Abstract:The Middle Ordovician submarine spilite-alkaline volcanic rock association in the Sbihuigou area in the Northern Qilian mountains was the product of island arc volcanism. Based on the studies of petrology, mineralogy, geocherr.istry of trace elements, magmatic inclusions in minerals and Sr isotope, the nature of the“ source" magma series of the spilite-alkaline volcanic rock association is determined and the equ- ence of the island arc volcanism is established in this paper. At first erupted a small amount of tholeiitic magma which was produced by the partial melting of the mantle wedge above subduction zone, then a lot of talc-alkaline magma. At the end of Middle Ordovician, the shoshonitic magma formed by a high pressure (1 GPa) fractional crystallization of calc-alkaline asalt magma in Moho-level charuber erupted, and resulted in the formation of shosho- nite lock association,Shoshonitic rocks in the Shihuigou area are stratigraphically highest and consist mainly of trachybasalt, leucite-tephrite, leucite-analcitite and leucite-trachyte porphyry. The development of the shoshonite rock association suggests that the palaeo-island arc system of the Northern Qilian mountains had reached to the rziature stage at the end of Middle Ordovician,

Abstract:The eclogites in Shandong and Jiangsu provinces can be classified into three types according to their occurrences in the field. Type I occurs in serpentinites as blocks or lenses; type II conformably in gneisses or schists as lenses or layers; and type III as lense in marble.Detailed studies on the field occurrences, petrolo- gy, minerrology of the eclogites have shown that type I may be a mantle-derived eclogite, its equilibrium P,T being 570℃,16×108Pa and has undergone another metamorphic event at 525℃and pressure greater than 11× 108Pa; types II and III are the metemorphic products of basalts under the condition of regional high pressure metamorphism,and their P-T paths of crystallization gradually change from 620-640℃,14—15×108Pa to 560℃,13.8×108Pa and from 670-690℃,14—24×108Pa to 745-755℃,15—22×108Pa respectively. The various eclogites formed at similar P,T forming mechanism may be different. classified into three prom ncescan . as blocks or lenses;typeand type III as Tense in marble. Detailed in gneisses or schists as lenses or ntinites layers; studies 0n the field occurrences，petrolo- gy, minerology of the eclogite,its equilibrium eclogites have shown that type I may be a mantle-derived P,T being 5700C， pressure metamorphism, and their from 620-640，14-15 x lOsPa basalts 16 x108Pa and has undergone another under the condition of regional high P-T paths of to 560， x lOBPa 13 crystallization gradually change .8x10gPa and from 670-690℃， 14-24 x 108Pa to 745-755.i5-23 formed at similar P and T, but their respectively. The various eclogitea P,T forming mechanism may be different.

Abstract:The Xinzhou-Hetai area is a chief gold belt in Guangdong, where there are the famous Hetai and Xinzhou gold deposits as well as some prospective gold occurrences of different types. There was no immediate geochronologic information on gold mineralizations before our work and their ages were determined only by inference based on geological data. We have got isotopic ages of the sericites (and muscovites)associated with gold in the main gold deposits and occurrences using 40Ar/39Ar method. All the samples were irradiated in the core of the fact- lily H4 of 49-2 reactor. Incremental heating experiments were performed on a mass spectrometer MM-1200. The standard biotite ZBH-25 was used as‘ flux monitor'. When J-value is corrected for the position of the sample in the reacter,the rela- five Variance can be about士 l%. According to the dating values obtained,there are four stages of gold minera- lization;esrly Jurassic (184-171Ma)，late Jurassic (141士6Ma)，early Cretaceous (132士2Ma)and late Cretaceous (99士1 Ma).

Abstract:The exposed area of the Panzhihua basic intrusion is about 38 kmz，I9km long and 2km wide. The layered structure in the intrusion is well developed. The intrusion body has K-Ar and U-Pb age of 306-320Ma and it can be divided into 4 zones from bottom to top. The main rocks of zone I are fine-grained olivine- gabbro, titanomagnetite rock and coarse-grained pegmatitic gabbro； those of zone II include titanomagnetite-gabbro and gabbro; the main rock of zone III are gabbro and anorthosite and zone MY is composed of amphibole gabbro. Samples that were studied by oxygen isotope analysis are from zones I-IV. The whole rock δ180 values for 6 samples are+6.27-+s6。91%，and for the other 2 samples- +8. 99- +9.19%，for 20 of 23 titanomagnetite samples δ18O values range from +0.55 to+3.46%, and for the other 3 samples - from +4.11 to +4.86%;for 12 of 21 plagioclase samples from +6.18 to +7.60%，and for the other 9 samples- +8.12 to +11.99%.One ilmenite sample has a δ180 value of +4. 56%.According to the oxygen isotope determination results it is suggested that the primary magma of the Panzhihua intrusion probably originated from the upper mantle. The ⊿δ18o values of the oxygen isotope fractionation between coexisting pla- gioclase and titanomagnetite for zone I are 5.03-9.46 and the oxygen isotope equilibrium temperature ranges from 455 to 730.For zones II, III, and IV the ⊿δ180 values of oxygen isotope fractionation are 2.87-3.94, 4.93-5.85, and 3. 87-6.19, respectively. While their oxygen isotope equilibrium temperatures are 871º-1045℃，650º-740℃and 621º-871℃，respectively.

Abstract:T his paper makes a historical review of the classification of igneous rock series, and points out ho w the modern idea of igneous rock series is developed as well as their difference in meaning in the past and at present, in order to clear up a misunderstanding as to the division of igneous rock series. In the first half of the twentieth century, the aubalkalic and talc-alkalic series were synonymously used. However, the aubalkalic rock series is not equivalent to the talc-alkalic series in the modern concept. The misunderstanding about the classification of igneous rock series in Chinese literature may be owing to little knowledge about the change in their meanings in the history.

Abstract:Decorated disiocations in olivine from the upper mantle xenoliths have been examined with a scanning electron microscope (SEM) using a backscattered electron image (BEI). Experimental results indicate that dislocation patterns and grain boundaries are a clear bright image and easily observable. The resolution of this method for dislocation observation is about an order of magnitude better than that of optical microscopic observation. The method of dislocation using a backscattered electron image is especially useful in the study of high dislocation density and dense dislocation boundary in naturally and experimentally deformed olivine and in the determination of quantitative parameters of microstructures.

Abstract:In recent years, the authors have found sixteen sorts of arsenate minerals in South China, which include dehaoite (?), copper silicarsenate (?), clinoclasite, olivenite, cornwallite, cornuhite, conichalcite, adamite, duftite, hayldonite, mimetesite, carminite, dussertite, scorodite, Ba-bearing pharmacosiderite and heudanite. The physical properties, optical constants, chemical composition, X-ray data, infrared absorption spectra and differential thermal analyses of the minerals are given in this paper, which serve as a sheet of fairly perfect data for arsenate minerals in China. Finally, the paper makes a preliminary discussion on the formation conditions of arsenate minerals.

Abstract:Metacinnabar and tiemannite are e.nd members of HgS-HgSe series, In meta- cinnabar, selenium is often seen in place of sulfur, and zinc in place of mercury;in tiemannite, sulfur is frequently in place of selenium. Like minerals in many isomorphous series, these two minerals are quite similar to each other and show regular variation in physical-optical properties, X-ray diffraction patterns and infrared absorption spectra. Metacinnabar, which is associated with such sulfides as cinnabar and sphale- rite, was formed in a sulfides-rich environment at fairly low temperature (190- 220'C). Tiemannite is associated only with quartz without such sulfides as sphalerite and cinnabar; it w as therefore for med in a sulfides-poor environ went at a bit higher to mperature (230-265'C).

Abstract:Pugou bauxite is a small-sized ore deposit, in which boehmite was discovered for the first time. With the help of polarizing microscope, XRD, 1R and SEM, the author has made a detailed study on the mineralogical properties of boeh mite. Boehmite, γ-A100H, belongs to orthorhombic system. α=β=γ=90º，a0=3.690A， bo=12.162A，co=2. 866A.The crystals are mainly blades and rhombohedral in shape, colorless or yellowish in color,and 0.5μ to 4μ in size. The XRD analyses demonstrate that the charaos}eistic lines of boehmite are d020=1.848, d22o=1.769 and do8o=1.529, The IR analyses show that the characteristic frequency bands are 3300cm-l， 3078em-1, 793cin-1and 364cm-1. Based on indoor studies and field investigation, the author puts forward a preliminary opinion concerning the origin of boeh mite. It is considered that boehmite was formed mainly in two ways during the supergene process: mainly through the direct crystallization of the Si-Al gel and secondarily from the desi- lication of kaolinite.

Abstract:The present paper deals with the 0--A1 center and E center in quartz, which can be used to deduce indirectly the major ore-forming stage according to the variation in the EPR spectra of quartz with the formation temperature of quartz veins. Calculated result using the data of EPR spectra of quartz indicates that the intensities of O--Al center show a positive correlation with the corresponding Gold content of quartz veins with a correlation coefficient γ=0.61 (a=0.O1). The intensities of O--Al center of the quartz veins from 4 drill holes have similar variation patterns to those of corresponding gold contents. The positive correlation of the O--Al center of quartz with the gold content can be regarded as an indicator of ore-potential in ore prognosis and prospecting.

Abstract:The birefringence indicatrix of crystal deduced by the author is a new kind of optical indieatrix indicating the birefringence of a crystal. In this paper, the equation of the birefringcnce indicatrix is given and, on the basis of this equation, the properties of the birefringence indicatrixs of all crystals with different optical properties are discussed.

Abstract:The Baiyun Obo ore deposit in Inner Mongolia of North China is the largest REE ore deposit ever discovered in the world,whose geology gas already been described by Bai Ge et al. The six ore sanapiles from the main orebody were isotopically analysed and an isochron age of 1.64±0.38(2σ) Ga has been obtai- ned,with the initial 143Nd/144Nd ratio (INd)being 0.51088±12(2σ),corres- ponding to eNd(t)=+6.1±2.4.The age is interpreted as the time of the empla- cement of the Nb-REE-Fe ore deposit.The positive eNd(t) value (+6.1) shows that the REE of theore deposit was derived from the depleted mantle sources. The result seems to wxclude any possibility of the mixing of sigificant crustal materials during the ore deposition.

Abstract:Based on analyses of detrital minerals from the Quaternary sediments in the Salawusu River area, the authors discuss the change in climatic environment of that area since the last stage of the Middle Pleistocene. It is pointed out thai(1) during the development of loessial palaeosoil and the deposition of aeolian sand, the climatic environments were warm-humid and dry-cold respectively; (2)the fluviolacustrine facies of Salawusu formation and the aeolian sand of Chengchun Formation of the late Pleistocene are products of warm-humid and dry-cold climatic conditions respectively, in which the lake-swamp facies of Middle Chengchun Formation was formed under cool and humid climatic condition, and(3)during the deposition of the lake swamp facies of Dagouwan Formation and the fluviolacustrine facies,black soil and secondary loess of Dishaogouwan Formation(all belonging to Holccene period), the climate was relatively warm-humid,and during the deposition of medern Maowusu sandy desert,the climate turned dry-cold again.

Abstract:A new type of X-ray powder diffractometric specimen holder made of quartz crystal plate parallel to (11.21) is recommended in this paper. A comparison of this new specimen holder with the holders available indicates that for this holder, instead of having a wide diffraction halo which is shown in the diffractometric curve of glass slide or diffraction peaks produced by specimen holder themselves which are present for unglazed ceramic tile or silver membranaceous filter, there is only an extremely low and smooth background in its diffractometric curve. It is andoubted that this new single-crystal non-diffracted specimen holder invented by the author would be helpful to the improvement of accuracy on determining diffraction patterns in the X-ray diffractometric powder technique.