Abstract:The formation conditions of topaz seem to be the key for the understan- ding of the topaz-bearing rock genesis.In order to quantitatively explain. the petrologic role of topaz, the authors used the thermodynamic properties of topaz and coexisting minerals (andalusite, muscovite,K一feldspars, albite, fluorite and quartz) as well as fluid components(H2O, HF, KF and NaF)to calculate the mineral equilibria of related reactions in the granite-H2O-HF system, which are expressed in logaHF-logaKF，logaHF-logaAn, logaHF-T and T-P diagrams. The major results are: 1 .An increase in HF activity of the granite-H2O-HF system is favorable to the formation of topaz. Within a specific range of HF activity, topaz may coexist with alkali-feldspars and muscovite. However, the condition of higher HF activitZr can only stablize the topaz+quartz assemblage. 2 .VVith the falling of temperature, the stability field of topaz is expa- nded relative to the stability fields of andalusite, muscovite, K-feldspar and albite, and the stability field of muscovite is expanded relative to the fields of andalusite and K-feldspar. 3.Fluorination reactions between plagioclase and HF produce the fluo- rite士topaz+quartz assemblage. They buffer the anorthite component activity it plagioclase. The system of higher af or aHF can only stablize albite along with topaz. 4 .Relative to the F-free granite system, the pressure lower limit: of muscovite stability descends and its temperature upper limit ascends in the F-bearing granite system. In the presence of topaz, muscovite as a magmatic mineral can be stable above the solidus of F-bearing granite under the pressures as low as(1-2)×108Pa. The above calculated results can be used to explain the formation condi- tions of topaz-bearing granitic rocks and their extreme differentiates a.nd the formation mechanism of alteration, zones in porphyry Mo, Sn deposits.

Abstract:There exists the thick-bedded formation of Hercynian marine volcanicrocks in southern Hulun Buir League,Inner Mongolia.The basic volcanic rocksof Late Devonian Lower Daminshan Formation(D3x)with a steeply-dippingREE distribution curve are complex of theoleiite and alkaline bsalt,indicating that their formation environment from the middle Devonian to the Early stageof Late Devonian was originally a peroiod of back-are rifting in the continent margin and that they might be products of partial melting of the mantle .Theiron magma debris discovered for the first time in the debris tuff at the top of the formation also supports this conclusion.The basic-acid rocks of Late Devonian Upper Daminshan Formation (D3s)are considered as arc calc-alkaline volcanic series that resulted from the crystallization and differentiation of magma,Their tectonic environment was probably an volcanic arc along the active contiDental margin, similar to things of andes Mountains.The Lower Carboniferous volcanc rocks are of alkaline series that erupted in an intraplate environment. Studies of petroloraery,petrochemistry rare earth elements as well as geote-ctonic environment fail to support the argument that the metallogenic condi-tion is very favorable for the formation of marine volcanics-hosted copperdeposits.

Abstract:The study araa lies between Clipperton and Clarion fault zones in Central Pacific, being in a pelagic environment far away from the continent. In this area, there are well-developed fractural structure and volcanic action as well as strong hydrothermal activity, thus forming a series of minerals related to hydrothermal activity，alteration and depasition, such as apatite, dahllite, REE-bearing apatitc, ;geyazite, barite, witherite, bismutite and spherulitic amorphous silica. This demonstrates that hydrothermal activity is not merely confined to the axial part of the ridge or the rift zone, and that wherever there is large-scale fault movement, there will appear submarine hydrother- mal solutions or thermal springs, accompanied by the formation of a series of minerals related to hydrothermal alteration.

Abstract:Through an analysis of basalts distributed along the Dunhua-Mishan deep faulted zone of Muling-Jixi area and the reconstruction of paloevolcanic mechanism, the present paper Points out that ruby and sapphire are related to mottled alkaline olivine basalts that contain deep ultramafite xenoliths and xenocrysts.The paleovolcanic mechanism controls the distribution of basalts and, furthermore,the disfribution of ruby and sapphire secondary deposits.

Abstract:Magmatic rocks of various periods and types, though different in absolute contents of chemical components, exhibit certaih genetic corrections in their inner structures of data Set.Using variation matrix analysis, subcompo}ition analysis and principal component analysis which all belong to the statistical analytic methods of compositional data, the present paper has studied the affinity of different typca of magmatic rocks formed in Variscaz:, Indosinian and Yanshanian periods in Ganze-Daofu area and, furthermore, dealt tentati- vely with their genetic connections.

Abstract:Green-pyroxenite xenoliths(inciuding green- pyroxene xenocrysts)that occur in the Early paleozoic alkaline mafic-ultramafic subvolcanic lamproph-yric complex within Langao County on the northern margin of Yantze plate might be classified into threo groups according to their potrotocrraphlcal facles and geochemical composition-All the green- pyroxenos in this area are green or pale,green colored,and can be easily distinguished from colorless pyroxenes.According to geochomical characterisics,most green-pyroxenes can be aseigned to Ca-Mg-Fe pyroenes rich in Na,while a fetw might be regarded as aeglrine-augite.Green-pyroxenes in the first group are rich in Mg and Ca but defi-cient in Fe and Na,while those in the second and the third group are rich in Fe and Na but deficient in Mg and Ca. Goochemical characteristics of all groen-pyroxenes change regularly,indicating that all green-pyroxenes crystal-lized from the same magma but at different depths:those in the socond group were formed under higher pressure than those in the first and the third group,Compared with those in the other two groups,the green-pyroxenes in the first group were crystallized at the later stage of the samo magmati evo-lutionary process. A study of the green-pyroxenite xenoliths shows that there existed ano-ther kind of magma-peralkaline basic magma derived from the small degree of partial melting of the metasomatized mantle at the early stage of the conti-nental rifting in Early Paleozoic,An investigation into peralkaline basic ma-gma would reveal more information about the tectonic movement of the conti-nental rift in North Daba Mountain and the evolution of lithosphere in South Qinling Mouptains.

Abstract:During the deformation of plagioclas^, two types of deformation. twin- nino, albit} twinning and periclinc twinning，are produced. Most researchers consider that albitc twirrirg is more readily formed than pericline twin- ring，so the frequency of albite twin is much higher than that of pericline twin. Deformation twinning ds widely developed in Precambrain gneiss of Shizui area, Wutaishan, Shanxi Province. In six of nine samples，the quantity of albite twin is higher than that of pericline twin, the frequency of peric- line being 39%，13%，30%，8%，33% and 12% respectively. The frequency of pericline twin is higher than that of albite twin in the remaining three samples(the frequency of pericline twin being 78%，58%，75% respectively). The deformation temperatures of these 9 samples were determined by defor- mation thermometer of periclirie twinning in plagioclase, being 581℃， 569℃，546℃，514℃，588℃，588℃ respectively for the first six samples，and 672℃，639℃，628℃ for the last three samples.Our work shows that deforma tion temperature plays a key role in controlling the types of deformation twinning. The high temperature favors the formation of pericline twin, while the low temperature the albite twin. According to our data, the temperature boundary is around 600℃.In literature, all samples with high frequency of pericline twin belong to high grade metamorphic rocks of granulito facies or transition zone from amphibolite to granulite facies, suggesting a possible high temperature deformation. This is in accordance with our conclusion. Upon rocks deformed at high temperature are often superimposed low temperature deformation of later stage, which is usually lower than 600℃. Therefore, albite twinning is mainly produced at later stage, and this accounts for the dominance of albite twin in most rock samples.

Abstract:In northern Suizhou, Hubei Province, greenschist-amphibolite facies regi- oral metamorphic rocks were formed in Caledonian period, and thrust nappa structure was developed in Indosinian-Yanshanian period.As a result, there exist different periods of mineralized and nonmineralized quartz veins which might be divided into four phases consisting of seven stages, in which the thrust nappe phase(Ш)is closely related to gold mineralization, which mainly occurs along the crenulation cleavage zones in the middle of the thrust nappe structure, controlled jointly by the crenulation and the listric faults among them. Based on study of quartz by means of electron paramagnetic resonance, thermoluminescent curve and trace element content, the author has systPmati- cally discussed the difference between. quartzs of different phases and attitu- des in relation to gold mineralization, and established prospecting mineralo- gical criteria of quartzs in ore-bearing altered shatter zones as follows: 1 .Quartzs show smooth EPR spectra and Fe3+ line character, with auto- rotation concentration of the Al-O一center higher than 1.3 ×1014 spins/mg; 2. Single peak or double peak often appears in the thermoluminescent curve, and the total integration intensity of thermoluminescence is higher than 0.2; 3. Au and Ag can be detected in most quartzs by azAutron activation. K/Na ratios are generally in the range of 8.33一46.94，with only a few being 1.91.Their ratios, however, are exclusively lower than 1.75.It is therefore Considered that the K/Na ratios larger than. 3 can be used.

Abstract:The present paper deals emphatically with such typomorphic characteristics of native gold from the Jinchangyu and Yuerya gold deposits as the mode of occl1rrence,grain size,shape,fineness,trace elements,and unit cell parameters as well as their significance in the study of ore genesis and prospecting.Systematic comparision and vestigation show that gold ore veins extend beneath the No.7 level of the northern ore belt in the Yuerya gold deposit,that the Yuerya gold deposit was formed in Mesozoic,and that the formation of the Jinchangyu gold deposit was related to ductile shear zone formed earlier than Middle Proterozoic and was rather intensely affected by late geologic activities.

Abstract:According to an analysis of biotite from Guojialing granudiorite in such aspects as its common characteristics, shape, composition, genetic diagram ard Mossbauer spectra, It iS shown That this mineral，rich in Fe, Fe3+，F- and Mg and deficient in OH-，was formed under an unstable. ard oxidized condition. The projections of its chemical composition fall into the diorite recrion, granite regior, as well as rear the granodiorito and adamellite ragion, sugge- stingy that a part of this mineral is primary biotite in granodiorite, and the other part is local remelting relic hiotite in biotite leptynite of Archean Jiaodong Group whos0e gold content is the highest(28.23 x 10-).After its formation, biotite underwent tectonic activity and alteration, forming chlorite and pyrite. All this shows that the formation condition and compositional characteristics of biutite are favorable for gold metallogenesis, i.e.，Guojialing granodioritc is favorable for the formation of gold deposits. Before 1986， people had all thought that the Guojialing granodiorite was unfavorable for gold metallization, and hence drilling and mining were always stopped whe- rever the work reached the Guojialing granodiorite. Nevertheless, our research has shown that this granodioritte body could form ore deposits, even rich ones, as is substantiated by the discovery of the Jiehe gold deposit in this body.

Abstract:A study of orthopyroxene samples from eastern Hebei shows that orthopyroxenes were formed by metamorphism of early and late stages.The variation in chemical cmposition of orthopyroxene is mainly related to conditons of metamorphism and types of coexistent minerals, and also controlled by the composition of the protolith.Geothermometer-geobarometer calculations indicate t=817-937℃，P=0.99-1.11GPa at the early stage metamorphism,and t=747-834.and t=747一834℃，p=0.95GPa at the latestage.