High pressure deformation in two-phase aggregates   总被引：1，自引：0，他引：1  

Li Li  Ahmed Addad  Donald Weidner  Hongbo Long  Jiuhua Chen 《Tectonophysics》2007,439(1-4):107-117

We investigate the rheological behavior of multi-phase aggregates at high pressure and high temperature. Using synchrotron X-ray radiation as the probing tool, we are able to quantify the stress state of individual phases within the aggregates. This method provides fundamental information in interpreting the behavior of two phase/multi-phase mixtures, which contribute to our understanding of the deformation process at deep earth conditions. We choose MgAl₂O₄ spinel and MgO periclase as our model materials. Mixtures of various volume proportions were deformed in a multi-anvil high pressure deformation apparatus at pressure of 5 GPa and elevated temperatures. Stress is determined from X-ray diffraction, providing a measure of stress in each individual phase of the mixture in situ during the deformation. Macroscopic strain is determined from X-ray imaging. We compare the steady state strength of various mixtures at 1000 °C and 800 °C and at the strain rate in the range of 1.8 to 8.8 × 10^− 5 s^− 1. Our data indicate that the weak phase (MgO) is responsible for most of the accumulated strains while the strong phase (spinel) is supporting most of the stress when the volume proportion is 75% spinel and 25% MgO. The intermediate compositions (40/60) are much weaker than either of the end members, while the grain sizes for the intermediate compositions (submicrons) are much smaller than the end members (5–10 μm). We conclude that a change in flow mechanism resulting from these smaller grains is responsible for the low strength of the intermediate composition mixtures. This study demonstrates an approach of using synchrotron X-rays to study the deformation behaviors of multi-phase aggregates at high pressure and high temperature.  相似文献   

Relation between electrical resistivity and earthquake generation in the crust of West Anatolia, Turkey   总被引：1，自引：0，他引：1  

Aysan Gürer  Murat Bayrak   《Tectonophysics》2007,445(1-2):49

In this paper, we present a relation between the earthquake occurrence and electric resistivity structures in the crust, in West Anatolia and the Thrace region of Turkey. The relationship between magnetotelluric georesistivity models and crustal earthquakes in West Anatolia, during a period from 1900 to 2000, is investigated. It is found that most of the large crustal earthquakes occurred in and around the areas of the highest electrical resistivity in the upper crust, although rare small magnitude earthquakes are observed in some parts of the conductive lower crust in West Anatolian extensional terrain. The high-resistivity zones may represent rocks that are probably mechanically strong enough to permit sufficient stress to accumulate for earthquakes to occur in western Anatolia and the Thrace region. However, some recent studies state that the generation of a large earthquake is not only a pure mechanical process, but is closely related to fluid existence. We also reviewed recent world-wide researches including results from the Anatolian data for the first time and discussed all general findings in combination. Our findings show that the boundary between the resistive upper crust and the conductive lower crust correlates well with the cutout depth of the seismicity in West Anatolia and Thrace. This boundary is also attributed to the fluid bearing brittle–ductile transition zone in world literature. Fluid migration from the conductive lower crust to the resistive upper crust may contribute the seismicity in resistive zones. Alternatively, the upper–lower crust boundary may act as a stress concentrator and fluids may help to release strain energy in brittle parts of lower crust, by small magnitude earthquakes, whereas they may help in focusing strain in mechanically strong and electrically resistive zones for large earthquakes to occur.  相似文献   

地下水水质检测中质量异议问题的原因分析   总被引：1，自引：0，他引：1  

郭秀红 饶竹徐建明  田来生 《岩矿测试》2006,25(2):177-180

通过对国土资源部某专业实验测试中心10年质量异议资料的分析，总结了地下水水质检测中容易产生质量异议的检测参数，分析了这些参数的特点，探讨了质量异议产生的原因和预防措施。1991～2000年问该实验室共有H2SiO3、Sr、NO2^-、I^-、SO4^2-等12项检测参数出现质量异议，大多为水文地质、水文地球化学、地下水环境质量研究和地下水开发利用所关心的关键参数。产生质量异议的原因多种多样，主要有委托方主观判断错误和在样品采集与运输过程中造成的污染、检测人员技术失误和疏忽、水样本身等原因。减少质量异议的有效措施包括选择合适的测试方法、严格的校审制度及提高取样质量等。  相似文献   

基于矢量网络分析仪的低频探地雷达系统野外实验及结果分析     

YAO Jian ZENG Zhao-fa HUANG Ling ZHANG Dai-guo College of GeoExploration Science  Technology  Jilin University  Changchun    China 《吉林大学学报(地球科学版)》2006,(Z2)

系统地介绍了基于矢量网络分析仪的步进频率探地雷达系统的基本原理及组成,同时采用该系统进行了野外勘探实验.通过对实验结果进行分析表明,低频探地雷达系统适合野外应用并具有准确的探测结果。  相似文献   

Diffusion-creep modelling of fibrous pressure-shadows     

J.R. Berton  D.W. Durney  J. Wheeler  J.M. Ford 《Tectonophysics》2006,425(1-4):191-205

Grain-scale deformation of a bimineralic composite by normal-stress-driven grain-boundary diffusive mass-transfer has been modelled using diffusion-creep software that, for the first time, allows different diffusion coefficients for interphase boundaries and grain-boundaries as well as for different components. By selecting suitable coefficients we have obtained a fully coupled mechanical and mass-transfer numerical solution for the formation of fibrous pressure-shadows or strain fringes at the interface between a rigid object and a deforming rock matrix of different compositions. The model is two-dimensional and run in pure-shear velocity mode to a stretch ratio of 1.4. The first results are reported, which show dissolution and face-controlled antitaxial growth of a soluble, polycrystalline, calcite matrix at the interface with a circular and relatively insoluble pyrite object.The ratio of CaCO₃ diffusion along calcite–pyrite versus calcite–calcite boundaries strongly influences the extent of pressure-shadow growth and the pattern of strains in the matrix. A low ratio produces little growth, significant perturbation, and deflection of total-strain axes around the pyrite. An intermediate ratio produces appreciable growth, little perturbation, and near-parallel total-strain axes. A high ratio produces larger pressure-shadows, and total-strain axes that bend in towards the pyrite as if it were a weak object. Sliding and rotation of matrix grains are also affected.These results differ fundamentally from purely physical models of ductile flow around a rigid object and demonstrate the influence of interface diffusional properties on the resulting behaviour. In particular, assumptions such as perturbation of the flow by the object, deflection of external foliation around pre-deformational porphyroblasts and relationships of pressure-shadow strain to bulk strain may need to be re-examined in the light of this finding.  相似文献   

Kinematics-Based Mathematical Model for Deforming Thrust Wedges     

Matty Mookerjee  Gautam Mitra 《Mathematical Geosciences》2008,40(3):249-275

Given the wealth of data concerning the kinematics of deforming fold-thrust belts (FTBs), first-order generalizations about how the major strain components vary within a deforming thrust wedges are considered. These generally observed strain patterns are used to constrain a general, kinematics-based, FTB-wedge model. We considered five strain components within a deforming thrust sheet: (1) thrust-parallel simple shear, (2) horizontal contractional strain, (3) thrust-normal reaction strain, (4) gravitational strain, and (5) a lateral confining boundary condition. After making assumptions about how these strain components vary within a model FTB-wedge, the incremental deformation matrix can be calculated for any given point within the deforming wedge. Thus, the material path of a given marker can be determined and an initially spherical marker’s strain path can be calculated as it moves through the deforming wedge. Furthermore, by illustrating various kinematic parameters of many initially spherical markers (for example, Flinn’s k-value, incremental octahedral shear strain, transport-perpendicular stretch), we have assembled representations of the kinematic properties of the entire model wedge. By including a flat-ramp-flat fault surface geometry for the model wedge, we are able to examine the kinematic effects of this relatively common structural geometry. Within the fault ramp segment there are greater incremental strain magnitudes, out-of-the-plane motion, and flattening strains. Additionally, data from this model suggests that gravitational strains potentially have a significant effect on the strain distribution within a deforming thrust wedge. M. Mookerjee is formerly Matthew Strine.  相似文献   

ESTIMATE OF DIFFERENTIAL FLOW STRESS AND STRAIN RATE FOR HONGHE FAULT ZONE          下载免费PDF全文

An Lin-Ji  He Yong-Nian 《地震地质》1987,9(1):53

Microstructures of quartz in Honghe mylonite zone are studied and recent result of microstructural paleopiezometry is used in this paper to estimate the differential flow stress and strain rate for the southern Honghe fault zone. The calculations show that the differential flow stress during the development of mylonites of the southern Honghe fault zone varied gradually from 45MPa in the south to 120MPa in the north. Because the formation depth of mylonite zone became shallow from south to north, this variation indicates the decrease of flow stress with depth. The strain rate was roughly of the order of 10-12/se  相似文献   

安塞油田H区开发中后期储层地质建模   总被引：9，自引：1，他引：8  

刘建华  朱玉双  胡友洲  毕义君  李莉  刘艳琴 《沉积学报》2007,25(1):110-115

安塞油田H区为低孔、低渗油藏,经过10多年的注水开采,己进入开发中后期,开发矛盾日益明显。分析总结安塞油田H区长6储层地质和沉积微相特征后,指出研究区属三角洲前缘亚相沉积,并详细分析了区内出现的三角洲前缘水下分流河道、河道侧翼、分流间湾、河口坝、水下天然堤和前缘席状砂等六种沉积微相的岩性、电性特征。最后采用指示模拟的方法建立了研究区的沉积微相模型,并以此模型为基础建立了研究区的储层参数模型。验证结果表明,在相控条件下所建模型与实际地质情况符合较好,为成功挖潜剩余油提供了保证。  相似文献   

一种改进的人工鱼群聚类算法     

李小培  张洪伟  邹书蓉 《成都信息工程学院学报》2014,29(5):485-490

为了克服K-Means算法对初始类簇中心、噪声点、孤立点敏感缺点,将K-Means算法和人工鱼群算法结合,提出了改进的人工鱼群聚类算法。在该算法中将类簇中心看作一条人工鱼,让每条人工鱼执行随机、觅食、聚群、追尾行为中的一种,并将更新后的位置作为K-Means算法的初始值,不断重复人工鱼的位置更新和K-Means操作,直到算法结束。由于在算法中加入了动态移动步长和全局人最优人工鱼位置,聚类的收敛精度和速度都得到提高。使用iris和glass数据集进行聚类时,与其他算法相比,文中的收敛时间缩短2.6%,精度提高1.36%。  相似文献   

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卢祥  袁运彬  蒋振伟 《大地测量与地球动力学》2014,34(3):137-141

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