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831.
832.
The article describes the characteristics of the Yagan metamorphic core complex, especially the associated detachment fault and various extensional structures in its footwall. The age of the complex is discussed in some detail as well. The basic features of the Yagan metamorphic complex (Jurassic in age) are similar to those of the metamorphic core complex (Tertiary in age) in the Cordilleran area; they are as follows: (a) mylonitic gneisses in the footwall, (b) chloritized sheared mylonitic rocks, (c) pseudotachylites and flinty cataclasites or microbreccias, (d) unmetamorphosed or epimetamorphic rocks in the hanging wall with a layer of fault gouges or incohesive fault breccia next to the detachment fault. In contrast to its Cordilleran counterpart, however, there are many extensional faults with different styles (from dactile low-angle normal faults through brittle-ductile to brittle high-angle normal faults)in the footwall. 相似文献
833.
小秦岭矿化带近东西向展布有5个金矿化宫集带(亚矿带)。其中以文峪-杨砦峪亚矿带矿脉密度最大,矿床数量最多。全区发育有两类金矿化,即含金石英脉型与蚀变岩型,两者空间发育具互补性特点以及一定的分带趋势。全区自西向东,石英脉型矿化所占比重渐减,蚀变岩型矿化逐增,至东部雪家山岩体以东则形成一些蚀变岩型小型矿床,垂向分布上,含金石英脉型矿化多在浅部;蚀变岩型矿化则多发育于深部。 相似文献
834.
基于对失饱和带毛管与潜水流间交互作用的分析,提出了以“失水带迟后反应”模式计算延迟给水下的定降深流动①的成因方法。它能自然地解释水位、水头的Walton三阶段演变规律,且拟合实测资料,具较强实用性。现行的纽曼代表性模型未能考虑延迟给水作用,因而其水位计算结果与实测线型相反.博尔顿法是经验性的,未予揭示该现象成因。本法基本上解决了上述问题。文后图示了各参变量对水头时空分布的影响。验算表明,将本法用于潜水出流试验推求含水层参数,可获更佳结果。 相似文献
835.
韩凤财 《华北地质矿产杂志》1994,9(4):365-368
经勘察评价和国家级评审鉴定,天镇县城关T_(67)井属锂-锶-偏硅酸三项达标的复合型优质饮用天然矿泉水。矿泉水产于近东西向挽近断裂带上,马圈痒地热田边部,地势平坦,环境无污染,交通便利,水质独特,水量丰富,具有综合开发优势,适宜建厂开发。 相似文献
836.
I. Lerche 《Pure and Applied Geophysics》1994,143(4):537-562
Equations have been presented previously which predict that reflector curvature can affect significantly seismic reflection amplitudes at both zero and nonzero source-receiver offsets. Here the fact that faults are generally concave-upward is used to examine the curvature effect for compaction-driven faults which the sediments have both exponential and logarithmic porosity decreases with increasing depth.The curvature effect is generally larger over upwardly concave reflectors where amplitudes can either increase with offset (exposed focus) or decrease with offset (buried focus). The magnitude of the effect depends on the ratio between the depth to the structure and the radius of curvature of the structure. A phase change of 90° also occurs at a critical offset in the case of an exposed focus concave-upward reflector, with decreasing amplitude at offsets larger than the critical value. Dip move-out (DMO) dominantly removes the amplitude variation with offset due to curvature. These results suggest that when looking for amplitude variations with offset in a fault prospect, DMO should be applied as a preprocessing step. Compaction-driven faults have an exposed focus and, for an exponential variation of porosity with depth, there is a maximum curvature effect at a depth roughly the same as the scaling depth for the porosity. Logarithmic porosity with depth variations suggest a continued increase in the curvature effect of faults with increasing depth, to a maximum amplitude increase of about 35% relative to a plane interface. 相似文献
837.
The frictional behavior of lizardite and antigorite serpentinites: Experiments,constitutive models,and implications for natural faults 总被引:2,自引:0,他引:2
Laboratory studies of the frictional behavior of rocks can provide important information about the strength and sliding stability of natural faults. We have conducted friction experiments on antigorite and lizardite serpentinites, rocks common to both continental and oceanic crustal faults. We conducted both velocity-step tests and timed-hold tests on bare surfaces and gouge layers of serpentinite at room temperature. We find that the coefficient of friction of lizardite serpentinite is quite low (0.15–0.35) and could explain the apparent low stresses observed on crustal transform faults, while that of antigorite serpentinite is comparable to other crustal rocks (0.50–0.85). The frictional behavior of both types of serpentinite is well described by a two-mechanism model combining state-variable-dominated behavior at high slip velocities and flow-dominated behavior at low velocities. The two-mechanism model is supported by data from velocity-step tests and timed-hold tests. The low velocity behavior of serpentinite is strongly rate strengthening and should result in stable fault creep on natural faults containing either antigorite or lizardite serpentinite. 相似文献
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