Abstract:The Middle Jurassic volcanic rocks of Haifanggou Formation in western Liaoning are intermediate-acid igneous rocks of the trachyandesite-trachyte-andesite-dacite assemblage. The volcanic rocks are close to calc-alkaline and high-K calc-alkaline series，and their whole rock Rb-Sr isochron age is 177.2±28.0 Ma. They are enriched in Al (Al2O3≥15.45％) and Na (Na2O/K2O≥1.35), and SiO2≥56.99％．They are characterized by strongly fractionated REE［(La/Yb)N≥14.80，(Ho/Yb)N≥1.15］, low Yb and Y(Yb≤1.42×10-6，Y≤15.18×10-6)，absence of Eu negative anomaly(0.86～1.03)，obvious depletion of Rb, Nb, Zr and Ti, relative enrichment of Sr, Ba, K and LREE，and low Rb/Sr ratios(＜0.1)．These volcanic rocks are geochemically similar to adakite，and are hence regarded as adakite-like rocks．The Sr, Pb and Nd isotopic data indicate that they were derived from the partial melting of ancient intermediate-basic metamorphic rocks in the lower crust，and thedepth of volcanic sources must have been very great．Studies show that the volcanic rocks were formed in an intraplate setting, with no direct relationship with the westward subduction of the Pacific plate． The lithospheric delamination must have been related to the obvious transformation of the Mesozoic tectonic stress field，the intense volcanic-magmatic activities and the formation of abundant fault basins in western Liaoning．The adakite-like rocks of Haifanggou Formation are of important geological significance in the study of magma derivation，crust-mantle process and geodynamics.

Abstract:The Caoshan and Jiguanshi intrusions composed of pyroxene dioritic porphyrite and granodiorite are exposed in the Shizishan orefield, Tongling, Anhui Province, eastern China. Based on new petrographic observations and microprobe analyses of pyroxene and hornblende megacrysts and cumulates from the intrusions, in combination with mineral crystallization temperature and pressure calculations, the authors found some evidence for the Mesozoic mantle-derived magma underplating in this area. The petrographic and mineralogical data presented in this paper suggest the existence of alkali-olivine basalt magma underplating before 140 Ma± in this area. The formation of the pyroxene megacrysts and the hornblende megacrysts as well as cumulates resulted from crystallization differentiation of intermediate-basic magma in the deep magma chamber at the depths of 28 km to 33 km through the assimilation of the underplated alkaline basaltic magma with the lower sima crust. The formation of the pyroxene cumulates resulted from the crystallization differentiation of intermediate magmain the shallow magma chamber at the depths of 19 km to 21 km, through the assimilation of the intermediate_basic magma with the epimetamorphic rocks.

Abstract:The southwestern margin of Alxa massif in northern China, one of the major provinces of mafic-ultramafi rocks, can be divided into Beidashan, Longshoushan and Beihaizi rock belts. Generally speaking, the Beidashan rock belt is represented by Yejili feldspar-bearing pyroxene peridotite, whose Sm-Nd rock-mineral isochron age is 773.1±10.8 Ma,εNd(t) values are +0.8～+10.8, and ΣREE are 7.59×10-6～20.34×10-6. The Longshoushan rock belt is represented by Jinchuan lherzolite and Zangbutai pyroxene peridotite, whose Sm-Nd rock-mineral isochron ages are 1 508±31 Ma and 1 511±168 Ma respectively,implying mantle products formed almost at the same time. Jinchuan intrusion has ΣREE of 3.33×10-6～115.52×10×10-6 and εNd(t) of -1.9～-4.3, but Zangbutai has εNd(t) of +2.6～+2.9, showing obvious differences. The Beihaizi rock belt is spread limitedly, whose gabbro Sm_Nd rock-mineral isochron age is 1 440±220 Ma,εNd(t)>0, and ΣREE are 179.64×10-6～207.76×10-6 . The Longshoushan and Beihaizi rock belts were both probably formed by the early Middle Proterozoic magma derived from the lower mantle due to the action of superplume. Their εNd(t) difference indicates that every rock body has its unique petrogenetic process. Yeliji rock body is the product of Later Proterozoic depleted mantle, whose formation environment and origin are remarkably different from those of Jinchuan rock body.

Abstract:Based on lithosphere discontinuity revealed by geological and geophysical characteristics of North China, the authors recognized three kinds of lithospheres in North China region, they are cratonic type lithosphere in Odros, orogenic type lithosphere in Yanshan-Taihang and rift type lithosphere in North China plain. According to petrological means, crust-mantle evolution models, the process of orogenic belt formation, and the relationship between seismic velocity and petrochemical composition, this paper has set up the crust-mantle petrological and petrochemical lithospheric structures of craton, orogenic and rift types in North China. Some important problems are also discussed in this paper, such as the geological implications of the crust-mantle structures and the thicknesses of crust and subcontinental lithospheric mantle in different types of lithospheres, the role of lithospheric discontinuities in the classification of the lithospheric units, and the continental dynamic significance of the formation of different types of lithospheres.

Abstract:Zircon SHRIMP dating was performed to study Yunmengshan gneissic granite and, as a result, four groups of zircon ages were obtained, namely,144±4 Ma, 160～163 Ma, 193～218 Ma and 2 416 Ma. The age of 144±4 Ma represents the emplacement age of Yunmengshan gneissic granites, and can serve as new important evidence for the emplacement of Yunmengshan gneissic granite. The two age groups of 160～163 Ma and 193～218 Ma probably represent the ages of zircon captured during the emplacement of magma. The age of the inherited zircon is about 2 416 Ma, identical with the zircon U-Pb upper-intercept ages by Davis (1996). This suggests that Yunmengshan gneissic granite was probably derived from partial melting of late Archean gneiss or that late Archean zircon was captured during magmatic intrusion.

Abstract:Detailed studies were carried out on the fluid inclusions in quartz from Liba, Jinshan and Maquan gold deposits in Zhongchuan area, western Qinling orogenic belt. Three types of inclusions can be recognized in these deposits, i.e., CO-2-H-2O, CO-2-rich and aqueous inclusions. The ore-forming fluids are mainly of CO-2-NaCl-H-2O type characterized by rich CO-2, low salinity, high temperature and immiscibility. In combination with the previous isotopic data, the regional geological setting and the features of diagenesis and metallogeny, it may be concluded that the ore-forming fluids were closely related to the Mesozoic syntexis or re-melted granitic magmas and their intrusions. The ore-forming fluids were derived from the deep magma and mixed with meteoric and metamorphic water. Some materials derived from the deep area might have been involved in the ore-forming system.

Abstract:Composed mainly of secondary quartz (50%～90%) and pyrite and minor realgar, orpiment, barite, illite as well as dickite, siliceous rocks are often characterized by typical hydrothermal metasomatic texture and metasomatic relict texture, and typical tectonite structures such as bracciated structure,cataclastic structure, porphyroclastic structure and small fissure and pore structures, with no sedimentary structures and textures. Gold-bearing or silver-bearing siliceous rocks are produced by silicification during mineralization. Undermicroscope, the silicification consists of 3 stages in the gold-forming period and 1 stage in the silver-forming period. REE compositions of the rocks show that ΣREE is especially low in silver-bearing rocks, LREE is richer than HREE in gold_bearing rocks, and MREE is rich in silver-bearing rocks. Therefore, the NASC normalized distribution curves dip towards right in gold-bearing rocks and upwards in silver-bearing rocks. In addition, the curves show slight negative ceriumanomaly and apparnt negative europium anomaly or indistinct positive europium anomaly, which differ from the curves of typical hydrothermal sedimentary chertsor sedimentary exhalation cherts with obvious negative cerium anomaly and positive europium anomaly. So the rocks should be typical jasperoid, which, instead of being formed by hydrothermal sedimentation or sedimentary exhalation between seawater and the surface of sediments, is a product of hydrothermal metasomatism. 

Abstract:The negative striations and micromorphology of pyrite crystals on a {210} face in the auriferous quartz vein were studied by means of differential interference microscope，SEM and TEM. The{210} faces of pyrite crystals are F-faces，which have developed free growth layers. The mechanism of their crystal growth is controlled by two-dimensional nucleation and layer-by-layer growth. Both simple pentagonal dodecahedron habit and other morphology of pyrite crystals develop free growth layers on the {210} faces. Some positive striations on the {210} faces are formed by piling up of steps of growth layers on the {100} faces, and other positive striations on the {210} faces are formed by piling up of steps of growth layers on the {210}faces. Transmission electron observation reveals that crystals with negative striation are formed through auto-epitaxial settlement of block nuclei 30～50 nm in diameter on growing crystals. Electronic diffraction pattern shows that the single block nuclei consist of many minute crystallites already formed in the solution. This suggests that these crystals have been grown in a reasonable environment characterized by very high super-saturation and low gradient of temperature. Their growth is not related to impurity. Based on an analysis of PBC theory and Donnay-Hark law, we can rea-sonably interpret the phenomenon why free growth layers are commonly seen on the {100} faces but are rarely developed on the {210} faces of pyrite crystals in nature. Besides occurring in the Shakanai mine of Japan, the pyrite crystals with negative striations are also developed in gold deposits of quartz-sulfide veins

Abstract:The (Ce,Sm)/Zr-pillared montmorillonite clay which is thermally stable at 300℃ can be obtained from ZrOCl2·8H2O solution by adding (Ce,Sm) cations, and d001 values are 2.1～2.3 nm at room temperature, 1.8～1.9 nm at 300℃. FTIR analysis shows that relatively strong chemical bonds of (［Si—O］—［H(O)—Zr(Ce,Sm)］) are formed between (Ce,Sm)/Zr polycations and Si—O tetrahedral sheets of the clay minerals. It is therefore held that (Ce,Sm)/Zr-pillared montmorillonite has a stable structure.

Abstract:Applying both the crystalline field theory and the group theory, this paper has systematically and theoretically explained the splitting of the energy levels of the transitional metal ions in various gemstones under different crystalization environments. In addition, a detailed analytical procedure is put forward and some examples are given.

Abstract:A series of modified montmorillonites were synthesized from Na-montmorillonite, which included Al-Ti-inorganic montmorillonite and Al-Ti-organic montmorillonite. The optimum Al-Ti and Al-montmorillonite radios were determined. Modified montmorillonites were utilized to treat imitative wastewater and chemical laboratory wastewater and Na-montmorillonite. The effects of optimum conditions such as Al-Ti proportion, pH value of wastewater, throwing amounts of Al-Ti modified montmorillonites and stirring time were investigated. The experimental conditions were optimized with the orthogonal experiment. The results show that the capacity of inorganic montmorillonite and organic montmorillonite is obviously better than that of original montmorillonite in water treatment. The removal rates of colority and turbidity are over 93%. The removal rates of COD are over 66.31% by organic montmorillonite. The result is satisfactory.

Abstract:Mineralogical characteristics of some typical varieties of Qingtian Stone were studied by such means as electron microprobe analysis, X-ray powder diffraction analysis and infrared absorption spectroscopy. It is found that chemical composition of Fengmen Qingtian Stone is characterized by rich alkali and Al and poor Si. The blue part of Landing Stone is composed of microcrystalline corundum. Lanhuaxing and Ziluolan Qingtian Stones have a complex mineral association: the blue or purple parts in the stones are dumortierite, the light white and rosy spots are andalusite, and the transparent spots are kaolinite. Shanpaolü is composed of chromian sericite instead of pyrophyllite, with a little quartz, pyrite, andalusite and illite. Its vivid green color is attributed to Cr. It should therefore be a new variety of carving stone.