Abstract:

The Jinling skarn-type iron deposit, located in the Zibo area of the northern West Shandong Block, exhibits close genetic relationships with the Jinling high-Mg diorite intrusion. Through petrographic observations of diorite intrusions and skarns in the mining area, this study identifies three distinct types of apatite: magmatic Ap1 in diorite, early hydrothermal Ap2 in skarn, and late hydrothermal Ap3. Geochemical investigations of these apatite generations provide critical constraints on the evolution of ore-forming fluids and the controlling mechanisms of iron mineralization. The diorite-hosted Ap1 shows elevated Cl content, while the development of hydrous minerals (e.g., amphibole and biotite) indicates a water- and Cl-rich magmatic system. Such magma generated iron-enriched fluids through intense hydrothermal exsolution under decompression conditions, establishing the foundation for iron enrichment. Hydrothermal Ap2 displays higher ⁸⁷Sr/⁸⁶Sr ratios compared to Ap1, with values approaching those of Ordovician gypsum-bearing carbonate strata, suggesting evaporite-derived materials were incorporated into the mineralization system through fluid-wallrock interactions. From Ap1 to Ap2, the Eu anomaly transitions from negative to positive values, indicating that carbonate assimilation progressively increased oxygen fugacity in the hydrothermal system. This promoted oxidation of Fe²⁺ to Fe³⁺ and subsequent magnetite precipitation. The gradual depletion of Fe, Mn, and rare earth elements from Ap2 to Ap3 reflects significant consumption of these elements during late-stage fluid evolution, coinciding decrease and progressive mineralization processes.

Abstract:

As one of the ubiquitous accessory mineral in granitoids, apatite can effectively monitor the variation of the parental magmatic melt and volatiles and serves as an important tool for tracing the petrogenesis of granitic intrusions and the related magmatic process. This paper conducts micro-area structure and in-situ major and trace element geochemical analysis of the apatite from the Haisigou monzogranite and granodiorite in the East Kunlun Mountains, and combines partial whole-rock geochemical studies to meticulously analyze the genetic types, magmatic physical and chemical conditions, and their evolutionary processes of granites. Furthermore, it explores the formation and evolution mechanisms of granitic intrusions. The results show that apatites in the monzogranite exhibit obvious oscillatory zonation, while apatites in the granodiorite lack any types of zonation. And all the apatites in the monzogranite and granodiorite show similar characteristics to rich-F apatites in composition. The apatite major and trace element compositions and whole-rock geochemical data reveal that the granodiorite has similar geochemical characteristics to I-type granites, while the monzogranite has compositions comparable to I-S transitional-type granites. The chemical variations of apatite zonations reveal that the magma reservoir of monzogranite was influenced by the melt component, heat and volatiles of mafic magmas, while the granodiorite magma reservoir is more likely to be affected by the heat and volatiles of the mafic magmas, and the participation of the mafic component is negligible. Combined with new regional studies, the Haisigou Triassic granitic intrusions might form accompanied with the slab break off at the late stage of the subduction of the Paleo-Tethys Ocea. In this context, the magmas in those reservoirs experienced crystal-melt segregations under the varying degrees of mafic magma recharge, and ultimately formed the monzogranite and granodiorite with cumulate affinities.

Abstract:

In the Awati-Manjar transition zone of northern Tarim Basin, the Ordovician sedimentary sequence is characterized by the presence of extensive diabase intrusions. These igneous intrusions are not only key evidence for the magmatic activity process of the Tarim Large Igneous Province, but also closely related to oil and gas migration and accumulation, providing guidance for oil and gas exploration. Based on seismic profiles and drilling data analysis, combined with isotopic dating methods, this study systematically studies the diabase intrusions in the Awati-Manjar transition zone, revealing their formation time and spatial distribution characteristics, and discussing their emplacement mechanism. The results show that the diabase intrusions can be divided into two types: steeply dipping intrusions and layered intrusions. Steeply dipping intrusions generally unconformably intrude into the Sangtamu Formation and are concentrated in the YM, GL, and MS drilling areas, as well as the AM and AM north drilling areas. Layered intrusions intrude conformably into the top of the Yijianfang Formation, Tumuxiuke Formation, and Lianglitage Formation and are concentrated in the MS and FY drilling areas, with small-scale distribution in the YM west, GL, and AM north. Steeply dipping and layered diabase intrusions can exist independently, but in most cases, they are closely connected in three-dimensional space, forming symmetrical or asymmetrical disc-shaped intrusions. Zircon U-Pb isotopic dating results indicate that the diabase intrusions crystallized between 303～285 Ma, and can be further divided into two stages. The intrusions of first stage are limited in distribution. They occurred around 303 Ma, corresponding to the first phase of magmatism in the Tarim Large Igneous Province. The intrusions of second stage, as the majority of the diabase in the study area, occurred around 285 Ma, corresponding to the third phase of magmatism in the Tarim Large Igneous Province. The diabase intrusions are composed of feeding veins, internal beds, inclined veins, and external beds from bottom to top, which make up of a vertically related intrusive system. The top of the Middle and Lower Ordovician serves as an important structural transition surface and lithological interface, controlling the lateral intrusion and expansion of the magmas. Meanwhile, the planar distribution features are jointly controlled by the mantle plume activity, the regional stress field evolution and the basement structure feature.

Abstract:

We reported zircon SIMS U-Pb ages, the whole rock geochemistry of the Shuanglang gabbro located in Longsheng County, North Guangxi from the western Jiangnan Orogen in this manuscript, to decipher their petrogenesis and tectonic setting. Samples comprised clinopyroxene and plagioclase with minor K-feldspar and Fe-Ti oxides. The Shuanglang gabbro with a zircon SIMS U-Pb age of 782±9 Ma. The bulk-rock have SiO₂ (50.05%~51.85%), Al₂O₃ (14.53%~15.42%) and CaO (6.95%~7.19%) contents, and MgO (8.97%~11.33%) and total FeO (10.63%~11.92%) contents. The samples display ocean island basalt (OIB)-like geochemical signatures, with the enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE) relative to heavy rare earth elements (HREE), with insignificantly negative Nb, Ta anomalies, and have high (⁸⁷Sr/⁸⁶Sr)_i (0.709 990~0.711 788) and negative εNd(t) (-2.4~-1.4) values resulted from the upper crust contamination. They are suggested to have originated from a small degree (3%~4%) of partial melting of the upwelling asthenospheric man-tle in an extensional setting of the garnet stability field. Based on the spatial distribution of the mafic-ultramafic rocks during 780~750 Ma in the western Jiangnan Orogen reported in both this study and previous publications and comprehensive analyses of them, we indicate that the subducted slab break-off triggered the partial melting of upwelling asthenosphere, which resulted into the formation of the OIB-like mafic-ultramafic rocks during 780~750 Ma in the western Jiangnan Orogen.

Abstract:

The study of Paleoproterozoic meta-mafic-ultramafic rocks in the North Liaohe Group of the Liao-Ji orogenic belt in the North China Craton provides critical evidence for understanding regional tectonic evolution. Through detailed field investigations, petrographic observations, and systematic geochemical analyses, combined with previous research findings, this study yields new insights into the petrogenesis and tectonic setting of these rocks. It also presents a preliminary discussion on the intrinsic genetic relationship between the geodynamic mechanism of the Liao-Ji orogen and the source of Ni-Co elements. Based on previous data, the protoliths of the meta-mafic-ultramafic rocks have a peak emplacement age of ~2 152 Ma and underwent regional metamorphism at approximately 1 882 Ma. Geochemical results indicate that the meta-ultramafic rocks are hornblende-chlorite schists with a cumulate origin. Their LREE enrichment and Nb-Ta-Ti depletion characteristics suggest that the primary magma likely experienced metasomatism by subduction-related fluids. The protoliths of the meta-mafic rocks are all subalkaline tholeiitic basalts, which can be classified into two types. The first type exhibits geochemical features similar to MORB, originating from a depleted asthenospheric mantle source with limited fluid metasomatism. Zircon Hf isotopes from this type provide direct evidence for Paleoproterozoic juvenile crustal growth events in the Liao-Ji orogen. The second type of meta-mafic rock shows significant LREE enrichment and Nb-Ta-Ti negative anomalies, indicating that their primary magmas were derived from an enriched lithospheric mantle source that was intensely metasomatized by subduction fluids.Based on the petrogenetic mechanisms and source characteristics of the meta-mafic-ultramafic rocks, this study proposes that they formed in a back-arc basin tectonic setting. The two types of meta-mafic rocks respectively record the complete evolutionary process of the back-arc basin from initial extension (enriched component) to maximum spreading (depleted component). Ni-Co mineralization is closely related to this evolutionary process: back-arc extension facilitated mantle melting and extraction of Ni-Co elements; magmatic underplating and cumulate processes achieved pre-enrichment; the addition of crustal sulfur triggered sulfide melt segregation; and the final collisional orogeny led to the extraordinary enrichment and formation of the ore deposits.

Abstract:

The Bashisuhong rare earth deposit is located at the northern margin of the Tarim Basin and the southern Tianshan region, at the junction between the Tarim Craton and the Central Asian Orogenic Belt. There has been ongoing debate regarding its formation age and tectonic attributes. To address these issues. this study focuses on the bimodal intrusive rocks discovered in the region and attempts to provide evidence to resolve the aforementioned problems. Through petrographic, zircon U-Pb geochronology, in situ Hf isotope analysis and geochemical studies of the rocks, the results show that the zircon U-Pb ages of the diabase and alkaline granite are 278.50±0.87 Ma and 275.89±0.94 Ma, respectively, indicating their formation in the Middle Permian. In terms of geochemical characteristics, both rocks have similar εHf(t) values (diabase average: 4.17, alkaline granite average: 3.42). The alkaline granite has high SiO₂, K₂O, Na₂O, and low MgO, CaO, with relatively high total rare earth element content, significant light/heavy rare earth element ractionation, and a distinct negative Eu anomaly, along with enrichment in high-field-strength- elements. The diabase has lower SiO₂, K₂O, higher MgO, CaO, relatively lower total rare earth element content, significant light/heavy rare earth element fractionation, a weak positive Eu anomaly, and elevated Ba content. In terms of rock genesis, the diabase originates from the asthenospheric mantle, undergoing low-degree partial melting; the alkaline granite magma originates from partial melting of lower-pressure, high-temperature crustal gabbro, displaying characteristics of A1-type granites. Combined with regional geological background analysis, it is concluded that the Bashisuhong alkaline intrusive complex formed in a non-orogenic intra-continental rift environment during the Middle Permian, driven by mantle plume activity, rather than in a post-collision orogenic extension tectonic background resulting from plate stress release. This provides new data for the study of the Late Paleozoic tectonic setting in the northern margin of Tarim.

Abstract:

This study presents a comprehensive analysis of Late Neoarchean TTG (tonalite-trondhjemite-granodiorite) within the Longshan Complex, situated at the southwestern margin of the North China Craton (NCC), providing critical constraints on the tectonic evolution of this region. These TTG, located in the Guanshan area of the Long-shan Complex, were dated using zircon U-Pb isotopic analysis, yielding crystallization ages of 2 535~2 485 Ma (2 503±39 Ma, 2 535±39 Ma). The zircon εHf(t) values of the TTG are predominantly positive, and show two-stage Hf model ages ranging mainly from 3.1 Ga to 2.8 Ga. These data suggest that the TTG originated from partial melting of ancient crustal material with contributions from depleted mantle-derived components. Notably, one sample(23LS28) displays uniformly positive εHf(t) values, with some zircons closely approximating the isotopic composition of the coeval depleted mantle. The two-stage model ages for this sample fall within 2.8~2.5 Ga, indicating derivation from partial melting of juvenile crustal material. The TTG exhibit high SiO₂, Na₂O, and low K₂O. Most samples are characterized by flat heavy rare earth element (HREE) patterns, moderately elevated Y and Yb concentrations, low Sr/Y and (La/Yb)_N ratios, and minor to negligible Eu anomalies (δEu = 0.70~0.96). These characteristics suggest that the TTG were generated by partial melting of source rocks under low- to medium-pressure (LP-MP) conditions, with amphibole, plagioclase, and minor garnet as the residual phases. However, one sample (22LS30) exhibits distinct geochemical features, including lower Y and Yb concentrations, higher Sr/Y and (La/Yb)_N ratios, and a pronounced positive Eu anomaly (δEu = 2.47). These attributes indicate a deeper melting environment, corresponding to high-pressure (HP) conditions, with garnet, amphibole, and rutile as the dominant residual phases. The high Mg^#, Cr, and Ni contents observed in all TTG are consistent with geochemical signatures associated with melts derived from the subducted oceanic crust. According to the chronology, isotope geochemistry and petrogeochemistry, these Late Neoarchean TTG belong to the NCC, and may have been in a subduction-related setting at this time. With the increase of subduction depth, the subduction fluid/melt continuously reacts with the mantle wedge, and the mantle interaction continues to strengthen. In addition, this study obtained metamorphic ages of 1 871±26 Ma and 459~335 Ma. The former age is consistent with the metamorphic events dated at 1.97~1.80 Ga in the NCC, while the latter aligns with the Paleozoic metamorphic events in the North Qinling Orogenic Belt. It is concluded that the TTG subsequently experienced metamorphism during Late Paleoproterozoic thermo-tectonic event and were eventually incorporated into the Longshan Complex during the Paleozoic orogenic event.

Abstract:

To explore the Paleozoic tectonic evolution characteristics of the southern margin of the Dunhuang block and constrain the activity trajectory of the southern side of the Central Asian orogenic belt, zircon U-Pb dating and petrological-geochemical analysis were conducted on the Haobula pluton. The LA-ICP-MS zircon U-Pb dating results indicate that the crystallization age of the Haobula pluton is 324.0±1.1 Ma, belonging to the Early Carboniferous period. Geochemical analysis of the rock reveals that the SiO₂ content of the Haobula pluton ranges from 65.31% to 75.50%, with an average total alkali (K₂O+Na₂O) content of 7.77%. The K₂O/Na₂O ratio varies from 0.90% to 1.35%. The Al₂O₃ content ranges from 13.41% to 16.05%. It belongs to the high-potassium calc-alkaline, peraluminous series. The pluton is relatively enriched in LREE and depleted in HREE (LREE/HREE=11.96~26.01), with a slight negative Eu anomaly (δEμ=0.70~1.01). It is relatively enriched in large-ion lithophile elements such as Rb, Ba, and K, as well as strong incompatible elements like Th, and depleted in high-field-strength elements like Nb, Ti, and P. Considering the regional tectonic features, it is believed that the southern margin of the Dunhuang massif was in the late stage of continental-continental collision (crustal thickening) during the Early Carboniferous.

Abstract:

Tonalite and trondhjemite (plagiogranite) are typical granitoid rocks that contains abundant plagioclase. IUGS defines tonalite as the plutonic rocks that contains more than 20% quartz and plagioclase portion higher than 90% of the feldspar minerals. Meanwhile, the trondhjemite is defined as the light-coloured (mafic minerals, M<10%) tonalite. Tonalite and trondhjemite are the important constitute of Precambrian continental crust, and they also occurred in the plutonic assemblage of arc systems and in the ophiolite suites. The trondhjemites exposed within TTG suites exhibit high aluminous character, but many trondhjemites occurred in ophiolite suites have low aluminous content. Using the QAP classification results discriminated by the actual mineral modes as the benchmark, two chemical diagrams, i.e., SiO₂'-CaO/(CaO+K₂O) plot and 100×(Mg+Fe)/Si-SiO₂ plot are proposed as the tools to discriminate tonalite and trondhjemite from the other granitic rocks. Furthermore, the ACNK-Al/Si plot and ACNK-FeO^* plot are suggested to separate the low-aluminous trondhjemite (LAT) from the high-aluminous trondhjemite (HAT). The case studies indicate that the new chemical procedure performs well for discrimination of tonalite and trondhjemite occurred within the TTG suites as well as those occurred in the ophiolite suites. Avoiding the calculation of normative minerals, the new chemical procedure is accurate, fast, and user-friendly than the scheme base on normative An-Ab-Or diagram, which is commonly used as the key plot to identify tonalite and trondhjemite for many years.

Abstract:

Bauxite is often associated with various critical metal elements such as gallium (Ga) and titanium (Ti). Studying the potential and comprehensive recovery and utilization of associated titanium resources in the accumulation-type bauxite in western Guangxi is conducive to the efficient utilization of mineral resources. This paper systematically collected the resource reserve data and ore quality characteristics of major accumulation-type bauxite deposits in western Guangxi, conducted a detailed survey on the current status of associated titanium resource utilization by major aluminum enterprises in the region, and focused on carrying out process mineralogy and ore beneficiation & metallurgical performance tests in the bauxite mining area on the periphery of Taiping, Pingguo City, Guangxi. On this basis, a comprehensive recovery and utilization process was proposed.The research shows that the associated titanium resources in the accumulation-type bauxite in western Guangxi are abundant, with the average content of titanium dioxide (TiO₂) ranging from 3% to 4%. The TiO₂ in the ore mainly exists in the form of anatase, which is difficult to be comprehensively recovered and utilized during the alumina production process. As a result, TiO₂ is further enriched in red mud, with its average content reaching approximately 6%. The comprehensive recovery and utilization of critical metal resources such as TiO₂ can be achieved through a process that first removes calcium and extracts iron from red mud, followed by extracting elements including titanium, scandium (Sc), and rare earths.

Abstract:

Pull-apart basins are special extensional structures formed at the linkage zones of en echelon strike-slip fault systems. They preserve important records of tectonic activity and evolution within strike-slip fault systems, therefore, serving as key windows for studying strike-slip faulting. This study summarizes geometrical characteristics and tectonic evolution of pull-apart basins and concludes that the geometric evolution of a pull-apart basin is controlled by the geometry of the initial master strike-slip faults. Underlapping configuration of the initial master faults will undergo the complete evolutionary sequence (spindle-shaped, lazy Z/S-shaped, rhomboidal-shaped, elongated rhomboidal-shaped) whereas overlapping configuration directly forms rhomboidal or elongated rhomboidal basins. The main factors influencing the characteristics and tectonic evolution of a pull-apart basin include the number of initial strike-slip faults (two or multiple), initial strike-slip geometry (fault separation and fault overlap, underlapping or overlapping configuration), initial strike-slip kinematics (pure strike-slip, transtension, or transpression), basement characteristics (thickness of brittle crust, salt structures in the basement, etc.), and its evolution stages. This study also introduces crack propagation and basin development of pure strike-slip, transtensional, and composite pull-apart basins, presents typical natural examples such as the Dead Sea basin and pull-apart basins in the Marmara Sea, and provides a method to deduce the minimum strike-slip displacement and the starting age of active pull-apart basins and the corresponding strike-slip faults based on relative extension ε^*_x (strike-slip offset divided by fault separation) and slip rate of the strike-slip fault. Current understanding of basin depocenter evolution, rift shoulder uplift, and extinction mechanisms of pull-apart basins remains inadequate. Their roles in major earthquake nucleation and surface rupture propagation require further investigation. The integrated application of field investigations, compilation of field examples, physical modeling, and numerical simulations shows potential to address these problems.

Abstract:

In 2024, a previously undocumented synthetic cubic zirconia product, traded as "heavy-zircon", emerged in the Wuzhou gem market (Guangxi, China). To address the lack of peer-reviewed data on its composition and identity, we performed a comprehensive mineralogical and gemological study using electron-probe microanalysis (EPMA), X-ray diffraction (XRD), fourier-transform infrared (FTIR), and micro-Raman spectroscopy. The material has a high relative density of approximately 7.40 and is primarily composed of Yb₂O₃ (51.08%~53.06%) and ZrO₂, with minor Y₂O₃. Its elevated density results from the incorporation of ytterbium (Yb), a heavy rare earth element. Single-crystal XRD confirms an isometric fluorite-type structure (space group Fm3m) with a lattice parameter a=5.134 8(18) Å and a unit-cell volume V=135.39(8) ų. The calculated chemical formulas are Zr_0.57Yb_0.40Y_0.03O_1.78□_0.22 or Zr_0.59Yb_0.41O_1.79□_0.21 (□ denotes oxygen vacancy). These results identify heavy-zircon as a high-density, ytterbium-rich variant of yttria-stabilized cubic zirconia. In accordance with gemological nomenclature, we propose "synthetic ytterbium-rich cubic zirconia" as its formal species name.

Abstract:

The problems of low hydrophilicity and low specific surface area of natural zeolite lead to its poor humidity control performance, and its large-scale promotion and application are limited. In order to solve this problem, the natural clinoptilolite zeolite in the Weichang area, Chengde, was taken as the research object, and the HNO₃ solution and NaOH solution were used to study the effect of acid/alkali treatment on the structure and humidity regulation performance of natural zeolite and its mechanism. The composition and structure of the material was analyzed using XRF, XRD, TG, FT-IR, N₂ adsorption-desorption technique, and SEM-EDX, etc. The moisture absorption and moisture release properties of the materials were evaluated using different types of saturated salt solutions. The results showed that the acid/alkali treatment could effectively change the composition, structure and moisture controlling properties of natural clinoptilolite zeolite. After alkali treatment, natural clinoptilolite zeolite transformed into Na-P-rich zeolite, the silica-aluminum ratio was reduced from 5.4 to 1.5, the surface hydroxyl content was enhanced by 4.9 times, and the moisture absorption and moisture-release amounts increased by more than 2.64 times and 3.23 times, respectively. After acid treatment, the silica-aluminum ratio of natural clinoptilolite zeolite was raised from 5.4 to 20.5, the surface hydroxyl content increased by 3.5 times, and the moisture-absorption and moisture-release amounts increased more than 1.49 times and 1.46 times, respectively. The alkali-treated zeolite exhibits a broad application prospect in the field of humidity-controlling.

Abstract:

Magnetic zirconium-iron oxide/palygorskite (MZIO/PG) as a low-cost adsorbent were produced by facile one-step co-precipitation technique and its properties for phosphorus adsorption were investigated by batch adsorption experiments. The adsorption kinetics characteristics and thermodynamic parameters were analyzed with a discussion on the adsorption mechanism. The results indicated that MZIO/PG composite adsorbent almost completely maintained the surface properties and structure of iron zirconium oxide, and the adsorption capacity of phosphorus can reach more than 90% of that of iron zirconium oxide. The adsorption kinetic data followed the pseudo-second-order model and Langmuir equation, Freundlich equation and D-R equation could all describe the adsorption equilibrium. The monolayer saturated adsorption capacity was 36.63 mg/g and the average adsorption energy is 19.4 kJ/mol. The increase in pH value impeded the adsorption and the ion strength has little effect on the adsorption. The adsorption had good selectivity and the adsorbent was easy to regenerate and effectively reused. The adsorption mechanism analysis found that ion exchange occurred between the surface hydroxyl of the adsorbent and phosphate groups, forming inner-sphere complexes.

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:

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:

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:

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:

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:

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:

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:

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:

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:

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:

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.

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.