桂北四堡群火山岩形成环境及构造意义   总被引：2，自引：0，他引：2  

廖宗廷  张起钻 《上海国土资源》1994,(2):1-10,18

通过野外地质、岩石化学、稀土配分、微量元素等的综合分析表明,桂北四堡群火山岩形成于火山岛弧的构造环境,由四堡群组成的地质体是中元古代位于扬子大陆边缘以南的岛弧地体,中元古代末期该地体与扬子大陆边缘发生碰撞拼贴造山作用,这一作用决定了中、晚元古代桂北及邻区的大陆边缘构造及其演化过程。  相似文献   

Sulfur K- and L-edge X-ray absorption spectroscopy of sphalerite,chalcopyrite and stannite     

Dien Li  G. M. Bancroft  M. Kasrai  M. E. Fleet  B. X. Yang  X. H. Feng  K. Tan  Mingsheng Peng 《Physics and Chemistry of Minerals》1994,20(7):489-499

Sulfur K-edge x-ray absorption spectra (XANES and EXAFS) and L-edge XANES of sphalerite (ZnS), chalcopyrite (CuFeS₂) and stannite (Cu₂FeSnS₄) have been recorded using synchrotron radiation. The K- and L-edge XANES features are interpreted using a qualitative MO/energy band structure model. The densities of unoccupied states at the conduction bands of sphalerite, chalcopyrite and stannite are determined using S K- and L-edge XANES features (up to 15 eV above the edge), combined with published metal K-edge XANES. The SK- and L-edge XANES also indicate that, for sphalerite, the Fe²⁺ 3d band at the fundamental gap has little or no bonding hybridization with S 3p and S 3s orbitals; for chalcopyrite, the Cu⁺ 3d and Fe³⁺ 3d bands have strong mixing with S 3p and S 3s states, while for stannite the Cu⁺ 3d band strongly hybridizes with S 3p and S 3s orbitals, but the Fe²⁺ 3d band does not. The post-edge XANES features (15–50 eV above the edge) of sphalerite, chalcopyrite and stannite are similar. These features are related to the tetrahedral coordination of sulfur in all these structures, and interpreted by a multiple scattering model. The resonance energies from both the K-edge and L-edge XANES for these minerals are well correlated with reciprocal interatomic distances and lattice spaces. Sulfur K-edge EXAFS analyses using Fourier transform and curve fitting procedures are presented. Comparison of the structural parameters from EXAFS with x-ray structure data shows that the first shell bond distances (BD) from EXAFS are usually accurate to ±0.02 Å, and that coordination numbers (CN) are generally accurate to ±20 percent. For sphalerite, EXAFS analysis yields the structure parameters for the first three neighbour shells around a sulfur atom; the BD and CN even for the third shell are in close agreement with the x-ray structure, and the Debye-Waller term decreases from the first shell to the third shell. It is shown that sphalerite (ZnS) is a good model compound for EXAFS analysis of sulfur in chalcogenide glasses and metalloproteins.  相似文献   

南岳雨凇分析     

朱明辉 王琪刘甜甜  廖春花禹伟 邓晓春 《气象科技》2006,34(4):436-440

分析了南岳雨凇与冷冬及西太平洋副热带高压的关系。结果表明,在冷冬年份,南岳雨凇日数偏多;在暖冬年份,南岳雨凇日数偏少。西太平洋副热带高压与南岳冬季气温密切相关。副热带高压偏弱时,南岳冬季偏冷;副热带高压偏强时,南岳冬季偏暖。副热带高压的588线北界偏北时,南岳冬季偏暖,反之偏冷。副热带高压的西伸脊点偏东时,南岳雨凇日数偏多,反之偏少,而且西太平洋副热带高压的变化超前于冷暖冬的变化。  相似文献   

柴达木盆地察尔汗贝壳堤剖面年代学研究^*   总被引：9，自引：6，他引：9  

张虎才  雷国良  常凤琴  樊红芳  杨明生  张文翔 《第四纪研究》2007,27(4):511-521

利用常规¹⁴ C、加速器(AMS)和²³⁰ Th等测年方法,对位于青藏高原东北部柴达木盆地察尔汗古湖贝壳堤剖面化石贝壳、湖泊沉积(包括现代沉积)样品有机质(包括碱性残留和胡敏酸组分)、碳酸盐(CaCO₃)和剖面顶部石盐(NaCl)晶体在不同实验室进行了系统的实验研究,探讨了不同样品测年结果的可靠性和精确性,并通过与已有研究结果的对比,对柴达木盆地贝壳堤剖面记录的察尔汗古湖高湖面演化历史进行了探讨,得出察尔汗古湖高湖面形成于约39.7~17.5 ¹⁴ C kaB.P. ; 研究证明柴达木盆地沉积物中有机质含量很低,且主要来源于菌藻类等低等藻类和微生物,受老碳和溶解物质影响强烈,因此必须经过多种方法综合测年才能比较可靠地确定所测样品的形成年代; 测年结果的不确定性不仅来源于样品自身元素(同位素)的特性和沉积过程中再沉积作用的影响,也可能源自于放射性¹⁴ C产生过程的不稳定性; 对比发现贝壳化石老于同层位有机质¹⁴ C年龄15~18ka,这可能与柴达木盆地所处的特殊地理位置和巨大的古湖泊面积及水体有关; 同时,不平衡铀系测年在确定开放体系矿物晶体年代应用中的可靠性尚须进一步深入分析,其机理也还需要探讨和实验研究。  相似文献   

The petrochemistry characteristics and petrogenesis of peraluminous granite in Tibet     

Liao Zhongli  Mo Xuanxue  Pan Guitang  Zhu Dicheng  Wang Liquan  Zhao Zhidan  Geng Quanru  Xiong Xingguo  Dong Guochen 《Frontiers of Earth Science》2007,1(2):194-205

There are 61 major peraluminous granitic bodies in Tibet (TPGs) along the south of the Bangong Co-Gêrzê-Amdo-Nujiang suture, whose lithology includes tourmaline granite, muscovite granite and two-mica granite. The TPGs have SiO₂ = 65.7%−79.52%, K₂O + Na₂O = 2.20%−12.51%, K₂O/Na₂O = 0.49−1.04 and A/CNK = 1.04−1.38. Al₂O₃ gradually decreases and the other oxides disperse with the increase in SiO₂. The rock series is mainly calc-alk series with high potassium. It has typical characteristics of strongly peraluminous granite. Based on the aluminum saturation index and QAP plots, the peraluminous granite plot is mostly within the continental collision granite (CCG) field, indicating that the peraluminous granites in Tibet formed in a continental collisional setting. Ab-Or-Q-H₂O phase diagram indicates the pressure of 0.5 × 10⁸−2 × 10⁸ Pa in TPGs, from which it can be deduced that the forming temperature was under 700°C. The TPGs mainly occurred at the collision stage between two continental crust plates, and the original magma is rooted in the remelting from the upper crust. It is the S-type granite in petrogenesis. The South Gandise belt and the Lhagoi Kangri belt have similar characteristics, suggesting that the two belts have the same magma source and the same tectonic setting. Translated from Acta Geologica Sinica, 2006, 80(9): 1329–1341 [译自: 地质学报]  相似文献   

Analytic stage–discharge formulae for flow in straight trapezoidal open channels     

Huasheng Liao  Donald W. Knight 《Advances in water resources》2007

Analytic stage–discharge formulae are derived for flow in straight trapezoidal channels, based on the 2D analytic velocity distribution in open channels given by Shiono and Knight [Shiono K, Knight DW, Turbulent open-channel flows with variable depth across the channel. J Fluid Mech 1991;222:617–46]. A simple hand-calculation method is provided. Legendre incomplete elliptic integrals of the first and second kinds and a binomial series expansion are used in the derivation of these analytic formulae, together with physically based hydraulic parameters, such as local friction factor (f), dimensionless eddy viscosity (λ) and secondary flow (Γ). The stage–discharge results obtained from the formulae are shown to be in good agreement with experimental data, as are the corresponding analytic velocity and boundary shear stress distributions. The influences of f, λ and Γ on the stage–discharge relationship are also discussed.  相似文献   

Numerical modeling of geothermal groundwater flow in karst aquifer system in eastern Weibei,Shaanxi Province,China     

Li Ming  Li GuoMin  Yang Liao  Dang XueYa  Zhao ChunHu  Hou GuangCai  Zhang MaoSheng 《中国科学D辑(英文版)》2007,50(1):36-41

The quantitative assessment of geothermal water resources is important to the exploitation and utilization of geothermal resources. In the geothermal water systems the density of groundwater changes with the temperature, therefore the variations in hydraulic heads and temperatures are very complicated. A three-dimensional density-dependent model coupling the groundwater flow and heat transport is established and used to simulate the geothermal water flow in the karst aquifers in eastern Weibei, Shaanxi Province, China. The multilayered karst aquifer system in the study area is cut by some major faults which control the regional groundwater flow. In order to calibrate and simulate the effect of the major faults, each fault is discretized as a belt of elements with special hydrological parameters in the numerical model. The groundwater dating data are used to be integrated with the groundwater flow pattern and calibrate the model. Simulation results show that the calculated hydraulic heads and temperature fit with the observed data well.  相似文献   

Toxicity of Ionic Liquids     

Dongbin Zhao  Yongcheng Liao  Ziding Zhang 《洁净——土壤、空气、水》2007,35(1):42-48

The dramatic growth in ionic liquid research over the past decade has resulted in the development of a huge number of novel ionic liquids, as well as many associated applications. The perceived environmentally friendly nature of ionic liquids, which results from their negligible vapor pressure, is now under scrutiny since although they will not evaporate into air, it is not possible to guarantee that they will never enter the environment. Toxicity research studies including ecotoxicity, have recently received broad attention and the commonly accepted notion that ionic liquids have low toxicity has been shown to be incorrect. This review attempts to highlight the progress of ionic liquid toxicity research, as well as the development of degradable and bio‐renewable ionic liquids.  相似文献   

Numerical modeling of geothermal groundwater flow in karst aquifer system in eastern Weibei, Shaanxi Province, China   总被引：2，自引：0，他引：2  

LI Ming  LI GuoMin  YANG Liao  DANG XueYa  ZHAO ChunHu  HOU GuangCai  ZHANG MaoSheng 《中国科学D辑(英文版)》2007,50(Z1):36-41

The quantitative assessment of geothermal water resources is important to the exploitation and utilization of geothermal resources. In the geothermal water systems the density of groundwater changes with the temperature, therefore the variations in hydraulic heads and temperatures are very complicated. A three-dimensional density-dependent model coupling the groundwater flow and heat transport is established and used to simulate the geothermal water flow in the karst aquifers in eastern Weibei, Shaanxi Province, China. The multilayered karst aquifer system in the study area is cut by some major faults which control the regional groundwater flow. In order to calibrate and simulate the effect of the major faults, each fault is discretized as a belt of elements with special hydrological parameters in the numerical model. The groundwater dating data are used to be integrated with the groundwater flow pattern and calibrate the model. Simulation results show that the calculated hydraulic heads and temperature fit with the observed data well.  相似文献   

A numerical case study of the passage of a cold surge across Taiwan     

Fang-Chuan Lu  Hann-Ming Henry Juang  Chi-Chang Liao 《Meteorology and Atmospheric Physics》2007,95(1-2):27-52

Summary A numerical study of a cold surge that occurred from 19–23 December 2001 was conducted to better understand the cold surge characteristics over the Taiwan area. The National Centers for Environmental Prediction (NCEP) nested Mesoscale Spectral Model (MSM) was used for this study. Simulation results demonstrated that the nested NCEP MSM captured salient features of the selected cold surge case. We demonstrated that the local minimum center of the time change of virtual potential temperature (dVPT) can serve as the location of severe weather of the cold surge for all Taiwan regions. Furthermore, thermodynamic equation analyses revealed that the leading edge of the cold surge was maintained primarily by meridian thermal advection, while diabatic heating, vertical and zonal thermal advections were less important. The cold surge flows were blocked and lifted by the Central Mountain Range (CMR) on its windward side, which increased the cold surge’s vertical extent upward and increased northwestward tilting in the vertical structure. The flow eventually ascended, switched direction toward Taiwan, and descended over its northwestern and eastern coasts. The physical and circulatory characteristics of the cold surge differed noticeably on both sides of Taiwan. The cold surge’s leading edge over the Taiwan Strait was northeast-southwest oriented and had evident wind shear; on the east side of the island, it was stronger in intensity and faster-moving than its counterpart on the west side. Sensitivity experiments revealed that the CMR’s trapping of cold surge flows on its windward side affected cold surge leading edge characteristics in the following five ways: (1) weakening its intensity over the ocean but enhancing it inland, (2) decreasing its southward speed, especially over the western low plains region, but increasing its movement on the east coast, (3) increasing its vertical altitude and narrowing the horizontal extent of its vertical tilting, (4) altering its upper vertical circulatory structure, and (5) trapping a V-shape density current and enhancing its intensity in connection with the land-sea contrast.  相似文献