Abstract:Precambrian granitoid rocks are widely distributed in northern Guangxi. According to rock associations, these granitoid rocks can be grouped into two types, i. e., graniodioritic rocks and biotite granitic rocks. The A/NKC values of both types of rocks are higher than 1.10, and hence they can both be assigned to aluminum over_saturation rocks. However, geochemical differences between the two types of rocks are also quite obvious. Compared with the biotite granitic rocks , the granodioritic rocks are relatively poor in silica and potassium and enriched in iron and magnesium, and have lower rubidium abundance and higher strontium and barium content. As for REE content, the granodioritic rocks have higherΣREE values and higher LREE/HREE ratios, whereas the biotite granitic rocks display quite clear negative europium anomalies. The variation ranges ofεNd(T) values of the two types of granitoid rocks are similar to those of the basement rocks (Sibao Group), but theεNd(T) values of granodioritic rocks are more close to those of the metamorphic mafic -ultramafic rocks of the Sibao Group, and the biotite granitic rocks are close to the metasedimentary rocks of the Sibao Group in this aspect. Based on a comprehensive analysis of their tectonic setting, it is concluded that the two types of granitoid rocks were formed at different stages of the collision between the Cathaysia block and the Yangtze block, and were produced by partial melting of the Sibao Group with different maturities at different depths.

Abstract:The authors have determined magnetic fabric parameters of the complex granite in Wangyunshan with the purpose of analysing dynamic state of the granite in the process of emplacement. Changes of tectonic environments, composition of the dark minerals in the rock units and basification of the granite in the process of emplacement find expression in changes of magnetic capacities. The attitude of magnetic foliation, which clearly suggests the emplacement of the magma in different tectonic units, is consistent with rock shapes and distribution of rock units. Magnetic lineations indicate emplacement centers of the granite, and different lineations imply different ways of emplacement and tectonic stress. Magnetic lineations of the magma in the early period were altered by those in the late period, and direction of magnetic lineation shows primitive flowing state of the magma. The strain state of the emplaced magma is shown by ellipsoid parameters, and distribution of stress field of the magma reflects the ways of emplacement and tectonic environment. Mechanism of granite emplacement reflected by regional structure, wallrock structure and other structures is substantiated by magnetic fabric parameters of the granite.

Abstract:The authors discovered directional arrangement of feldspar and mica microcrystals and elongated spherulite in the high t-p experimental products. This phenomenon is consistent with the geological fact. It is hence considered that the directional arrangement of potash feldspars in the peripheral part of some granitoids might have resulted from magma flowing.

Abstract:Volcano-intrusive rocks in the Mesozoic volcanic belt along the northern margin of Dabie Mountains can be subdivided into three rock series, i.e., high-potassium calc-alkaline series (HKCA), alkaline series (A) and shoshonitic (SHO) series. 14 samples were measured for the Rb-Sr and Sm-Nd isotopic compositions, and the results show that the initial Sr ratios (ISr) are 0.707 50~0.710 54, 0.708 43~0.710 14 and 0.708 73~0.709 12, the initial Nd ratios (εNd) are -17.2~-19.1, -14.7~-15.8 and -20.7~-21.7, and the two-stage depleted-mantle model ages (TDM) are 2.32~2.48Ga, 2.12~2.20 Ga and 2.60~2.68 for HKCA, A and SHO, respectively. A comparison of Nd isotopic composition between these vol cano-in-trusive rocks and the basement metamorphic rocks shows that the HKCA rocks were mainly derived from the Dabie Group-like crustal rocks, alkaline rocks were mainly derived from Dabie Group with small amounts of younger crustal rocks (Luzhenguan Group and Foziling Group), and the shoshonitic rocks were mainly derived from enriched mantles probably with incorporation of small amounts of even older Taishan Group_like crustal rocks.

Abstract:Distributed along the Jinshajiang-Ailaoshan fault zone, the alkaline-rich porphyry zone was formed in Paleogene (from 62 Ma to 23.18 Ma). The petrochemical and isotopic geochemical characteristics of the porphyriessuggest that the tectonic setting is predominantly shear-compression and locally extension, uplifting (diapir) of the Protererzoic basement metamorphic rocks of Mt. Cangshan is also a product of the same setting. The alkaline-rich porphyry results from upward erosion of deep EMⅡfluid contaminated in different degrees by crustal components. Porphyries keep a trace of both Yangtze block and Gandwana continent, as shown by lead isotopes.

Abstract:There are mainly felsic granulites in Tongbai area located at southern fringe of the North China plates. A study of the mineral chemistry and the features of the mineral paragenesis and the calculation with thermobarometers revealed that the granulites in Tongbai area were formed under thep-tconditions of 700~840℃and 0.61~0.85 GPa, belonging to typical medium-pressure type, and the geothermal gradient is approximately from 28 to 31℃/km. The granulite facies metamorphism probably occurred at the late stage of Early Palaeozoic.

Abstract:This paper has mainly studied chemical composition of clinopyroxenes from the kamafugitic series in Lixian County, West Qinling. The phenocrystal clinopyroxenes show complex types, complicated compositions, and multiple origins. The groundmass clinopyroxenes can be grouped into two pyroxene types: high-Ti aluminian diopside and Ti-bearing diopside which crystallized from the comagmatic melts. The substitution of CaTiAl2O6 for Ca(Mg, Fe)Si2O6 is common during the crystallization of diopsides, with the late melt rich in Ti and Al but poor in Si and Mg. Baicaoshan volcanic pipe is the product of an evolved magma with an evolutionary trend of Ti, Al, Fe, Na enrichment and Mg, Si depletion, which can be expressed by the substitution of CaTiAl2O6 and NaFe3+ Si2O6 for Ca(Mg, Fe)Si2O6 during the crystallization process of diopsides. The diopsides of this area are comparable with diopsides from kamafugitic series in typical areas of the world, showing that bulk composition of kamafugitic rocks provides constraints on mineralogical composition and crystal lattice features.

Abstract:The equation for estimatingαCO2 in metamorphic fluid of carbonate rocks is formulated by thermodynamic calculation for equilibrium state of decarbonation. The application of this method to marble from Jining Group in Inner Mongolia reveals that theαCO2 value of fluid in the progressive stage of granulite facies metamorphism is higher than 0.50,which is consistent with the data from recent researches. All evidence displays that theαCO2 value of fluid increased gradually in the progressive metamorphic process and reached 0.80 in its peak stage, which is attributed to the continuous separation of CO2with the intensification of decarbonation. Morever, some variations ofαCO2among samples (from 0.537~0.643) also suggest that CO2in the decarbonation process is most likely derived from internal buffering rather than from the deep source.

Abstract:Ultrafine needle-shaped wollastonite powder with large aspect ratio has immense application value in industry. There are two ways of increasing aspect ratio of needle-shaped ollastonite powder. One is the good selection of preparation machine with suitable omminution mechenism. The other is the proper processing condition. The authors used a ertical impact-classified mill in the experiment. For the purpose of attaining the preparation im of large aspect ratio, the main technological parameter was adjusted. It is indicated that the mll is quite suitable for the preparation of needle-shaped wollastonite powder, and the adjustment of main parameters (federate, impact rotational speed and classified rotational peed) has a strong influence upon the aspect ratio and the grain diameter of the product.Through the experiment, the authors have succeeded in preparation of needle-shaped wllastonite powder whose average diameter is 3.3μm and whose aspect ratio is 15.

Abstract:In accordance with coal sample observation by scanning electron microscope (SEM) and researches based on such subjects as anthracology, tectonic geology and material mechanics, the endokinetic fractures in coal are further classified into dewatering fractures, condense fractures and static pressure fractures, while the exogenetic fractures are further divided into tensile fractures, pressure fractures, shrink fractures and slack fractures, consistent with the development regularity of the geometric shapes, sizes and arrangement of fractures. The evolution, identification and controlling factors of the microfractures in coal are discussed, and the role of various fractures in coal reservoir is also analyzed. The researches on coal microfractures are of great significance in the study of coal reservoir, the exploration and development of coalbed methane, and the drainage of coal gas from coal mines.

Abstract:Silicated graphite is a new type carbon-graphite base compound material characterized by excellent performance and extensive application. Physical property and silication condition of carbon graphite base material are two key factors affecting silicated graphite preparation by LSP method. According to plenty of tests the physical property of the base material must have expansion coefficients between 3.7×10-6/℃and 5.3×10-6/℃and approximately match the SiC expansion coefficient; the base material must be isotropic and experience graphitization; the porosity is about 50% and the open holes possess no less than half of total holes;the smaller the open holes and the bigger the inside and outside surface areas, the better the condition will be.The optimum silication conditions seem to be 1 900℃~2 000℃in temperature, 1 h in time, more than two times of silication and vacuum degree≥10-3Pa.

Abstract:Wollastonite and hydrochloric acid react quickly when the pH value is not higher than 1.5. This paper studies the chemical conditions and distribution of such elements as Si,Ca, Fe and Mg in solid phase and liquid phase after reaction. When the pHvalue is 0.3~0.6,the ratio of silica in liquid phase (silica sol) is the highest. Ca is mainly in liquid phase, with always a little in solid phase. The specific surface area of solid phase is large in rapid reaction.If PEG is added to the system before reaction and the PH value is adjusted to 4 after reaction, porous silica with specific surface area larger than 430 m2/g and pore size of 1~2 nm can be prepared. The product can be used in the preparation of nano-composite based on silica and catalyst holder.

Abstract:The weathering and oxidation of sulfides within mine tailings lead to acid drainage and release of heavy metals, which pollute ground water and surface water and damage ecological environment. Recent researches show that many factors can affect weathering of mine tailings. This paper points out that grain sizes, pH values and concentrations of organic matters in mine tailings can affect weathering and oxidation of sulfides. The qualitative observation and quantitative test of sulfides with optic microscope indicate that the rate of oxidation follows the sequence of PbS>ZnS>Fe1-x S>CuFeS2>FeS2 within sulfides of the same grain size. The experimental results also suggest that organic matters in mine tailings can prevent sulfide minerals from weathering and oxidation.