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41.
42.
20 0 1年 11月 14、 15日新疆喀什台记录到 86次振动事件 (“奇异震群”事件 )。为识别其性质 ,应用波谱分析、偏振分析等方法 ,对该事件和同范围构造地震的地震波特征进行了对比研究 ,发现 :(1)喀什“震群”的全波列衰减比构造地震的全波列衰减快很多 ;(2 )与构造地震的速度谱相比 ,“震群”的频谱相对较为“集中”,而构造地震的则较为“发散”;(3)“震群”位移谱的拐角频率和卓越频率均较构造地震的相应量高出一倍多 ,且离散较小。通过对喀什“奇异震群”这些特征进行分析研究 ,认为这一事件极有可能是人工事件 相似文献
43.
1998年1月5日烃阳Ms 4.8地震是陕西省近40年来发生的最大一次地震。研究了此次地震的构构背景和地球物理场特征。 相似文献
44.
The Serra Gelada sea cliffs are carved in Mesozoic carbonate rocks belonging to the External Zones of the eastern Betic Cordillera (Alicante, SE Spain). Several normal faults with vertical slips of more than a hundred metres have played an important role in the origin of this coastline. Some previous studies propose that the present cliff morphology was mainly originated by Quaternary fault activity. However, the integration of geomorphological features, stratigraphical and sedimentological data, together with the results of the tectonic analysis of fractures occurring in Serra Gelada, and a detailed study of seismic reflection profiles carried out in the adjacent continental shelf, indicate that these normal faults were active mainly during the late Miocene. Therefore, the Serra Gelada sea cliffs represent a tectonically controlled long-term landscape. Thus, normal faults have not significantly modified the Serra Gelada relief since then. Furthermore, the northern part of the Serra Gelada cliff may be considered as an inherited pre-Quaternary relict palaeocliff since it has only undergone very little erosive recession. 相似文献
45.
Effective timescales of coupling within fluvial systems 总被引:1,自引:0,他引:1
This paper presents a review of the coupling concept in fluvial geomorphology, based mainly on previously published work. Coupling mechanisms link the components of the fluvial system, controlling sediment transport down the system and the propagation of the effects of base-level change up the system. They can be viewed at several scales: at the local scale involving within-hillslope coupling, hillslope-to-channel coupling, and within-channels, tributary junction and reach-to-reach coupling. At larger scales, coupling can be considered as zonal coupling, between major zones of the system or as regional coupling, relating to complete drainage basins. These trends are illustrated particularly by the examples of hillslope-to-channel coupling in the Howgill Fells, northwest England, badland systems in southeast Spain, alluvial fans in Spain, USA and UAE, and base-level-induced dissection of Neogene sedimentary basins in southeast Spain. As the spatial scales increase, so do the timescales involved. Effective temporal scales relate to magnitude and frequency characteristics, recovery time and propagation time, the relative importance changing with the spatial scale. For downsystem coupling at the local scale, the first two are important, with propagation time increasing in importance in larger systems, especially in those involving upsystem coupling related to base-level change. The effective timescales range from the individual event, with a return period of decades, through decadal to century timescales for downsystem coupling, to tens to hundreds of thousands of years for the basinwide response to base-level change. The effective timescales influence the relative importance of factors controlling landform development. 相似文献
46.
滇西北石鼓片岩变质变形特征及其划分 总被引:3,自引:0,他引:3
滇西北金沙江结合带东侧的石鼓变质岩系,可划分为石鼓岩群和巨甸岩群。石鼓岩群受区域动力热流变质作用改造,主期变形环境为中、深部构造相;巨甸岩群受区域低温动力变质作用改造,与之相伴的构造形迹属中、浅部构造相。石鼓岩群包含羊坡岩组和露西岩组,巨甸岩群可进一步划分为陇巴岩组和塔城岩组。同一岩群的岩组,变质作用、构造变形特征相同,但变质岩石组合及原岩特征却有明显差别。 相似文献
47.
A detailed investigation permitted us to obtain quantitative data concerning fine geometric structures of 4 faults of the active Maxianshan-Xinglongshan fault system and the latest movement along them. Of them the northern Maxianshan border fault is a large-scale, strongly active Holocene reverse sinistral strike-slip fault, the other 3 faults, the southern Maxianshan border fault and the southern Xinglongshan border and the northern Xinglongshan border faults are the accompanying active late-Pleistocene thrust faults, which are incorporated into the main strike-slip fault, the northern Maxianshan border fault at depth. It is the most important earthquake-controlling fault in the Lanzhou area, the fault influences and constrains the seismic activity in the area. 相似文献
48.
49.
滇西思茅大平掌矿区火山岩特征及其构造环境 总被引:3,自引:0,他引:3
滇西大平掌铜多金属矿床的含矿建造(龙洞河组)主要由细碧岩-角斑岩-石英角斑岩和流纹岩-硅质岩组成,伴有部分火山角砾岩、凝灰岩,属双峰式火山岩组合。火山岩具明显的Na2O>K2O和Nb、Ta、Zr、Hf、Ti亏损。岩石化学和微量元素判别标志指示含矿建造形成于岛弧裂陷环境。结合区域构造古地理资料分析,它是滇西南古特提斯洋壳在晚石炭世-早二叠世由西向东俯冲过程中岩浆作用的结果。 相似文献
50.
以大别造山带南部菖蒲地区为解剖区,结合区域地质调查分析,建立了包括浅变质岩层、超高压变质岩片在内的构造地层序列—岩片组合。对其组成特征、界面性质、形成时代、变形序列等,进行了较系统阐明,并对叠加褶皱型式及形成机制进行了讨论。 相似文献