Abstract:The metabasites in the Archean Yishu}i complex of Shandong province wvere dated for the first time by the Sm-Nd whole rock isochron method at 2997 Ma, which confirms the existence of Middle Archean granulite facies supercrust rocks in the Tancheng-Lujiang fault of Central Shandong. The Yishui complex coasists mainly of two-pyroxene plagioclase granulite, two- pyroxene plagioclase gneiss, two-pyroxene itabirite(small amounts)，two-pyro- xene amphibolite and charnockite. They make up the oldest massif in Shan- dong-the Gongdanshan massif, which corresponds approximately to the Jiaadong Group in age but might be somewhat lower in horizon. The Yishui complex has been subjected to high amphibolrte facies to granulate facies metamorphism, and the protolith of metabasites is something like K-depleted tholeiite whose REE patterns are of flat type and LREE-enriched type with εNd(t) being +3.8 ±0.3.The materials came from the depleted (upper) mantle, which is lithologically very similar to some granulate facies rocks in the northern margin of the North. China platform, suggesting the similarity of their provenances in chemical characteristics. Nevertheless, their major REE patterns are somewhat different from each other, indicating the geochemical inhomogeneity of Archean rocks in different areas.

Abstract:Three different series of Carboniferous-Permian volcanic rocks are reco- gnized in southwestern Yunnan of the eastern Tethyan orogenic belt, i. e. plateau tholeiitic, alkaline basaltic and MORB-like rocks. Geochemical studies support fihe understanding that the volcanic rocks are associated with the development of the Changning-Menglian rift basin do the eastern side of the Baoshan-Shan State terrane, and are unlikely to represent rocks produced in ocean floor and oceanic island envi:ronments.It is inferred that, with the thinning of the continental crust and the local emplacement of the oceanic crust, this region experienced progressive rifting. As a result of different de- grees of melting at different depths of the maatle, three different sorts of magma were formed and then evolved into three series of volcanic rocks. The closure of the lift basin was related to the westward subduction of the Lancang- jiang oc^an beneath the Baoshan-Shan State terrane,as is evidenced by the arc volcanic suite of the Lincang-Jiughon gebelt east of the Changning-Menglian belt. The corfvective mantle and the change in convection patterns are pre- sumed to have been responsible for the rifting, spreading of the initial coeanic crust and collision of terrance.

Abstract:Copper-nickel deposits of industrial value have so far been found in eigh- teen rock bodies along seven rock belts of China. According to their rock as- semblages, these nickel-bearing rock bodies might be divided into three types; ultrabasic rocks, norite and komatiite, with most ore deposits occurring in the first type. Metallization shows the character that small rock bodies formed large nickel deposits. The nickel-bearing magma is of komatiite series instead of belonging to tholeiitic series. The ore-forming magma was formed through partial melting of the upper mantle, with the source area characterized by en- richment of U and Th and depletion of Cr. The continental margin with well developed deep faults is the most favorable place for the development of ni- ckel deposits.

Abstract:A suite of basic to intermediate-acid marine volcanic rocks related to copper sulfide mineralization are developed along Shexian-Xiuning belt, which were formerly regarded as diabase veins or dikes. They are distributed in Niuwu Formation of Proterozoic Shangxi Group consisting mainly of slate- phyllite series with complete Bouma sequence and typical features of turbidite. The Sm-Nd isochron dating of volcanic and related rocks appears as an ideal straight line with a correlation coefficient 0.998. The isochron age is 1286 Ma, which seems to be the oldest age ever obtained for this area. These data suggest that the volcanic rocks along Shexian-Xiuning belt could not be products of Late proterozoic back-arc extension. According to varnous aspects of studies carried out in this area, it is held that the geotectonic setting for volcanic rocks of this belt is a Middle Proterozoic island arc. The Sm-Nd model age is not remarkably different from the isochron age. This has led us to consider that volcanic rocks were formed in a very active environment during Proterozoic, probably in an island arc along the margin of the Yangtze paleoplatfoxm. Nd isotopic studies of volcanic rocks show Sm/Nd=0.318, (143Nd/144Nd)1=0.51118 and: εNd(t))=3.9±0.44, implying that the marine volcanic rocks along Shexian-Xiuning belt might have been derived from the depleted mantle.

Abstract:Epidotes are extensively seen in various metamorphic rocks of the Bikou Group, especially in such metabasites as greenschist and blueschist. X(ps) values of epidotes from greenschist are in the range of 0.23--0.37, mostly 0.30-0.32.Epidotes from different samples show considerable compositional variation,whereas those from the same sample are quite similar in composition, indicating that their composition is related. to bulk composition. As for epidotes from blueschist, X(ps)=0.22-0.36, and their composition varies remarkably even.in the same sample. In general, fine-grained epidotes contain relatively low ps while things are just the opposite for coarse--grained ones which commonly exhibit zonal structure characterized by the gradual decrease of ps towards the core, suggesting that the bluescbist might have experienced a pressuree-decline metamorphic process. In addition, a few pumpellyites are occasionally observed in the group; nevertheless, they are all enveloped in epidotes and fail to constitute an independent metamorphic facies.

Abstract:Celestite in western Jiangxi--eastern Hunan area occurs mainly in Lower Permian nodular limestone composed of bioclastic micritic limestone or marl,with a small quantity seen in calc-magnesian shale. Its crystals commonly elongate in prismatic form parallel to a or b axis, and the aggregates are spatially in radiate arrangement and hence look like chrysanthemum in full bloom. Such a crystal habit is rather unique in celestite. The chrvsanthemum-shaped celestite is greyish white, commonly with yellowish or reddish tint; transparent to trenslucent; vitreous luster; fragile;hardness 3-3.5; specific gravity 4.0. Crystals elongate in prismatic form parallel to a or b axis, and aggregates assume radiate form. Under microscope,the mineral is colorless to pale blue, its shape changes from prismatic to parallelogramic or rhombic depending on its orientation in thin section, and its cleavages are well developed. Refractive indexes measured by the immersion method: Ng= 1.630, Np= 1.622. Its X-ray diffraction and infrared data are consistent with the data of standard celestite. Compared with celestite abroad,celestite from this area is purer in compsition and contains lower barium and calcium, which exist in the form of isomorphous substitution. Based on studies, the atrthors consider that the celestite may have been crystallized around the crystallite or the colloidsl SiO2 nucleus in favorable horizons of the carbonate mud during diagenesis. Its crystallization process is similar to the formation of spherulitic siderite: under the redtiction condition of diagenesis, free Sr(2+) combines with SO4(2-)to form dispersed SrSO4 molecules,which, with the intensification of diagenesis, transform into tiny colloidal spots and grow around the nucleus and along the a axis in the form of radiate aggregates that look like chrysanthemum in full bloom.

Abstract:Experimental studies on the absorption of attapulgite and the effect of attapulgite on the mecbanic properties of composites are dealt with in this paper. The results of the experiments indicate that attapulgite has a strong absorption effect on organic matters, especially on those that possess polarityor polarity groups. The absorption of attapulgite is attributed to the electric unsaturation at the surface of the attapulgite crystal and in the channel of zeolitic water resulting from its spscial structure. Attapulgite can be used as the filling material of phenolphthalein poly (ether ether ketone) composites (PEK--C). By pretreating the attapulgite With aldehydes such as butyral-dehyde and benzaldehyde, the interfacial adhesion between the filler and thematrix can be improved, and thus Young'S modulus, tensile strength and elpngation at break of composites can be enhenced. Acetalation with benzal-dehyde gives better filler-matrix bond and enhances the tensile properties of the composites more effectively than acetalation with butyraldehyde.

Abstract:The electron and hole centers in qttartz are of great significance in gold prospecting. The existence of such centers. is attributed to defects in crystals resulting from isomorphism between cations of different valences. The common hole centers in quartz include Al-O-, Ti-O- and Fe-O-, while electron centers comprise Al(3+) + M, Fe(3+) + M, Ti(3+) + M etc. Electron paramagnetic tesonance and thermoluminescence are effective methods for detecting electron and hole centers. In quartz from gold deposits, the Al-O- hole center shows positive cortelation with gold concentration. The number and intensity of peaks of the thermoluminescent cutves are obviously related to stages of gold mineralization:the curve of the early barren quartz shows nearly Symmetric pattern; that of the major stage auriferous quartz is of multimodal type; the curve of the late quartz, low in gold, is marked by unimodal--bimodal type with rather intense luminescence. The thermoluminescence of quartz is connected to certain extent with dis-tribution of orebodies: the bimodal or multimodal curve commonly indicates orebodies, whereas the unimodal curve usually marks country rocks. Vertically,the intensity of thermoluminescence tends to increase with the buried depth of the orebody. The thermoluminescence curve of auriferous quartz is usually of multimo-dal type, with. the principal peaks generally negatively skewed. The barren quartz usually has an asymmetric, gentle and unimodal type curve with weak intensity of luminescence.

Abstract:Based on the determination of physical properties and chemical composition of native gold and pyrite from the newly-discovered Maopai gold depo-sit, the present paper deals with minerageny of native gold and pyrite. Various crystal forms of gold and pyrite could be observed along the vertical section of the orebody, and the formula for morphologic parameters might be used to judge the downward extension and the denudation degree of the orebody and the ore belt. The "Maopai-type" gold deposit has some unique cha-racteristics: ores are rich in gold. and poor in sulfides; pyrite contains high gold (>200 g/t), very low Sb and Hg and no As, and has fairly stable Co/Niratios, somewhat large cell parameter a0 and high infrared absorption peak.

Abstract:Located in Lingshou County, Hebei Province, the Tuling-Shihu gold district lies at the exocontact zone between the Yanshanian granodiorite and metamorphic rocks of the Archean Fuping Group. Sulfur isotope composition of pyrite from gold veins suggests that the ore-forming. solation of gold was consanguineous with the granodiorite magma. Pyrite in gold veins is depleted in sulfur. From gold ore veins to altered wall rocks, Co, Ni, Se, Co/Ni and S/Se of pyrite increase whereas An, Ag, As, and Au/Ag decrease. The contents of these elements in pyrite and related parameters are good indicators for grold grades of ore veins and sampling locations of pyrite and also functions of oreforming temperatures.