Ri-μi/μm-Ci dependent oblateness of deformed pebbles in the Baraitha conglomerate,Central India and tectonic implications     

Prakash P. Roday  Gopal Maheshwari  Narendra H. Vaghmarey 《Journal of Earth System Science》1990,99(2):321-338

Strain analysis of the Baraitha conglomerate is attempted by direct measurements on extracted pebbles and by micrometric analysis. The overall deformation is of flattening type, with thek value lower by more than half in the matrix than in the pebbles. The viscosity contrast between pebbles and matrix (μ _i/μ_m) is in the ratio of 2:1 and the bulk deformation appears to be strongly controlled by C_i (concentration of pebbles expressed as percentage). The total shortening (≃35%) in the Baraitha conglomerate is comparable with the shortening accomplished in the folding of the overlying Bijawar Group volcanosedimentary sequence. The bulk strain axesX _t, Y_t andZ _t, as determined from the analysis of the deformed conglomerate, are unsymmetrically oriented with reference to folds formed by oblique flexural-slip with neitherX _t norY _tcoincident with the fold hinges. The lack of transection of folds by cleavage again suggests flattening deformation. The extension in theY _tdirection is greater in the matrix than in the pebbles.  相似文献   

我国钻孔应力-应变地震前兆监测台网的现状   总被引：10，自引：3，他引：10  

邱泽华  张宝红 《国际地震动态》2002,(6):5-9

当今的地震成因理论表明：地震是地应力（应变）积累到一定程度，使断层滑动而发生的。由此可见地应力－应变观测的重要性。我国的钻孔应力－应变地震前兆监测网，是全国地震前兆监测台网的一个组成部分。观测对象包括：体应变，分量应变，分量应力和钻孔应力－应变差应变。文章通过分析调查结果，比较详细地介绍了我国的钻孔应力－应变地震前兆监测台网的现状。  相似文献   

姑咱地震台前兆观测数字化建设项目简介   总被引：1，自引：0，他引：1  

李学川 《四川地震》2002,(3):32-34,40

介绍了姑咱数字形变台的观测环境和仪器配置布设安装情况。对系统的性能特点和试记中有待改进的问题也做了简要的总结。  相似文献   

Analysis Method for Predicting Strain in Interior Beds and Sub-Resolution Faults from Area Balance Theory in Extensional Basins   总被引：1，自引：0，他引：1  

Groshong Jr R H 《中国地质大学学报(英文版)》2002,13(4)

Extensional basins include mainly grabens and half grabens displaced along a lower detachment. Based on area balance theory, there is a linear relationship between a height of regional and the lower detachment h on the outside of the basin and “lost area S“ from the regional in the basin. The pre-growth beds above lower detachment are of the same extensional displacement so that an “S-h diagram“ can be used to determine the depth to lower detachment and to calculate the total extensional displacement of the beds above the lower detachment. The extensional displacement is dominated by the heave of various scale normal faults. The displacement of obvious faults can be immediately figured out from the measured bed-length. The requisite extension calculated by area balance is the layer-parallel strain, which could be accommodated by displacement on sub-resolution faults. Accordingly, the layer-parallel strain can help us predict the magnitude and distribution of sub-resolution faults on the basis of analysis of the structural style and rheological behavior.  相似文献   

Structure of the Mérida Andes, Venezuela: relations with the South America–Caribbean geodynamic interaction     

Felipe E. Audemard  Franck A. Audemard   《Tectonophysics》2002,345(1-4)

For over 50 years, several models based on diverse geologic concepts and variable quality of data have been proposed to explain the major structure and history of the Mérida Andes (MA), in western Venezuela. Lately, this chain growth and associated flexural basins deepening have been related to incipient type-A subductions of either polarity, accounting for the across-chain asymmetry. However, these recent models have not well integrated the present tectonically active setting driven by neighboring major plate interactions. At present, this chain exhibits ongoing strain partitioning where cumulative right-lateral slip along chain axis is as much as half of, or about the same, as the transverse shortening since late Miocene, thus implying that the NNE-directed Maracaibo block extrusion with respect to the South America (SA) plate is not a secondary feature. Consequently, this paper discusses some limitations exhibited by the SE-directed continental subduction models—Maracaibo crust underthrusting the Mérida Andes—in the light of available geological and geophysical data. Besides, it is herein proposed that the Mérida Andes structuration is related to a NW-directed, gently dipping, incipient type-A subduction, where chain growth and evolution are similar to those of a sedimentary accretionary wedge (i.e., Barbados), but at crustal scale and with ongoing strain partitioning. This continental subduction is the SE portion of a major orogenic float that also comprises the Perijá range and the Santa Marta block.  相似文献   

饱和冻结粉土在常应变速率下的单轴抗压强度   总被引：4，自引：1，他引：4  

李海鹏  朱元林  潘卫东 《冰川冻土》2002,24(5):659-664

Uniaxial compressive strength tests were conducted on the saturated frozen Lanzhou silt (loess) at various constant strain rates and at various constant temperatures. It is concluded from the test results that: the compressive strength (σ f) is very sensitive to temperature (θ) and increases with the temperature decreasing as a power law. Compressive strength is sensitive to strain rate () and increases with strain rates increasing within a certain range of strain rates as a power law. Compressive strength decreases when time to failure (tf) increases, also following a power law. Finally, Compressive strength of frozen silt with higher dry density (γd) is higher than that of frozen silt with lower dry density. The difference between them is mainly influenced by strain rate.  相似文献   

煤的比表面积 孔体积及其对煤吸附能力的影响   总被引：20，自引：0，他引：20  

钟玲文  张慧  员争荣  雷崇利 《煤田地质与勘探》2002,30(3):26-28

在液氮温度下，通过测试煤样在气体饱和蒸气压力范围内对N2的吸附过程及吸附量，用BET降BJH理论模型计算出煤的孔体积和孔表面积。同时，对煤样进行等温吸附CH4试验，根据试验结果,探讨了煤的孔体积，孔比表面积及与孔类型的关系，及其对煤吸附能力的影响，即煤对CH4的吸附能力与总孔体积，总孔比表面积，微孔比表面积呈正相关。  相似文献   

Crustal movement and deformation in Taiwan and its coastal area   总被引：1，自引：0，他引：1  

李延兴  胡新康  李智  耿洪  郭良迁  郭逢英  史粦华  林继华  丁学仁  刘序俨 《地震学报(英文版)》2002,15(5):510-518

Introduction Both Taiwan Island and Chinese mainland belong to Eurasian plate in geological structure. And the nearest distance between Taiwan Island and Fujian Province, which is located on the opposite coast, is only 130 km. Although there are high-precision GPS networks in both Taiwan and Fujian Province, joint GPS measurement cannot be made directly because of the inconvenient contact due to the strait between them. However, the GPS networks arranged on b…  相似文献   

A New Method for Clay Mineral Analysis and Its Application in Geology   总被引：3，自引：0，他引：3  

WANG Hejing  LU Anhuai  CHEN TaoThe Key Laboratory of Orogenic Belts  Crustal Evolution  Ministry of Education  Chin  School of Earth  Space Sciences  Peking University  Beijing  China 《《地质学报》英文版》2002,76(4):429-436

X-ray diffraction (XRD) peaks in a low-angle diffraction section of clay minerals, especially those of authigenic origin, have broadening and tailing features in shape. Using the five basic parameters, peak position, peak height, width, shape coefficient and asymmetry, to describe an XRD peak is more accurate, comprehensive and integrated than using only 3 of them, position, height and width. Following the concept of the five basic parameters of an XRD peak, the program Decoform proposed in this study provides more information in mineralogical analyses by fitting actual XRD profiles. In combination with the HW-IR plot, Decoform can be systematically and accurately used in the comprehensive analyses of crystallinity, domain size, lattice strain and quantitative phase. It is also of value for the geological investigations of diagenesis, metamorphism, basin maturity, structural stress field and so on.  相似文献   

负压条件下考虑土体损伤和流变的有限元分析   总被引：8，自引：2，他引：8  

吴跃东  余湘娟  殷宗泽 《岩土力学》2002,23(2):137-141

介绍了在负压条件下软基加固的各种理论计算，并采用平面应变有限元法进行分析，计算中考虑了土体的流变和施工扰动引起的损伤。计算结果与某高速公路试验段现场观测的结果比较接近，说明计算方法是合理可行的。  相似文献