Abstract:Erkeshan, Wudalianchi and keluo volcanic groups distribute in a single te- ctonic belt. From Neogene to Holocene, they erupted continuously, Volcanic rocks belong to a seriese of ultrabasic--intermidiate, alkaline--peralkaline potassium-rich rocks. In present paper they are named as picrite-leucitite, oli- vine-leucite basalt and leucitebasalt. The rocks in three volcanic groups are very similar in petrology and geochemistry, that shows their close relationship them. But they are different from Cenozoic volcanic rocks of other areas in northeastern China by high abundance of K2O,AIk and Poor CaO, and characteri- zed by much rich incompalible elements and LREE, the primary magma also has relatively high content of mantle compatible elements(such as Cr, Ni). Consequently, they belong to potassinm-rich type which are ready found in the world。 Based on the petrology, geochemistry and calculation, we suggest that the picrite-leucitite and olivine-leucite basalt were solidified by primitive magma which derived from phlogopite-bearing lherzolite mantle by partial melting, the degree of partial melting is respectively 3.5% and 4.3%about. Leucite basalt was solidified by secondary magma, which was produced by fractional crystallization of a small amount(14%)of accumulative rock from primitive magma and assimilation of granite(28%)。

Abstract:Thirty-seven new K-Ar ages are reported for minerals from some veintype tungsten deposits and for igneous rocks in south China. The intrusion ages range from 183.1 Ma to 99.5 Ma(except one of 715.6 Ma), most of them about 150 Ma with isochron age of 132.1 Ma, placing them in early Jurassic to Cretaceous in age. The ages of the intrusions associated with tungsten mineralization are getting younger from the central part to the margines in the South China tungsten province. The mineralizations associated with these intrusions, dated by vein-mica, occurred so closely in time with the various intrusions, it cannot be meaningfully separated by K-At dating, although in most cases appears to be slightly younger. Mineralization is essentially penecontemporaneous with intrusion. As a result of that the initial (40)Ar/(36)Ar ratio of intrusions is much higher than that ratio of present atmospheric argon, so it is suggested that there was excess of radiogenic argon in existence during the intrusions were formed.

Abstract:The Kuan Ping Group is a sequence of the sedimentary-volcanic series of the early-middle Proterozoic, which hadbeen suffered multiple deformation and metamorphism. It consists of the greenschist with magno-siliceous marble and sericite quartzschist in the lower part of the Kuan Ping Group. In the middle, it is composed of the mica-quartz schist with magno-siliceous marble and amphibolite. The biotite marble and amphibolite occur in the upper. By recovering the primary rock they belong to the volcanic siliceous (Mg-rich carbonatite)-basic volcanic subformation, volcano-flyschoid subformation and flyschoid-earbonatite subformation, respectively.The Kuan Ping Group is distributed along the southern margin of North China Platform as a narrow belt, extended approximately 4 km from east to west and the total thinkness is more than 8 Km. It is possessed of the common feutures of the eugeosyncline sediment. According to the primary rock formation, it is believed that is not with the typical character of the ophiolite and is not also the product of the oceanic spreading ridge. The composition of the basic volcanic rock is similar to the K-poor tholeiite of the transition region between the coean and continent, and their tectonic enviroment is similar to that of the continent margin basin.

Abstract:The widely distributed Archaean rocks of Wulashan Group in the area mainly belong to granulite facies. The rocks of Wulashan Group consist of granulite,granulitite and amphibole-plagioclase-gneiss in lower unit.The rocks of middle unit are composed of biotite-amphibole-plagioclase-gneiss, interca- lated with granulite, amphibolite and magnetite-quartzite. The rocks of upper unit consist of biotite ( or amphibole)-plagioclase-gneiss, quartzite, cordierite- bearing-sillimanite-garnet-K-feldspar-gneiss and marble intercalated with ma- gnetite-quartzite. Energy dispersive X-ray spectrometer and wet, chemical analysis were carried out on orthopyroxene, clinopyroxene, garnet, amphibole, biotite and plagioclase from the rocks. It appeared that chemical equilibrium was approximated. Metamorphic crystallization temperatures,obtained by the Wood-Banno, Nehru-Wyllie and Lindslay-Dixen two-pyroxene geothermome- ter method fall in the range 768-857`G.Metamorphic temperatures obtained by the Perchuk's amphibole-orthopyroxene, biotite-clinopyroxene geothermo- meters diagrams range from 700-835 C.Metamorphic temperatures by Saxe- nays garnet-biotite geothermometer diagram range from 770-820℃ with a mean of 795℃. Pressure calculated by Wood garnet-orthopyroxene geobaro- meter method is 9.9×108Pa. Pressure calculated by Newton-Perkins and Wells garnet-orthopyroxene-plagioclase geobarometer methods range from 8.3 to 10.1 with a mean of 9.2 × 108Pa. *Institute of Geology, Academia Sinica.

Abstract:The disposal of the nuclear waste has become urgent. Its purpose is to isolate the wastes from hnmanbeing. The most liable method now is the geological disposal, that is, to explore a closed and security natural burrier. For this reason, the study of the rocks is very important. Different countries has selected different rocks. No matter what kind of rocks to choose, each utilizes certain characteristics of the rocks. Amony those rocks, the halite, clay and granite are most commonly selected.

Abstract:The pseudomorphic octahedral chlorite and serpentine in chromitite of western Ali, Tibet were previously discussed by the authors (1983). Recently, they have found pseudomorphic octahedral diopside, tremolite, and chlorite in serpentinized harzburgite of the same area. The Ca-rich and Al-poor characteristics of octahedral diopside suggest a metasomatic reaction under the condition of lowering temperature and pressure. This is consistent with the characters of cell parameters of octahedral diopside. The Si-rich and Al-poor features of octahedral chlorite are similar to conditions of octahedral diopside, but are completely different from the chemical characters of hypabyssal hydrothermal chlorite. The octahedral diopside is also obviously distinct from diopside of hypabyssal altered ultramafite in chemical composition. The chemical fratures of these two octahedral silicates may be attributed to hydrothermal metasomatism during the early stage uplifting and emplacement of the mantle rock. The reactions of ringwoodite-octahedral diopside-octahedral tremolite and ringwoodite-octahedral serpentine-octahedral chlorite are dealt with in this paper.

Abstract:A famous precious gem found in China and called tianhuang has been investigated by such means as X-ray diffraction, infrared spectroscopy, differential thermal analysis and electron microscopy. The results indicate that this mineral is a rare sort of nacrite and can be grouped into three kinds according to gemmology:1. Tianhuang gel: having nacrite as main composition, occasionally with a small amount of illite.2. Tianhuang stone., a mixture of nacrite and dickite in varying proportions.3. Gold coated with silver: golden-yellow nacrite wrapped in dickite which is pure white in colour and transparent to semitransparent.This type of gem is very rarely seen in the world and is only found in Bantian gravel bed in Shoushan, Fujian province. It is so valuable that its price is three times as high as that of gold. The indicators for primary tianhuang ore are also discussed in this paper.

Abstract:The kaolin deposits in Suzhou consist mainly of kaolinite, 7 halloysite and 10 halloysite, with less sericite and montmorillonite and varying amounts of alunite, gibbsite and phosphate minerals in company. On the whole, kaolinite and 7 halloysite are dominant in the upper part of the orebody and 10 halloysite in the middle and lower parts.Montmorillonite, gibbsite and secondary leaching type alunite are frequently seen near the bottom, together with localized phosphate minerals. The chemical compositions of kaolin minerals are approximately equal to theoretical values and SiO2/Al2O3 ratio of the major ore is close to 2.These mineral associations are products of different geological processes in different periods. After their formation, the kaolin minerals are only in temporary equilibrium with the surrounding environment and are thus in a relatively stable structural state. With the variation in surrounding geochemical environment, these minerals will change their stable structures gradually into unstable structures to reach new equilibrium. The conversion mainly includes (1)the transformation of halloysite into kaolinite, (2)the formation of secondary leaching type 10 halloysite, (3)the mutual conversion between halloysite and gibbsite and (4)the formation of Ca-montmorillonite. Based on the above discussion, the author has established a formation and evolution sequence for kaolin deposits and dealt tentatively with the relationship between the mineral evolution and the transformation of orebodies.

Abstract:Eleven pyrite samples from a certain gold-silver ore deposit in Zhejiang province have been examined to find out the relationship between such isomorphous impurities in pyrite as Co,Ni, As, Sb and the 57Fe Mossbauer parameters at 298 ºK. As a result, the following conclusions have been reached. (1)The relationship between the electric quadrupole splitting (QS) of pyrite and its arsenic content obtained by means of linear regression of six pyrite samples with available quantitative arsenic analyses is QSpr=0.612+ 0,00925As(at%).Antimony impurity has a similar but a bit smaller effect on the QS of pyrite. (2)The linear equation for the relationship between the QS of pyrite and its cobalt content obtained from the QS and Co contents of pyrite as well as synthesized Co0.25Fe0.75S2 and Co0.99 Fe0.01 S2 is QSpy-co=0.608一 0,0087Co (at%).Nickel impurity has a similar but somewhat larger effect on the QS of pyrite, (3)The QS of pyrite depends on the atomic percentage ratio of its impurities(As+Sb)/(Co+Ni)，i, e.，the QS value increases with the growing ratio. (9)As the contents of impurities in pyrite are related to formation condition, the QS of pyrite might find application in such aspects of ore research as the genesis of ore deposits, the division of ore-forming stages, the metallogenic zoning and the mineral assemblages, and therefore can surely play its role in the prospecting, evaluation and exploration of ore deposits,

Abstract:Regularity of elliptical polarized motion by turning the stage of an ore microscope is investigated, and variation in outer rectangle of the ellitical pola- riled light is analysed. Formulae for motion track of major axis of the ellipse are obtained in the case of phase-difference being 0º，90º and 180ºrespectively. Motion track of the major axis of an ellipse is drawn in the range of phase difference from 0º to 45º，and rotation angle of the stage corresponding to the largest apparent angle of rotation (Ar) is analysed.

Abstract:The iron meteorite in Longche township is adout 36cm in length, 24cm in width and 20cm in thickness, with a weight of 97.5 kg. Its surface color is brown while its fresh fracture is gray-silver-colored. A lot of rounded melt cavities are found in the outer crust of this meteorite, together with clear melt crust and break-up faces. The melt crust is composed of microcrystalline magnetites. Using such means as electron microscope, electron probe, spectrum analysis, X-ray Mossbauer spectrum and chemical analysis, the authors have succeeded in identifying the minerals in the iron meteorite, which are mainly kamacite, taenite and plessite with less schreibersite and magnetite.In addi- lion, some fairly perfect crystallites can be seen under the scanning electron microscope. The chemical composition of the iron meteorite is; Fe 90.21%，Ni 7.78%， Co 0.43%，P 0.0131% and S 0.0255%(98.4586% total). Kamacite is tabular in form and is interIayered with taenite, forming the Widmanstatten structure. The thickness of the kamacite plate is 1.2一1,5mm, suggesting that this iron meteorite is of a medium-coarse-grained octahedral type .It experienced shock metamorphism during its flying in the space, which caused the meteoritic minerals to have apparent Neumann Lines. The zero-valence state of iron in the iron meteorite indicates that it was formed under a strong reduction condition.