Abstract:Early Carboniferous volcanic rocks in East Kunlun Mountains are distributed along Mid-Kunlun deep fault zone and consist mainly of basalts overlain by andesites and dactite. They were formed sequentially in setting of mid-cean ridge, ocean island and island arc. The mid-ocean ridge basalt has lower K2O, P2O5,SiO2, REE, FeO*/MgO and LREE/HREE values,and higher CaO, FeO*and MgO contents than the island-arc basalt. The ocean island basalt is characterized by highest TiO2and lowest K2O contents, but its REE and LREE/HREE values are between values of the other two sorts of basalts. The study on the tectonic setting of the volcanic rocks shows that the Mid-Kunlun suture was dominantly in“spreading”state in Early Carboniferous, resulting in the formation of mid-ocean ridge basalt and ocean island basalt, and then evolved into“closing”state, giving birth to island-arc basalt, andesite and dacite at the end of Early Carboniferous. The identification of the ocean-ridge basalt is important to the understanding regional tectonics and its evolution.

Abstract:The present paper deals with volcanic rocks of the Changning-Menglian belt (C1-P 2) and the south Lancangjiang belt (P1-T3) in "Sanjiang" region, Southwest China. Based On geological and petrological characteristics of these volcanic rocks, the authors studied their major elements, REE and trace element and, furthermore, determined their tectonomagmatic types. Volcanic rocks along the Changning-Menglian belt are basalts and ophiolite complex of oceanic ridge paraoceanic ridge type, which represent remnants of the Lancangjiang ocean. The South Lancangjiang volcanic belt is a composite volcanic arc resulting from eastward subducting and collision of the Lancangjiang ocean. The two volcanic belts, distributed in pairs, are products of the Lancangjiang oceanic suture zone.

Abstract:Jiuhuashan K-feldspar granite is a calcium_low granite body characterized by rich alkali-siliceous components and poor basic constituents. With oxidation degree somethat high,aluminium index colse to 1, and K2O approximately equivalent to Na2O, the granite should be of I-type. Nevertheless, its biotite is siderophyllite, and its initial87Sr/86Sr ratios are nonuniform and a bit higher (>0.707). These characteristics are not so consistent with features of I-type granaite. Consideridng Rb-Ba-Sr fractionation character and intense deficiency of MREE and using trace element web diagram, the author has revealed the intense magmatic crystallization and differentiation process and pointed out that this process had to do with the compositional variation of biotite and the obvious increase of strontium isotopes.The source materials of Jiuhuashan granite body were probably derived from middle and lower crust (εNd=-4.9~-6.6). Having experienced long unstable crystallization differentiation, the magmatic chamber eventually produced acid oversaturated magma, whose emplacement together with the early-mplaced Qingyang granodiorite body formed a complex batholith.

Abstract:The process of karst soil formation lies in the decrease of C, Ca, Mg and accumulation of Fe, Mn, Cu, Pb, Zn and acid indissoluble substance. The biomass carbon is vast at the experimental site. Experiments show that plant remnant is rapidly decomposed in the first season after bury and hence releases a large volume of CO2to take part in karstification. The organic carbon content of soil (SOC) is great, and SOC is preserved in large quanitites. Loosely combined SOC content of surface material, slope and saddle soil is high, serving as the potential source of karst CO2. SOC may be oxidized by acid solution (KMnO4solution). SOC in LayerA is more easily oxidized than that in Layer B. The field monitoring experimental study on CO2in soil and its emission rate suggests that karstification is more active under the humid weater condition. The characteristics of C13indicate that SOC is the main source of soil CO2, and soil CO2 is an important source of karst spring HCO-3. The experiments on relationships of soil, organic matter and limestone dissolution reveal that karstification is obviously stimulated by soil and organic matter. Karst is better developed in humid season and in slope.

Abstract:Silicified limestone is extensively developed in the Xikuangshan antimony deposit. In this paper, the composition and trace elements, REE and oxygen isotope characteristics of the silicified limestone are systematically studied. In addition, the probable answers to the genesis of silicified limestone and the silicification substages in relation to antimony mineralization are discussed in this paper.

Abstract:Joints are distributed widely in granite materials and affect the sawn goods performance of the rock. The beautiful sensation and the wear of rock_processed products are influenced by joints. Through the study of joints of different sizes in granite mass, it is known that joints not only control lumpiness of granite materials but also provide a good structural environment for weathering of the rock, causing the continuous development of weathering and the deeping of decoloration. The joints compose multiple patterns, and hence from numerous dark lines and spots on the polished surfaces of the rock, which reduce the average polishing glossiness and uniformity. Therefore , the study of joints of different sizes is an important link in the evaluation and exploitation of rock material resources.

Abstract:Montmorillonite in Heping County, Guangdong Province, was studied by chemical analysis, DAT, TG, XRD, IR and EPR. It is found that montmorillonite dehydrates adsorbed water and interlayer water when the temperature is between 126~148℃, and that this process is reversible. When the thermal treatment temperature reaches 659℃, the hydroxyl in octahedra sheet begins dehydrating, but the layer structure remains unchanged. When the temperature reaches 900℃, the layer structure of montmorillonite is destroyed, and the new mineral phase SiO2_χis formed; when the temperature reaches 1200℃, cristobalite and mullite appear;when the temperature reaches 1350℃, cordierite occurs. There are two main signals in montmorillonite EPR: one (g=4.16) is a sharp peak corresponding to the structural Fe3+ions of octahedron sheet in montmorillonite, and the other (g=2.1) is a broad peak corresponding to Fe3+of the amorphous oxide and hydroxide adsorbed on montmorillonite surface. Both peaks change greatly after thermal treatment at different temperatures. When the temperature is lower than 500℃, the signal with g=4.16 does not show obvious change; when the temperature is higher than 900℃, the change becomes remarkable; when the temperature equals 1350℃,the signal decreases again and a new signal with g=9.39 appears. The signal with g=2.1 weakens gradually and eventually disappears with the rising temperature. This change is attributed to the structural change and migration of Fe3+ions in montmorillonite.

Abstract:The growth model of the chrysanthemum stone occurring in Qixia Formation of South China has been studied in this paper. The chrysanthemum stone is composed of celestite, and formed by a core and many petals. The core consists of grain aggregate and the petals are of radial arrangement. Through a comparison with the Diffusion_Limited Aggregation (DLA) model, the authors have established a growth model of the chrysanthemum stone. Due to the resistance of the mud media to the crystal growth and the control role of the crystal structure, there is no branching in the growth model of the chrysanthemum stone, which is different from things of the DLA model. Nevertheless, there exists“branch_between”in the growth model which forms more and more crystal columns, like the branching in the DLA model. As the crystalline substance (SrSO4) moves toward and condenses at the center, and the mud media are pushed outward, the concentration of SrSO4gradually decreases from the center outwards. Hence, the formation of the“branch_between”phenomenon becomes more difficult, and the H (the interval of the crystal columns at the moment of“branch_between”) becomes increasingly larger from the center outwards. There is a critical value H0during the change of H. When H H0, the petals are formed. H0is the key to form the boundary of the core and the petal. The change rate of H, defined asβ, determines the morphological parameterσ(length of petal/diameter of core). Based on the model, one can obtain the relationshipσ≈β-0·5. ln the real morphology of the chrysanthemum stone, H0≈ 0·5mm , which is independent of the occurrence place. However,σis related to the occurrence place. This indicates that the change rate of H(β)depends on the occurrence place. In addition to the“branch_between”and the evolution of H, there must exist“geometric superseding”in the growth of the chrysanthemum stone, because all the petals have the same crystal form: {011}.

Abstract:Shahewan rapakivi granite which intruded into the Qinling orogenic belt in 195~213 Ma is a young intrusion. The type, chemical composition andt—pcondition of biotite from this rapakivi granite are discussed in this paper. The biotite is Mg_Fe biotite, which has higher Mg than biotite from S_type and I_type granite. FeO and Al2O3of this granite is similar to those of I-type granite. Si is from 2.99 to 2.6, higher than Si of A-type granite and lower than that of I-type granite. Al2O3and TiO2show negative correlation, being similar to character of biotite from A_type granite. The crystalline condition of biotite ist=750~820℃and logfO2 =-8.5 ~-9.5, which are higher than the values in average granite.p=0.1 GPa±. The above character indicates that biotite of Shahewan rapakivi granite is different from biotite from S-type and A-type granite as well as I-type granite, showing that this rapakivi granite is a transitional type between I-type granite and A-type granite and is a product of special tectonic condition. The result is consistent with conclusions from our other studies and is also supported by researches on other rapakivi granites. In short, our studies show that chemical composition of biotite can determine type of gra-nite and provide information for the formation environment of the intrusion.

Abstract:The Fanshan potassic alkaline complex was formed by three periods of intrusive rocks,which were all penetrated by vein rocks. The first period intrusive rocks are layered ultramafic rocks that have rhythmic structure. Gigantic apatite-magnetite deposits occur in layered rocks.he main types of first period intrusive rocks are pyroxenite, biotite pyroxenite, pegmatoid orthoclase-biotite pyroxenite, magnetite apatite rock, apatite rock and interstitial orthoclase pyroxenite; the second period intrusive rocks might be divided into three rock types, viz., coarse- grained orthocalse pyroxenite, coarse-grained pyroxene syenite, and coarse-grained schorlomite-orthoclase pyroxenite; the main types of the third period rocks include trachytoid pyroxene syenite, fine-grained orthoclase pyroxenite, fine-grained pyroxene syenite and porphyroid pyroxene syenite. The three kinds of vein rocks are syenite, hornblende syensite and carbonatite.Au abundance (6.1×10-9) of the Fanshan complex is 1.74 times that of the crust (3.510-9). The determination of rocks of different intrusive periods suggests that the average Au content of the first, second, third period rocks and vein rock syenite are 8.8×10-9, 5.1× 10-9, 7.4×10-9and 4.2×10-9, respectively. In addition, Au content of various rocks of the irst period was determined: pyroxenite 9.31×10-9, biotite pyroxenite 7.78×10-9, pegmatoid orthoclase-biotite pyroxenite 7.40×10-9, interstitial orthoclase pyroxenite 8.00×10-9,magnetite apatite rock 13.78×10-9, apatite rock and biotite-apatite rock 11.80×10-9, and biotite rock 18.63×10_9. These data suggest that Au content shows vertical rhythmic variation in the profile of the layered rocks, and decreases from west to east. These phenomena imply that Au tended to concentrate in the melt with high content of Fe, Mg, Ca and P during the primary magmatic differentiation and then became richer in the fluid due to magmatic fractional crystallization.

Abstract:Tourmaline is a kind of gem material with complex structure, composition and isomorphous substitution,which resuslt in diverse types and colors of this gem. Irradiation is fairly important among the color enhancement methods of tourmaline, whose composition almost covers the whole periodic table. This paper deals with the tourmalines irradiated by 12 MeV high energy electrons. Tests on some physical properites of both untreated and treated samples were made. As a result, the authors have found that irradiation of high energy particles can cause some changes of physical properties of this gem, such as density, cell dimensions and color. One of the causes of color change is that irradiation creates and removes some crystal defects called color centers. There are two kinds of color centers, namely the electron center and the vacancy center. The actions of particles or rays on ions of Mn, Fe, Ti, Cu, Al, Si and O in OH may be probably the cause for the deep hue of some irradiatied samples. Irradiation may alter the ion valence state and its position, and hence create the color center. Irradiation also reduces the total element composition of the gem and raises its hardness. Navertheless, it only causes negligible changes on reflection indieces, and the changes of cell dimensions vary with treated colors.

Abstract:The Shimen As(Au) deposit in Hunan Province, characterized by a pipe-shaped orebody and typical structural model of three layers, is belived to be of hot spring origin. Systematically described in this paper are such genetic mineralogical features of realgar from this As(Au) deposit as its mode of occurrence, chemical composition, physical properties, unit-cell parameters, infrared spectra and sulfur isotopic composition. The realgar is high in S but low in As,and contains Sb and trace amounts ofHg, Se, Te, Bi and Au. Unit cell parametersa0=9.309 ~9.511°A,b0=13.52~13.61°A,c0=6.572~6.593°A; crystallochemical formula (As0.9997 Sb0.0013)1.0010S. Infrared absorption appears at 343 and 375 cm-1;δCe<1, exhibiting obvious negative anomaly. These typomorphic characteristics are of great significance in the study, evaluation and prospecting of other realgar deposits (occurrences).