Abstract:Many of the porphyry, porphyry-skarn and other hydrothermal ore deposits in Ch na are characterized by the"multi-type". They form deposit series regionally and deposit systems locally. With emphasis on universal significance of the multiple minerogenetie models, this paper points out that the multiplieity of the source rocks, emplacement and mineralization of the granitic magma is one of the important geneses of the complex and various mineral deposits. Thus, it is essential to study emphatically on the multiple minerogenetic models to developing the mineralization theories and extending the train of thoughts of the exploration.

Abstract:This paper presents the phase relationships in the biotite gneiss-H20 system by melting experiment at 0.1-0.2 Gpa pressures. The solidus temperatures are 762℃ at 0.1 Gpa and 712℃ at 0.2 Gpa. The biotite-out temperatures are 787℃ at 0.1 Gpa and 737℃ at 0.2 Gpa, while the Quartz-out temperatures are 837℃ at 0.1 Gpa and 787℃ at 0.2 Gpa. Using Burnham model (1979), the estimated H2O-solubility of the biotite gneiss welt at liquidus temperature is 3.8% at 0.1 Gpa and 5.8% at 0.2 Gpa, Based on the results of the melting experiment and the. paleogeotherm of the early Precambrian continental crust in ea3tern Hebei Province, the widespread migmatization of the early Precambrian amphibolite facies rocks in the region may result mainly from the partial melting of the crustal rocks (biotite gneiss). The experiment results and the present geother in this region suggest that the crustal low-velocity layer may result from the presence of interstitial hydrous fluids rather than the partial melting.

Abstract:The Pl-lherzolite is located between the harzburgite and cumulates in the Hongguleleng ophiolite and parallel to the mylonitized zone at the top of the harzburgite.The Pl-lherzolite differs from the cumulates in having blastic texture and high-temperature deformed fabric of Ng[100] characteristic of the mantle peridotite and yielding orthopyroxene. In respect of mineralogy and petrology as well as strontium isotope, the Pl-lherzolite exhibits some features of transition from the cumulates to the mantle peridotite.The appearance of new-born minerals(clinopyroxene and plagioclase) in the Pl-lherzolite provides an evidence for the penetration of basic melt. The mylonitized zone may be a passage for the basic melt derived from the bottom of the magma chamber, which has penetrated into the harzburgite.From the above, the authors conclude that the Pl-lherzolite is the product of the reequilibrium between the depleted harzburgite and the basic melt.

Abstract:The Proterozoic Mayuan group is well developed in Northern Fujian province. 7 samples of epi-meso metamorphic rocks from the Mayuan gronp and 2 samples of muscovite granites were taken to be measured by Sm-Nd and Iib-Sr radioactive isotopic method, The Sm-Nd isotopic isochron age of whole rock for 7 samples is 2116±22(2σ)Ma, INd=0.51027+2(2σ)，εNd (t)=7.29+0.17. Ab-Sr isotopic isochron age of whole rock for 6 samples is 375+28(2σ)Ma, 87Sr/86Sr(i)= 0.703+3(2σ); The age of 2116Ma, the earliest age of strata in Fujian and Jiangxi provinces, represents a formation age of the Mayuan group and the age of 375Ma 一一metamorphic age of the Mayuan group. From the data of εNd (t) and 87Sr/86Sr (i), it may be postulated that original rocks of the Mayuan group in Northern Fujian province had been mostly formed through volcanism.

Abstract:There is a large-scale alkali-rich intrusive rock zone, with an NNE striking in linear distribution, in the coastal area of east Zhejiang. It is composed of alkali-feldspar granites and alkaline granites. The alkali-rich intrusive rocks are characterized by Si-high (SiO2>76%), alkali-rich(Na2O K2O>8.2%), Al-low (Al2O3<12.5%), Ca-and Mg-poor (CaO<0.4%,MgO<0.20%) and concentrations of Rb, Th(U),Nb (Ta), Zr, Zn,Ga, etc. The chondrite-normalized REE patterns exhibit a gently right-dipping V-type curve with a severe depletion in Eu. The characters arc essentially identical with those of alkaline granite in Kuiqi, Fujian and similar to those of the A-type granite in the achlan folded zone of southeast Australia. The, above studies indicate that the alkali-rich granite zone was formed as a result of the magmatic evolution at the late stage of the Yanshanian movement, controlled by a regional deep fracture, that is to say, its formation may be attributed to the upward intrusion of deep-source alkali-rich magma during the tension of the deep fracture on active continental margin.

Abstract:Creedite and gearksutite,two rare minerals of hydrous aluminium and calcium fluorides in the world, have been found in the Xikuangshan antimony deposit, Hunan province. They were form ed in late hydrothermal stage, and their mineralo- gical characteristics,such as crystal form, chemical composition, X-ray powder diffraction data, unit cell parameters,differential thermal curves and infrared absorption spectra, have been studied. Mineralogical study of creedite sho ws that its crystals are euhedral grains 1- 10μ in diameter, its chemical composition is close to the theoretical value, its calculated crystallochemical formula is Ca3 Al2..043 F8.162 (OH)1.947(S04)1.011 2.204 H2o,quite similar to its ideal one, its unit cell parameters are ao=14.123A，bo=8.510A，Co=9,950A，β=94º54´,and V0=1187. 063A3 and its X-ray powder diffraction data,differential thermal curve and infrared absorption spectra are basically similar to those of other specimens fcund abroad. Mineralogical study of gearksutite shows that its crystals are euhedral platy and flaky grains 2-5μ in diameter, its chemical composition and crystallochemical formula, CaAl1.032 F4.038 (OH)1.033·1.100 H20, CaAl1.017 F3.977 (OH)1.074·1.092 H2O, are closer to theoretical value and ideal formula than those of known ones, and its X-ray powder diffraction data and differential thermal curve are also basically similar to those of specimens found in other areas. The infrared absorption spectra of gearksutite have been obtained for the first time by determining specimens from Xikuangshan.

Abstract:The chrysotile asbestos deposits in ultramafic rocks of Northwest China ean be divided into three types, i.e.,Mangya type, Xiaobabao type and transition type. A number of chrysotile asbestos samples from different mineral deposits were studied by means of scanning electron microscopy and high-resolution transmission electron microscopy. As a result, the authors have obtained high-quality mierographsandlattice images for these samples. A contrastive study of the characteristics of electron micromorphology and lattice images of chrysotile asbestos fibers from different types of ore deposits shows that the asbestos fibers of Mangya type and Xiaobabao type differ rather obviously from each other in such aspects as cleanliness of fiber face, diameter of inner tube or [thickness of tube wall, filling state of inner tube and associated minerals among fibers, flexibility, properties of lattice images, and structural defects. The asbestos fibers from Northwest China might be divided into soft type and hard and stiff type. The fibers of Mangya are different from those of Xiaobabao in physical properties and uses. The tectonic Setting, fiber-forming temperatare, stability of minerogenic geochemical process and media are basic factors affecting the growth of fibers and the crystallochemical characteristics of chrysotile asbestos, and this accounts for the differences mentioned above.

Abstract:Grandidierite, a rare mineral with ideal chemical formula (Mg, Fe)AI3SiBO9 was discovered in 1987 in Jixi County, Heilongjiang Province. X-ray diffraction analysis and transmission electron microscopic study (TEM)of the mierostructure of grandidierite show that this mineral belongs to orthorhombic system with the unit cell parameters a=10.318(2)A, b=10.981(1A), c=5.753(1)A and the space group Pbnm. Microstructural analysis of the complex (high-order) twins is very complicated, Formerly, much study was devoted to simple high-order twins existent in metal materials and minerals, with less attention paid to the study of the complex (high-order) twins in the low symmetrical minerals. When studying the microstucture of grandidierite by means of TEM in our laboratory, we discovered for the first time complex (high-order) twins in the mineral and obtained the selected area electron diffraction (SAED) and the electron micrograph of the high-order twin. The SAED and the bright field image of TEM have been used jointly to determine the complex (high-order) twins in grandidierite, i.e., (202) growth twin, (280) (202) sec3ndary order twin, (041)(280)(202) third order twin, and (443) fourth order twin. The structural relationship between the complex (high-order) twins in the mineral has been illustrated, and the analytical method for the microstruetures of the minerals with low symmetry and complex (high-order) twins has been summarized. Experimental results show that there are splits of electron diffraction spots in four directions, i.e., along [202], [280]T, [041](TF), [443], suggesting that there are plane defects on the crystallographic planes (202), (280)T, (041)(TF), (443) in the mineral. The discovery and study of the microstruetural characteristics of the low symmetrical and complex (high-order) twins in borate mineral have furnished new data to modern mineralogy.

Abstract:Zn-tennantite is a rare mineral discovered in a skarn lead-zinc deposit in Inner Mongolia. The associated minerals include chaleopyrite, sphalerite and galena. Zn-tennantite occurs as xenomorphic granular aggregates 0.2-0.5mm in diameter. It is lead grey in color, H_(VRN)=339-388 kg/mm2. Under microscope reflection color is greyish blue with a faint greenish tint.Electron microprobe analysis gives S 25.94, As 10.70, Cu 39.67, Zn 7.36, Sb 9.81, Bi 5.81,Ag 0.18 and Fe 0.37. The calculated chemical formula is (Cu(10.02) Ag(0.03))(10.05) (Zn(1.81)Fe(0.11))(1.92)(As(2.29)Sb(1.29)Bi(0.45))(4.03)S(13), quite similar to the ideal formula (Cu, Ag)(10) (Zn, Fe)2 (Sb, As)4S(13). The x-ray powder pattern of Zn-Tennantite is identical with that of tetrahedrite. Unit cell parameter a0=10.322(). The strongest lines in the powder diffraction pattern are 2.98(A), 1.82(A)and 1.56(A).It is smaller than tetrahedrite.

Abstract:sulfur isotope analysis was made for various types of gypsum.anhydrite and polyhalite from four drill holes in this reconnaissance area.This pager descrihes δ34S characteristics of veinlike anhydrite，anhydrite and hydrated anhydrite, suggesting that gypsum was mainly formed by the hydration of anhydrite under the action of underground water. The microscopic observations of poly halite, its texture and structure and its sulfur isotopic composition all paint to the existence of "primary" polyhalite and the extensive develop ment of secondary polyhalite(replace ment type). Sulfur isotope studies of anhydrite fro m various sections of Triassic in this area indicate that δ34S values of T1j4-T2l1 are comaratively stable (between 29-31%)，implying a shallow-water and salinized sedimentary environment. After T2l2,δ34S values tended to decrease progressively. Such evolutionary regularity is consistent with things in other areas of Sichuan basing suggesting a transgression-regression salt-forming environment It is thus concluded that δ34S values and charcteristics of anhydrite may serve as indicators to divide strata,especially strataof evaporates. This result has added to and enriched the knowledge sulfur isotope composition and evolution of marine Triassic sulfates in the world.