大别山碧溪岭地区超高压变质岩构造分析   总被引：7，自引：1，他引：7  

索书田  钟增球等 《地学前缘》2001,8(2):385-394

大比例尺 (1∶10 0 0 0 )构造制图及构造分析表明 ,碧溪岭地区超高压变质岩石含有丰富的构造演化历史记录。同碰撞或挤压组构只保留于榴辉岩及其它超高压变质岩透镜体内部 ,表现为高角度网络状超高压剪切带与弱应变透镜体域规律组合格式。前者由面理或糜棱岩化榴辉岩组成 ,后者由块状榴辉岩及石榴橄榄岩组成。碰撞期后伸展构造表现为区域性的假单斜状 ,内部呈低缓角度的网络状强应变带及所环绕的透镜状弱应变域组合格式 ,强应变带的岩石为由榴辉岩退变成的角闪岩相高压片麻岩及部分熔融形成的含榴花岗岩 ,透镜状弱应变域的岩石为弱角闪相改造的榴辉岩及石榴橄榄岩。不同尺度上同碰撞或挤压组构及碰撞期后伸展组构所显示的这种残斑基质流变学结构样式 ,虽然与先期原岩成分、结构、流变学的不均一性有关 ,但主要是多期递进应变分解作用的结果 ,支持榴辉岩“原地”成因模式。依据构造学证据和可利用的岩石学及同位素年代学资料 ,分析了超高压变质岩石的形成及折返过程 ,指出碧溪岭地区超高压变质岩石是在 2 45～ 2 10Ma形成的 ,碰撞期后伸展作用主要发生在 2 0 0～ 170Ma。在超高压变质岩石向地壳表层折返过程中 ,张扭作用可能有重要功能 ,不支持碧溪岭地区遭受过多期超高压变质作用的推论。  相似文献   

圆梁山隧道毛坝向斜段典型岩溶现象及发育分布特征   总被引：11，自引：0，他引：11  

屈科  许模  徐则民  王科  蒋良文 《地质灾害与环境保护》2001,12(1):43-47

圆梁山隧道毛坝向斜段核部及两翼的可溶地层中发衣分布有大量的典型岩溶现象，本文详尽讨论了岩溶洼地，槽谷，巨型组合槽谷和地下溶洞等大型岩溶形态的基本特征，形成机制，受控因素，并进一步认识到其发育分布主要受控于岩性和构造因素。  相似文献   

正常固结饱和粘性土的不排水强度     

侯龙清  黄松华  罗嗣海 《上海国土资源》2001,(Z1):59-61

本文以有效应力强度理论和Henkel孔隙水压力公式为基础,建立了各种类三轴与平面应变试验条件下正常固结饱和粘土的不排水强度公式及相互关系;初步估计了粘土强度随固结增长的计算公式.  相似文献   

Strain and tilt changes measured during a water injection experiment at the Nojima Fault zone, Japan   总被引：2，自引：0，他引：2  

Kunio Fujimori  Hiroshi Ishii  Atsushi Mukai  Shigeru Nakao  Shigeo Matsumoto  Yasuhiro Hirata 《Island Arc》2001,10(3-4):228-234

Abstract In order to make geophysical and geological investigations of the Nojima Fault on Awaji Island, Japan, three boreholes measuring 1800 m, 800 m and 500 m deep were drilled into the fault zone. The fault is one of the seismic source faults of the 1995 Hyogo-ken Nanbu earthquake of M 7.2. A new multicomponent borehole instrument was installed at the bottom of the 800 m borehole and continuous observations of crustal strain and tilt have been made using this instrument since May 1996. A high-pressure water injection experiment within the 1800 m borehole was done in February and March 1997 to study the geophysical response, behavior, permeability, and other aspects of the fault zone. The injection site was located approximately 140 m horizontally and 800 m vertically from the instrument. Associated with the water injection, contraction of approximately 0.7 × 10⁻⁷ str (almost parallel to the fault) and tilt of approximately 1 × 10^-7 rad in the sense of upheaval toward the injection site were observed. In addition to these controlled experiments, the strainmeter and tiltmeter also recorded daily variations. We interpret strain and tilt changes to be related to groundwater discharge and increased ultra-micro seismicity induced by the injected water.  相似文献   

General characteristics of the recent horizontal crustal movement in Chinese mainland   总被引：5，自引：0，他引：5  

顾国华  申旭辉  王敏  郑贵明  方颖  李鹏 《地震学报(英文版)》2001,14(4):384-393

1 Introduction of GPS observation dataThe Crustal Movement Observation Network of China (CMONOC) is a major scientific project in China organized by China Seismological Bureau and paticipated by the Bureau of Surveying and Mapping of the General Staff, the Chinese Academy of Sciences and the National Bureau of Surveying and Mapping. Based on the observation data of 25 fiducial stations and 56 basic stations in CMONOC (Figure 1 and Table 1), collected from August 26 to September…  相似文献   

Model of rigid and elastic-plastic motion in intraplate blocks and strain status of principal blocks in Chinese mainland   总被引：5，自引：1，他引：5  

李延兴  黄珹  胡新康  帅平  胡小工  张中伏 《地震学报(英文版)》2001,14(6):603-610

Introduction The Chinese mainland is located in the southeastern part of Eurasia plate and encircled by India, Eurasia, Pacific and Philippine Sea plates. It is one of areas with the strongest tectonic de-formation, especially Qingzang (QinghaiXizang) plateau and NS tectonic zone where the tec-tonic activity is more intensive and intricate. The main part of tectonic activity of Chinese mainland includes a series of tectonic zones and active blocks divided by them. Therefore, the research…  相似文献   

Evaluation of response and energy in actively controlled structures     

Kevin K. F. Wong  Rong Yang 《地震工程与结构动力学》2001,30(10):1495-1510

A computational method of energy evaluation is derived to study the elastic responses and energy distribution of actively controlled single‐degree‐of‐freedom (SDOF) structures during earthquakes. Contrary to the common perception that applying active control force pumps energy into the structure, the applied control force can actually reduce the energy in the structure by reducing the input energy from earthquakes to the structure. In addition, applying control force can dissipate a large amount of energy in the structure when this control force is applied in the direction opposite to the displacement and velocity responses. To demonstrate this energy mechanism in active controlled structures, the two most popular control algorithms, optimal linear control (OLC) and instantaneous optimal control (IOC) algorithms, are used to calculate the control response and energy spectra. One‐step time delay is incorporated into the algorithms to take into consideration the practical aspect of active control. The effects of different earthquakes and damping ratios on control energy and response spectra are studied. These studies show that both OLC and IOC are very effective in reducing the structural displacement and velocity responses by reducing the input earthquake energy as well as dissipating a large amount of energy in the structure. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

On the origin of inhomogeneity of anomalous birefringence in mixed crystals: an example of alums     

A. G. Shtukenberg  Yu. O. Punin  E. Haegele  H. Klapper 《Physics and Chemistry of Minerals》2001,28(9):665-674

 Optical anomalies (deviations of the symmetry of optical properties from the ideal symmetry of the crystal) occur in many minerals and synthetic compounds and have been under investigation since the last century. An important feature of optically anomalous mixed crystals is a high degree of optical inhomogeneity, whereas the optical patterns of mixed crystals without anomalies are usually rather uniform. This work is devoted to the study of this phenomenon. As a model object we have chosen mixed alum crystals, which were known for their anomalous birefringence and which revealed the following types of optical inhomogeneities: (1) sector zoning; (2) concentric zoning; (3) subsector zoning; (4) stripes normal to growth front. The inhomogeneity of anomalous birefringence of mixed crystals of alums can be explained by superposition of several effects: mismatch strain, strain along dislocations and growth ordering of isomorphous components. Optical inhomogeneities due to the sector zoning of crystals and their dislocation structure arise even under stationary growth conditions and stationary micromorphology of the growing face. Both variable growth conditions and the relief of the growing face strongly intensify the optical inhomogeneity due to three interrelated factors: (1) a significantly inhomogeneous mismatch strain; (2) a variable degree of ordering of isomorphous components due to the compositional inhomogeneities; (3) different degrees of ordering of isomorphous atoms caused by different orientations, heights and velocities of growth steps. These effects lead to the formation of subsector zoning and zoning superimposed on the optical sector zoning. These optical structures are crossed by birefringent stripes arising from dislocations. Received: 29 March 2000 / Accepted: 11 March 2001  相似文献   

Synchrotron X-ray powder diffraction study of natural P2 /n-omphacites at high-pressure conditions     

A. Pavese  V. Diella  D. Levy  M. Hanfland 《Physics and Chemistry of Minerals》2001,28(1):9-16

 Synchrotron X-ray powder diffraction experiments at high pressure conditions (0.0001–13 GPa) were performed at ESRF (Grenoble-F), on the beamline ID9, to investigate the bulk elastic properties of natural P2/n-omphacites, with quasi-ideal composition. The monoclinic cell parameters a, b, c and β were determined as a function of pressure, and their compressibility coefficients are 0.00277(7), 0.00313(8), 0.00292(5) and 0.00116(4) GPa⁻¹, respectively. The third-order Birch-Murnaghan equation of state was used to interpolate the experimental P−V data, obtaining K ₀=116.6(±2.5) GPa and K′₀=6.03(±0.60). K ₀ was also determined by means of the axial and angular compressibilities [122.5(±1.7) GPa], and of the finite Lagrangian strain theory [121.5(±1.0) GPa]. The discrepancies on K ₀ are discussed in the light of a comparison between techniques to determine the bulk modulus of crystalline materials from static compression diffraction data. Received: 22 February 2000 / Accepted: 10 July 2000  相似文献   

体应变观测中的气压干扰机制和排除方法的研究   总被引：7，自引：0，他引：7  

张凌空  何世海  刘北顺 《地震》1996,(2)

建立体应变理论气压干扰模型,通过实际观测资料研究了气压对体应变月变和日变的干扰过程,探讨消除干扰的方法,且和水位资料作了对比分析。  相似文献