissolution decarbonation, melting decarbonation, and redox decarbonation. By integrating these mechanisms with the thermal structure of global subduction zones, the paper investigates the distribution of carbon states and its migration patterns. Furthermore, it explores the impacts of these processes on the oxidation processes within both shallow and deep Earth environments.

Abstract:

High-purity quartz is widely used in high-tech industries such as semiconductors, photovoltaics, optical communication, and light sources. It plays an important role in national strategic emerging industries, economic security, and national defense security, and is a scarce resource in the world and China. Vein quartz is one of the ideal raw materials for processing high-purity quartz raw materials. Based on extensive collection and research of vein quartz exploration results, this article divides the mineralization zones of vein quartz deposits in China according to their tectonic environment, distribution characteristics, mineralization characteristics, and controlling factors, and briefly describes the mineralization characteristics of each mineralization zone; Summarized the ore-forming laws of vein quartz deposits in China. The main types of vein quartz deposits are magmatic hydrothermal vein type, followed by metamorphic hydrothermal vein type, and pegmatite vein type. The main mineralization periods are Yanshanian, followed by the Hualixi, Caledonian, Jinning, and Indosinian periods. 27 vein quartz mineralization zones have been preliminarily divided, and it is proposed that 5 vein quartz mineralization zones, including the Lüliang, South Qinling, Tongbai-Dabie, East China Sea-Ganyu, and Altai blocks, are important high-purity quartz vein quartz mineralization zones in China. The summary of the mineralization rules of vein quartz and the division of mineralization zones provides a theoretical basis for the exploration and deployment of vein quartz.

Abstract:

The coal measure resources in Antarctica possess great potential yet have received limited research. The discovered coal measures are predominantly Permian strata, with a few being Mesozoic-Cenozoic strata. The coal measures are essentially distributed in the Transantarctic Mountains and Prince Charles Mountains, with some parts found in West Antarctica. The coal-abundant strata in the Transantarctic Mountains are mainly Permian-Triassic Victoria Group of the Bacon Supergroup, and the coal-abundant strata in the Prince Charles Mountains are mainly Permian Bainmedart Coal Measures of the Amery Group. The coal in Antarctica exhibits the characteristics of a high thermal order and is mostly thermal metamorphic coal. The coal in the Transantarctic Mountains is mostly anthracite, super anthracite, or natural coke, which has the characteristics of high alteration. The coal in the Prince Charles Mountains region has the characteristics of high volatility and low sulfur. The vitrinite reflectance, which represents the maturity of coal measures, gradually decreases to a relatively stable trend as the formation age from old to new in the Bainmedart Coal Measures. The development of major coal measures in Antarctica reveals that during the Late Paleozoic and Early Mesozoic, the Antarctic was warm and humid with lush vegetation, and the sedimentary environment was vastly different from that of today. The existing coal measures were mostly developed at the intersection of river and lake sedimentary facies. The development and history of the thermal evolution of coal measure disclose that the formation of Antarctic thermal metamorphic coal measure is related to the breakup of Gondwana. The linear distribution along the Transantarctic Mountains of the Ferrar Large Igneous Province is coupled with the location of typical Permian coal measures, and the dike formed by the Jurassic short-term concentrated thermal event can be regarded as the signal of the commencement of thermal alteration of the coal measure, while the heat rise caused by the further breakup of Gondwana at the end of Cretaceous may be the main cause of the high coal rank and high maturity of the Antarctic coal measure.

Abstract:

Soil organic carbon pools are one of the hot topics in carbon cycle research, among which dissolved organic matter (DOM) is the most mobile and active, and clay-grained minerals are the most active mineral components in soil. Clay-grained minerals have a significant impact on the stability of DOM. Therefore, the adsorption characteristics and control mechanisms of three common soil clay-grained minerals, allophane, kaolinite and hematite, on DOM were explored in detail from the perspectives of adsorption kinetics and thermodynamics. The results indicate that three minerals can effectively adsorb PDOM, and the adsorption capacity of allophane on PDOM is higher than that of kaolinite and hematite, but its adsorption capacity per unit area is weaker than the other two; Kinetic and thermodynamic data indicate that the PDOM uptake by allophane may be largely controlled by physical means, while that by kaolinite and hematite are chiefly through chemical forces. Differences in the interfacial properties of the three minerals lead to different absorption characteristics. Among them, the specific surface area is the main factor leading to the difference in the total amount of adsorption, while the adsorption strength depends on the pH value of the reaction system, the density and availability of the adsorption sites. This study provide a basis for understanding the sequestration of organic matter by soil clay-grained minerals.

Abstract:

In the process of treating landfill leachate using the upflow anaerobic sludge blanket (UASB), microbial mineralization products can deposit and block the circulation and effluent pipes. Repeatedly replacing pipes to remove blockages is a labor-intensive process and exerts a negative impact on the stable operation of the system. The mineralogy and microscopic structural features of scaling in UASB system pipelines were investigated by mineralogical characterization methods in this study. The mechanism of scaling formation was explored. It provides a theoretical foundation for the prevention, inhibition, and cleaning of scaling in UASB reactor pipelines. The results indicated that the pipe scaling constituted a complex mixture of microbial mineralization products and organic matter, primarily consisting of acid-soluble materials. The main crystalline phases were monohydrocalcite and struvite. Struvite presented columnar crystals with diameters ranging from 0.2 nm to 0.5 mm, and arranged in bundles or radiating patterns. Monohydrocalcite appeared as spherical particles with diameters ranging from 50 nm to 350 nm. The anaerobic process producing methane production of landfill leachate consumed H⁺ and generated a large amount of CO₂, which increased the carbonate alkalinity of the anaerobic digestate. Meanwhile, organic nitrogen was ammonified, and organic phosphorus was converted into phosphate. In the digestion, phosphate, magnesium, and ammonium ions combine to crystallize into struvite, while calcium ions and carbonate ions combine to crystallize into calcite. Although the ion concentrations in the anaerobic digestate were supersaturated for hydroxyapatite and calcite, the presence of magnesium ions and high concentrations of organic matter in the anaerobic digestate may inhibit their nucleation and crystal growth. In the UASB system, struvite undergoes heterogeneous nucleation on the pipeline surface, growing into large columnar crystals. Monohydrocalcite filled the gaps between struvite crystals, incorporating a small amount of organic matter. Then, struvite and calcium carbonate were cemented together, forming pipe scaling with a certain level of strength resisting to fluid flushing. Considering the use of an in-situ acid dissolution method with 5% acetic acid to remove pipe scale, the residual acidity of the acid wash solution will keep as low as possible without altering the pH of the liquid inside the large-scale UASB reactor. Additionally, Low concentration acetic acid can serve as a substrate for methane-producing bacteria to enhance methane production.

Abstract:

Building on previous research, we employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating method to maximize sensitivity and minimize elemental fractionation effects. This was achieved by improving the testing process, optimizing the instrument parameters, and incorporating auxiliary gas sensitization equipment, such as nitrogen. In this study, three standard zircons—Qinghu, Plešovice, and Tanz—were dated using beam spot diameters of 32, 24, and 16 μm, respectively. The experimental results reveal that with a 32 μm beam spot, standard zircon Qinghu ²⁰⁶Pb/²³⁸U age range is 162~157 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 159.5±0.8 Ma (2σ, n= 6, MSWD=0.36); Standard zircon Plešovice ²⁰⁶Pb/²³⁸U age range is 340~334 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 337.1±1.5 Ma (2σ, n=27, MSWD=0.085); Standard zircon Tanz ²⁰⁶Pb/²³⁸U age range is between 574~562 Ma, weighted average ²⁰⁶Pb/²³⁸U age 566.6±2.9 Ma (2σ, n=29, MSWD=0.070). With a 24 μm beam spot, standard zircon Qinghu ²⁰⁶Pb/²³⁸U age range is 162~157 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 159.3±0.7 Ma (2σ, n=30, MSWD=0.22); Standard zircon Plešovice ²⁰⁶Pb/²³⁸U age range is 341~334 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 337.2±1.5 Ma (2σ, n=29, MSWD=0.13); Standard zircon Tanz ²⁰⁶Pb/²³⁸U age range is 568~561 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 566.5±2.9 Ma (2σ, n=30, MSWD=0.054). With a 16 μm beam spot, standard zircon Qinghu ²⁰⁶Pb/²³⁸U age range is 163~154 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 159.5±1.4 Ma (2σ, n=25, MSWD=0.45); Standard zircon Plešovice ²⁰⁶Pb/²³⁸U age range is 340~334 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 337.3±2.0 Ma (2σ, n=30, MSWD=0.063); Standard zircon Tanz ²⁰⁶Pb/²³⁸U age range is 575~563 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 567.0 ±4.3 Ma (2σ, n=30, MSWD=0.028). The weighted average ages of the three standard zircons (Qinghu, Plešovice, and Tanz) are consistent with their recommended values within the margin of error. These findings demonstrate the feasibility of using small beam spot sizes (24 μm and 16 μm) for zircon LA-ICP-MS U-Pb dating. This refined method extends the applicability of LA-ICP-MS zircon U-Pb dating, making it suitable for small zircon grains with complex structures. This model has significant theoretical research implications and economic value.

Abstract:

Jingtieshan iron mine of Jiuquan Iron and Steel Group Co. is a typical complex refractory iron oxide ore. The original ore has a low iron grade, multiple types of iron minerals, and complex symbiotic relationships, making the ore extremely difficult to select. In order to improve the grade, recovery rate, filtration performance and other indicators of concentrate, starting from the perspective of process mineralogy, the differences in disseminated particle size, hardness, density and magnetic properties between raw ore and roasted ore of Jingtieshan complex refractory iron oxide ore and their washability characteristics of JISCO were analyzed to judge the advantages and disadvantages of the current mineral processing technologies. On this basis, combined with the characteristics of different beneficiation processes, ore properties, production costs, concentrate quality, and filtration performance, a new combined beneficiation process of intelligent preselection-fine breaking-dry grinding-suspension magnetization roasting-gravity separation-magnetic separation-fine sieve-reverse flotation is recommended.

Abstract:

This paper discusses the petrogenesis of the two-mica granite and its genetic relationship with pegmatite in Jiajika area, west Sichuan Province, by detailed field investigation and laboratory analysis. The whole rock analytical results show that SiO₂ content of two-mica granite is 73.93%~75.06%, and total alkali is 7.90%~8.36% with high concentration of K, suggesting high-K calc-alkaline series; the content of Al₂O₃ is 14.24%~14.77%, and A/CNK=1.14~1.24, implying strong peraluminous S type granite; ΣREE=31.18×10^-6~41.67×10^-6,LREE/HREE=4.15~6.41,δEu=0.46~0.70, and CaO/Na₂O=0.07~0.12(<0.3),indicating that its source might have been pelite with rare content of psammite, and high ratio of Al₂O₃/TiO₂ (133.1~279.8) implies that it is high-pressure-low-temperature post-collision granite. The SiO₂ content of the granite pegmatite is 72.59%~80.91%, the total alkali is 5.26%~10.60%, Al₂O₃ is 11.79%~17.64%, σ=0.74~3.80; A/CNK=0.98~2.38; ΣREE=4.03×10^-6~8.29×10^-6, LREE/HREE=2.61~10.40, and δEu=0.18~0.68. There are considerable differences between two-mica granite and granite pegmatite in the aspect of the content of major and trace elements. And there is close genetic relationship between granite and pegmatite in the area. Magma immiscibility might be the key factor for the formation of (ore-bearing) granite pegmatite. The pegmatite melt riched in volatile components might be separated during the upwelling of granite magma and metasomatized minerals in wall rock to further concentrate rare metal elements during its migration. The difference between two-mica granite and pegmatite might cause the apparent differences in REEs and elements such as Th, Sr, Ti, Y, Rb and Nb. The different characteristics of pathways and environments that the pegmatite melt passed and emplaced might have resulted in element concentration variance in different sites. In comparison with two-mica granite, there existed a certain degree of jumping characteristic during the formation and evolution of the pegmatite in Jiajika area.

Abstract:

Guilin Chicken Blood Red Jasper (CBRJ) is a kind of quartz jasper. It is characterized by bright red to black colors and high hardness. However, few researches have been focused on the field occurrence, geological background, rock structure and genesis of its color. Field surveys indicate that the Guilin CBRJ is hosted in low-grade metamorphic sandstones which experienced vapor-water hydrothermal metamorphism and iron oxide dissemination. It occurs in the Sanmenjie Formation of Neoproterozoic Danzhou Group in Longsheng area in the north of Guangxi. Tectonically, the ore deposit of Guilin CBRJ is located at the juncture of Yangtze and Cathaysian plates, which has undergone a complex geological process. Its formation was related to multi-phase tectono-magmatic activities from Neoproterozoic to Triassic. Detailed analyses of mineralogy, micro-texture and geochemical composition of Guilin CBRJ were carried out by polarizing microscope, X-ray diffraction, and electronic microprobe. The results indicate that the CBRJ is mainly composed of quartz and hematite, with dolomites in some samples. Quartz grains exhibit two types of allotriomorphic equigranular texture and idiomorphic porphyroblastic texture. The latter one, in which distinct enlargement texture can be observed, reveals a metasomatic metamorphism phase. Hematite occurs in three types: ① single crystal existent between or inside the quartz particles, ② dusty crystals wrapped in the quartz particles, and ③ disseminated crystals filled between the quartz particles. The Fe³⁺ in the hematite should be responsible for the color of the CBRJ. Electron microprobe analysis shows that the hematites of single crystal and disseminated crystals have 78.9%～85.6% iron oxides, but the dusty crystal is too small to be analyzed. In combination with the different generations of quartz and hematite, the authors have reached the conclusion that the formation of different types of these minerals in the Guilin CBRJ was consistent with the regionally geological evolution in this area.

Abstract:

The Hongyuntan iron deposit is hosted in pyroclastic rocks of the Lower Carboniferous Yamansu Formation. The ore bodies occur as layers, stratoid bodies or lenses. The principal ore mineral is magnetite, together with minor maghemite, specularite, pyrite and trace chalcopyrite. The gangue minerals include garnet, diopside, actinolite, chlorite, tremolite, epidote, biotite, albite and quartz. The ore structures are mainly of massive and disseminated forms, with occasional banded or veined forms. The ore textures are of subhedral-anhedral granular and metasomatic types. The wall rock alteration shows symmetrical zoning, and the alteration colors change from dark to light from ore bodies outwards. On the basis of observed mineral assemblages and ore fabrics, two periods of ore deposition were recognized, i.e., skarn period and hydrothermal ore-forming period, which could be further subdivided into four metallogenic stages, namely skarn stage, retrograde alteration stage (main ore-forming stage), early hydrothermal stage and quartz-sulfide stage. Electron microprobe analyses show that the end member of garnet is mainly andradite-grossularite. The composition of pyroxene is mainly diopside-asteroite. The amphiboles is composed mainly of actinolite and tremolite with minor magnesiohornblende. The composition of these skarn minerals suggests that skarn in the Hongyuntan iron deposit is calcic skarn, belonging to metasomatic skarn. The characteristics of main and trace elements suggest that the formation of magnetite was closely related to the skarn. In combination with geological characteristics, the authors suggest that the skarn might have resulted from interaction between Ca-rich pyroclastic and Fe-rich magmatic hydrothermal fluid which was transported along the fault system. The formation of magnetite was hence related to the regressive metamorphism of the skarn.

Abstract:

This paper has mainly recommended a mineral abbreviation list (see Table 2 and Table 3). Table 2, which contains 243 minerals, was compiled by IUGS Subcommittee on the Systematic of Metamorphic Rocks (SCMR) in 2007. The author selected other 29 minerals and, on such a basis, formulated Table 3. Thus, the total mineral abbreviations come to 272. It is hoped that they can be popularized in future and become more and more perfect through utilization, so as to provide a basis for ultimate standardization and unification.

Abstract:

This paper presents partition coefficients of 69 chemical elements (Li, Rb,Cs, K, Na, Ca, Ba, Sr, Mn, Fe, Mg, Cu, Pb, Zn, Co, Ni, Be, La, Ce, Nd,Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc, Cr, In, Ga, Al, B,Cd, Sb, Bi, U, Th, Zr, Hf, Si, Ti, Ge, Sn, Mo, Nb, Ta, W, V, P, F, Cl,S, N, O, C, As, Pu, Re, Os, He, Ne, Ar, Kr and Xe) and the univalent radical (OH) in 28 minerals (olivine, clinopyroxene, orthopyroxene, amphibole,biotite, Phlogopite, plagiocla-se, K--feldspar, quartz, magnetite, ilmenite, garnet,zircon, apatite, allanite, topaz, sphene, cordierite, hauyne, leucite, nepheline,whit-lockite, brookite, petovskite, melilite, armalcolite, spinel and rutile) from 8 types of rocks, namely metaluminous (ultra) basic rock, peralkaline (ultra) basic rock, metaluminous intermediate rock, peralkaline intermediate rock,metaluminous acid rock, peralkaline acid rock, peraluminous acid rock and ultra-acid rock. It is found through an integrated ahalysis and comparison that the composition and structure of minnerals and melts seem to be the most important factors controlling mineral-melt element partitioning. Importanceshould be attached to minral structure and Al-supersaturation of melt which have, not been discussed by research workers. Finally, the present state and theproblems to be solved in the study of mineral--melt element partition coefficients are analysed, and the future trends of this research field are predibted.

Abstract:

本文以表格的形式列举了经国际矿物学协会(IMA)新矿物与矿物命名委员会(CNMMN)批准、并于2003年度正式发表的新矿物共55种,其中硅酸盐31种,磷酸盐5种,砷酸盐2种,硫酸盐4种,硫化物3种,碳酸盐2种,钒酸盐2种,硼酸盐1种,硒化物1种,硫盐1种,氧化物1种,氢氧化物1种,复杂卤化物1种.文中表格依次列出了矿物的中外文名称及化学式、晶系及晶胞参数、主要粉晶数据、物理性质、光学性质、产状及共生(伴生)组合等.

Abstract:

The combination of multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and laser ablation provides a useful tool for tracing the geological process by analyzing minerals under microscales. As one of the non-traditional stable isotopes, boron isotope has attracted more and more attention. In this study, the authors developed an in-situ method for high-precision analysis of B isotope in tourmaline with high-content boron and muscovite with low-content boron. Tourmaline and glass reference materials were applied to correcting the mass fractionation respectively, and in-situ B isotopes of two natural samples from southwestern Tianshan were also tested. In addition, the boron isotope of the in-house standard T-PKU was calibrated as -13.07‰±0.42‰ (2SD, n=66). The above testing results reveal that the condition of LA-MC-ICPMS is stable for a long term and suitable to producing high quality data about tourmaline with minimum spot size of 10 μm and muscovite with > 20×10^-6 B concentration. The B isotopes of tourmaline and paragonite in Tianshan samples are helpful for tracing fluids sources.

Abstract:

Highgrade black jadeite is a kind of upscale and fashionable jade material that has become one of the jadeites characterized by fastest growing values in the past 20 years. Based on a comparison of mineralogical and geochemical characteristics between black jadeites (inky black jades）from different producing areas of the world, the authors hold that the black jadeites currently on the market can be mainly classified into jadeite jade, omphacitic jadeite jade and hornblende jade whose main components are jadeite, omphacite and dark green hornblende respectively. They include blackchicken jade, ink jadeite and blackkosmochlor from Myanmar and jade negro and galactic gold from Guatemala, with blackchicken jades similar to those from Myanmar also seen in Japan and Kazakhstan. The research results suggest that the main mineral composition, jade structure and inclusion characteristic combinations of black jadeite jades from different producing areas have their respective typomorphic natures, which can be used as the distinctive characteristics for their sources.

Abstract:

Early Paleozoic volcanic rocks in Tianshui and Baoji areas along the eastern segment of North Qilian orogenic belt consists of Hongtubu basaltic lavas and Chenjiahe intermediate-acid volcanic rocks. Geochemical analyses show that Hongtubu basaltic lavas are similar to the intercalated basalts in Chenjiahe intermediate-acid volcanic rocks in characteristics, both fallen in the tholeiite series with high TiO2 (1.50%～2.73%). Their∑REE are 65.97×10-6～133.46×10-6 and 78.04×10-6～175.55×10-6 respectively， both are slightly enriched in LREE ［(La/YbN being 2.00～4.40 and 2.71～4.40 respectively］，and both have no obvious Eu anomaly or weak Eu negative anomaly（δEu being 0.85～1.10 and 0.85～0.99 respectively）. Basalts from two groups are typically characterized by selected enrichment of LILEs, low abundances of HFSEs relative to NMORB, and prominent troughs of Nb and Ta, with low Nb/La ratio（0.28～0.43）, which indicates the affinity of these volcanic rocks to island arc tholeiite（IAT）. In addition, εNd（t）（+2.22～+4.08）values of basalts suggest that their mantle sources are similar to the depleted mantle source. Zr/Nb=17.21～36.33 and Ce/Nb=5.73～8.17, implying geochemical characteristics of N-MORB. Sr, Nd and Pb isotopes from Hongtubu basalts are similar to those in Chenjiahe basalts in composition. In the diagrams of εNd(t)-(87Sr/86Sr)t, (207Pb/204Pb)t-(206Pb/204Pb)t,(87Sr/86Sr)t-(206Pb/204Pb)t and εNd(t)-(206Pb/204Pb)t for basalts, the data are fallen in the DM, EMⅠand EMⅡ areas, probably with a little crustalontamination, indicating that the magma of basalts might have had a mixed gin.Thentermediate-acid volcanic rocks from Chenjiahe belong to the calc-alkaline series,they have relatively high abundances of REE∑REE=127.51×10-6～276.01×10-6）, and are significantly enriched in LREE[（La/YbN= 4.79～13.51]. Most intermediate-acid volcanic rocks show weak Eu negative anomaly (δEu=0.53～1.20). The trace element patterns of Chenjiahe acid volcanic rocks are similar to those of the ocean ridge granite (ORG), with marked troughs of Nb, Ta, Zr and Hf. A synthetic study shows that the Chenjiahe intermediate-acid volcanic rocks in the eastern segment of North Qilian orogenic belt were formed in an island-arc setting, whereas the Hongtubu basalts were formed in an intra-arc rift setting (or an initial back-arc basin setting), probably being products of the early spreading evolution of the island_arc system towards the back-arc basin in the eastern segment of North Qilian during late Early Paleozoic. The results obtained provide evidence for the existence of the trench-arc-basin system at the juncture of Qilian and North Qinling orogenic belts.

Abstract:

The geochemical characteristics and abnormal sources of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in the soil of Southern Xuancheng were analyzed and studied by using the 1:250 000 land quality geochemical survey data. It is found that the geological background is the main controlling factor for the content of soil elements, and that the spatial distribution characteristics of heavy metal elements in the surface and deep soil in the area are significantly consistent with the geological background and sedimentary environment. The high content of heavy metal in the soil parent rock geological background (Hetang Formation, Piyuancun Formation and Lantian Formation, etc) is the main influencing factor for the high anomaly of soil heavy metal elements. In addition, mining and atmospheric dry and wet deposition are also one of the factors affecting high anomaly of heavy metals in soil. It is found that Pb, Hg, Cd and Cr in soil have input sources of atmospheric dry and wet deposition. The main impact index of heavy metal in soil pollution risk in the survey areas was Cd. The proportion of samples that soil Cd exceeded the control value of soil pollution risk of agricultural land was 2.56%. The morphological analysis results show that soil Cd is mainly in ion-exchange state. Combined with crops investigation, it is found that there is a certain ecological risk in the area with high abnormal soil Cd.

Abstract:

The Cuonadong leucogranite is one of the most important parts of North Himalayan leucogranite belt. Geochemical data show that Cuonadong leucogranite is the calcium alkaline and strong peraluminous granite with high silica (SiO₂ is 74.20%~74.52%), poor iron (Fe₂O₃ is 0.04%~0.20%, FeO 0.04%~0.58%), poor magnesium (MgO is 0.06%~0.14%), and calcium alkaline (σ is 2.15~2.32) as well as strong peraluminous nature (A/CNK is 1.11~1.15). Its total rare earth is relatively low (∑REE is 47.24×10^-6~57.59×10^-6), with enrichment of LREE (LREE is 39.85×10^-6~49.23×10^-6), depletion of HREE (HREE is 6.91×10^-6~8.68×10^-6) and obvious negative Eu anomaly (0.49~0.80). It is characterized by an enrichment of some large ion lithophile elements (Rb, Th, U, K) and loss of high field strength elements (Nb, Ta, Zr Ti). Zircon U-Pb dating results show that the Cuonadong leucogranite's formation time is Miocene (21 Ma), which belongs to the peak of the late stage of north Himalayan leucogranite (24~12 Ma). Zircon εHf(t) values are negative with a wide variation (-3.92~-17.64), which shows that its magma source was the crust, mostly from the metapelite, with the probable mixing of many kinds of materials in its source. The petrogenesis of Cuonadong leucogranite is that the high Himalayan crystalline rock series experienced decompression melting during the rapid pull-back of the plate in the post-collision tectonic setting, with the initial magma crystallization temperature being 675~702℃.

Abstract:

Quantitatively determining the timescale during mantle-derived magma ascent from the source to eruption or emplacement is essential for the understanding of magmatism, however, the timescales of eruption/emplacement are still poorly constrained. Shanxi Datong Cenozoic volcanic field, north of the North China Craton, is an ideal area for the investigation. In this study, we focused on the mantle olivine xenocrysts entrained in ca. 0.2 Ma Shenquansi alkali basalt, and its timescale of residence in the host magma prior to eruption. According to mineral chemistry, cores of these mantle olivine xenocrysts have Fo values up to 97.7, which can be defined as extremely magnesian olivine. They are also characterized by the extremely low contents in Ca, Mn and Ni, suggesting they were captured from metasomatized mantle peridotite. Moreover, both of the mantle olivine xenocrysts display complex CaO profiles, attributed to complex magmatic processes in the magma plumbing system. The reaction rim widths of one olivine xenocryst vary significantly, implying it has experienced multiple crack processes when captured or dur- ing transport. The Fo values of the mantle olivine xenocrysts rims are about 70, indicating they are in diffusion equilibrium with the host magma (alkali basalt) at rims. Timescales obtained by Fe-Mg diffusion chronometry of olivine mantle xenocrysts show that they have only resided in the magma for months. For a lithospheric mantle thickness of 40~70 km, the fastest average ascent rate may exceed 500 m/d.

Abstract:

In this paper,LA-ICP-MS zircon U-Pb dating was carried out for four samples of volcanic rocks from Qingshan Group in Jiaodong area and, as a result, their concordant ages were obtained, which are 119.4±0.9 Ma, 118.2±1.0 Ma,120.2±0.9 Ma and 120.0±0.8 Ma, respectively. The results show that all the volcanic rocks in Jiaodong area were formed from about 120 Ma to 118 Ma in the Early Cretaceous period. The ages of Qingshan Group volcanic rocks from Shandong Province controlled by Tan-Lu fault are similar to those from the Su-Wan segment of the Tan-Lu fault zone,but younger than those around the Tan-Lu fault zone,which indicates that the duration of volcanic eruption along Tan-Lu fault is probably longer than the duration in other areas under the background of lithospheric thinning in eastern China. Geochemically, all the intermediate and acidic volcanic rocks have high K₂O, ALK, LREE values and low MgO, TiO₂, Ni, Cr, HREE values. According to the geochemical features, the volcanic rocks can be subdivided into trachyte-trachydacite and rhyolite. The trachyte-trachydacite is characterized by LILE enrichment(Rb,Ba,K)and HFSE depletion(Nb,Ta,Ti,P), but the rhyolite exhibits stronger depletion of Ba,Sr and HFSE (Ti,P). Compared with the rhyolite,the trachyte-trachydacite possesses higher Sr and Ba values as well as La/Nb and Ba/Nb ratios,but lower Rb/Ba ratios and δEu values. All these data indicate that they might have been derived from different magma sources. It is inferred that the trachyte-trachydacite rocks were derived from the mixture of the partial melting of the lower crust(Yangtze Craton or North China Craton)and enriched lithospheric mantle. In addition, the rhyolites were related to the partial melting of the lower crust in the regional extension environment and high geothermal anomaly background with crystallization differentiation during the magma evolution.

Abstract:

Cordierite is a mineral material characterized by low thermal expansion coefficient and good thermal shock resistance. Cordierite mineral material is relatively rare in nature, so cordierite is synthesized usually by the method of artificial synthesis. Based on the newest investigation results of synthetic cordierite, this paper deals with the progress of researches on such synthesis methods of cordierite as high purity oxide solid reaction at high temperature, natural mineral solid reaction at high temperature, the utilization of industrial wasted materials, the employment of agricultural wasted materials, the sol-gel and the low-temperature combustion synthesis. At present, the method of natural mineral solid reaction at high temperature is used for the preparation of cordierite in industry. In spite of a lot of advantages, this method also has many disadvantages. Therefore, the development trend of cordierite synthesis seems to solve the problem as to how to apply other synthesis methods to industrial preparation.

Abstract:

At present, the infrared transmission spectroscopy is the best technique for determining whether jadeite is polymer-impregnated or not, and the infrared reflectance spectroscopy is a nondestructive and rapid determination method that provides mainly the fundamental frequency vibration spectra data of minerals and shows new application potentials in gemological research, especially in the identification of gem species. The gemological application of IR reflectance spectroscopy and the identification system of IR spectra of gems, including a database of 318 spectra and a searching and identifying program, are described in this paper.

Abstract:

Petrology, geochemical and Nd isotopic data are reported for the Neoproterozoic Danba metabasalt in the Kangdian Rift on the western margin of the Yangtze block. Samples were collected from alkaline basalts, which are enriched in MgO, TiO₂, with Mg^# being 0.51～0.59. They have high total rare earth elements and show high fractionation between LREE and HREE. The trace elements are characterized obviously by enrichment of Th, Nb, Ta, Zr, Hf and LREE but depletion of Y and HREE. Their geochemical and Nd isotopic characteristics suggest that they are similar to OIB. The basaltic magma was generated in an intraplate setting, and was generated by partial melting of OIB mantle source region, with variable degrees of contamination of SCLM during magma ascending; in addition, some samples might have experienced contamination of the lower crust. These samples reveal some plume magmatism characteristics in petrochemistry, and imply that magmatism was probably related to the Neoproterozoic plume event, which resulted in the breakup of Rodinia supercontinent.

Abstract:

As more and more treated turquoises appear on Chinese gem market, the authors collected lots of turquoises from different deposits on Chinese gem market in order to sum up the characteristics of the natural turquoises on Chinese gem market. At the same time, different types of treated turquoises were studied to find general difference between them and natural turquoises. The results show that natural turquoise and treated turquoise have different shades of color, inclusions and appearances. IR spectra of both natural and treated turquoises were studied, indicating that there are absorption peaks at 1 735, 1 600 and 1?500 cm^-1 in treated turquoises, which are caused by the man-made polymer. If the turquoise is treated by polymer, there are absorption peaks at 1 735, 1 600 and1 500 cm^-1 in a turquoise, and this can serve as convincing evidence in this aspect.

Abstract:

The newly-exposed lower strata of the Xiamaling Formation near Tielingzi Village in Jixian County contain rich siderites. This paper reports the basic geological characteristics of these siderite-rich strata in terms of the field outcrop, petrology and major elements. Studies show that the profile is characterized by black shale interbedded with silty iron-rich layers/siderite concrete layers, and also has minor siltstone. Some iron-rich strata have turned into limonite layers in the outcrop because of intense weathering. Siderite is the main iron mineral phase in the strata. Siderites can form iron concretes, showing micritic or microcrystalline granulitic textures under the microscope, or form silty ferruginous layers with almost a comparable amount of silty quartz; it can also distributed sporadically in siltstone and black shale with relatively coarse particles. There also exists very little siderite residue in weathered limonite layers. The overall features of major elements show that the strata are rich in SiO₂, TFe and TOC, but poor in MnO, CaO, MgO, P₂O₅ and S. Except for ferriciron in weathered layers, there is mainly ferrous iron in the strata. The TOC content decreases in order of siderite concrete, silty iron-rich layer, black shale and siltstone. The correlation diagram between TFe and Al₂O₃ content shows a negative correlation in iron-rich layers, while a positive correlation between them exists in normal black shale and siltstone, which suggests that iron in the former form originated from the ocean itself, while iron in the latter form originated mainly from terrigenous detritus. In addition, FeO content has a positive correlation with TOC content in fresh samples, which implies that the genesis of siderites may have some relationship with organic matter.

Abstract:

From the discovery of the first new mineral hsianghualite in 1958 to the end of 1995,74 new minerals found in China had been approved by IMA CNMMN. Among them, 2/3 were discovered after 1981. The discovery of new minerals in China has the following features:(1) With the development of analytical methods, the number of new minerals discovered per year increases gradually: from the end of 1950s to 1960s, only one new mineral was discovered every year on the average, whereas from 1980s till now, three new minerals were discovered averagely every year. (2) The structures of many new minerals have been determined. (3) Most of the new minerals are in the lower category, mainly in the monoclinic system, and perfect crystals are rare; hsianghualite has the most abundant crystal faces, whose ideal faces can reach 146. (4) Among those new minerals, silicates take the first place in number, followed by native elements, alloys, and then oxides. (5) The modes of occurrence of new minerals are varied, most of them occurring in oxidized zones of various deposits and deposits related to ma fic or ultramafic rock masses. There are a few new minerals occurring in skarn and placer deposits or even in cosmic dusts and meteorite.(6) The new minerals are characterized by wide but uneven distribution. Till now, new minerals have been discovered in 20 provinces or autonomous regions, especially in Hebei, Qinghai, Inner Mongolia and Henan. The number of new minerals found in North China is larger than that found in South Chine. (7) The number of discoverers of new minerals is in tens. The first discoverer of new mineral is Prof. Huang Yunhui, whereas Prof. Yu Zuxiang is the one who discovered the most numerous new minerals in China, totally disclosing 11 new minerals by himself or together with other experts. Most of the discoverers are members of the Chinese Academy of Geological Sciences, China University of Geosciences, and Institute of Geochemistry, Academia Sinica as well as other educational and scientific research institutions. The discovery of new minerals has promoted the development of mineralogy in China. Tens of discoverers were awardees of the National Natural Sciences Prize or the Science and Technology Progress Prize of the Ministry of Geology and Mineral Resources for the discovery and research results of new minerals in 1980s. More than 60 new mineals discovered in China were collected by the Geological Museum of China, with some of them exhibited in the Minerals and Rocks Exhibiting Room.

Abstract:

Indosinian S-type granites are widely distributed in central Inner Mongolia on the northern margin of North China landmass. Spread in nearly EW direction, the granites have formed a gigantic compound granite belt, with porphyritic biotite-admellite and moyite being the two main types. SiO2is abundant, Al2O3is 12.38%~15.34%. A/NKC (molecule ratio)>1.1, K2O/Na2O=1.1~3.1,δ=1.9~2.6,ΣREE is 45.778 ×10-6~486.501×10-6, andδEu=0.1~0.8. A series of zircon U-Pb surface ages (207~227 Ma) for the granites have been recently obtained from 1/50 000 regional geological survey. As the lithofacies and geochemical characteristics of the granites are similar to those of S-type granites, the authors conclude that the Indosinian granite in this area was formed in a post-collision setting instead of in the setting of syn-collision between North China plate and Siberia plate.