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81.
程各庄断裂断层泥显微结构特征及其断裂活动性探讨 总被引:1,自引:0,他引:1
程各庄断裂是马坊-夏垫断裂带北段的一条东分支断裂,根据其断层泥的显微结构,石英碎屑SEM特征,热释光年龄综合分析,结果表明,该断裂不同区段的最新活动都是以粘滑迷主,但各个区段不同地质时期其活动方式和强度不同。 相似文献
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武功山东区存在一条大型韧性剪切带。鞘褶皱倒向以及旋转变形构造(如S-C面理组构、旋转碎斑系、雪球构造和粒内显微破裂构造等)显示此剪切带为由南向北逆冲推覆性质。砾石、黄铁矿还原斑和石英斑晶的有限应变分析表明剪切带西段和东段岩石分别以收缩型椭球和压扁型椭球变形为特征。剪切带的主要变形时代是早古生代,可能与早古生代华夏陆块和扬子陆块之间的碰撞造山作用有关。 相似文献
84.
满城冰雹微结构的观测研究 总被引:2,自引:0,他引:2
根据河北满城1986—1990年4000多个冰雹样品和843个冰雹切片的观测资料,对冰雹微结构特征(即冰雹胚胎、层次、冰晶和气泡)进行了统计分析,并推论出冰雹生长(即环境温度和海拔高度)的情况。 相似文献
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Shaocheng Ji Kazuko Saruwatari David Mainprice Richard Wirth Zhiqin Xu Bin Xia 《Tectonophysics》2003,370(1-4):49-76
Ultra high-pressure (UHP) eclogites from Sulu region (China) represent mafic components of the continental crust, which were first subducted to mantle depths greater than 100 km and then exhumed to the earth's surface. Detailed investigation of microstructures, chemical compositions, petrofabrics and seismic properties of the UHP eclogites can provide important information on the operating deformation mechanisms and rheology of subducted continental crust and on the origin of seismic reflections within the upper mantle. We present here results from field, optical and TEM observations, electron back-scattered diffraction (EBSD) measurements and numerical computations of the seismic properties of UHP eclogites collected from fresh surface outcrops at the drill site (Maobei, Donghai County, Jiangsu Province) of the Chinese Continental Scientific Drilling Program (CCSD). Two types of eclogites have been distinguished: Type-1 (coarse-grained) eclogites deformed by recovery-accommodated dislocation creep at the peak metamorphic conditions, and Type-2 (fine-grained) eclogites which are composed of reworked Type-1 materials during recrystallization-accommodated dislocation creep in shear zones which were active during the exhumation of the UHP metamorphic rocks. Both garnet and omphacite in these eclogites deformed plastically and the flow strength contrast between these two constituent minerals is apparently much less than an order of magnitude under the UHP metamorphic conditions. Plasticity of eclogites under UHP conditions can effectively facilitate channeled flow along the interplate shear zone. The preservation of the relict crustal materials within the continental lithosphere may produce regionally extensive, strong, seismic reflections in the upper mantle. This may explain the origin of mantle reflections observed in many areas of the world. 相似文献
87.
Footwall rocks of the northern Snake Range detachment fault (Hampton and Hendry's Creeks) offer exposures of quartzite mylonites (sub-horizontal foliation) that were permeated by surface fluids. An S–C–C′ mylonitic fabric is defined by dynamically recrystallized quartz and mica. Electron backscatter diffraction analyses indicate a strong preferred orientation of quartz that is overprinted by two sets of sub-vertical, ESE and NNE striking fractures. Analyses of sets of three perpendicular thin sections indicate that fluid inclusions (FIs) are arranged according to macroscopic fracture patterns. FIs associated with NNE and ESE-striking fractures coevally trapped unmixed CO2 and H2O-rich fluids at conditions near the critical CO2–H2O solvus, giving minimum trapping conditions of T = 175–200 °C and ∼100 MPa H2O-rich FIs trapped along ESE-trending microcracks in single crystals of quartz may have been trapped at conditions as low as 150 °C and 50 MPa indicating the latest microfracturing and annealing of quartz in an overall extensional system. Results suggest that the upper crust was thin (4–8 km) during FI trapping and had an elevated geotherm (>50 °C/km). Footwall rocks that have been exhumed through the brittle-ductile transition in such extensional systems experience both brittle and crystal-plastic deformation that may allow for circulation of meteoric fluids and grain-scale fluid–rock interactions. 相似文献
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This paper reports on the compressive strength and microstructure of unfired clay masonry bricks. Blended binders comprising of lime-activated Ground Granulated Blastfurnace Slag (GGBS) and Portland Cement (PC)-activated GGBS were used to stabilise Lower Oxford Clay (LOC) for unfired masonry brick production. The compressive strength of the stabilised bricks incorporating lime–GGBS–LOC was higher than that of PC–GGBS–LOC. Scanning Electron Microscopy (SEM) with a Solid-state Backscattered Detector (SBD) and Energy Dispersive X-ray (EDX) analysis was employed to obtain a view of the microstructure and to conduct an analysis on the morphology and composition of the dried unfired clay brick samples, after 28 days of moist curing. The analytical results together with the physical observations have shown the formation of Calcium Silicate Hydrate (C-S-H) gel and additional pozzolanic (C-S-H) gel. The quantification of the compound content of the unfired bricks showed the presence of Calcite (CaCO3), Quartz (SiO2), Alumina (Al2O3) and Wollastonite (CaSiO8) crystals. Traces of other crystals were also detected. 相似文献