Abstract:Geological and geochemical characteristics of the Early Ordovician volcanic rocks from North Qilian Mountain show that they are of the basalt-andesite association with no acid rocks or volcanic rocks of the shoshonite series. Their geochemical features indicate that they are of the calc-alkaline series characterized by enrichment of LREE and LILE and depletion of HFSE. They were formed in an island-arc environment of moderate maturity, and the volcanic rocks present in Dongshuixia area might have been formed in an intra-arc rift.

Abstract:According to types and associations as well as chemical composition of Mesozoic volcanic and intrusive rocks the authors have divided the Mesozoic continental margin in southeastern China into three tectonomagmatic belts: the continental margin volcanic(magmatic)arc (Cva)，the continental margin back-arc and interarc basin belt(Abv0 and the rifting volcanic (magmatic) belt(Rv)，with a thorough study of their Sr, O, Pb and Sm, Nd isotopic compositions. These characteristics show that the three belts have both similarities and differences: Cva has relatively low initial 87Sr/86Sr ratios(commonly < 0.7100)and δ180 values(mostly <10%)，remarkable variation in Pb isotopic composition relatively high εNd values(averagely -5 .3) and slightly lower fA values(crustal component);Abv has comparatively high initial 87Sr/86Sr ratios(mostly 0.7100 0.7140)and ε18O values(7%一14%0)and fairly stable Pb isotopic composition relatively low eVd values(averagely -6.3)and slightly higher fA values (averagely 0.596);Rv has relatively and quite stable initial 87Sr/86Sr ratios(averagely 0.7071)and considerable variation in δ180 values(5%0一11 .5 %0)，rather low 206Pb/204Pb and 207Pb/204Pb values，and notable variation in εNd values(-17. 5 - +2.9 , averaely -3.3)，with fA and fP values(componems of the mantle)being close to each other. As mentioned above, these isotopic compositions indicate that the mama of Cva and Abv was derived from a mixture of the depleted mantle and the upper crust in the continental margins, the former being mainly mantle source and the latter being mainly crust source and that the mama of Rv was formed by a mixed source of epicontinental or intracontinental replacement-depleted mantle and lower crust materials.

Abstract:Massive dolostones of the Ordovician Majia}ou Group can be grouped into fine saccharoidal dolostones and coarse saccharoidal dolostones. An analysis of inclusions offers the most direct information for the study of origin of the massive dolostones. Inclusions are poorly developed in the host dolomites of fine asccharoidal dolostones} but are well developed in pore-filling calcite crystals. The homogenization temperatures of these inclusions(24 samples) range from 49℃ to 74℃，and the maximum depth of inclusion formation calculated from such temperatures is 172m. It can thus be inferred that the host dolomites of fine saccharoidal dolostones must have been formed in shallow burial environments with the depth of less than 172m. Inclusions are well developed in the host dolomites of coarse saccharoidal dolostones. Analytical data of Raman Spectra show that these inclusions are commonly methane-bearing ones,suggesting that they must have been formed in deep burial environments. The lowest homogenization temperature of these inclusions is 104℃ (with no pressure correction).and the least depth for inclusion formation corresponding with such a temperature is about 2600m. It is hence believed that the coarse saccharoidal dolostones must have been formed in deep burial environments with hot water dolomitization.

Abstract:The research on fluid-rock interaction has broken through the rather static solid earth philosophy. Researches in such aspects as the open system, nonequilibrium and kinetics constitute the frontiers of geosciences, with the fluids within the earth's interior as the target. Oxygen isotope exchange reactions in the minerals-fluid system fall imo 5 kinetic models: closed, “closed", unidirectional open fluid-buffered and rock-buffered systems. 18O/16O exchange mechanisms are chiefly diffusion-control and surface-control. The latter is generally accompanied by strong mineralogical alteration, whereas the former lacks such alteration. The granitefluid systems chiefly include the epizonal system, the mesozonal and/or long-lived system as well as the homogenized equilibrium system. The 18O/16O exchange reaction between granite and fluid is mostly ascribed to the open system nonequilibrium type. The essence of syntectonic fluid-rock interaction lies in the coupling of deformation with fluid chemical reactions. Mechanisms of fluid circulation and mass transport comprise mainly advection or infiltration diffusion and composite advection-diffusion.

Abstract:In Ahhui Province there are three granitoid intrusions namely Hongihen, Guandian and Chuxian, distributed on the northern bank of the Yangtie River. Various petrochemical parameters show that they are of I一type. Nevertheless, their Vd, Sr and Pb isotopic ratios are all relatively low(∈tNd = -13. 5一-15. 5, ItSr=0.7058-0.7065, 206 Pb/204pb=16. 50-16 .99，207pb/204pb=15.29-15.37)，suggesting that they are anatectic granitoids derived from Archean granulites in the lower crust. This granite type has not been included in known genetic classifications of granitoids.

Abstract:Franckeite(Pb5Sn3;Sb2S14)is a kind of complex layered sulfide. The structure can be viewed as an alternate stacking of two false tetragonal symmetric t sheets(galena PbS sheets) and one false hexagonal symmetric h sheet(berndtite SnS2 sheet)along[100].Two kinds of sheets are packed in order of htthtt……along a axis. Because the unit cell of t sheets cannot correspond with the unit cell of h sheet and the missed matching between t sheets and h sheets the incommensurate-sinusoidal modulation waves have formed along c axis. Using type CSTMM一9000 Scanning Tunneling Microscopy, the authors observed the cleavage face {100}of franckeite and obtained excellent distinct atomic resolution STM image.The lattice parameters AB=0.366nm, AD=0.620nm indicated h sheet atomic arrangement of the cleavage face. The modulation sinusoidal waves of 4.7nm along caxis and a superstructure long period of 6. 98nm along b axis were also observed.Meanwhile the microtopographic character of franckeite was investigated with STM.

Abstract:The western Tianshan high-pressure low-temperature metamorphic belt in Xinjiang, extending west-east for about 200 km along the Paleozoic suture between the Yili-Central Tianshan and Tarim plates, is mainly composed of garnet, amphibole, omphacite, phengite,paragonite, epidote, chlorite, albite, quartz,sphene, ruble etc. Garnets comprise predominantly almandine componem(Alm45-72)and，next, grossular(GrO9-36)，pyrOpe( Py2-24)and spessartine( Spe0-27).The garnet porphyroblasts contain zoisite, paragonite, albite, sodic amphibole, omphacite and quartz inclusions and are retrograded to chlotites along the margin. Amphibole might be classified imo three types, namely sodic amphibole(glaucophane,ferro-glaucophane, crossite, riebeckite, magnesio-riebeckite)，sodic-calc maphibole(barroisite and win- chite) and talc amphibole(actinolite).The sodic amphiboles assume coarse-,medium-,fine-grained and fibrous assemblages, with the majority being fine-grained(0.1-0.5 mm)in size. A few sodic amphiboles are slightly retrograded to chlorites or actinolites.The jadeite content of omphacites in eclogues is between 39.38% and 54.14% averagly 45.48%.The cation number of Si of phengites changs from 3.31 to 3.57，averaging 3.41.The ration number of Na of paragonites changes from 0. 64 to 0. 90, 0. 85 on the average. The conditions of peak eclogue facies metamorphism are estimated to be 520士80℃and 1 .2-1 .4 GPa. The metamorphic mineral assemblages reveal that the high P/T belt has underdone a metamorphic evolution process from lawsonite-blueschist facies through eclogite facies and epidote-blueschist facies to greenschist facies.

Abstract:Ferruginous minerals in polymetallic nodules from the East Pacific basin were studied by means of transmission electron microscope (TEM). Nine species of ferruginous minerals were identified in the nodules, namely ferocyhyte, akagancite, goethite, ferrihydrite, hematite, magnetite, maghemite, chromite and the hisingerite-like mineral. Both feroxyhyte and vernadite assume curled fibrous aggregates under TEM. It is considered that part of Fe3 converted nonbiologically from Fe2 in the ooze is trapped and then precipitates as feroxyhyte with vernadite during the deposition of Mn4. Goethite is too small to be recognized even under TEM. It was for the first time that ferrihydrite was discovered in oceanic nodules. The fact that the electron diffraction pattern of ferrihydrite contains the electron diffraction of goethite suggests the reciprocity between them. Hisingerite-like mineral which mainly consists of Si and Fe has been discovered both in polymetallic nodules and in sediments. This mineral was previously considered to be a mixture of ferruginous minerals and silicates. As samples of this mineral from various places are similar to hisingerite in structure, TEM morphological features and chemical composition, the authors believe that it is an independent mineral instead of a mixture, and hence temporarily name it hisingerite-like mineral.

Abstract:The Bitian ore deposit is a silver-dormnant large-、iie copper-gold-silver deposit related to Late Yanshanian subvolcanic rocks. Species of metallic deposits are quite complicated: Besides commonly-seen pyrite ,chalcopyrite and bornite, there exist varied copper-bismuth sulfosalt minerals(sandber}erite, Bi-tennantite, Bi-tetrahedrite, aikinite, wittichenite)，tungsten-tin sulfides(mawsonite, kiddcreekite)and polymetallic sulfides. In addition to argentite, gold-silver minerals mainly include native gold, electrum, kiistelite and native silver of goldsilver series. These minerals were formed at bornite-chalcopyrite-pyrite Stacey gold-silver polymetallic sulfide stage and native silver-quartz stage respectively under differem physicochemical conditions. Most chalcopyrite, bornite, copper-bismuth sulfosalt minerals and tungsten-tin sulfides were formed under the conditions of medium-high temperature (260-380 ℃)，relatively high sulfur fugacity(1gfs2=-8.74一-12.06)，high salinity of fluids and boiling, whereas polymetallic sulfides and gold-silver minerals were formed under the conditions of medium-low temperature(120-260 ℃)，comparatively low sulfur fugacity(lgffs2= -11 .6一-19.5)and also relatively low salinity of fluids. The discovery of varied types of copper-bismuth sulfosalt minerals indicates a certain defree of bismuth enrichment in the Bitian silver-dominant large-siie copper-gold-silver deposit. Therefore, importance should be attached to the study of the mode of ocurrence of bismuch.

Abstract:This paper has dealt with chemical composition trace elements characteristic parameters and crystallochemical structure of biotite in Yangxi granite body. Biotite in Yangxi granite body is 1 M polytype ferruginous biotite. Chemical composition of all biotite samples from Yangxi granite body is similar to each other with the exception of No. 16-12 sample, which has more Al, Mn and less Si，Ti.Special chemical features of biotite from Yangxi granite body are consistent with features of biotite from South China granites.KAl(KAl=Al/Si+Al+Fe+Mg)values range between 0.19 and 0.23，averaging 0 .2112; K/Na ratios range generally between 10.5 and 19. 6, averaging 19.5470 ; MF(MF=K+ +Na + /Ca+ Mg) values range generally between 0.70 and 0.96，averaging 0.9014 ; m(m=Mg/ Mg+∑Fe+Mn)values are generally between 0.364 and 0.389， averaging 0. 3509. Tetrahedral ions of biotite from Yangxi granite are Si4+ and A13+，whereas Fe2+ and Mg2+ are the major octahedral ions. Interlayer ions are K+，Na+ and Ca2+.The average b0 value is 9.238A.The average c0 value is 10.035A. Characteristics of biotite from Yangxi granite show that the granite is of crystal transforrnation type probably mixed with small amounts of mantle materials. The No. 16一12 sample collected near a Nb, Ta mineralised spot has more Al, Mn and less Si，Ti，with m value being 0.2037，which is much lower than the average m value. Its KAl value is 0.272， which is considerablyhigher than the average KAl value. Its MF value is 1.4769,which is also remarkbly higher than the average MF value. Samples taken near the scheelite ore deposit show little difference from those taken far away from the scheelite ore deposit. Their biotite only has a bit higher Ti content and slightly lower K and Va content， suggesting that the constituents of the granite body have little to do with the scheelite deposit.