Abstract:The importance of the greenstone formations preservative in the cratons and the ophiolite complexes present in the geosynclines of China has become increasingly recognized during the last few years.The purpose of this paper is to make a comparison between greenstone suite and ophiolite suite and to show their differences.It is well known that the greenstone and the ophiolite are actually different both in their concepts and characters. The authers have made in this paper the comparison between them using the data from the world.It is believed that greenstone belts were derived from Archean basin with sialic basement and ophiolites were formed in the oceanic basin with simatic basement. Greenstone belt is as an autochthonous volcanic-sediment located within the cratons, while ophiolite is regarded as an allocthon emplaced into the geosyncline. In general, the age of greenstone is confined to Archean and ophiolite belongs to phanerosoic age. Greenstone sequence can be divided into three divitions (or subsequences), from the lower to the upper horizon, they are ultramafic layer (including komatiites), mafic volcanic layer, sialic volcanic and sedimentary layer. In the ophiolite sequence peridotite tectonite occurs as a basement in the lower part, and in the middle of section there occur the cumulative rocks which on the top are overlain by the mafic lava. Unlike the ophiolite sequence, the greenstone sequences have lock of sheeted dyke complex. The volcanic rocks of greenstone in petrochemistry exhibit generally a bimodal suite which is absented for volcanic of ophiolites. The greenstone sequence shows generally 1-3 or more cycles of development, and ophiolite suite has only one sequence.In addition, greenstone suite differs from ophiolite sutite either in geochemistry and REE, or in metamorphism, tectonics, and mineralizations.

Abstract:Central Baiyin Ore zone is tectonically located in the east part of the North Qinlian Caledonian eugeosyncline, which is a convergent residual arc subducting to the south. The magmatic activities in this region were of frenquent and here develops mainly a suite of submarine spilite-keratophyre formation, which can be divided into 4 volcanic cycles showing the basic-acidic-basic eruptive sequence. The spilite-keratophyre formation in chemcal composition, characteristic index and standard mineral contents similar to that of the other areas in the world, but in these characteritics shows difference from the normal basalt. The spilite showing as a curve with larger slope and higher alkalinity is plotted in the upper part of the Rittmann index diagram, while the keratophyre in this diagram is shown as a curve with smaller slope and lower alkalinity. The data of trace elements, oxide contents and their ratios in various rocks indicate that both spilite and keratophyre primarily may be arc basalt of calcic-alkaline series.The REE data for these rocks all show LREE abundance with no Eu depletion, which is coincident essentially with the normalized pattern.The material sources belong to the syntexis transformation crust.The main oxides, trace elements and the REE geochemical feartures mentioned above indicated that tectoic setting of this region may belong to a trough-convergent arc and active continental margin. Having study the syntexis transformative crust and the K-spilite, we suggested, that the volcanic rocks were driven from a relative deep source and formed in a submarine volcanic arc setting away from the trough.

Abstract:There are no reports before about volcanic rocks in Dahongyu Formation, Changchong System of Ming Tombs area. One layer of tuffite was discovered by tile authors. The tuffite was composed of three different colour beds.The clay mineral is mainly montmorillonite. The pyroclastic minerals include sanidine in thick-plate shape and euhedra zircon with short cone-shaped twin.Obvious welded tuff texture and pseu-flowage structure have been found in tile tuffite, tuffite contains higher K_2O contentTherefore, the authors consider that this layer could be tuffite. Its attitude is consistent with the sedimentary formations of Dahongyu Formation,Hence, the tuffite should be ejected in the time of forming Dahongyu Formation.

Abstract:The rhyolitic magma includes two immiscible melts, of which one is more enriched in SiO2 ana depletea in FeO, By contrary, the other is enriched in Fe0 and depleted in Si02. In the view of the melt structure, the former is enricheh in bridging oxygen, and the later--in free oxygen. The depolymeriza- tion of water may lead to changing the melt structure of rhyolitic magma, i, e. lowering its polymerizing degree. Therfore, the viscosity of water-bearing rhy- olitic magma is lawer than that of basalt magma and thus the flow structure is generally well developed in the rhyolite. So that it should avoide mixing the difference between rhyolites and acidic ignimbrite on research work.

Abstract:Cosmic dusts with black colour, strong magnetism and average grade of 0.206mm (from 0.1 to 0.4 mm) has been first found in the artificial pla- cers from Dajishan granite, The shapes can be divided into three groups; sphere, ellipse sphere and irregular, According to the compositions, two types, iron and silicate spherules, are distinguished, The main minerals are as follows; wustite, magnetite, a-Fe, Cu, albite and K-feldspar. The fabrics are skeleton crystal, brain-pattern, lace-Iike, pearl-string etc, Chromite, SiC and whitneyite also exist in the artificial placers, All these imply that the particles are of cos mic genesis derived from exterrestrial space, We suggest that; (1) the cosmic dus tis products of nonequilibrium crystallization under the condition of low oxy- gen fugacity, high temperature and rapid drop in temperature; ( 2 ) the source of cosmic dust has a strong relation to the genesis of Dajishan granite, the co- smic dust may be the residules of strata from which granitic magma is origi- nated; (3} cosmic dust in granite can be used as an indicator of genesis study of granitic rocks.

Abstract:Metaperidotite occurring at the bottom of the Yaluzanbujiang ophiolite suite has extensively experienced strong deformation. According to main characteristics of plastic deformation in the studied massifs and X-ray fabric analysis, the fabrics of olivine can be classified into three main types: [100], [010] and [001], which all assume the maximum pattern and are respectively parallel to lineation, The development of fabrics closely related to deformation conditions (such as flow stress, temperature and strain rate), deformation mechanism and deformation evolution results from dislocation movement.The fabric transformation of olivine in metaperidotite shows obvious regularity. In general, there is a progressive transition from high temperature [100] fabric to low temperature [010] and [001] fabrics in the process of deformation. The high temperature plastic flow fabrics affect and restrict the development of low temperature ones, and the overprinted deformation is favorable for the formation of [100] preferred orientation and the transformation from [100] fabric to [001] and [010] fabrics.

Abstract:Olivine and enstatite collected from harzburgite at the bottom of ophiolite in eastern Dngqn are rich in Mg (Fo= 91.3- 92.2, ave. 91.9; En= 87.9- 92.4, ave. 90.5). MgO content of both ol and opx is similar to that of most ophiolites in the world, but is higher than that of the abyssal peridotite, indicating that the source materials are likely to be very refractory. The Cr/(Cr+Al) ratios of spinel from harzburgite range from 0.56 to 0.66, which are also higher than those of abyssal peridotite (lower than 0.6), suggesting higher degree of partial melting for harzburgite from Dngqn. In cumulate ultramafic rocks, olivine is absent, whereas orthopyroxene (bronzite) is dominant. Bronzite has higher MgO content in comparison with other types of ophiolite and is associated with both Ca-rich plagioclase and quartz, implying that the primary magma might be boninitic magma rich in SiO2, MgO and poor in TiO2, Na2O as compared with MORB. Experiments show that the associations of both Opx+ Pl and Opx + Cpx + Pl seen to have features of high pressure reaction relative to those of plutonic rocks (cumulate or non-cumulate) beneath mid-oceanic ridge. Mineralogical study suggests that ophiolite and boninite in Dngqn are genetically related to each other. The Dngqn ophiolite represents part of plutonic rocks related to boninite and occurs probably on the bottom of intraoceanic island arc, similar to things in the island arcs of western pacific ocean.

Abstract:The Tongshan skarn type copper deposit in Guichi county has well-developed garnet skarn zone. Garnets in this area can be classified into three types, i. e., andradite, grossularite and andradite-grossularite, of which the last type is most commonly seen. The massive garnets are isotropic, while subhedraleuhedral garnets are anisotropic with well-developed zonal structure. According to the calculation of isomorphic end molecule percentage of garnets, the zoned garnets have three variation types in their molecule components. Studies show that the zonation and nonhomogeneity of garnets are related not only to their isomorphic molecule percentage, but to their formation environment as well.

Abstract:In this paper the characteristics of IR spectra, Raman spectra and EPR spectra of cassiterites from Yunlong are studied and their geological significances are discussed. According to the spectral shape, absorption strength and frequency, the IR spectra of Yunlong cassiterites might be divided into two types, i. e., type A and type B. The spectra of type A have the same characteristics as the spectra of cassiterites from Nb-, Ta-bearing pegmatite type and granite type tin deposits, whereas the spectra of type B are identical with those of cassiterites from hydrothermal tin deposits in features. Combined with macroscopic geological investigations, it is found that the IR spectra of cassiterites formed in oxidic stage belong to type A and those of cassiterites formed in sulfidic stage belong to type B. A study on IR spectra of the cassiterites indicates that these two ore-forming stages are characterized by different metallogenic mechanisms and processes. The metallogenic process of oxide stage and that of sulfide stage are similar to the ore-forming process of magmatic deposits and that of hydrothermal tin deposits respectively. The symmetries of the spectral shape and vibration frequencies of Raman spectra vary considerably with the changes of cassiterites in composition and structure, suggesting the difference in formation condition of cassiterites. In the EPR spectra of Yunlong cassiterites the g factore of V(4+) spectrum are =1.9265, g=1.9184, and the constants of superfine structure are A=38.17 (10(-4)cm(-1))and A=124.88(10(-4)cm(-1)). The researches on stability field of V(4+) show that the Yunlong cassiterites were mainly formed in relatively alkaline and somewhat reducing environment.

Abstract:The physical-mechanical behaviours of Boxian meteorite have been studied by means of varied experimental techniques. The whole stress-strain curve of the meteorite is drawn on a MTS servo-controlled testing machine, and the compressive strength, elastic modulus and Poison's ratio are determined as well by way of uniaxial compression. The attenuation properties of stress wave are also investigated with the aid of the pulse transmission-amplitude ratio method,and this then gives the quality factor. In addition, the elastic wave speed and the density and porosity are obtained by using pulse method and liquid-soaking method respectively.Finally, a special analysis with discussion is given concerning the relationships between experimental results of Boxian meteorite and physical-mechanical behaviours of other meteorites or rocks in the earth. It is rather ready to point out that the surroundings of Boxian meteorite in its parent body is Similar to the environment at the top of the upper mantle. It could therefore be deduced that Boxian meteorite was located some 20km beneath the surface of the parent body before separation.

Abstract:Apatites from syntectic granitoids are characterized by their rather perfect crystallization, relative density(3.103-3.141)，microharchiess(442一461 kg/mm2) and peculiar contents of some elements; Cu 1970-2373 ppm, Pb 292.92-480 PPm, F 25367-38950 ppm, Cl 2917一4798.75 ppm. In contrast, apatites from the transformation granitoids have relative densities 3.142-3.165, microhardness 461-483 kg/mm2, Cu 12.8-23.4 ppm, Pb 260-306 ppm, F 42400-75000 ppm, Cl 95-438 ppm, and relatively rich REE.In addition, apatites from the transformation granitoids have somewhat higher infrared spectroscopic data (1050一1046 cm(-1) than those from the syntectic granitoids(1048一1044 cm(-1)， 602-601 cm-1.The initial 87Sr/86Sr ratio of apatites from syntectic granitoids is 0.70564-0.70566 while that of apatites from the transformation granitoids is 0.72116. From the above discussion, we may reach the conclusion that these two types of granitoids had different source materials and were formed under different physical-chemical conditions, i. e., the magma of the syntectic granitoids came from greater depth while the magma of the transformation granitoids was a kind of remelting magma derived from crustal materials.