Abstract:The Putuoshan pluton is a typical multi-stage I-A composite granitic complex in the coastal area of southeastern China. Zircon U_Pb dating demonstrates that it consists mainly of three stage magmatic intrusions, which are from early to late quartz diorite porphyry (≈170 Ma), biotite moyite (≈110 Ma), and miarolitic moyite (≈90 Ma). Among them, the biotite moyite, which oftencontains abundant meladioritic enclaves, forms the main body of this pluton. This paper is mainly devoted to the study of the biotite moyites (host rocks) and the meladioritic enclaves. Geochemically, the host granites are characterized by high silica and alkali contents, and show metaluminous to weakly peraluminous attribute. They are also enriched in LILE (e. g., Rb and Th) and LREE, with LREE/HREE ratios ranging from 8.58 to 13.83, and depleted in Sr, Ba, P and Ti, etc. In the chondrite-normalized REE patterns, they display moderately to strong negative europium anomalies (δEu=0.29～0.43). Integrated geochemical data suggest that the host rocks are highly fractionated I-type granites. The variation of major and trace element abundances between the host granites and the meladiorite enclaves shows the evolutionary tendency of magmatic mixing. The host granites and the meladiorite also have similar Nd isotopic compositions, with εNd(t) values being -6.30～-6.60 and -6.95～-7.12 respectively, which are all indicative of mixing of crustal and mantle materials. Based on a comprehensive analysis of their tectonic settings as well as geological and geochemical data, the authors hold that the meladiorite enclaves in the Putuoshan pluton were generated by mixing of mantle-derived basic magma and its induced crustal felsic magma in a tensile environment.

Abstract:Qitianling granites are located in southern Hunan. Recent geological survey shows that there exists a superlarge tin polymetallic deposit there. The contents of major, minor, and rare earth elements of Qitianling granites were analyzed by ICP-AES and ICP-MS. The contents of major elements indicate that these granites are of metaluminous type characterized by rich Si, Al and alkali and poor Mg and Fe, suggesting that they might have experienced remarkable crystal differentiation. The contents of rare earth elements (REE) are rather high, being 199.28×10-6～448.34×10-6 (307.03×10-6on average) and characterized by rich light REE and poor heavy REE. In addition, these granites are obviously rich in large lithophile elements, especially rich in Rb and Th, but poor in Ba, Nb, Ta, Sr, P, Eu and Ti, implying that the source of the granites might have derived from crust rocks. Based on a comparison between Qitianling granites and Qianlishan granites, this paper points out that granites in these two places have similar geochemical features. Furthermore, the genesis, age and mineralization of Qitianling granites are discussed. The formation of superlarge Sn-polymetallic deposits might have caused by the ascending of the mantle which resulted in the remelting of crustal materials together with hydro-thermal activity under the Jurassic extensional setting, which led to the enrichment of metal elements.

Abstract:Alkaline intrusive rocks in Mesozoic-Cenozoic Lanping red bed basin of Yunnan Province were studied with the Ar-Ar isotope dating method. The results show that the Zhuopan alkaline intrusive complex in Yongping and the Lianhuashan alkaline beschtauite in Weishan have Ar-Ar plateau ages of 36.70 Ma and 38.81 Ma, respectively. Tectonic evolution of Lanping basin, controlled by closure of Palaeo-Tethys and collisional orogen between India plate and Asia continent, has undergone three evolutional stages, i.e., intracontinental rift, sag basin and strike-slip basin. The Himalayan basin at the strike-slip stage can be divided into four tectonic phases. The intrusion of alkaline complex is the first tectonic phase. Alkaline intrusive rocks in Lanping basin make up part of alkaline_enriched intrusive belt along the NW_striking Jinshajiang-Honghe fractured zone in the eastern margin of Qinghai-Tibet plateau. During the tectonic evolution of Jinshajiang-Honghe fractured zone from transitional compressional-shear deformation (42～24 Ma) and transitional extensional-shear deformation (24～16 Ma)to EW-striking extensional processes (＜16 Ma), alkaline rocks in Lanping basin were developed in the transitional compressional-shear deformation phase. The intrusion of alkaline complex and the tectonic evolutionin Himalayan period are controlled predominantly by mantle uplifting and partial melting generated by remnants of westward subducted Palaeo_Tethyan Yangtze block.

Abstract:The recognition of this kind of strontianiferous aragonite is important in the study of isomorphism and inner structure of aragonite. Its discovery and study are of great significance in the application and exploitation of the mineral. By such means as infrared spectrometer, Raman spectrometer, visible spectrophotometer and SEM, this paper has analyzed characteristics of the spectra, texture, color-causing mechanism, distribution of Sr2+, Ca2+ ,Cu2+ and layering of the mineral. The infrared absorption and Raman frequency of v1, v2, v3, v4 of CO2-3 are found just between aragonite and strontianite, which is attributed to substitution. Meanwhile, there is a splitting peak v4 of CO2-3 in the infrared spectra. EMPA reveals that CuO content is 0.00%～0.39% in blue strontianiferous aragonitebut very rare in white strontianiferous aragonite. It is found that the color mechanism of blue strontianiferous aragonite has something to do with Cu2+ .Surface scanning shows that Sr2+ and Ca2+are distributed along the zonal texture while Cu2+ is in random distribution. In addition，SEM shows that strontianiferous aragonite displays different microstructures and morphologic features. The changes in microelement contents, temperature and pressure cause the formation of different color zonal textures.

Abstract:Sanukite is a type of black vitreous Mg-rich volcanic rocks first recognized in the northern part of Shikoku in Japan. It occurs mainly in the Miocene (11～14 Ma) Setouchi volcanic belt, and is typically high in Mg number (Mg/Mg+Fe2+>0.6), SiO2 (andesitic to dacitic), Cr and Ni contents and K/Na ratios (0.33～0.52). The Setouchi sanukite is located in fore_ or back-arc basins, and originated in subduction of the young and hot Philippine Sea plate and pull-apart of the Shikoku basin. Shirey and Hanson (1984) first used ‘sanukitoid' to name some Archaean intrusive and extrusive rocks with the above geochemical characteristics. Geochemically, sanukite resembles adakite except for somewhat higher Mg, Cr and Ni contents, indicating that it can be produced directly from a mantle source through partial melting, whereas adakite is merely produced by partial melting of a basaltic source. Sanukite is widespread in Archaean, indicating a higher geotherm of the mantle wedge or the subducting plate. The early sanukite has only been found in Late Archaean (<3.0 Ga), probably indicating that the modern style plate tectonics was initiated at that time and that plate subduction came to be an important geological process only after 3.0 Ga.

Abstract:This paper presents an overview of the fundamentals, techniques, influencing factors, and applications of the apatite (U-Th)/He dating method. (U-Th)/He dating of apatite is a newly developed low-temperature thermochronometry and has been gradually applied to different geological aspects, such as dating, tectonics, geological thermal history and paleotopography. The closure temperature of the apatite (U-Th)/He age is only about 75℃, which is lower than that of any other known technique, suggesting that apatite He age provides some information on the final stages of cooling. By combining apatite (U-Th)/He with other methods such as feldspar multidomain thermochronometry and fission track technique, more detailed and robust cooling histories may be obtained. Compared with other techniques, the attractions of the apatite He method lie in sensitivity to previously inaccessible temperature ranges, high precision and less sample mass. Although this technique remains at the developing stage, it may after all beaccepted as a quite effective method for the low-temperature thermochronology. It is noted that this field is growing rapidly, and what is presented in this paper is likely to be superseded in the coming years.

Abstract:The geopolymer gel, which can be linked with other minerals in geopolymer, is the source of material strength. In this experiment, geopolymer gel was prepared by the aluminosilicate sol obtained after the extraction of potassium from slate with the addition of NaOH at 60℃. XRD, SEM, IR and NMR wereused to investigate the structure of the gel at different solidification time spans. The result shows that there is no new crystal phase produced during the formation of the gel, implying that the gel is amorphous. It is also shown that with the change of the solidification time, the［SiO4］4- tetrahedron of the gel depolymerizes at first and polymerizes afterwards. The gel forms a compact mass after polymerization.

Abstract:With the development of nanometer science and technology, some specific characteristics of nanometer substances have been revealed, which, however, are attributed to their crystal structures and crystal chemistry characteristics. To detect specific characteristics of the nano-talc, we must base our study on the crystal structure and crystal chemistry theory, and then give some theoretical foundation to the determination of optimum talc particle dimension. According to the cell parameters and the atomic arrangement of talc, the authors put forward the minimum dimension of talc nano-particle. By calculating the crystal cell number, the atomicity, the surface layer atomicity and its proportion, this paper deals with the relationships between these factors and the dimension of talc. The optimum dimension of talc nano-particle is assumed to be about 165 nm.

Abstract:In this paper, the adsorption behavior of humic acid (HA) on kaolin was investigated and the characteristics of HA-kaolin complexes were studied by means of X-ray diffraction pattern,TGA and IR. According to the results obtained,when the HA-kaolin complexes are washed six times,the HA can be stably combined with the kaolin; the Fruendlich-type equation can describe the adsorption isotherm of HA on kaolin well,and the K_f of HA on kaolin is 0.857; there exist apparent absorption peaks of hydrocarbon in the IR; chemical adsorption plays a major role in the interaction between HA and kaolinite, and the adsorption behavior mainly takes place on the hydroxyl sites of aluminum.