Abstract:The Jiangnan ophiolite zone is located in the southeastern margin of the Jiangnan Ancient Continent, which extends more than 200km from Yiyang County of Jiangxi Province to Shexian County of Anhui Province. Our rese- arches confirm that: 1 .The Fuchuan ophiolite massif is well-reservel, consists of harzburgite, cumulus gabbro and spilitic pillow lavas (from bottom to upper). 2. The northeastern Jiangxi basic-ultrabasic complex zone is comparable to the Fuchuan ophiolite. They form the Jiangnan ophiolite zone. This zone stretches along the southeastern margin of the Jiangnan Ancient Continent and is named as the Jiangnan ophiolite zone. 3. The Jiangnan ophiolite zone is developed in slightly metamorphic socks of Proterzioc Era and is inferred to be formed during 950一1400Ma. 4. volcanic rocks of the Jiangnan opiolite zone are a series of spilite- keratophyre, they show a model strongly enriched in LREE which suggests that ophiolite zone may be formed in the initial spreading stage of a back- asc basin. 5. Geochemistry and pertrochemistry of cumulates and volcanic rocks show an obviously inter-compensative and systematic evolution trend. These rocks resulted from the evolution of the same magma chamber.

Abstract:The Shuangxiwu volcanic socks near Xiqiu belong to spilite-keratophyre series, which is chemically rich in Na2O and poor in K20, CaO and contains a lot of albite. Based upon original rock texture, presence of primary albite and evolution patterns of elements, it is shown that the spilite-keratophyre near Xiqiu might be crystalized directly from a kind of spilitic magma. The Xiqiu quartz-diorite is closely associated with the Shuangxiwu volca- nic rocks and intruded into the latter. The age of Xiqiu quartz-diorite given by Rb-Sr isotopes is about 853Ma, initial 87Sr/86Sr in whole rock is about 0.7024. Comparison of major elements, trace elements and isotope compositions, reveals a serial evolutionary trend between the Xiqiu quartz-diorite and Shu- angqiwu spilite-keratophyre. So it is believed that they are comagmatic in origin. The Xiqiu quaitz-diorite, differing from other genetic types in geologic, petrographic and chemical aspects, is surely of mantle-derived granitoid.

Abstract:Morphology, distribution, associated 工ocks, phase relationship, mineral com position as well as texture and structure studies indicate that in the studied region the crustal movement was rather stable and sea water rather deep and quiet in Middle Silurian. The characters of the sedimentary environment are also reflected in such trace elements as U, Zn, V, Mo, Cu, Co, Ni, Mn, Ba, Sr,P and organic substances (carbon and asphaltene) in the silicious limestones. The assemblage of these elements are usually precipitated in a relatively closed, oxygen-lacking reducing environment. The silicious limestones were formed mainly by chemical precipitation under the function of biota.

Abstract:A kind of white clay rock similar to grog matericals is found in Early Carboniferous coal seams in northern Shanxi. here it is called "Burned kaoli- nite clay rock",because it is formed by the metamorphism spontaneous com- bastion of the coal. Studies with microscope and electron microscope, chemical analysis, diffe- rential thermal analysis as well as X-ray diffraction analysis etc., reveal that the clay rock consists of metakaolinite with mullite or kaolinite, locally with epigenetic allophane.

Abstract:Daguzhai and Luobuli granites occur as two small bodies of different genetic types. On the basis of field investigation and the study of petrology, petrochemistry and rare-earth elements as well as characteristics of strontium and oxygen isotopic compositions, it is believed that the Daguzhai granite is formed by the transformation of the upper caustal material through remelting, while the Luobuli monzogranite is generated by mixing of the mantle magma and the crustal materials basd on the data of inclusion thermometry and biotite chemical analysis, their crystallization conditions and emplacement depth are estimated. Besides,the genesis of andalusite and sillimanite in the Daguzhai granite is discussed on the basis of thermodynamic theory and geo- logical occurrence.

Abstract:In this paper, the authors have studied systematically the complex stru- ctures of alkali feldspars of volcaniclastic rocks in the northeast part of iangxi province, mainly through X-ray single crystal analysis (including. precessioi. method, standard orientation oscillation method and Weissenberg: method)，accompanied' by X-ray powder diffraction, electron probe analysis. and complex struotural analysis. Ten kinds of diffraction patterns of single crystals were concluded and discussed (some of which have not been reported yet).With messages got from the study, the authors tried to infer the cooling history of the rocks. The alkali feldspars which have .side band diffraction and two phases (sodic and potassic phases) that are coherent were measured in order to determine the period of modulation (lamellar spacing) and the direction of exsolution. The structure of sanidine in one of the areas was also determined.

Abstract:119Sn and 57Fe Mossbauer spectra of franckeite from D;ichang, Guangxi province, have been studied at zoom temperature. The relevant Mossbauer pa- rameters are given. The measured 119Sn spectrum shows that all the tin ions in the sample are Sn0' (no Sn2+ in it).The Sn spectrum consists of two com- ponent spectra, which were assignedto Sn4+ in pseudotetralronal (T layer) and pseudohexagonal (H layer) structures of the mineral, respectively. Both the coordination numbers are six. The Sn4+ in T layer occupies the octahedral site with greater distortion, and thus has a greater QS value. The Sn'*-—S bond has greater ionicity and less covalency.The 57Fe spectrum shows that all the iron ions in the sample are Fe2+ (no Fe3+ in it).The 57Fe spectrum also consists of two component spectra, which were assigned to high-spin Fe2+ (with stranger ionicity) in T layer and low-spin Fe2+ (with stronger cova- lency) in H layer, respectively. The site populations of the Sn4+ and Fe2+ were obtained from percent areas of the component spectra. The positive and ne- gative valency charges in the chemical formula of the sample are 27.99 and 28.02, respectively, which leach a equilibrium of charges. Based on the results of single crystal X-say diffraction, Mossbauer and chemical analyses of this sample, the crystal chemical formula of Dachang franckeite can be written as 〔(Pb0.732Sb3+0.086Sn4+0.083Fe2+0.078Ag0.021) 1.000S]·0.366(Sn4+0.459Sb3+0.440Fe2+0.10)1.000S2]. It is proved that excess opposite electric charges connect the T layer with the H layer.

Abstract:From more than three hundred experiments we have confirmed that the physicochemical conditions of formation of globular uraninite are variable in a wide range and put forward a new mechanism of itsl formation. U308 is not a transition product during the synthesis of gobular uraninite. When pyrite reduces UO2+2 to form globular uraninite, the valence state of Fe and U has a synchronous relationship both in growth and in decline. Hematite and glob- ular uraninite are two products of different stages in process of evolution, and the former precipitates-earlier than the latter. The globular thorium-bearing uraninite crystallises out within the range of 150-200℃·Thorium is substitu- ted in the form of isomorphism for U0* in crystal lattice. The thorium content of globular thorium-bearing uraninite increases with the strengthening of reducing field.

Abstract:This paper reports the oxygen isotope data of metamorphic minerals. in the Chencai Group and the determination of their metamorphic temperatures using these data. Two rock samples were collected from the Dingjiawu .strata profile in the Chencai Group, Zhuji: Pure quartz, magnetite and garnet were separated from the samples. The BrPs technique was used in extracting oxygen from these minerals. Oxygen reacted with graphite to generate CO2, and then the oxygen isotope ratio was measured on ME1T-250 model mass spectrometer. The Δ18O values of two quarts-magnetite pairs calculated in the samples were, yielding temperatures of 554 and 573℃，respectively, which is geologically rea- sonable. In contrast, the temperature calculated from quartz-garnet pair was high anomaly of 623℃，indicating that oxygen isotopes are not in equilibrium between two minerals. Thus, the average temperature of 565士10℃，calcula ted from two quartz-magnetite pairs, is selected as metamorphic temperature of rocks in the Chencai strata. Oxygen isotope thermometry, therefore, is one of the available techniques for the determination of temperatures of metamorphic rocks.

Abstract:Based on a study of the X-ray optics of the monochromator, of Guinier- type focusing camera, the important role of this kind of camera in improving the resolving power for X-ray diffraction patterns is analysed. It is considered that the improvement in resolution was resulted from the following considera- tions;(1)the monochromator is made to reflect only the a1-component of the Ka doublet;(2)the efficient radius is much increased and the spectral line widths are much reduced by using of the focusing camera; and( 3)the effect of combination of Ka doublet污due to the arrangement of the moncchromator corresponding to the focusing camera in the form of the(+，一)model, based on the conception of double crystal diffraction. Experiments showed that Guinier focusing monochromator camera is chasa- cterized by high sensitivity and resolution and more accurate d-values, thus greatly promoting the "indexability" of a Guinier pattern. By comparing the techniques of Debye-Scherer camera and diffractometer, the advantages of the monochromator technique is emphasized, and some experimental methods for obtaining d spacings of high precision are proposed.

Abstract:Igneous rocks have been divided into three major petrogenetic series: the subalkaline, the alkaline and the strongly alkaline series. A newe method of distinguishing them is proposed in the paper, based on the analysis of pro- perties of major rock-forming oxides. Among oxides comprising igneous sock, SiO2 is an acid oxide, K2O and Na2O are strongly alkaline oxides, Mg0 and Ca0 are mildly alkaline oxides. During fractional crystallization, SiO2 first combines with Mg0 and Ca0 to form forsterite, diopside and enstatite etc. and the seperatian of these mine- rals doesn't change the alkalinity of the magma considerablely. It is discove- red that in the diopside and enstatite SiO2 wt% are approximately equal to (CaO+ 1.5Mg0) wt%.Hence, the relative proportion of (SiO2-Ca0-1.5Mg0) wt% with alkali in rocks can be used to determine the alkalinity of rock series. Boundaries amomg suballLaline series, alkaline series and ;strongly alkaline series are presented in the (SiO2-CaO-Mg0) wt%o υs. (K20 +1.5Na20) wt% diagram based on 263 groups of sock composition data from recent text books. The new method is more accurate in comparision with the SiO2-alkali dia- gram given by Miyashiro and by MacDonald and Katsura, especially for the rocks containing very high or very low silica.