Abstract:

Granites serve as critical indicators of crust-mantle material cycling. Their genetic evolution provides essential constraints for deciphering continental crustal accretion-differentiation processes, unraveling the dynamics of orogenic mechanisms, and elucidating the evolution of deep-seated geochemical reservoirs. To constrain the Late Mesozoic tectonic evolution of the Yanshan Fold Belt along the northern margin of the North China Craton, we conducted systematical investigations of the Shayukou granites in Beijing. These investigations included petrographic analysis, zircon U-Pb geochronology, whole-rock major and trace element geochemistry, and Lu-Hf isotopic analyses. Zircon U-Pb concordant ages from the Shayukou monzogranite yield 134±1, 132±1, 132±1, 131±3, 130±4 and 133±2 Ma, respectively, constraining the pluton emplacement to the Early Cretaceous. Geochemical analyses reveal the following characteristics: the Shayukou monzogranites possess high silica (SiO₂ = 63.70%～69.13%), alkali enrichment (Na₂O+K₂O = 9.48%~10.81%), and peraluminous composition (A/CNK=1.05~1.13 and A/NK=1.26~1.29), classified as high-K calc-alkaline I-type granites. The rocks exhibit pronounced enrichment in large-ion lithophile elements (LILEs; e.g., Rb, K, Ba) and light rare earth elements (LREEs), coupled with depletion in high-field-strength elements (HFSEs; e.g., Nb, Ta, Ti). Diagnostic features, including elevated K₂O, Sr, (La/Yb)_N ratios, and suppressed MgO, Y, and Yb contents, collectively characterize them as C-type adakites. Zircons from the Shayukou monzogranites exhibit εHf(t) values ranging from -23.84 to -19.76, with two-stage Hf model ages (t^C_DM) of 3 768~3 408 Ma, indicating derivation from the partial melting of Paleoarchean crust. The low zircon saturation temperatures, ranging from 637°C to 699℃, classify the monzogranite as a low-temperature granite, suggesting the generation of magma involved infiltration of external fluids. Integrated with regional tectonic evolution, the Shayukou granite formed in a setting associated with the subduction of the Paleo-Pacific Plate. The underplating of mantle-derived magma, along with fluid fluxing, initiated the partial melting of thickened Archean igneous lower crust. Subsequently, the magma underwent limited fractional crystallization and crystallized at low temperatures.

Abstract:

The Triassic volcanic rocks in the East Kunlun Orogenic Belt (EKOB) hold valuable magmatic-tectonic information, serving as a crucial probe to investigate the processes of the Paleo-Tethys orogeny. This study focuses on the Middle Triassic Naocangjiangou Formation and the Late Triassic Elashan Formation volcanic rocks, emphasizing petrology, zircon U-Pb geochronology, and zircon trace elements geochemistry to provide key evidence for the magmatic-tectonic evolution of the EKOB during the Triassic. The Naocangjiangou Formation is predominantly composed of dacites, while the Elashan Formation primarily consists of rhyolites and andesites. Geochronological results indicate that the dacites of the Naocangjiangou Formation formed during the Middle Triassic (249~243 Ma), whereas the rhyolites and andesites of the Elashan Formation formed in the Late Triassic (221~219 Ma). Zircons from the Middle Triassic dacites can be classified into two types based on Ti content: low-Ti (1.42×10^-6 to 4.83×10^-6) and high-Ti (3.25×10^-6 to 72.5×10^-6). The low-Ti zircons exhibit lower rare earth element (REE) contents (561×10^-6 to 1 190×10^-6), while the high-Ti zircons have higher REE contents (1 817×10^-6 to 6 236×10^-6). Late Triassic andesitic magmatic zircons show relatively high Ti contents (11.3×10^-6 to 31.2×10^-6) and lower REE contents (∑REE = 312×10^-6 to 1 107×10^-6), whereas Late Triassic rhyolitic zircons exhibit lower Ti contents (1.70×10^-6 to 8.58×10^-6) and REE contents (355×10^-6 to 1 670×10^-6). Zircon genesis analysis reveals that the high-Ti zircons in the Middle Triassic dacites are hydrothermal in origin, while the low-Ti zircons from the Middle Triassic and all Triassic zircons from the Late Triassic are of typical magmatic origin. Zircon Ti thermometry and crustal thickness studies indicate a significant increase in magmatic temperatures and crustal thickening in the EKOB between 243 Ma and 219 Ma. Synthesizing regional geological data, this study concludes that the EKOB experienced continuous subduction of the Paleo-Tethyan oceanic crust during the Middle Triassic, followed by crustal thickening due to collision in the Late Triassic. Notably, no significant lithospheric thinning occurred in the EKOB during the Triassic. This research further demonstrates that zircon trace element compositions cannot reliably reveal the tectonic settings of felsic magmatic rocks in orogenic belts, underscoring the need for cautious application of this method.

Abstract:

The late Mesoproterozoic igneous rocks in the western margin of Yangtze Block are important for understanding the tectonic evolution and its role in reconstruction of the Rodinia supercontinent. In this paper, we report new zircon U-Pb ages, whole rock major and trace elements, and Nd-Hf isotopic analyses of the plagioclase amphibolites and granites in the Cuoke area on the western margin of the Yangtze Block. Geochronological results show that the granites and plagioclase amphibolites have similar late Mesoproterozoic zircon U-Pb ages of 1 160.5 Ma and 1 170.2 Ma, constituting a bimodal igneous assemblage. The plagioclase amphibolites belong to the tholeiite series and characterized by enrichment in LREEs and LILEs, and have OIB-like affinities with No obvious Nb and Ta anomalies, and with positive εNd(t) and εHf(t) values, indicating that they were derived from the asthenospheric mantle source. The granites belong to the peralkaline A-type series and characterized by have high Fe/Mg and Ga/Al ratios, with positive εNd(t) value and εHf(t) values, indicating that they were derived partially from the newly formed crust. Geochemical characteristics indicate that the Cuoke plagioclase amphibolite and granite were likely formed in an intra-plate rift basin on the passive continental margin, and are unrelated to the Grenvillian Orogen in the western Yangtze Block. Based on previous research results, it is believed that the western margin of the Yangtze Block during the late Mesoproterozoic belonged to a passive continental margin rift environment, and the Yangtze Block was in the peripheral rather in the center in the configuration of Rodinia.

Abstract:

The Aizi pluton in the north of Guangdong is located in the central-western part of the Guidong complex pluton and consists of biotite granite. Currently, research on the formation age and genesis of this rock mass is weak, which is helpful to perfect the magmatic activity pedigree in the eastern Guizhou area, and provide new constraints on the petrogenesis and tectonic background. In this paper, LA-ICP-MS zircon U-Pb chronology, mineral-petrogeochemistry and Hf-Nd isotopes have been studied for Aizi biotite granite. The mineralogical characteristics indicate that the zircons in the Aizhi biotite granite are magmatic zircons, and the apatites are fluorapatites. The zircon U-Pb dating results indicate that the emplacement age of the Aizhi biotite granite is 159±1 Ma, which is a product of the early Yanshanian in South China. The geochemical characteristics of the rocks reveal a SiO₂ content ranging from 67.93% to 69.80%, a high total alkali content (K₂O+Na₂O=7.32% to 7.53%) and A/CNK ratio of 0.95 to 0.99. The rocks are enriched in Rb, Th, and U, while depleted in elements such as Ba, Nb, Ta, Sr, Zr, and Hf. The LREE/HREE ratio varies between 7.24 and 10.17, with a pronounced negative Eu anomaly (δEu=0.43 to 0.50). The εHf(t) values of the Aizizi biotite granite range from -8.7 to -5.4, while the εNd(t) values range from -9.3 to -9.1, corresponding to t_DM2 values of 1 725～1 519 Ma and 1 711～1 689 Ma, respectively. The above geochemical and isotopic characteristics indicate that the Aizhi biotite granite belongs to the high-potassium calc-alkaline series, quasi-aluminous S-I transitional granite, which is mainly formed by partial melting of Paleo-mesoproterozoic crustal-derived arenite under medium to high temperature and low pressure. Comprehensive studies suggest that the Aizhi biotite granite formed in a tectonic setting of lithospheric extension and thinning caused by the subduction of the Pacific plate.

Abstract:

The Xiwanggou mafic-ultramafic complex is located in the eastern segment of the Central Kunlun Zone and the magma differentiation is sufficient with lithologies consisting of gabbro facies, pyroxenite facies, and peridotite facies. Amphibole preserves crucial information regarding magmatic evolution and the geological setting of its formation, and it is ubiquitously present across diverse lithologies within Xiwanggou complex. In this study, we use the characteristics of major and trace elements contents in amphiboles, in conjunction with whole-rock geochemistry and the major element characteristics of plagioclases, to discuss the petrogenesis and magmatic evolution of the complex. The findings offer novel constraints on the tectonic evolution of the East Kunlun spanning from the Late Paleozoic to the Early Mesozoic. Experimental results demonstrate that all the amphiboles are mainly classified as pargasite and Mg-hastingsite of magmatic origin, bearing the typical hallmarks of subduction amphiboles. Calculations indicate that the crystallization at the range of 889~971℃, 191~280 MPa, △NNO+0.2~+1.8, and the magma water content is 2.8%~4.6%. From these results, it can be inferred that during the magma evolution, it underwent the process of cooling, decompression, reduction, and water enrichment. The compositions of amphibole melt at equilibria display highly comparable trace element and rare earth element signatures. Major element contents reveal that the melt compositions associated with amphibole crystallization in pyroxene peridotite, olivine pyroxenite, and gabbro are relatively primitive, while the melts during amphibole crystallization in amphibole gabbro exhibit relatively evolved characteristics. Comprehensive analysis indicates that the diverse rocks within the Xiwanggou complex were formed during different evolution stages of homologous magma. As the magma ascended and emplaced, it progressively evolved, becoming enriched in Si and depleted in Mg, and underwent the fractional crystallization of plagioclase. These rocks thus serve as critical magmatic records, documenting the subduction of the Paleo-Tethys Ocean beneath the East Kunlun Orogen during the Early-Middle Triassic period.

Abstract:

The Lijiagou granite pegmatite-type lithium deposit is a super-large ore deposit in western Sichuan. Currently, the enrichment mechanism of lithium in the pegmatite of the Lijiagou deposit remains unclear. This paper focuses on multi-stage and multi-type muscovite and cassiterite in the pegmatite of the Lijiagou deposit, conducting microstructural observations, electron probe microanalysis (EPMA), LA-ICP-MS analysis, and cassiterite U-Pb dating. The study categorizes muscovite in pegmatites into three types: ① primary muscovite (Ms), a product of the magmatic stage, with a relatively low-Li content ranging from 2 089×10^-6 to 4 561×10^-6; ② transitional muscovite (TM), formed during the magmatic-hydrothermal transition stage where melt and fluid coexist, resulting from the exsolution of volatile-rich fluid leading to the enrichment of Li element, with a Li content ranging from 8 173×10^-6 to 25 307×10^-6; ③ hydrothermal muscovite (HM), formed by fluid metasomatism, where the Li element gradually decreases during this stage (with a minimum of 642.7×10^-6). The microregional compositional characteristics indicate that the K/Rb and Nb/Ta values gradually decrease from Ms to TM, indicating a higher degree of evolution of the Lijiagou deposit. Meanwhile, cassiterite in the pegmatite is classified into four types, from early to late, namely, relatively uniform structure (Cst-1) → inhomogeneous core-edge structure (Cst-2, Cst-3) → white patchy structure (Cst-4), with gradually increasing contents of elements such as Fe, Nb, and Ti. Combine with the Ta/(Nb+Ta) value, it is inferred that cassiterite exhibits characteristics of early Fe enrichment and late Nb enrichment during magmatic evolution. The significant increase of Ti content in white patchy cassiterite (Cst-4) reflects the metasomatic action of hydrothermal fluids. Furthermore, U-Pb dating of cassiterite within pegmatite containing spodumene reveals the depositional age of the Lijiagou deposit to be 196.18±4.39 Ma (n=18, MSWD=0.62). Based on existing research, it is determined that there are two stages of mineralization in the Lijiagou deposit, with ages of 211~205 Ma and 199~186 Ma, respectively. This paper believes that the mineralization process of the Lijiagou pegmatite experienced a melting-fluid evolution stage. The fluid exsolution resulted in the enrichment of Li element, which entered the spodumene lattice and precipitated into ore after reaching supersaturation, ultimately forming the Lijiagou pegmatite-type lithium deposit.

Abstract:

The Gejiu polymetallic tin ore cluster developed a series of basic-intermediate-acidic-alkaline magmatic rocks during the Late Yanshan period, the genesis and evolution of which are crucial for an in-depth understanding of the Gejiu tin-copper symbiosis and the formation processes of various types of tin ores. However, the nature of the granite source area, the type of genesis, and the evolutionary processes related to the ore-forming process remain widely debated. As a pervasive mineral, the trace element characteristics of apatite can serve as a tracer for magma-fluid evolution process and fluid alteration process. Therefore, this study focuses on apatite in different types of rocks from Gejiu as the research object, and through EPMA and LA-ICP-MS analysis, the main and trace element content characteristics of apatite in each rock body were obtained. Using the fractionation characteristics of rare earth elements, combined with various trace elements with typical discrimination, the granite of different source areas and different types of genesis were indicated. The results show that the Shenxianshui K-feldspar granite and Longchahe monzogranite developed in the western part of the Gejiu fault are crust-mantle mixed-source I-type granites, and their apatite is of magmatic type, with a right-skewed distribution trend of rare earth elements, and high Sr (135×10^-6~280×10^-6), V (0.86×10^-6~28.6×10^-6), Ce (2 147×10^-6~6 541×10^-6), high Th/U (2.09~6.93), and La/Sm (2.27~5.45) characteristics. This type of granite body has not formed tin, copper, and other metal ore deposits. The Laoka biotite granite, muscovite granite, and sericite granite distributed in the eastern part of the Gejiu fault are S-type granites derived from meta-sedimentary rocks and are the main carriers of tin, copper, and tungsten ore formation. Their apatite is mainly of hydrothermal type, with a relatively flat rare earth element pattern, and has higher Mn (337×10^-6~4 415×10^-6) content and lower V (0.14×10^-6~11.6×10^-6), La (190×10^-6~1 440×10^-6), Ce (706×10^-6~4 856×10^-6) content, as well as lower La/Sm (0.52~3.03). These characteristics reveal the rock-forming and ore-forming specificity of apatite in the Late Yanshan magmatic rocks of Gejiu, and indicate that different source magma coexisted on both sides of the Gejiu fault during the same period, providing new insights into the rock-forming and ore-forming processes of the Gejiu ore cluster.

Abstract:

The Longshan Complex, distributed in Baoji of Shaanxi Province and Tianshui of Gansu Province, is located at the junction of the Qinling orogenic belt and the Qilian orogenic belt, and is the material basis for understanding the tectonic evolution and attribution of the region. In this paper, detailed petrography, mineral chemistry, phase equilibrium modeling and titanite U-Pb geochronology studies were carried out on garnet-bearing amphibolites samples collected from the Longshan Complex.Based on detailed petrographic observations and mineral chemical analyses, it was determined that the garnet-bearing amphibolites recorded three stages of metamorphic mineral assemblages. The mineral assemblage in the prograde metamorphic stage (M1) is represented by fine-grained plagioclase, amphibole and quartz in garnet; the mineral assemblage in the peak metamorphic stage (M2) is represented by plagioclase+amphibole+quartz+garnet+ilmenite+titanite+melt; and the mineral assemblage in the retrograde metamorphic stage (M3) is represented by plagioclase+amphibole+quartz+ilmenite+melt, forming a symplectite texture.According to the geothermobarometers, the temperature and pressure conditions in the prograde metamorphic stage (M1) are 563℃ and 0.82 GPa. The results of phase equilibrium modeling for the peak metamorphic stage (M2) show that the temperature and pressure conditions are 800~818℃, 1.28~1.32 GPa and 740~770℃, 1.17~1.20 GPa. For the retrograde metamorphic stage (M3), the temperature and pressure conditions of one sample calculated by phase equilibrium modeling are 691~703℃, 1.03~1.06 GPa, and the temperature and pressure conditions of another sample obtained by the geothermobarometer are 683℃ and 0.8 GPa. The amphibolites have experienced the prograde metamorphic stage to the peak metamorphic stage and then to the retrograde metamorphic stage, and recorded a clockwise metamorphic p-T path. The peak metamorphic temperature and pressure conditions are close to or similar to those in many areas of the Qinling Complex. The results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) titanite U-Pb geochronology show that the intersection ages of titanite in the garnet-bearing amphibolites are 380.5±4.8 Ma, 430.8±6.7 Ma, 431.6±6.1 Ma and 433.4±4.0 Ma. In summary, by comparing the metamorphic temperature and pressure conditions and metamorphic ages of the Longshan Complex with those of the Qinling Complex, it was found that the metamorphic age of the Longshan Complex in this region is close to the last retrograde metamorphic age of the Qinling Complex in the eastern section of the North Qinling, and the peak metamorphic temperature and pressure conditions are similar to the granulite facies metamorphism of the Qinling Complex in the western section of the North Qinling. It is speculated that the Longshan Complex may be the western extension of the North Qinling orogenic belt.

Abstract:

Tourmaline is a boron-bearing cyclosilicate mineral with complex chemical compositions. It can remain stable in a wide range of p-t conditions (t=150~900℃, p=6 MPa~6 GPa), making it an ideal tracer mineral for understanding geological process in different tectonic environments. We provide a comprehensive summary of the mineralogical characteristics and geochemical compositions of tourmaline, with a particular focus on the main factors controlling its boron isotopic compositions, including the boron source, equilibrium and/or Rayleigh fractionation, and the evolution of ore deposit. We further summarize and review the applications of tourmaline in key areas, including its major and trace elements, stable isotopes (H-O, Si, B), and radiogenic isotopes (Rb-Sr, Sm-Nd) for tracing the sources and evolution of geological fluids, as well as its role in investigating the metallogenic processes of various deposit types (e.g., IOCG and orogenic gold deposits). Finally, this study highlights several promising directions for future research on tourmaline. In particular, further investigations are expected to achieve breakthroughs in crystal-chemical structure determination, in-situ micro-scale isotopic analyses (e.g., Li, Mg), the construction of p-t-T trajectories to trace fluid evolution, and the reconstruction of paleo-seawater boron isotope signatures. Comprehensive studies integrating tourmaline mineral chemistry, isotope geochemistry, and geochronological approaches will not only advance our understanding of fluid formation and evolutionary mechanisms, but may also provide crucial clues for deciphering the environmental evolution of early Earth.

Abstract:

Basalt fiber, a type of high-performance fiber, is produced by drawing from basalt or rocks of similar compositions after high-temperature melting. The homogeneity of the melt during fiber preparation critically determines fiber quality, yet the dynamic phase transition process during basalt melting remains poorly understood. This study investigated the melting behavior of Hainan Island basalt for fiber production through high-temperature melting experiments, combined with X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses. The results showed that under an air atmosphere, the sample lost adsorbed water from room temperature to 113℃, smectite melted at 804~849℃, pseudobrookite, clinopyroxene and plagioclase with low-An melted in large quantities at 1 075~1 193℃, and high-An plagioclase and hematite melted at 1 220~1 297℃. The various mineral components melted in order of melting point from low to high, but during the melting process, oxidation reactions occurred to produce hematite and pseudobrookite, causing the complete melting temperature of basalt to increase by about 120℃. The grain size of hematite increased significantly with increasing temperature, which was attributed to crystal regrowth at high temperatures. This study provides a theoretical basis for optimizing the melting process of basalt for fibers.

Abstract:

A series of lamprophyre dykes that crosscut the main foliation of the ultrahigh pressure (UHP) metamorphic metapelite have been recently discovered in the Yuka terrane, North Qaidam Orogen, which are composed predominantly of biotite/phlogopite, amphibole, K-feldspar and plagioclase. To investigate their petrogenesis and tec-tonic setting, systematic petrological, geochemical, mineral electron microprobe analyses and biotite ⁴⁰Ar/³⁹Ar dating have been performed on two lamprophyre samples. Bulk-rock geochemistry reveals that the Yuka lamprophyres are potassic calc-alkaline types, which are characterized by medium SiO₂ content of 55.19%~55.78%, high potassium (K₂O/Na₂O=1.72~4.41) and high Mg^# (MgO=7.52%~9.90%, Mg^#=66~72). They also exhibit enrichment in light rare earth elements (LREE) and large ion lithophile elements (LILE, e.g., Rb, Ba, Pb), coupled with depletion in heavy rare earth elements (HREE) and high field strength elements (HFSE, e.g., Nb, Ta, Ti), displaying typical subduction signatures. Nb/Ta ratios fall between continental crust and the primitive mantle values, while Nb/U ratios resemble global subducted sediment averages, indicating source metasomatism by mobile elements rich subduction fluids. Mineral geochemistry analysis show that phlogopite relics in phenocrystic biotite,phenocrystic biotite, and matrix biotite crystallized at temperatures of 1 098~1 167℃, 1 054~1 106℃ and 1 049~1 101℃, respectively. Their crystallization pressures are 1.62~2.12 GPa, 1.51~1.63 GPa, and 1.57~1.66 GPa, respectively. The calculated oxygen fugacity (log f_O2) ranges from -4.42 to -5.90, -5.80 to -6.71, and -5.84 to -6.67 for these phases, suggesting a high oxygen fugacity environment. Biotite/phlogopite from the lamprophyre analysed by ⁴⁰Ar/³⁹Ar laser step-heating dating yielded a plateau age of ca. 360 Ma, indicating the dike formed in the Late Devonian to Early Carboniferous. Taken together with field occurrence, whole-rock and mineral geochemical characteristics, geochronology and regional tectonics, we propose that the Yuka lamprophyre formed in a post-collisional lithospheric extensional tectonic setting during the North Qaidam Orogen evolution, which likely originated from partial melting of phlogopite-bearing spinel facies iherzolite at the garnet-spinel transition zone (~70 km depth) within a metasomatized, high-oxygen fugacity enriched mantle.

Abstract:

In order to study the effect of magnesium-iron-manganese-zirconium quaternary hydrotalcite (MgFeMnZr-LDH) on the passivation remediation of antimony (Sb)-contaminated soils, MgFeMnZr-LDH was added to the yellow soil with a Sb content of 1 450 mg/kg and for 45 d of flooding, and NaH₂PO₄, Na₂HPO₄ and ethylenediaminetetraacetic acid (EDTA) were used to extract soil available Sb(Ⅲ) and Sb(Ⅴ); different forms of Sb(Ⅲ) and Sb(Ⅴ) in soil were extracted by Wenzel sequential extraction procedure; the correlation between the addition of MgFeMnZr-LDH, soil available Sb and different forms of Sb were discussed, and the passivation mechanism of MgFeMnZr-LDH on soil Sb was explored. The results showed that with the increase of MgFeMnZr-LDH addition, the total content of available Sb extracted by Na₂HPO₄, NaH₂PO₄ and EDTA gradually decreased, with maximum reduction rates of 26.5%, 25.2%, and 35.5%, respectively, in which the percentage of available Sb(Ⅲ) also decreased gradually; soil content of Sb (Ⅲ) and Sb(Ⅴ) decreased significantly in the non-specifically adsorption state(F1), the specifically adsorption state(F2), and the amorphous iron and aluminium oxide-bound state(F3), and increased significantly in the crystallized iron and aluminium oxide-bound state(F4); F3 and F4 had the largest variation in percentage. The material additions showed highly significant negative correlation with F1, F2, F3 of Sb(Ⅲ) and Sb(Ⅴ), highly significant positive correlation with F4 of Sb(Ⅲ) and Sb(Ⅴ), and significant positive correlation with the residual phases Sb(Ⅲ)(F5)in the soils. MgFeMnZr-LDH gradually transformed F1, F2 and F3 of Sb in soils into F4 and F5 through electrostatic, ion exchange, coordination, precipitation and oxidation, which reduced the bioeffectiveness of Sb and realized the passivation remediation of Sb-contaminated soil.

Abstract:

Sedimentary rocks are widely distributed on the surface and contain abundant solid minerals and hydrocarbon resources.The accurate identification of sedimentary rocks is of great significance for basic geological research and the exploration of solid minerals and hydrocarbon resources. At present, lithology identification of sedimentary rocks mainly relies on visual identification, optical identification and X-ray powder diffraction analysis. These methods have many problems such as great influence of subjective factors, long experiment period and high cost which can not meet the needs of real-time lithology results acquisition in the field. In this paper, four typical sedimentary rocks of terrigenous clastic rocks (sandstone and mudstone) and carbonate rock (limestone and dolomite) are identified rapidly by the quartz abundance index (8625D), carbonate abundance index (6500D), carbonate composition index (2340W), illite-smectite mixed layer abundance index (2200D), kaolinite abundance index (2160D2190) and rock brightness index (Albedo-SWIR), which is combined infrared reflectance spectroscopy with binary intersection graphic method. The overall recognition rate is more than 90%. This study provides a rapid, non-destructive and objective identification method for sedimentary rock lithology and has a good application prospect, which plays an important significance for the subsequent research on detailed cataloging of cores, stratigraphic division, sedimentary facies division, and physical property evaluation of carbonate reservoir.

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:

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:

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:

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:

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:

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:

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:

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:

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.