共查询到20条相似文献，搜索用时 125 毫秒
1.
第四纪松散沉积物中活断层滑动面的显微构造研究方法 总被引：3，自引：0，他引：3
第四纪松散深积物中的活断层滑动面是重要的古地震遗迹，也是鉴定古地震事件和确定古地震时代的重要标志。以往，以第四纪松散沉积物中活断层滑动面主要借助宏观观察进行研究，但遇到了一些难以解决的问题，如隐性断层问题。作者利用显微构造分析，找到了研究这些问题的途径，其方法是对第四纪松散沉积物进行定向原状样品采集，通过室内样品固结，显微薄片制作和显微构造现象观察等，从显微域里研究各种变形现象。用此方法，可以在没有宏观资料支持的情况下确定断面的运动性质；发现并描述第四纪松散沉积物中的隐性断层，研究断层的尖来机制，还可以对工程建设场地发现的不同松散沉积物相接触的现象进行活断层鉴别。 相似文献
2.
模拟断层泥的摩擦实验对地震的成核及断层带变形组构的研究具有重要意义。文中对辉长岩摩擦实验中的断层泥变形组构及形成机理进行了研究 ,以期从实验室角度来理解地壳深部断层活动的性质和特点。断层泥剪切组构中的边界剪切带 ,R1,Y剪切面比较发育 ,T裂隙次之 ;R2 ,P ,X剪切面不发育。R1面与边界面的夹角较小 ,平均在 1 1°左右 ,为单剪变形过程中达到破裂极限状态时形成的 1组库仑破裂面。分析表明R1面密度随正应力的增加而明显增高。而在相同的正应力下 ,随温度的增高 ,R1面的密度也有增加的趋势。当温度高于 5 0 0℃时 ,断层带内的斜长石出现塑性变形特征 ,R1剪切面与矿物的压性面理组成典型的S -C组构 相似文献
3.
4.
5.
断层泥的再生显微结构特征及其地震地质意义 总被引：3，自引：1，他引：3
三轴剪切摩擦实验后的断层泥与天然断层泥的再生显微结构特征研究表明，断层泥的显微结构特征与断层滑动方式之间有一定的关系，稳滑使断层泥变形均匀，产生低角度剪切（＜１４°）、布丁构造和颗粒碎裂流动。粘滑使断层泥局部发生强烈变形、高角度剪切（＞１４°）和碎粒出现随机裂纹等。断层泥的再生显微结构特征可用作鉴别古地震的存在 相似文献
6.
7.
中国大陆区断层蠕动的若干地质形迹 总被引：2，自引：0，他引：2
中国大陆区多数活动断裂虽未见有引起地表变形的明显断层蠕滑运动现象，但仍不乏断层蠕滑运动的种种地质形迹，如区域性有序的地裂运动，沿断裂分布的线性变形带，以及与地质滑动速率相比大大偏低的地震滑动速率等．认识并查明断层蠕滑运动这一重要活动习性，在理论上和实际中均有重要意义． 相似文献
8.
在2008年汶川5.12大地震同震主地表破裂带—北川-映秀破裂带中,多处断层滑动面上可见到具有强烈变形特征的薄层断层泥.在地表垂直位移量较大的西南段和东北段,选取八角庙、和尚坪和沙坝探槽中的断层泥为研究对象,利用立体镜和扫描电镜对断层泥的组构特征和Y剪切面上的微-纳米级颗粒进行形态和结构研究.观测研究结果显示,汶川5.12大地震的同震断层泥发育有明显的Y和R剪切和平直擦痕.断层滑动摩擦面磨损、研磨、粉末化则是汶川同震断层泥中微-纳米级颗粒形成的主要途径.地震断层滑动会产生摩擦热,但并不排除热分解在断层泥滑动面上纳米粒子形成过程中的重要作用.断层摩擦滑动面上普遍存有微-纳米单体及其复合体两类颗粒,微-纳米颗粒形态有球状、蚕虫状、饼状和块状等.其主要结构是散布状和堆积状结构,但也有少量条带状和层状结构,而结构单元之间常有空隙,显现松散接触.在条带状和层状结构中,仅有异化的单体颗粒,而在散布状和堆积状结构中除了主要是由单体颗粒异化形成的蚕虫状,块状和圆饼状形态的复体颗粒外,还有未变形的单体球状颗粒.Y剪切面上微-纳米颗粒的散布状、堆积状、条带状和层状结构都是在相同的地震快速变形过程中极端不平衡条件下形成的.条带状和层状结构是塑性变形,而散布状和堆积状则是脆性变形,不连续的动态摩擦(断层粘滑)是松散结构形成的主要机制.汶川地震同震断层滑动面微-纳米级颗粒的结构是地震断层滑动留下的地质形迹(不是假玄武玻璃),是地震断层滑动的记录,它可作为判定古地震断层的一种标准. 相似文献
9.
本文采用宏观与微观相结合的方法 ,研究六盘山东麓断裂的滑动方式。结果表明 :(1)根据断层泥组构特征 ,六盘山东麓断裂可划分为北、中、南 3段 ,这与前人宏观分段结果相一致 ;(2 )北段断层泥局部强烈变形 ,发育牵引褶皱 ,吕德剪切角 (R1)介于 11°～ 2 6° ,以及伊利石无明显的优选方位组构 ,表明该段断层活动是以粘滑为主的左旋走滑运动 ;(3)中、南段断层泥普遍变形 ,吕德剪切角 (R1)一般小于 11° ,P叶理、带状褶皱和肠状构造发育 ,以及伊利石复杂的优选方位组构 ,显示该断层的活动是以蠕滑为主的多期逆冲滑动 相似文献
10.
利用光学和电子显微镜研究了海原断裂带西段断层泥的粒径分布，５微米至１厘米的粒径段，断层泥具有自相似特征，断层面的粘滑摩擦的特征位移参数可由分维上限（约１厘米）确定。同时用分形理论分析了断层泥粒度分重量百分比的分形结构特征，探讨了粒度成分分维值与断层运动特征的关系。 相似文献
11.
在不同的压力、温度和孔隙压力下进行了含四种不同断层泥标本的强度试验。碎屑型断层泥对压力很敏感,对温度无反应,对孔隙压力的反应符合有效应力律。粘土类断层泥则对温度和孔隙压力有明显响应。这些力学性质的差别反映了具体变形机制的差别 相似文献
12.
Kiran Kumar Singh Thingbaijam Sankar Kumar Nath Abhimanyu Yadav Abhishek Raj M. Yanger Walling William Kumar Mohanty 《Journal of Seismology》2008,12(1):107-123
Recent seismicity in the northeast India and its adjoining region exhibits different earthquake mechanisms – predominantly
thrust faulting on the eastern boundary, normal faulting in the upper Himalaya, and strike slip in the remaining areas. A
homogenized catalogue in moment magnitude, M
W, covering a period from 1906 to 2006 is derived from International Seismological Center (ISC) catalogue, and Global Centroid
Moment Tensor (GCMT) database. Owing to significant and stable earthquake recordings as seen from 1964 onwards, the seismicity
in the region is analyzed for the period with spatial distribution of magnitude of completeness m
t, b value, a value, and correlation fractal dimension D
C. The estimated value of m
t is found to vary between 4.0 and 4.8. The a value is seen to vary from 4.47 to 8.59 while b value ranges from 0.61 to 1.36. Thrust zones are seen to exhibit predominantly lower b value distribution while strike-slip and normal faulting regimes are associated with moderate to higher b value distribution. D
C is found to vary from 0.70 to 1.66. Although the correlation between spatial distribution of b value and D
C is seen predominantly negative, positive correlations can also be observed in some parts of this territory. A major observation
is the strikingly negative correlation with low b value in the eastern boundary thrust region implying a possible case of extending asperity. Incidentally, application of
box counting method on fault segments of the study region indicates comparatively higher fractal dimension, D, suggesting an inclination towards a planar geometrical coverage in the 2D spatial extent. Finally, four broad seismic source
zones are demarcated based on the estimated spatial seismicity patterns in collaboration with the underlying active fault
networks. The present work appraises the seismicity scenario in fulfillment of a basic groundwork for seismic hazard assessment
in this earthquake province of the country. 相似文献
13.
本文对龙门山断裂带金河磷矿浅钻岩芯中的三种断层泥开展了低速到高速摩擦滑动的实验研究，并对实验变形样品开展了BET比表面积研究.摩擦实验在干燥和孔隙水压条件下开展，速率范围涵盖20 μm·s-1~1.4 m·s-1.实验结果显示，三种断层泥在干燥条件下的摩擦性质差别不大，但在孔隙水压条件下，三者的中低速摩擦强度与层状硅酸盐矿物的种类而非总含量紧密相关，蒙脱石和伊利石相比绿泥石更能有效地弱化断层.三种断层泥在孔隙水压条件下存在中低速率域的速度强化，暗示着对断层的加速滑动存在一定的阻碍作用.孔隙水压下，黄绿色和灰绿色断层泥的初始动态弱化非常迅速并伴随断层泥层的瞬时扩容，凹凸体急剧加热导致的局部热压作用可能是造成这种力学行为的物理机制.在经历高速滑动之后，三种断层泥在干、湿条件下的BET比表面积都显著降低，暗示着可能发生了颗粒烧结.中低速域内，孔隙水的存在使得断层泥呈现分散式的剪切变形，BET比表面积的增加因此比干燥条件下更加明显.对表面能的估算表明，颗粒磨碎所消耗的能量至多不超过摩擦力做功的8%，暗示着断层作用中颗粒磨碎所占的能量比例较低. 相似文献
14.
柔性断层错动产物的微观研究方法初探 总被引：2，自引：0，他引：2
柔性断层错动产物一般尚未固结,难以对其进行定向取样,固化和磨制薄片,笔者经过长期努力提出解决这个问题的方法并将其应用于郯—庐断裂带赤山段晚更新世以来活动性的研究中。笔者按总结出的方法定向采取断层泥,对其固化并磨制定向薄片,在镜下仔细观测,发现众多变形现象和由其反映的运动学和动力学方面的重要信息。属脆性变形的有:长英质矿物颗粒被错移并形成棋盘格式构造,脆—塑或塑性变形发生在粘土和云母类的矿物中,尤其是“帚”状扭折和先扭后错现象在云母中非常普遍。恢复薄片的自然产状后,宏微观构造具统一性。据变形产物赋存的地质时代,它们应是断裂晚更新世以来活动的微观证据。文中笔者除系统介绍了柔性断层产物的采样、固结、磨片和应用此种技术的实例外,还探讨了显微构造分析在活断层研究中应有的地位和作用。 相似文献
15.
5.12汶川地震同震地表破裂带在虹口八角-深溪沟一带主要出露于三叠系须家河组的炭质泥岩中,同震断层泥在颜色、结构上与老断层泥和围岩类似。通过开挖探槽,系统采样,采用粉晶X射线衍射定量分析方法,研究了同震地表破裂带的围岩、断层角砾岩、老断层泥和新断层泥的矿物成分特征。同震断层泥的主要成分为石英和黏土矿物,含微量长石和白云石;断层泥的显著特征为高黏土矿物含量,从同震断层泥、老断层泥、角砾岩到围岩黏土矿物含量依次降低,黏土矿物以伊利石和伊蒙混层为主,含微量绿泥石和高岭石,矿物组成明显比地表破裂带北段同震断层泥简单。不同颜色的同震断层泥成分略有不同,黑色断层泥中伊利石含量明显高于白色断层泥;老断层泥中含有方解石和白云石,而同震断层泥不含方解石,只含微量白云石。同震断层泥中伊蒙混层高含量表明,在本次地震错动中有富含K的流体参与。 相似文献
16.
Francis T. Wu 《Pure and Applied Geophysics》1978,116(4-5):655-689
Fault gouges have been observed in the surface outcrops, in shallow excavations, and in deep (300 meters below the surface) tunnels and mines in fault zones. The 2-microns fractions in these fault gouges may compose a few percent to more than fifty percent of the total mass in the outcrops, and the mineralogy of the 2-microns fractions consists of a variety of clays (the common ones are montmorillonite, illite, kaolinite, chlorite, vermiculite and mixed-layer clays) and some quartz, feldspars, etc.Although we cannot yet conclude directly from the studies of gouges that similar gouges exist at depths where many large shallow earthquakes are generated, there is a strong possibility that they do, based on (1) available equilibrium data on various clays — for example, kaolinite has been found to exist at 4 kb and 375°C (±15°C) (Thompson, 1970) and montmorillonite + kaolite has been found to exist at 450°C and 4 kb (Velde, 1969); (2) the compatibility of laboratory velocity data in gouge (Wang
et al., 1977) with those in a model for central California (Healy andPeake, 1975); (3) the capability of clays to undergo sudden earthquake-like displacements (Summers andByerlee, 1977); (4) the petrology of intrafault cataclastic rocks in old fault zones (Kasza, 1977); and (5) the compatibility of gouge mineralogy with the mineralogy of hydrothermal clay deposits.If clay gouges are indeed significant components of the fault zone at depth, then the mechanical properties of clays under confining pressures up to 4 kb are important in the behavior of faults. Very few experiments have been performed under such high pressures. But from the physical makeup of clays, we can infer that (1) the range of possible behavior includes stable sliding with vermiculite and montmorillonite (asByerlee andSummers, 1977, have proven) to stick-slip-like behavior with kaolinite, chlorite, etc.; (2) the absence or presence of water will greatly affect the strengths of gouges — it is possible that water may reduce the strength of gouge to a fairly small value. 相似文献
17.
THE GEOLOGICAL AND ROCK MECHANICAL DISTINCTION EVIDENCE BETWEEN STICK-SLIP AND CREEP IN HOST ROCK SEGMENTS OF FAULT 
下载免费PDF全文
下载免费PDF全文 ZHOU Yong-sheng 《地震地质》2019,41(5):1266-1272
Paleo-seismic and fault activity are hard to distinguish in host rock areas compared with soft sedimentary segments of fault. However, fault frictional experiments could obtain the conditions of stable and unstable slide, as well as the microstructures of fault gouge, which offer some identification marks between stick-slip and creep of fault.
We summarized geological and rock mechanical distinction evidence between stick-slip and creep in host rock segments of fault, and analyzed the physical mechanisms which controlled the behavior of stick-slip and creep. The chemical composition of fault gouge is most important to control stick-slip and creep. Gouge composed by weak minerals, such as clay mineral, has velocity weakening behavior, which causes stable slide of fault. Gouge with rock-forming minerals, such as calcite, quartz, feldspar, pyroxene, has stick-slip behavior under condition of focal depth. To the gouge with same chemical composition, the deformation mechanism controls the frictional slip. It is essential condition to stick slip for brittle fracture companied by dilatation, but creep is controlled by compaction and cataclasis as well as ductile shear with foliation and small fold. However, under fluid conditions, pressure solution which healed the fractures and caused strength recovery of fault, is the original reason of unstable slide, and also resulted in locking of fault with high pore pressure in core of fault zone. Contrast with that, rock-forming minerals altered to phyllosilicates in the gouges by fluid flow through degenerative reaction and hydrolysis reaction, which produced low friction fault and transformations to creep. The creep process progressively developed several wide shear zones including of R, Y, T, P shear plane that comprise gouge zones embedded into wide damage zones, which caused small earthquake distributed along wide fault zones with focal mechanism covered by normal fault, strike-slip fault and reverse fault. However, the stick-slip produced mirror-like slide surfaces with very narrow gouges along R shear plane and Y shear plane, which caused small earthquake distributed along narrow fault zones with single kind of focal mechanism. 相似文献
18.
19.
Development of faults as zones of deformation bands and as slip surfaces in sandstone 总被引：10，自引：0，他引：10
Three forms of fault are recognized in Entrada and Navajo Sandstones in the San Rafael Desert, southeastern Utah; deformation bands, zones of deformation bands, and slip surfaces. Small faults occur asdeformation bands, about one millimeter thick, in which pores collapse and sand grains fracture, and along which there are shear displacements on the order of a few millimeters or centimeters. Two or more deformation bands adjacent to each other, which share the same average strike and dip, form azone of deformation bands. A zone becomes thicker by addition of new bands, side by side. Displacement across a zone is the sum of displacements on each individual band. The thickest zones are about 0.5 m and total displacement across a thick zone rarely exceeds 30 cm. Finally,slip surfaces, which are through-going surfaces of discontinuity in displacement, form at either edge of zones of highly concentrated deformation bands. In contrast with individual deformation bands and zones of deformation bands, slip surfaces accommodate large displacements, on the order of several meters in the San Rafael Desert.The sequence of development is from individual deformation bands, to zones, to slip surfaces, and each type of faulting apparently is controlled by somewhat different processes. The formation of zones apparently involves strain hardening, whereas the formation of slip surfaces probably involves strain softening of crushed sandstone. 相似文献