Abstract:The Gaudeanmus area lies within the southern Central Zone of the NE-trending branch of the Damara orogen. Petrographical and geochemical characteristics of alaskite as well as its petrogenesis and geological features in the Gaudeanmus area of Namiba were studied in this paper. The alaskite sample displays variable mineral and chemical composition. The alaskites in this area range in composition from tonalite to alkali-feldspar granite. The alaskites have been divided into six distinct types based wholly on observable field characteristics of color, grain size, texture, radiometric measurements by scintillometer and macro-scale mineralogy. Cross-cutting and structural relationships were used to create a chronological sequence from type A which is the oldest to type F which is the youngest. Geochemical analyses show that the alaskites contain high silica and alkali, with relatively low manganese, magnesium, sodium, phosphor and calcium. The alaskites show peraluminous to metaluminous characteristics and belong to high-K calc-alkaline to shoshonite series. Major elements of different types of alaskites do not show characteristics of homogeneous evolution, so they are inferred to be products of different stages of orogeny.

Abstract:The Toudaohe pluton, located in Mingshui area of middle Da Hinggan Mountains, is mainly composed of granodiorite and monzogranite. LA-ICP-MS zircon U-Pb data indicate that the Toudaohe pluton formed during the Middle Triassic with the ages of 243～240 Ma. Geochemically, the granitic rocks are high in SiO₂ (61.32%～78.19%), and Al₂O₃ (11.85%～16.87%), but low in total Fe₂O₃ (0.56%～5.93%), MgO (0.16%～3.30%), and CaO (0.26%～2.94%), suggesting that they are high-K calc-alkaline I-type granites. These granitoids have low total REE content (ΣREE=75.5×10^-6～149.49×10^-6) with fractionated REE , and no remarkable Eu anomalies. Moreover, they are enriched in large ion lithophile elements (e.g., Rb, Pb, Th, U), and depleted in high field strength elements (e.g., Nb, Ta, Ti). Zircon Hf isotope analyses show that these granitoids have high initial ¹⁷⁶Hf/¹⁷⁷Hf ratios (0.282 811～0.283 227), positive εHf(t) values (6.55～21.28), and young Hf two-stage model ages of 595～1 107 Ma. These geochemical characteristics indicate that the source materials of Toudaohe pluton were juvenile igneous crust rocks which originated from depleted mantle during the Mesoproterozoic to Phanerozoic period. Based on regional geological investigations and spatial and temporal distribution of the coeval igneous materials, the authors hold that the Middle Triassic Toudaohe pluton was emplaced in a post-orogenic extensional environment linked with the final closure of the Paleo-Asian Ocean.

Abstract:The Eastern Tianshan area with numerous Late Paleozoic granitoids constitutes the southwestern part of the CAOB. The intrusive tectonic setting of these granitoids has been a highly debated issue. The Dananhu Aketag granitic pluton located on the south margin of the Eastern Tianshan Mountains is composed mainly of porphyry K-feldspar granite. SHRIMP zircon U-Pb dating yielded a ²⁰⁶Pb/²³⁸U age of 306.5±2.8 Ma(MSWD=0.53), which is interpreted as the formation age of the pluton. All samples from the pluton are characterized by high values of SiO₂, K₂O, Na₂O and low values of CaO, MgO, P₂O₅, TiO₂, suggesting weakly peraluminous rocks (A/CNK=1.01～1.03, A/NK=1.09～1.12). The samples exhibit a relative enrichment of LREE as well as negative anomalies of Eu. In the primitive mantle (PM) normalized trace element patterns, all of these rocks are enriched in large ion lithophile elements (LILEs, Cs, Rb, Th, K) and strongly depleted in high field strength elements (HFSEs, Nb, Ta, P, Ti) in comparison with the primitive mantle. They have high Ga/Al ratios and belong to A2-type granite. These characteristics suggest that the Aketag pluton was generated by the partial melting of mafic lower crust in a post-collisional setting. An important implication is that the ocean in the Eastern Tianshan area was closed before Permian.

Abstract:Intermediate to mafic dyke swarms were newly discovered in Urho area in the south of the Hala'alat Mountain which is located in the east of Western Junggar. The dyke swarms intruded into the Permian Jiamuhe molasse formation. The nearly NE-SW-trending dyke swarms are parallel to Darbut Fault. The rocks are mainly composed of diabase, diabase porphyrite and gabbro-diorite, which have features of low K calc-alkaline basalt to andesite series, as shown by geochemical analyses. The dyke swarms have low REE (34.53×10^-6～82.43×10^-6) and the anomalies of δEu (0.74～0.98) and δCe (0.98～1.15) are not obvious. REE distribution patterns are of the right-oblique type (LREE/HREE=2.47～7.18). All samples are characterized by the enrichment of LILEs (K, Rb, Ba, Sr) and depletion of HFSE (especially Nb, Ta), showing the characteristics of island-arc zone. Positive εNd(t) values (5.51～5.71) and relatively low initial Sr isotopic ratios (0.703 802～0.704 223) indicate the depleted mantle-related source. The source was the depleted mantle wedge and the magma was genetically influenced by the subduction components. The dyke swarms in Urho area suggest that the subduction between plates still went on after the completion of the compressional orogeny in early Permian. The lagged arc magmatism occurred later than the subduction in the west and middle of Western Junggar, suggesting that the final completion of the subduction in Western Junggar was in late Early Permian.

Abstract:Located in northwestern Jiujiang-Ruichang metallogenic area, the Dongleiwan skarn Cu-Mo-Au polymetallic deposit belongs to Jiujiang-Ruichang Cu-Au orefield, which is a component part of the Middle-Lower Yangtze River Cu-Au metallogenic belt and the Daye-Jiujiang metallogenic subzone. Petrographic and microthermometric studies of fluid inclusions in quartz from the main metallogenic phase (quartz-polymetallic sulfide phase) show that the inclusions related to mineralization include mainly four types. Homogenization temperature and salinity w(NaCl_eq) of the ore-forming fluids are concentrated in 210～350℃ and 1%～9% respectively, suggesting medium-high temperature and medium-low salinity. Gases of fluid inclusions mostly contain H₂O and CO₂, followed by N₂, CO and O₂, with a small amount of CH₄ and C₂H₂. Cations of liquid composition mostly consist of Ca²⁺, K⁺ and Na⁺, followed by a small amount of Mg²⁺, while anions are mainly Cl^-, SO₄^2-, followed by NO₃^- and NO₂^-, and the fluid is of the CO₂-H₂O-NaCl-CaCl₂ (KCl) system, with the calculated ion concentrations ranging from 3.1% to 34.5%. Hydrogen-oxygen isotope characteristics show that the δ¹⁸O_H2O values of the ore-forming fluids in the main metallogenic stage are in the range of 0.93‰～5.20‰, and δD_V-SMOW values vary between -81‰ and -64‰, which implies that the ore-forming fluids were mainly derived from magmatic fluids, with the mixture of a small amount of meteoric water. The δ³⁴S_V-CDT‰ values of sulfides range from -2.2‰ to 3.4‰. Lead and rhenium isotopic composition of the ore indicates that the ore-forming materials of the Dongleiwan deposit were derived mostly from the upper mantle, and partially from the crustal materials. The Dongleiwan deposit is a hydrothermal metasomatic skarn type deposit. The folds and fractures of this area provided the migration pathway for mineralization, and magmatic emplacement developed skarn type magmatic fluid subsystems, accompanied by Cu (Mo, Au, etc.) mineralization. These factors eventually led to the formation of the ore deposit.

Abstract:The Yinachang Fe-Cu-Au-REE deposit is located in the middle of Yunnan Province along the southern part of Kangdian axis and at the southwest edge of the Yangtze block. According to differences in mineral association, ore structure, texture and wall rock alterations, two mineral assemblages can be recognized, i.e., Fe-Cu-REE-feldspar-silicate assemblage of pre-dominant mineralization stage and Cu-Au-quartz-carbonate assemblage of post-mineralization stage, and the Fe-REE-feldspar-silicate assemblage can be further divided into magnetite- albite-REE subassemblage and chalcopyrite-K feldspar-garnet-biotite subassemblage. S, Pb, H, O isotopic researches on chalcopyrite, fluorite, quartz and calcite of the chalcopyrite-K feldspar-garnet-biotite subassemblage and the Cu-Au-quartz-carbonate assemblage suggest that the metal and fluid sources of the chalcopyrite-K feldspar-garnet-biotite subassemblage were dominantly derived from magma, while the ore-forming materials of the Cu-Au-quartz-carbonate assemblage had a complicated metal source, and its fluid was probably of metamorphic hydrothermal origin.

Abstract:The Early Triassic is a highly anomalous period in earth history, but little attention was given to this period in comparison with the Permian-Triassic boundary. The evolution of carbon and strontium isotopes of marine carbonate can give the information about the ecosystem function and environment change of the transitional period. According to the data concerning carbon and strontium isotopes during Early Triassic obtained from eastern Sichuan area, the isotope scattergram can be drawn, with which we can analyze the geological processes as well as the controlling factors. As shown by the scattergram, strontium isotope evolution curve increases monotonously, which is in high consistency with features of other areas in the world, suggesting that the increased content of highly radiogenic strontium was the leading factor for this phenomenon. In the carbon isotope scattergram, there exists violent fluctuation, which can be attributed to the migration of a large quantity of phosphate into the ocean which caused the blooming of the algae and the enhancement of the ocean primary productivity. The absorption and release of methane hydrate were not the main factors causing the fluctuation, whereas the persistent effects, such as the sea water reversion, can well explain the anomalous curve. Nevertheless, the mechanism should be further investigated. In addition, it is necessary to combine the organic carbon with the inorganic carbon and to consider the Early Cambrian.

Abstract:The Mengyejing potash deposit in Jiangcheng area of Yunnan Province is the unique ancient chloride type solid potash deposit in China. The main salt minerals include halite, sylvite and carnallite, with sylvite being the most important potassium-bearing mineral. In this paper, the authors used cooling-heating methods to study the homogenization temperatures of primary halite fluid inclusions in order to obtain the information concerning the deposit formation and ancient temperature of the salt lake. The result shows that, in order of white halite layer →grayish sylvite layer →carnallite-bearing grayish sylvite layer, the homogenization temperatures increase gradually in order of 23.8℃→27.7℃→38.6℃. This trend is consistent with the crystallization sequence of salt minerals, i.e., halite→sylvite→carnallite. Therefore, the evaporative intensity for the carnallite-bearing upper sylvite layer is obviously higher than that of the lower sylvite layer and the halite layer, implying that the formation of potash deposit might have resulted from the continuous concentration and salinization of the lake brine, and this salinization trend was probably caused by the rise of the brine temperature in the lake. Moreover, the change of brine temperature was influenced by atmospheric temperature. Therefore, the homogenization temperature of primary fluid inclusions in different layers of the deposit can not only reflect the ancient water temperature directly during the formation of the deposit but also indicate environmental atmospheric temperature of that time.

Abstract:The red dot and flame figure inclusions in Nanhong jade are red spherulite and red tube-like inclusions in quartz. Microscope observations and scanning electron microscope studies show that the red spherulites include the red core, black coccosphere and red surface, and are distributed in the intermittent layers of rhomb in "three-color" type quartz. The flamed tube-like inclusions mainly occur in striped quartz, perpendicular to the rhomb of quartz. The interior of the tube is black with red shell. The color and transparency of the spherulite and red tube-like inclusions have directly effects on the color and luster quality of Nanhong jade. Studies show that the red spherulite and red tube-like inclusions are mainly composed of platy hematite. The directions of c-axis in hematite from spherulites change regularly, which is likely related to its V₂O₅. The relationships between quartz and associated minerals and their analytical results indicate that hematite is of hydrothermal origin, and its temperature is about 160℃. The organic matter of the fluids, which led to the formation of spherulite and red tube-like hematite inclusions, probably came from the carbonate in Permian Maokou Formation.

Abstract:In this study, organopalygorskite clays were prepared as the adsorbent by using anionic and cationic surfactant as modifiers, and the adsorption properties and mechanisms of adsorption of reactive red were investigated, with a discussion on the adsorption thermodynamics. The results demonstrate that the hydrophobicity of organopalygorskite clay surface is enhanced and Zeta potentials are influenced, and anion-cation organopalygorskite clays possess the synergic adsorption of the reactive red in water within the appropriate ratio. The adsorption isotherms are nonlinear and can be described by Langmuir and Freundlich equations, and adsorption enthalpy is -12.23 kJ·mol^-1. There is no strong chemical interaction in the adsorption process and adsorption is mainly expressed as the collaborative effects of partition, hydrogen bond forces, dipole bond forces, van der Waals forces etc.

Abstract:In this study, tunnel-structured cryptomelane was synthesized by a reflux method, and its crystal structure, crystal cell parameters, particle morphology and specific surface area were characterized. The degradation activity of cryptomelane on phenol with or without light was evaluated. In addition, the effect of pH and mineral loads on degradation of phenol were also investigated. The results indicated that a small amount of phenol was degraded by cryptomelane without irradiation, but a large amount of phenol was degraded under irradiation. The decrease of pH, the proper mineral loads and the concentration of phenol can all promote the degradation of phenol.

Abstract:Experimental researches constitute one of the sources of the innovation of granite and adakite theory and hence play an essential role in this aspect. In recent years, researchers in China have made great achievements in granite and aidakite experimental research. This paper discusses some experimental researches on issues related to adakite and puts forward some opinions: ① The bottom of the lower crust lacks water, the dehydration partial melting of granite is under the condition of less water, and hence the experimental results should be treated with caution in the case of saturated water and increased water; ② Attention should be paid to the problem whether there appears plagioclase in the residual phase component or not, and the consideration of both garnet and plagioclase can lead to a correct conclusion; ③ What is the real meaning of garnet-in line under 1.0 GPa pressure? It only suggests that the melt balance with garnet-in has lower Yb. However, besides adakite, Himalayan type granite also has lower Yb, and therefore the emergence of plagioclase should also be considered: if garnet appears but plagioclase disappears, the melt is adakite; if both garnet and plagioclase appear, the melt is the Himalayan type granite. Researches abroad fail to consider Himalayan-type granite, and hence some experimental data under the condition of 1 GPa provided by foreign researchers should be used carefully, because some of the melts belong to the Himalayan type granite instead of adakite; ④ The metamorphic reaction is different from the partial melting reaction. The metamorphic reaction result cannot be interpreted as the result of partial melting reaction. The metamorphic reaction occurs in the case of increasing temperature and pressure and is not the main way to produce granite; the partial melting reaction that occurs under the constant pressure and increasing temperature is the main way to produce granite. The author emphasizes that the recent experimental study of adakite conducted by researchers in China has made great progress, and China is at a leading level in the world in this field. The difference in opinions is inevitable and normal.