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1.
沂沭断裂带及其附近断裂的断层泥分形特征及其地震地质意义 总被引：7，自引：0，他引：7
利用岩石碎裂数目的分形理论，分析，计算了沂沭断裂带及其西侧北西向断裂的断层泥粒度成分的分维值，讨论了断层泥粒度成分分维的地震地质意义，研究结果表明，沂沭断裂带内的断裂活动的强度大于北西向断裂活动强度；Ｆ２是沂沭断裂带中活动最强的一条断裂，断层泥粒度成分分维值可作为表征断裂活动时代，破裂形式和断层泥形成斫代等的参量；分维值还与断层泥的母岩，厚度，粘土矿物含量和所处的断裂部位等相关。 相似文献
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In this work,the fractal dimension of granulometric composition in the fault gouge from the Yishu fault zone and northwest-trending faults on its west side is calculated and studied based on the fractal theory of rock fragmentation.The seismo-geological implications of the fractal dimension of granulometric composition in fault gouges are also discussed.The results show that the Yishu fault zone is more active than the northwest-trending faults and the Anqiu-Juxian fault is the most active in the Yishu fault zone.The fractal dimension of fault gouge is a parameter describing the relative active age and rupture mode of the fault and forming age of the fault gouge.The fractal dimension value is also related to the parent rock,thickness,structural position,and clay content of the fault gouge. 相似文献
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Fractal research of fault gouge 总被引：1，自引：0，他引：1
ＦｒａｃｔａｌｒｅｓｅａｒｃｈｏｆｆａｕｌｔｇｏｕｇｅＳＨＵＮ－ＭＥＩＳＨＡＯ（邵顺妹）ａｎｄＪＩＮ－ＣＨＡＮＧＺＯＵ（邹瑾敞）ＥａｒｔｈｑｕａｋｅＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆＬａｎｚｈｏｕ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａ... 相似文献
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The particle size distributions of fault gouge from the San Andreas, the San Gabriel, and the Lopez Canyon faults in Southern California were measured using sieving and Coulter-Counter techniques over a range of particle sizes from 2 m to 16 mm. The distributions were found to be power law (fractal) for the smaller fragments and log-normal by mass for sizes near and above the peak size. The apparent fractal dimensionD of the smaller particles in gouge samples from the San Andreas fault, the San Gabriel fault and the Lopez Canyon gouge were 2.4–3.6, 2.6–2.9 and 2.4–3.0, respectively. The averageD for the Lopez Canyon gouge was 2.7±0.2, which is in agreement with earlier studies of this gouge using planar 2-D sections. The fractal dimension of the finer fragments from all three faults is observed to be correlated with the peak fragment size, with finer gouges tending to have a largerD. A computer automaton is used to show that this observation may be explained as resulting from a fragmentation process which has a grinding limit at which particle reduction stops. 相似文献
6.
The microstructural state and evolution of fault gouge has important implications for the mechanical behaviour, and hence
the seismic slip potential of faults. We use 3D discrete element (DEM) simulations to investigate the fragmentation processes
operating in fault gouge during shear. Our granular fault gouge models consist of aggregate grains, each composed of several
thousand spherical particles stuck together with breakable elastic bonds. The aggregate grains are confined between two blocks
of solid material and sheared under a given normal stress. During shear, the grains can fragment in a somewhat realistic way
leading to an evolution of grain size, grain shape and overall texture. The ‘breaking up’ of the fault gouge is driven by
two distinct comminution mechanisms: grain abrasion and grain splitting. The relative importance of the two mechanisms depends
on applied normal stress, boundary wall roughness and accumulated shear strain. If normal stress is sufficiently high, grain
splitting contributes significantly to comminution, particularly in the initial stages of the simulations. In contrast, grain
abrasion is the dominant mechanism operating in simulations carried out at lower normal stress and is also the main fragmentation
mechanism during the later stages of all simulations. Rough boundaries promote relatively more grain splitting whereas smooth
boundaries favor grain abrasion. Grain splitting (plus accompanying abrasion) appears to be an efficient mechanism for reducing
the mean grain size of the gouge debris and leads rapidly to a power law size distribution with an exponent that increases
with strain. Grain abrasion (acting alone) is an effective way to generate excess fine grains and leads to a bimodal distribution
of grain sizes. We suggest that these two distinct mechanisms would operate at different stages of a fault’s history. The
resulting distributions in grain size and grain shape may significantly affect frictional strength and stability. Our results
therefore have implications for the earthquake potential of seismically active faults with accumulations of gouge. They may
also be relevant to the susceptibility of rockslides since non-cohesive basal shear zones will evolve in a similar way and
potentially control the dynamics of the slide. 相似文献
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断层泥粒度成分的分形研究 总被引：10，自引：3，他引：10
用分形理论分析了断层泥粒度成分的分形结构特征，其分维在２～３之间，平均值为２．８左右。分维可作为定量描述断层泥粒度成分的参数，分维值高的断层泥，自组织程度高，其形成演化处于高级阶段。探讨了断层泥的分维及其物理力学性质指标和断层运动特征的关系 相似文献
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断层岩的粒度分布包含岩石破裂机制、摩擦性质和地震能量分配等重要信息。筛分-称重和激光测量是分析断层岩三维粒度的2种有效方法,但每一种方法的测量范围仅有3个量级,难以全面反映断层岩的粒度分布特征。利用上述2种方法对汶川地震断层滑动带上的断层岩（简称断层岩）的粒度分布进行了测量,粒径测量范围从0.2μm至16mm,跨度达到5个数量级。结果显示：1）存在临界粒径dc（0.95～1.90μm）。粒度大于和小于dc的颗粒满足不同的颗粒数（Nd）-粒径（d）分布关系,表明该断层岩的粒径分布不具有自相似性特征。2）利用粒度大于dc的颗粒计算出的分形维数与断层岩类型有很好的相关性,即断层带边缘的角砾岩的平均分形维数为2.6,核部压碎角砾岩的平均分形维数约为3.0,中心断层泥的分形维数约为3.5。粒径小于dc的颗粒的分形维数为1.7～2.1。分形维数的突变反映出断层破裂机制的复杂性,即在不同的粒度域,岩石的破裂机制不尽相同。3）依据粒度分析结果,估算出汶川地震断层泥的单位破裂能（Es）为0.63MJ/m2。 相似文献
9.
Changes in magnetic and fractal properties of fractured granites near the Nojima Fault, Japan 总被引：2，自引：0，他引：2
Abstract Anisotropy of magnetic susceptibility (AMS) has been used to infer finite strain fabrics in plastically deformed rocks, but there are few studies of magnetic properties in fractured fault rocks. Changes in magnetic and fractal properties of fractured granites from the Disaster Prevention Research Institute, Kyoto University (DPRI) 500 m drilling core towards the Nojima Fault and of the well-foliated fault gouge are described. Fractal analysis of fractured granites shows that the fractal dimension ( D ) increases linearly toward the gouge zone of the fault. In weakly fractured granites ( D = 1.05–1.24), it was found that the degree of AMS correlates positively with the fractal dimension, suggesting a fracture-related magnetic fabric due to fracturing. In strongly fractured granites ( D = 1.25–1.50), weaker, nearly isotropic AMS is found, suggesting erasure by the fragmentation of the magnetic minerals. Within the fault gouge zone, an isotropic AMS fabric was found, as well as twofold increases in magnetic intensity and susceptibility. These changes reflect the production of new magnetite grains, subsequently confirmed by hysteresis studies, which suggests that fault gouge might be regarded as the source of the regional geomagnetic field contrast along active faults. Thus, AMS is clearly a potentially useful tool for inferring the fracturing texture of magnetic minerals in fractured rocks and detecting active faults from the high susceptibility contrast of fault gouge. 相似文献
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Detailed observation of the microstructural features of 11 fault gouge and 3 fault breccia samples collected from Tianjingshan-Xiangshan
fault zone has revealed that fault gouge can be classified into 3 types: flow banded granular gouge, foliated gouge and massive
gouge. The determination of the shape preferred orientation (SPO) of survivor grains in fault gouges indicates that the foliated
gouge displays a profound SPO inclined to the shear zone boundary, similar to theP-foliation; flow banded granular gouge displays a SPO parallel to the shear zone boundary, while massive fault gouge and fault
breccia display a random SPO. All these fault gouges fall in different fields of shear rate ternary diagram. 相似文献
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Fractals,fault-gouge,and friction 总被引：5，自引：0，他引：5
The particle-size distribution of a natural fault-gouge has been determined over the range from 5 m to 40 cm. The gouge is self-similar over the range from 5 m to 1 cm having a fractal dimension of 2.60±0.11. The lower and upper fractal limits were also determined. The lower fractal limit occurs at a dimension of about 1–10 m where mineral cleavage and intergranular porosity dominate the cataclasis. The upper fractal limit occurs at particle sizes on the order of 1 cm where the scaled particle density decreases abruptly by a factor of about three. By analogy to soil-mechanics shear box tests and laboratory rock friction experiments, it is argued that the upper fractal limit of the gouge determines the characteristic displacement parameter in stick-slip friction models. A characteristic displacement on the order of 1 cm is consistent with estimates based on numerical simulations of faulting. 相似文献
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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
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本文对海原断裂的断层泥的各类特征进行了系统的研究,分析了断层泥带内部的小型断裂类型,探讨了断层泥组分的有机地球化学意义。通过对比,确立了石英碎屑表面机械作用成因的电子显微构造特征组合为活断层的判别标志。本文将石英碎屑表面电子显微溶蚀构造分为五类,据此分析了断层活动时期和状态。研究中还发现了断层泥带内部电子显微结构类型,进而分析了断层活动与微结构、粒度分布间的关系。最后还讨论了断层泥形成演化过程以及断层泥对全新世以来断层滑动性能影响及其与地震活动的关系 相似文献
16.
Koichiro Fujimoto Hidemi Tanaka Takayuki Higuchi Naoto Tomida Tomoyuki Ohtani Hisao Ito 《Island Arc》2001,10(3-4):401-410
Abstract Mineralogical and geochemical studies on the fault rocks from the Nojima–Hirabayashi borehole, south-west Japan, are performed to clarify the alteration and mass transfer in the Nojima Fault Zone at shallow depths. A complete sequence from the hornblende–biotite granodiorite protolith to the fault core can be observed without serious disorganization by surface weathering. The parts deeper than 426.2 m are in the fault zone where rocks have suffered fault-related deformation and alteration. Characteristic alteration minerals in the fault zone are smectite, zeolites (laumontite, stilbite), and carbonate minerals (calcite and siderite). It is inferred that laumontite veins formed at temperatures higher than approximately 100°C during the fault activity. A reverse component in the movement of the Nojima Fault influences the distribution of zeolites. Zeolite is the main sealing mineral in relatively deep parts, whereas carbonate is the main sealing mineral at shallower depths. Several shear zones are recognized in the fault zone. Intense alteration is localized in the gouge zones. Rock chemistry changes in a different manner between different shear zones in the fault zone. The main shear zone (MSZ), which corresponds to the core of the Nojima Fault, shows increased concentration of most elements except Si, Al, Na, and K. However, a lower shear zone (LSZ-2), which is characterized by intense alteration rather than cataclastic deformation, shows a decreased concentration of most elements including Ti and Zr. A simple volume change analysis based on Ti and Zr immobility, commonly used to examine the changes in fault rock chemistry, cannot account fully for the different behaviors of Ti and Zr among the two gouge zones. 相似文献
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断层岩,尤其是断层泥的磁性异常近年来被研究人员广泛关注,但关于其磁性异常的形成原因尚没有统一的解释．海原断裂是青藏高原东北缘一条重要的走滑断裂,前期研究发现海原断裂带景泰段出露有数十米至上百米的断层岩,是理想的研究材料．本研究选取海原断裂带景泰段老虎山山前一个断层岩剖面作为研究对象,拟通过测量断层岩的磁化率（χ）、非磁滞剩磁（ARM）、饱和等温剩磁（SIRM）、等温剩磁（IRM）以及磁化率随温度变化曲线（χ-T曲线）等磁学参数并结合粒度、碳含量、X射线衍射（XRD）等分析方法来探究海原断裂带老虎山段不同颜色断层岩的磁性特征及其形成机制．磁学研究显示黑色、红色及杂色断层泥相较于围岩和破碎带显示了低磁性,尤其是黑色断层泥,其磁化率值均小于10×10~(-8 )m~3·kg~(-1)．碳含量及矿物相分析结果指示黑色断层泥与断裂带附近石炭系煤层具有相似的矿物相组成,结合相似的χ-T曲线推断石炭系煤层为黑色断层泥的母岩．石炭系煤层经断层活动卷入断层,在断层强烈剪切摩擦作用下不断细化,形成伊利石等黏土矿物,并促使一部分顺磁性含铁硅酸盐矿物或其他含铁矿物发生化学变化形成亚铁磁性矿物,使得黑色断层泥的磁化率较其母岩石炭系煤层有一定升高．通过黑色断层泥的铁磁性磁化率结合χ-T曲线计算获得断层泥所经历的最高温度约为420℃,不超过450℃．老虎山段厚层碳质断层泥的存在为该地区发现的浅层蠕滑现象提供了一种解释． 相似文献
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The mechanisms of finite brittle strain 总被引：1，自引：0，他引：1
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Despite the insight gained from 2-D particle models, and given that the dynamics of crustal faults occur in 3-D space, the question remains, how do the 3-D fault gouge dynamics differ from those in 2-D? Traditionally, 2-D modeling has been preferred over 3-D simulations because of the computational cost of solving 3-D problems. However, modern high performance computing architectures, combined with a parallel implementation of the Lattice Solid Model (LSM), provide the opportunity to explore 3-D fault micro-mechanics and to advance understanding of effective constitutive relations of fault gouge layers. In this paper, macroscopic friction values from 2-D and 3-D LSM simulations, performed on an SGI Altix 3700 super-cluster, are compared. Two rectangular elastic blocks of bonded particles, with a rough fault plane and separated by a region of randomly sized non-bonded gouge particles, are sheared in opposite directions by normally-loaded driving plates. The results demonstrate that the gouge particles in the 3-D models undergo significant out-of-plane motion during shear. The 3-D models also exhibit a higher mean macroscopic friction than the 2-D models for varying values of interparticle friction. 2-D LSM gouge models have previously been shown to exhibit accelerating energy release in simulated earthquake cycles, supporting the Critical Point hypothesis. The 3-D models are shown to also display accelerating energy release, and good fits of power law time-to-failure functions to the cumulative energy release are obtained. 相似文献