Distribution and Influence of Iron Phases on the Physico—Chemical Properties of Phyllosilicates     

MERVATSAIDHASSAN SAYEDMAHMOUDSALEM 《中国地球化学学报》2002,21(1):29-39

Clay minerals from different Cretaceous stratigraphic successions of Egypt were investigated using XRD,DTA,dissolution analysis(DCB),IR,Moessbauer and X-band Electron Spin Resonance(ESR) spectroscopies.The purity of the samples and the degree of structural order were determined by XRD.The location of Fe in the octahedral sheet is characterized by absorption bands at-875cm^-1 assigned as Al-OH-Fe which is present after chemical dissolution of free iron.The Moessbauer spectra of these clays sow two doublets with isomer shift and quadrupole splitting typical of octahedral coordinated Fe^3 ,in addition to third doubler with hyperfine parameter typical of Fe^2 in the spectra of Abu-Had kaolinite (H)sample.6-lines magnetic hyperfine components which are consistent with those of hematite are confirmed in the spectra of both Isel and Rish kaolinite samples.Goethite was confirmed by both IR and DTA.Multiple nature of ESR of these clays suggested structural Fe in distorted octaedral symmetry and as non-structural Fe.Little dispersion and low swelling indices as well as incomplete activaiton of investigated montmorillonite samples by NaCO3 appear to be due to incomplete disaggregation of montmorillonite particles.This can be explained by the ability of Fe-gel to aggregate the montmorillonite into pseudo-particles and retard the rigid-gel structure.However,extraction of this ferric amorphous compound by dithonite treatment recovers the surface properties of the montmorillonite samples.On the other hand,amounts and site occupation of Fe associated with kaolinite samples show a negative correlation with the parameters used to describe the degree of crystalline perfection,color,brightness and vitrification range of these kaolinite samples.  相似文献   

Rupture nucleations in the 1995 Hyogo-ken Nanbu earthquake and its large aftershocks   总被引：1，自引：0，他引：1  

Bunichiro Shibazaki  Yasuhiro Yoshida  Mamoru Nakamura  Masao Nakamura  Hiroshi Katao 《Geophysical Journal International》2002,149(3):572-588

  相似文献   

基于C-C方法的Lyapunov指数计算   总被引：11，自引：0，他引：11  

陶诏灵  陈国华 《南京气象学院学报》2002,25(4):555-559

识别混沌是对非线性时间序列进行分析，预测，控制的基础，克服已有文献用Lyapunov指数识别混沌时计算Lyapunov指数的不足，用C－C方法计算相空间重构的参数，然后利用混沌的遍历性及定义，提出计算最大Lyapunov指数的新方法，典型实例证明新算法的高效性与正确性。  相似文献   

表生介质中铜的赋存相态研究——以敖格道仁诺尔铜多金属矿(化)区为例   总被引：2，自引：0，他引：2  

王瑞廷  欧阳建平  蒋敬业 《矿物学报》2002,22(1):30-34

表生介质中铜的赋存相态对其表生异常的发育有重要意义。通过对敖格道仁诺尔铜与金属的矿化区内土壤及湖各湖积物中铜的七种赋存相态的分析研究，认为在土壤剖面上的不同层位之间，铜的赋存相态存在差异，而这种差异又随近矿地段和矿体上方土壤空间位置的不同有所变化。铜的这种赋存相态特征受研究区地理景观条件、土壤结构类型、土壤环境的化学物理参数及铜的表生地球化学性质等内外因素制约的。对这些制约因素的深入研究是表生异常形成机制及其评价研究的基础。  相似文献   

Physical meaning and prediction efficiency of the load/unload response ratio of rocks in strain-weakening phase before failure     

许昭永  杨润海  王彬  赵晋明  王赟赟  梅世蓉 《地震学报(英文版)》2002,15(1):47-55

Introduction In studying the instability of a non-linear system, YIN (1987), YIN and YIN (1991), YIN, et al (1994), and Yin, et al (1994, 1995, 2000) have presented a concept of load/unload response ratio (LURR) of the system. When the system is in a stable state, its response process to the load/unload follows the same trajectory on the stress-strain diagram, and the load/unload response ratios are equal. However, when the system departs from a stable state, its response to the load/un…  相似文献   

Cathodoluminescence, electron microscopy, and Raman spectroscopy of experimentally shock-metamorphosed zircon     

Arnold GucsikChristian Koeberl  Franz BrandstätterWolf Uwe Reimold  Eugen Libowitzky 《Earth and Planetary Science Letters》2002,202(2):495-509

Thorough understanding of the shock metamorphic signatures of zircon could be the basis for the use of this mineral as a powerful tool for the study of old, deeply eroded, and metamorphically overprinted impact structures and formations. This study of the cathodoluminescence (CL) and Raman spectroscopic signatures of experimentally (20-60 GPa) shock-metamorphosed zircon single crystals contributes to the understanding of high-pressure microdeformation in zircon. For all samples, an inverse relationship between the brightness of the backscattered electron (BSE) signal and the corresponding cathodoluminescence intensity was observed. The unshocked sample shows crosscutting, irregular fractures. The 20 GPa sample displays some kind of mosaic texture of CL brighter and darker domains, but does not exhibit any shock metamorphic features in BSE or CL images. The 40 GPa sample shows a high density of lamellar features, which might be explained by the phase transformation between zircon- and scheelite-structure phases of zircon and resulting differences in the energy levels of the activator elements. The CL spectra of unshocked and shocked (20, 40, and 60 GPa) zircon samples are dominated by narrow emission lines and broad bands in the region of visible light and in the near-UV range. The emission lines result from rare earth element activators and the broad bands might be associated with lattice defects. Raman spectra revealed that the unshocked and 20 GPa samples represent zircon-structure material, whereas the 40 GPa sample yielded additional peaks with relatively high peak intensities, which are indicative of the presence of the scheelite-type high-pressure phase. The 60 GPa sample has a Raman signature that is similar to that of an amorphous phase, in contrast to the observations of an earlier TEM study that the crystalline scheelite-structure phase is stable at this shock pressure. The 60 GPa Raman signature cannot be explained at this stage. The results show a clear dependence of the CL and Raman properties of zircon on shock pressure, which confirm the possible usage of these methods as shock indicators.  相似文献   

Initial rupture process of microearthquakes recorded by high sampling borehole seismographs at the Nojima fault, central Japan     

Yoshihiro Hiramatsu  Muneyoshi Furumoto  Kin’ya Nishigami  Shiro Ohmi 《Physics of the Earth and Planetary Interiors》2002,132(4):269-279

We analyze high sampling waveforms of the initial part of P-wave recorded at the 1800-m-deep borehole seismographs at the Nojima fault from December 1999 to May 2000 to clarify the initial rupture process of microearthquakes. We select 12 events with high S/N, whose magnitudes range from −0.3 to 2.2 and hypocentral distances from 1 to 11 km. We adopt the two different source models by Sato and Hirasawa (1973) and by Sato and Kanamori (1999). The former (model by Sato and Hirasawa (SH model)) generates only a ramp-like onset of velocity pulse. The later (model by Sato and Kanamori (SK model)) is able to generate a weak initial phase that is controlled by a trigger factor and the length of pre-existing crack. We perform the waveform inversion to estimate the optimum source parameters of each model. Waveforms of 5 of the 12 events are clearly reproduced by both SH model and SK model with a large trigger factor and a small length of pre-existing crack. The others are explained by not SH model but only SK model with a small trigger factor and a large length of the pre-existing crack, indicating that the weak initial phase is a nucleation phase and reflects the source process. These seven events satisfy roughly a relation that a large event has a large length of the pre-existing crack; the final crack length is proportional to the length of the pre-existing crack.  相似文献   

Low-Temperature Plasticity of Naturally Deformed Calcite Rocks     

Klaus WEBER 《《地质学报》英文版》2002,76(3):292-299

Optical, cathodoluminescence and transmission electron microscope (TEM) analyses were conducted on four groups of calcite fault rocks, a cataclastic limestone, cataclastic coarse-grained marbles from two fault zones, and a fractured mylonite. These fault rocks show similar microstructural characteristics and give clues to similar processes of rock deformation. They are characterized by the structural contrast between macroscopic cataclastic (brittle) and microscopic mylonitic (ductile) microstructures. Intragranular deformation microstructures (i.e. deformation twins, kink bands and microfractures) are well preserved in the deformed grains in clasts or in primary rocks. The matrix materials are of extremely fine grains with diffusive features. Dislocation microstructures for co-existing brittle deformation and crystalline plasticity were revealed using TEM. Tangled dislocations are often preserved at the cores of highly deformed clasts, while dislocation walls form in the transitions to the fine-grained  相似文献   

古气候变化吸引子维数对比研究     

袁林旺  周春林  刘泽纯 《地理与地理信息科学》2002,18(3):94-96

对世界上不同地区的多条古气候曲线 ,采用相同的间距和同一种算法进行关联维数计算 ,结果表明各系统均具有非线性作用产生的混沌现象。与太阳辐射曲线关联维数对比表明 ,太阳辐射控制了气候变化的基本格局 ,在此基础上叠加了区域性特征。  相似文献   

2001年4月22日阳江4.2级地震前部分地震波参数变化特征     

华卫 《华南地震》2002,22(3):58-64

应用广东数字遥测地震台网的数字化的地震形资料，研究阳江地震前，地震波波形时间线性度、平均半周期和地震波波形空间线性度等地震波参数变化特征。结果表明，震前半年时间内，上述地震波参数不同程度地出现下降异常。利用线性偏振度自动检测的P、S波初至具有可靠的精度，为广泛利用地震波参数预报地震提供了方便。  相似文献