Abstract:Himalayan granitoids in western Qinghai_Xizang plateau are distributed near the Taaxi-Hongshanhu suture. The rock assemblage is of diopside syenite-diopside granite-biotite (monzonitic) granite type. The rocks consist mainly of K-feldspar, plagioclase, quartz, biotite, diopside and hornblende. Chemical composition is characterized by rich alkali and high content of potassium with high value of K 2O/Na 2O, rich Rb, Sr, Ba, Th, U and LREE. Sr and Nd isotopic composition shows mantle characteristics. All these feature indicate that the rocks are of shoshonitic series.

Abstract:The study and discussion of petrology and geochemistry have revealed that there exists two kinds of A-type granites in Tongbai-Dabie orogenic belt: peralkaline and aluminous granites.The peralkaline A-type granites include alkaline feldspar granite and quartz syenites, characterized by ACNK=0.72~0.97 and NKA=1.02. The aluminous A-type granites also include alkaline feldspar granite and quartz syenites, characterized by SiO2=67.73%~77.60%, rich alkali, Na2O+K2O=7.97%~9.60%, ACNK=0.72~1.03, NKA=0.84~0.97, rich REE,δEu=0.12~0.57 and rich Zr, Nb, Ga and Y. Compared with high fractionated I_type granites, the high Si(SiO2>72%) aluminous A-type granites show rich Fe (FeOT>1.50%),high Zr+Nb+Ce+Y and Ga/Al as well as high zircon saturation temperature (845~880℃).The A-type granites were formed in a post-orogenic environment. It is suggested that Tongbai-Dabie orogenic belt entered the phase of extension and collapse in Late Cretaceous, during which the orogenic movement ended.

Abstract:This paper discusses the merits and shortcomings of the estimation methods previously used for the degree and mass of magma degassing in the volcanic eruption. On the basis of these methods, the authors propose a new petrological method for the estimation performed at various stages in the process of volcanism, and illustrate the detailed steps as exemplified by the Jingpohu Holocene volcanic eruption. This example shows that the degrees of degassing are changeable in the eruption, and that the major volatiles and their released mass cannot be inferred in the light of their relative abundances in glass inclusions. Finally, the possible application of this new method is discussed.

Abstract:Triassic strata with more than 10000 m in thickness are dominated by marine sediments in northern Three-River area of eastern Tibet. Composed of one or two dominant components of clastic, carbonatic and volcanic rocks, the sediments are characterized by abyssal sediments formed by debris flows and turbidities of terrigenous, basinal and volcanic sources, and accumulated in Jomda arc basin and Sinda back_arc basin. The deep-water sediments seem to be the response to active tectonics, and hence are of indicating significance to trace tectonic activity in Three-River area.

Abstract:The drastic lithofacies change of the Dahongyu Formation in less than 4 km within the Ming Tombs District of Beijing is a phenomenon rarely seen both in China and abroad, From east to west, there are Tailing section composed of grey brecciated silicified rock black silty tuffaceous shale yellow feldspar-bearing quartz sandstone, the hill top section consisting of impure sandstone muddy dolostone, and the Deshengkou section comprising muddy dolostone quartz sandstone tuyffite. As the last two sections have been discussed before, this paper deals mainly with the Tailing section. According to macroscopic, microscopic, geochemical, and isotopic geochemical data, the authors hold that the grey brecciated silicified rock and black silty tuffaceous shale were formed under the influence of volcano-seismic event, thus serving as a kind of event message-bearing rock, whereas the overlying yellow feldspar-bearing quartz sandstone was formed in a normal littoral environment. A model for the event message-bearing rocks of the Dahongyu formation is advanced in this paper.

Abstract:The fluid action in the ductile shear zone is a complicated tectonic physochemical process coupled with the mechanic and chemical process, and is also a self-organizing process. It not only affects the deformation mechanism as well as mineral constituents and chemical components of rocks and accelerates the growth and development of deformation structure, but also controls the reactivation, migration, enrichment and precipitation of ore-forming substances of gold deposits hosted in the ductile shear zone. Based on this review, authors indicate that the readjustment of mineralogical and chemical compositions and volume changes are the main research areas of the fluid action in ductile shear zone. The study on the fluid action in ductile shear zone will be carried out in the following aspects: evolution history of tectonicfluid, tectonic physicochemistry, and the strain model and its features.

Abstract:There are abundant dark inclusions in the Neoproterozoic tonalite pluton near Mozitan town, northern Dabie Mountain, which probably contain some information on the early evolution of the crust in this area. Preliminary studies of three inclusions have revealed amphibole facies of the main stage of metamorphism with constituent minerals of feldspars, amphiboles,chlorites and opaque minerals. These inclusions underwent relatively intense mylonitization of post-metamorphism, probably associated with activities of Xiaotian-Mozitan faulted zone. No veins of syn-or post-metamorphism exist within and around the inclusions. Chemical analysis othree inclusion samples shows that major elements are characterized by SiO2content of 49.10% ~53.27%, TiO2of 0.74%~1.32%, Al2O3of 11.80%~15.72%, Na2O of 1.39%~ 3.58%,K2O of 4.32%~6.17%, P2O5of 0.82%~1.02% and REE abundance of 332.85× 10-6~440.23×10-6, with obvious enrichment of LREE and no evident Eu anomaly for right_dipping REE patterns, Their143Nd/144Nd ratios are 0.511790~0.512185,εNd(0) are equal to -8.9~-17.6 and87Sr/86Sr are 0.708732~0.709417. Sm-Nd dating for these samples yields depleted mantle model ages of 1854 Ma, 1899 Ma and 1578 Ma. No evidence of metasomatism in these inclusions can reach the following deductions on the basis of above data: (1) primary protoliths of these inclusions may be alkaline-rich basic magmatic rocks which were probably formed in the extensional tectonic setting within continents, (2) Precambrian bodies much older than the rocks may exist in Dabie Mountain, and Dabie metamorphic complexes were possibly part of the early Precambrian block.

Abstract:Hemimorphite has been found in the oxidized zone of the Lehong Pb-Zn deposit, Yunnan Province. It occurs as veinlet-like or fine_grained botryoidal aggregates in fissures of cave walls within the oxidized ores. The mineral was studied by such means as physical and optical examination, chemical analysis, X_ray powder diffraction, IR spectral analysis, TG and DTA. Microscopic studies give the following optical data:Ng=1.637,Nm=1.618,Np=1.615,(+)2V with optic angle of 45°. Chemical analyses show that the formula of this mineral is Zn3.98(Si2.01Al0.01)2.02O7(OH)2.03·0.88H2O, and X-ray powder diffraction data indicate that its unit cell parameters area=0.8380(4)nm,b=1.0718(7)nm,c=0.5125(6)nm. The mineral assemblage of the oxidized ore mainly includes limonite, goethite, hemimorphite, zinkspath and secondary carbonate. Studies show that most former zinkspaths were altered into zinc bicarbonate [Zn(HCO3)2] and zinc sulfate (ZnSO4) under the strong acid oxidizing-leaching condition, whereas ZnSO4and Zn(HCO3)2were combined with the silica gel in the oxidized zone to form hemimorphite. Therefore, it is considered that the development of hemimorphite depends on strong oxidizing-leaching process in the Pb-Zn deposit, that is to say,the stronger the process, the more favorable the formation of hemimorphite. Hemimorphite is not only the main economic secondary zinc mineral but also an important indicator for the prospecting of primary Pb-Zn deposits.

Abstract:Fluorannite is a new mineral of trioctahedral mica group, belonging to the F_rich analogue of annite. It is present in the fluorannite differentiates at the top of the Suzhou A-type granite located in the western suburb of Suzhou City. It was previously named Li-bearing biotite, an361 nite or F-rich annite-like biotite. Flourannite occurs as enhedral-subhedral tabular-sheet crystals, iron_black in color with a submetallic luster.D(meas.)=3.18 andD(calc.)=3.23 g/cm3. Optical properties under the condition of Na light are: biaxial negative,Ng=Nm= 1.648,Np=1.596, and 2V(meas.)≈0°, 2V(calc.)=0°, Y=b=Nm. The mineral shows strong pleochroism:Ng,Nm andNp are reddish, dark green and pale brown respectively. Chemical constituents (wB%) calculated by means of EPMA, wet analysis and atomic ab- sorption spectrometry are SiO234.12 (32.38~35.98), Al2O313.89 (12.68~14.50), FeOTotal33.26 (32.97~34.88), FeO 26.19, Fe2O37.86, MgO 1.49 (1.24~1.82), MnO 0.68 (0.58~0.92), Li2O 0.47, TiO21.29 (1.08~1.52), ZnO 0.27 (0.14~0.28), NiO 0.01 (0.00~0.04), K2O 8.73 (7.98~9.10), Na2O 0.19 (0.10~0.34), Rb2O 0.42, CaO 0.02 (0.00~0.10), BaO 0.44 (0.00~0.51), SrO 0.01 (0.00~0.07), H2O+0.91, F 3.91 (2.98~4.34), Cl trace, and S 0.00, O=F 1.65, totally 99.25. An empirical chemical formula formulated on the basis of (O+F+OH+Cl+S)=12 and the assumption that the sum of tetrahedral cations equals 4 is (K0.92Na0.03Rb0.02Ba0.01)0.98(Fe2+1.82Fe3+0.49Al0.19Mg0.18 Li0.16Ti0.08Mn0.05Zn0.02)2.99(Al1.17Si2.83)4.00O10(F1.03OH0.50O0.47)2.00, with the simplified formula being KFe2+3AlSi3O10F2. X_ray single-crystal structure analyses with an antomatic four-circle diffractometer shows fluorannite to be monoclinic, space groupC2/m,Z=2; the mineral is a 1M polytype,a=0.5369(8)nm,b=0.9289(3)nm,c=1.0153(8)nm;β=100.49(1)°,andV=0.4980(2) nm3. Crystal structure determination, infrared spectral analysis and M ssbauer spectral analysis of fluorannite were conducted. In fluorannite monomineralic differantiates, the overwhelming majority of fluorannite crystallized directly from a silicate melt that evolved from an A_type granitic magma at the late stage. It had abundant F, Fe and lithophile ore-forming elements, and was relatively enriched in alkalis (K≥Na), but was depleted in water. The new mineral fluorannite and its name were approved for publication by IMA CNMMN 999-048.

Abstract:Interaction between the zincon (zinc reagent) and trace mercury in pH 6.70 buffer solution (the system KH2PO4_NaOH) gives rise to a purplish red complex compound. There is a linear relation between the absorptivity and the Hg2+content at the maximum absorption. The peak of the absorption spectrum isλmax=545 nm, which has a bathochromic shift of about 55 nm relative to zincon (the peak of zincon isλmax=490 nm). The apparent molar absorptivity is 2.8×105L·mol-1·cm-1. The standard curve is in the range of 0.1~25μg·mL-1, obeying the Lamber_Beer law, and the detection limit is 0.01μg·mL-1for Hg2+at same conditions, basic conditions of determination were studied. The reaction is fast, senstive and easy to operate and shows a good reproducibility. It can be applied in the determination of trace mercury in industrial waster water, soil, minerals and organisms.

Abstract:Studies of beryls from Xuebaoding by means of crystal chemistry, optical analysis, EPR and infrared spectroscopy indicate that beryls have high alkali ions and water content. Ferric ions(Fe3+) occupy octaheral sites, whereas ferrous ions(Fe2+), alkali ions and water molecules exist in the channel sites. There are two types of water molecules in the channel structure, namelyⅠtype andⅡtype.Ⅰtype water molecules can probably be further divided into two subtypes(Ⅰ1andⅠ2). The combination of ferrous ions(Fe2+) with water molecules in the channel structure results in hydrated ferrous ions[Fe2+(H2O)]. The green colour of beryls is caused by ferric ions(Fe3+). The thermoluminescence strengths and peak temperatures of beryls can be regarded as the typomorphic characteristics. The deposit is genetically of hypothermal type. Ore-forming solutions have abundant acidulous water and mephitic air.

Abstract:With the purpose of studying the cation distribution in Ni(1-x)ZnxFe2O4spinel, a series of joined ZnFe2O4-NiFe2O4spinels were synthesized by dry reaction of oxides at 1×105Pa and 1400℃in a vertical atmospheric furnace. Some of the spinels were re-equilibrated at the temperatures of 1100℃and 1600℃to show the temperature dependence of the cation distribution.Samples were quenched in H2O or liquid nitrogen. No other minerals or redidual oxides were found after run by examination with optical microscopy and powder X-ray diffraction. The lattice parameters of spinels were measured by means of powder X - ray diffraction As there are not any influence of other minerals on the diffraction peaks of spinels, the precision of most lattice parameters obtained can be determined as±0.008. At the same time,we calculated theoretically the lattice parameters of the same spinels by adjusting the cation distribution in Ni(1-x)ZnxFe2O4spinels. Finally, by comparing the lattice parameters of spinels measured from powder XRD and those obtained from calculation, we obtained the cation distribution of Ni2+, Zn2+and Fe3+in Ni(1-x)ZnxFe2O4spinel at different temperatures. The results show that, at temperatures≤1400℃, the tetrahedral sites in Ni(1-x)ZnxFe2O4spinel are occupied by Zn2+and Fe3+, whereas the octahedral sites by Ni2+and Fe3+. But at temperatures≥1600℃, it seems that the cation distribution of Ni2+, Zn2+and Fe3+in different sites are in random.The site occupancies of Fe3+in a spinel was reexamined by M ssbauer spectroscopy,which gave the result consistent with that obtained by theoretical calculation within acceptable errors (2%).

Abstract:Based on fluid inclusion and oxygen isotope data, this paper holds that high18O ore-forming fluids were formed by mixture of magmatic fluid and evolved seawater. High salinity [w(NaCleq)=5.7%~21.3%] and rich gas indicate the contribution of magmatic fluid to oreforming fluids. Background felsic volcanics at Gacun are extremely enriched in18O compared to isotopically normal felsic rocks (14.2‰~17.5‰vs 6‰~10‰).This has been interpreted in terms oy pervasive and widespread exchange with marine water under the condition of low temperature and a high water/rock ratio, which supports the mineralogical evidence of intense hydrothermal alteration. Wholerockδ18O values of stockwork samples from Gacun orebodies are relatively uniform (10.5‰~13.1‰), showing depletion of18O relative to the other Gacun volcanics less intensely affected by the ore-forming solutions. These relations signify that the ore-forming process postdated the early hydrothermal event that enriched the Gacun volcanics with18O. The presentδ18O values of 10.5‰~13.1‰for the stockwork rocks are therefore believed to have been reached through two successilve stages of hydrothermal alteration: early18O enrichment to values near 16.2‰in the regional,pervasive and low temperature event, followed by18 O loss to around 10.5‰~13.1‰induced by evolved marine water in stockwork vents.