Abstract:Niangniangshan alkaline volcanic complex developed in the late stage of Mesozoic volcanic activities in Ningwu volcanic structural depression was special type of rock association, In general, they were characterized by rich-potassium, LREE and other hygromagmaphile elements in geochemistry, This alkaline volcanic complex can be subdivided into two parts, belonging to the products of two sub-cycles of volcanic activities respectively, The lower part of this rock association bears pseudoleucite, characteristic mine- ra.l rich in potassium, and the upper part of this association bears hattyne, characteristic mineral rich in sodium, In this paper, we suggest that they came from a same magma chamber with compositional gradients by means of the petrologic, petrochemistry and trace elements geochemistry study. The crystal fractionation accounts for coming to compositional gradient in the chamber, but thermogravitational effect may play some role during magma differentiation, particularly for the generation of capping layer rich in volatile components, The mass balance calculations quantitatively modeled the crystal fractionation process in the chamber, and confirmed the results observed. That is to say, as a mineral of the lower density, leucite phenocrysts accumulated in the top part of the chamber, whereas those phenocrysts having higher density (such as pyroxene, hatiyne, plagi- oclase) settled downward in the chamber.

Abstract:In this paper ophiolites in the Western Zhungeer are divided into two types: One of them is assemblage of metamorphic peridotite troctolite gabbro (abbreviated to PTG series); another is that of metamorphic peridotite pyroxenite gabbro (abbreviated to PPG series).The former is represented by the Dalabute and Hebukesaier belt; the latter is represented by the Tangbale and Mayileshan belt. The PTG and PPG series follow Al-rich and Ca-rich evolutional trend respectively. Therefore, two types ophiolites are very different in rock associations, mineralogy, rock chemistry, REE geochemistry and types of chromite deposits.Genetic mechanism of metamorphic peridotite in the ophiolites is partial melting of the upper mantle peridotite. Difference between two types ophiolites is dicided by degree of the partial melting. But, the crust rocks (included to accumulating complex, sheeted sill complex and lava) is formed by crystallization of the magma. The different rock associations of pyroxenite gabbro and troctolite gabbro in the accumulating complex are related to depth of formation of magmatic chambers and oxidation state of magma in the spreading ridge.

Abstract:Panxi Rift with the dome-shaped volcano pattern has undergone three evolutionary processes：the lithosphere dome by mantle bulge, the continen- tal crust dome and the subvolca,no-dome, With the dome structure develop- ang, the magmatism gradually evolved from deep-seated matte source, mid- hypabyssal mantle source assimilated and contaminated by the continental crust to super-hypabys}al mantle source mixed with the crust.So we believe that there exist two-times magma chambers of lower, middle and high seats under the Rift during the developmental stage of the Rift with dame-sha- ped volcano pattern, The primary magma rising to the surface from the magma source had suffered stagnation, tra.etional crystallization and assimi- lative五ybridization of the continental crust in chambers at different depths, therefore it might have produced different paragenetic association types of the equilibrium minerals and different trends of the magmatic differentia- tion, Panxi Rift belongs to undeveloped type but with longer evolutionary time. It has a geological history about 200 million years(418-21OMa)，evo- lying from the lithosphere dome by mantle diapir (O-S)-the continental crust dome(D-C)一the continental crust fracture(P)-the subvolcano dome

Abstract:The Presinian spilite-keratophyre series in Xichang-central Yunnan renion is confined mostly to the Dahongshan and Hekou nroups, In regional tectonics it sca- tteredly exposed on the both sides of Anninghe-Yimen deep fracture. The spilite- keratophyre series is closely associated with comcagmatic volcanics or hypabyssal intrusions including albite gabbro-diabase, albitophyre and quartz alhitophyre. The keratophyre represented by alhitc granulite from the jiangyi-Pintan for- mation of Hehou group has a zircon U一Pb age of 1.725Ga, the enigmatic gneiss in the Dibadu formatioan, which is wer-laid by Dalzongshan croup, yields a Rb-Sr age of 1.706Ga, and the remant mirimatic gneiss in Iiangding group, a crystalline ba- sement in this region, gives zirco UL-Pb ages from 2.061 to 2.951Ga Threrfore, Dahongshan and Hehou groups would have age from 1.7 to 2Ga. The spilite-kera- tophyre series is petrochemically similar to those in the other parties of the world,except for having higher Na20 (6-8wt%)，Fe2O3+Fe0 and TiO2 and lower K2O, Mg0 and Ca0 contents, According to the Wrigh1 alkalinity coefficient, the spilite- keratophyre in this region should be belonged to the subalkalic rock series. The presence of remained magmatic flowage structure, felsophyric and spheru- litic textures in the rocks, absence of replacement remnant of intermediate and ba- sic plagioclase in the albite and consitence of composition of Na2O in the rocKS indicate that the spilite-keratophyre in this region is neither metasomatogenic nor metamorphogenic but rather the magmatogenic rock resulted from the crystallization of intermediate-basic magma enriched in Na and H2O, The sampler from the spilite-keratophyre are plotted to the field A in the logτ-lonσ diagram .On the basic of the rocl; associa`ion and some field critera, The spilite-keratophyre should be considered to be an eruptive-sedimentary in a bathyal environment.

Abstract:A data base management system for volcanic rocks based on dBASE Ш has been set up on microcomputer. The system for research of petrochemistry and geochemistry of volcanic rocks consists of six data bases: description of rock, analysis of oxide, REE, trace elements, isotope and minerals. More than two hundreds of information or data are stored in the six bases. The management system can be used to set up the structure of data bases, manage data, provide interfaces for application programs and exit system. The application programs contain those for the calculation of geochemistry and petrochemistry of volcanic rocks,mathematical statistics and for drawing various geochemistry diagrams. Data bases for volcanic rocks, its management system and application programs provide a convenient, practical and efficient tool for the research of geochemisty and petrochemistry of volcanic rocks.

Abstract:Tengchong, one of the largest geothermal areasin China, covers an area of 6000 km2 and is noted for a great number of hot springs, As a result of frequent geothermal activities, all the rocks, mainly late Tertiary arkose and arkosic conglomerate composed of granitic gravels, granites basalts and andesites, have been altered intensely. The hydrothermal altered, mineral assemblages include (1)siliceous minerals, dominantly quartz and opal; (2)sul- fates, mainly alunite; (3)kaolin minerals, chiefly kaolinite with small amoun- is of halloysite and dickite; (4) montmorillonite and chlorite; (5)interstra- tified minerals of illite/montmorillonite (I/M);(6)phosphates such as goyazite and woodhouseite. The species and contents of the principal altered minerals are control- led by properties of the original rocks, Generally speaking, arkose and arkosic conglomerate and granites have been altered into kaolinite, and basalts into illite and smectite together with a little interstratified minerals of I/M, Silicified minerals are often developed in andesites, There occurs. the sequence of argillization from andesite-granites-basalts-arkose and arko- sic conglomerates in which kaolinization is developed widely, Different altered minerals are distributed selectively in different grain diameters. Studies show that kaolinites are enriched in the grain size of <2um, interstratified minerals of I/M in the grain size of glum, and sericites, quartz and opal gathered together in the coarse grains. Studies show that arkose and arkosic conglomerates are responsible for the formation of kaolin minerals in the process of alteration, The kaolin deposit is formed through geothermal alteration of these rocks because they are extensively distributed in the geothermal area.

Abstract:Imogolite is a hydrous aluminium silicate mineral with a fibrous shape and a low degree of crystal structural order. This paper reports the imogolite occurring in kaolin deposits of weathering residual type formed by the weathering of Guoshan granite at Tongan county, Fujian province. The mineral was studied by analytical electron microscopy (AEM) including transmission electron microscopy (TEM),selected area electron diffraction (SAED) and energy dispersive X-ray spectra (EDS).The fibrous shape is the most characteristic property of imogolite. Imogolite appeared in the electron microscope as thread-like or fibrous particles eseveral am long and 60-250 wide, but without well-developed tubular shape.Selected area electron diffraction of threads gives a typical electron diffraction pattern characterized by three diffuse rings at 3.30, 2.10 and 1.40 spacings. These three reflections on the electron diffraction pattern may be assigned the following indices:d2, 04, 06. The repeat distance along the fibrous axis calculated from the 06 reflection is 8.4.Imogolite varies widely in chemical composition and its chemical data are still limited. Energy dispersive X-ray spectra(EDS) analyses show that the imogolite is composed mainly of SiO2, Al2O3 and H2O. Small amounts of K2O and Fe2O3 in the form of impurities are also detected.This is the first discovery of imogolite, a paracrystalline aluminosilicate mineral, in China.

Abstract:Ferrimolybdite hasbeen found in the oxidized zone of the Jinduicheng por- phyry molybdenum deposit, Shaanxi province. The mineral occurs as bundles of fine fibers and encrustations in fissures of weathered rocks and molybdenite- bearing quartz veins, In surface exposures, the mineral is associated with. quartz, limonite, goethite and jarosite; in hand specimen, it occasionally co- retains residue of molybdenite and grades into surrounding limontie, The ferrimolybdite has been studied by such means as physical and optical exa- urination, chemical analysis, X-ray diffraction, Mossbauer spectra, IR spe- ctra, TG and DTA. The formula of the mineral is Fe2(Mo04)3.6.8H20, in which. iron is proved to be all in the form of Fe3+ by Mossbauer spectra, X-ray diffraction patterns of the mineral are comparable with those of syn- thetic ferrimolybdite (Kerr, P.F.et al.，1963) but show more reflection lines than other naturally occurring ferrimolybdite. According to geological environment and related mineral association of ferrimolybdite and conditions for forming synthetic ferrimolybdite as well as Titley 's experimental results, it is considered that formation and stabi- lity of the mineral are probably coatorlled by acid oxidized environment, and the presence of molybdenite and pyrite yields molybdenum and iron neces- sary to the formation of supergene ferrimolybdite. Although ferrimoiybdite fails to form supergene enrichment economic va- lue in this molybdenum deposa, it remains an indicator mineral in search for primary molybdenum deposits.

Abstract:The present paper deals mineralogically with the collophane collected from phosphorites in Dianchi area, Yunnan province in respect to its physical properties, chemical composition and genetic mechanism. On such a basis, it holds that collophane occurs mainly in three forms in phosphorite: gelatinous, intraelastic and bioclastic. SEM studies of all the three types demonstrate that this colloidal mineral is made up primarily of supermicroscopic low-carbonate fluorapatite aggregates, phosphate microframboids, and radiated fibrous apatite.Chemical and infrared analysis, together with the measurement of cell parameters, clearly shows that different types of collophane differ more or less from each other, especially in contents of CO2 and P2O5. A comparison of mineralogic characteristics indicates that, with the advance in diagenesis and metamorphism, collophaae tends to evolve into crystalline fluorapatite and exhibits obvious decarbonization.REE geochemistry of the collophane typifies a high abundance of yttrium group elements, showing a cerium-deficient pattern after chondrite-normalization.All this suggests that the collophane has a close genetic linkage with, among others, a higher fo2 prevailing over the geochemical barrier.

Abstract:The J rock body formed in Caledonian period mainly consist of greyish white medium-coarse grained biotite diorite granite and yellowish red porphyritic biotite granite. Through the study on inclusions, length/ width ratio, grain size, rare earth, uranium and thorium of zircon and other accessory minerals, the authors consider that the original rocks of the J rock body are sedimentary metamorphic rocks.The rich uranium, rich HREE in zircon and the hydrothermal type accessory mineral assemblage of the rock body provide basis for the evaluation of uranium potential in the studied area.

Abstract:This paper discusses the confusion in writing forms of adjectival modifiers for mineralogical nomenclature, especially in Chinese, and analyses the reasons resulting in this situation. Based on the above analyses, the author proposes a unified rule for writiag adjectival modifiers in the mineralogical nomenclature in Chinese.