用云南下关测点的水压致裂结果分析地形起伏对应力测值的影响     

刘建中  高强  刘玉琢  张雪 《地震研究》1988,(6)

本文以云南下关黄草坝的水压致裂应力测量结果为例,讨论了地形起伏对云南区应力测值的影响。结果表明,地形起伏对应力测值的绝对影响随深度的增加衰减缓慢,相对影响急剧减小。100米以内深度的应力测量,地形影响可能给测值带来10%以上的误差。云南区的水压致裂应力测量深达500米,是可以排除掉地形起伏的影响的。  相似文献   

Energy aspects of continuous fracturing of rocks     

V. I. Kondaurov 《Pure and Applied Geophysics》1986,124(4-5):749-757

In this paper the processes of rock deformation are discussed, which are accompanied by an accumulation of defects or by continuous fracturing. The influence of fluids and of the electrical and magnetic fields is neglected. A model of fracturing, based on some energy consideration is introduced.  相似文献   

Fluid infiltration into fault zones: Chemical,isotopic, and mechanical effects     

R. Kerrich 《Pure and Applied Geophysics》1986,124(1-2):225-268

Fluid infiltration into fault zones and their deeper-level counterparts, brittle-ductile shear zones, is examined in diverse tectonic environments. In the 2.7 Ga Abitibi greenstone belt, major tectonic discontinuities, with lateral extents of hundreds of kilometres initiated as listric normal faults accommodating rift extension and acted as sites for komatiite extrusion and locally intense metasomatism. During reverse motion on the structures, accommodating shortening of the belt, these transcrustal faults were utilised as a conduit for the ascent of trondhjemitic magmas from the base of the crust and of alkaline magmas from the asthenosphere and for the discharge of thousands of cubic kilometres of hydrothermal fluids. Such fluids were characterised by ¹⁸O=+6±2, D=–50±20, ¹³C=–4±4, and temperatures of 270 to 450°C, probably derived from devolatilisation of crustal rocks undergoing prograde metamorphism. Hydrothermal fluids were more radiogenic (⁸⁷Sr/⁸⁶Sr=0.7010 to 0.7040) and possessed higher than did contemporaneous mantle, komatiites or tholeiites, and thus carried a contribution from older sialic basement. A provinciality of⁸⁷Sr/⁸⁶Sr and ¹³C is evident, signifying that fault plumbing sampled lower crust which was heterogeneous at the scale of tens of kilometres. Mineralised faults possess enrichments of large ion lithophile (LIL), LIL elements, including K, Rb, Ba, Cs, B, and CO₂, and rare elements, such as Au, Ag, As, Sb, Se, Te, Bi, and W. Fluids were characterised by X_{CO 2}0.1, neutral to slightly acidic pH, low salinity 3 wt-%, K/Na=0.1, they carried minor CH₄, CO, and N₂, and they underwent transient effervescence of CO₂ during decompression. Clastic sediments occupy graben developed at fault flexures. The⁴⁰Ar/³⁹Ar release spectra indicate that fault rocks experienced episodic disturbance on time scales of hundreds of millions of years.At the Grenville front, translation was accommodated along two mylonite zones and an intervening boundary fault. The high-temperature (580°C) and low-temperature (430 to 490°C) mylonite zones, formed in the presence of deep-level crust-equilibrated fluids of metamorphic origin. Late brittle faults contain quartz veins precipitated from fluids with extemely negative ¹⁸O (–14 per mil) at 200 to 300°C. The water may have been derived from downward penetration into fault zones of precipitation of low¹⁸O on a mountain range induced by continental collision, with uplift accommodated at deep levels by the mylonite zones coupled with rebound on the boundary faults.Archean gneisses overlie Proterozoic sediments along thrust surfaces at Lagoa Real, Brazil; the gneisses are transected by brittle-ductile shear zones locally occupied by uranium deposits. Following deformation at 500 to 540°C, in the presence of metamorphic fluids and under conditions of low water-to-rock ratio, shear zones underwent local intense oxidation and desilication. All minerals undergo a shift of –10 per mil, indicating discharge of meteoric-water-recharged formation brines in the underlying Proterozoic sediments up through the Archean gneisses, during overthrusting; 1000 km³ of solutions passed through these structures. The shear zones and Proterozoic sediments are less radiogenic (⁸⁷Sr/⁸⁶Sr=0.720) than contemporaneous Archean gneisses (0.900), corroborating the transport of fluids and solutes through the structure from a large external reservoir.Major crustal detachment faults of Tertiary age in the Picacho Cordilleran metamorphic core complex of Arizona show an upward transition from undeformed granitic basement through mylonitic to brecciated and hydrothermally altered counterparts. The highest tectonic levels are allochthonous, oxidatively altered Miocene volcanics. This transition is accompanied by an increase of 12 per mil in ¹⁸O, from +7 to +19, and a 400°C decrease in temperature. Lower tectonic levels acted as aquifers for the expulsion of large volumes of higher-temperature reduced metamorphic fluids and/or evolved formation brines. The Miocene allochthon was influenced by a lower-temperature reservoir inducing oxidative potassic alteration; mixing occurred between cool downward-penetrating thermal waters and the hot, deeper aqueous reservoir.In general, flow regimes in these fault and shear zones follow a sequence, from conditions of high temperature and pressure with locally derived fluids at low water-to-rock ratios, during initiation of the structures, to high fluxes of reduced formation or metamorphic fluids along conduits as the structures propagate and intersect hydrothermal reservoirs. Later in the tectonic evolution and at shallower crustal levels there was incursion of oxidising fluids from near-surface reservoirs into the faults. In general, magmatism, tectonics, and fluid motion are intimately related.  相似文献   

小秦岭金矿液压致裂成矿机制初探     

尉向东  徐莉  刘长命  盛吉虎 《河南国土资源》1994,(1)

根据小秦岭石英脉型金矿床石英脉的空间分布、结构构造特征和矿床形成的温压条件,提出小秦岭金矿的液压致裂定位机制。在成矿期间容矿空间的扩张与矿液的充填是同时的,容矿空间的形成是矿液液压致裂作用的结果。在成矿过程中,随着矿液自身压力的逐渐增加,当达到或超过围岩静压力时,围岩便产生张裂,矿液随之充填沉淀。照此反复进行,矿脉逐渐增生,最终形成不同期次、不同矿化阶段的脉状金矿床。  相似文献   

Active faults, seismicity and recent fracturing in the lithosphere of the Baikal rift system   总被引：1，自引：0，他引：1  

S. I. Sherman  V. M. Dem''yanovich  S. V. Lysak 《Tectonophysics》2004,380(3-4):261-272

A map of major active faults has been constructed for the Baikal rift system (BRS). Recent active faults are identified using seismological data. The BRS seismicity of the past 40 years is statistically analyzed. Areas of a “stable” concentration of epicenters are revealed. On this basis, a zone of recent fracturing of the lithosphere is identified and its relation to active and developing faults of the BRS is analyzed. The zone of the lithosphere fracturing is a major tectonic structure, which controls both the recent seismic process and the reactivation of ancient faults. It is demonstrated that the available seismological data can provide a basis for a detailed classification of faults by degree of their tectonic activity. Regularities in the distribution of strong earthquakes along the zone of the recent fracturing of the lithosphere are established, as well as regularities in the distribution of strong and weak seismic events relative to transform and other faults. The degree of the fault reactivation is determined by their spatial closeness to the axial zone of the recent rupturing of the lithosphere.  相似文献   

伸展型脆-韧性剪切带对沃溪钨锑金矿床的构造控制   总被引：6，自引：0，他引：6  

汪劲草  夏斌  雷鸣波  谭碧富 《吉林大学学报(地球科学版)》2003,33(2):135-140

湖西沃溪钨锑金矿床受控于一条伸展型顺层脆-韧性剪切带。带内岩石在非共轴顺层剪切构造动力作用下发生变形分解，形成泥质构造根岩强变形带和砂质构造根岩弱变形域。泵吸中心-弱变形城中的承压矿液沿砂质构造根岩的ab面发生水力压裂而产生“D”型张剪裂隙。构造-流体双重动力系统的周期性振荡使主裂隙系统发生周期性的破裂-愈合作用而形成条带状复脉。矿液是通过隐蔽的低角度正断层、强变形带内的构造面理及弱变形城中的微裂隙系统运移的，说明在靠近滑脱面的弱变形城中水力压裂作用会增强，其矿化类型将以蚀变岩型为主、脉型为辅。  相似文献   

Low-Temperature Plasticity of Naturally Deformed Calcite Rocks     

Klaus WEBER 《《地质学报》英文版》2002,76(3):292-299

Optical, cathodoluminescence and transmission electron microscope (TEM) analyses were conducted on four groups of calcite fault rocks, a cataclastic limestone, cataclastic coarse-grained marbles from two fault zones, and a fractured mylonite. These fault rocks show similar microstructural characteristics and give clues to similar processes of rock deformation. They are characterized by the structural contrast between macroscopic cataclastic (brittle) and microscopic mylonitic (ductile) microstructures. Intragranular deformation microstructures (i.e. deformation twins, kink bands and microfractures) are well preserved in the deformed grains in clasts or in primary rocks. The matrix materials are of extremely fine grains with diffusive features. Dislocation microstructures for co-existing brittle deformation and crystalline plasticity were revealed using TEM. Tangled dislocations are often preserved at the cores of highly deformed clasts, while dislocation walls form in the transitions to the fine-grained  相似文献   

Evaluating changes in ecological land and effect of protecting important ecological spaces in China     

GAO Jixi  LIU Xiaoman  WANG Chao  WANG Yong  FU Zhuo  HOU Peng  LYU Na 《地理学报(英文版)》2021,31(9):1245-1260

It is important to quantitatively analyze the effects of protection of important eco-logical spaces in China to ensure national ecological security.By considering changes in the ecological land,this study examines the effects of protecting three types of important natural ecological spaces in China from 1980 to 2018.Moreover,considering important ecological spaces and their surroundings yields differences in the effects of protection between internal and external spaces,where this can provide a scientific basis for the categorization and zoning of China's land.The results show the following:(1)In 2018,the ratio of ecological land to important natural ecological spaces accounted for 92.64％.This land had a good ecological background that reflects the developmental orientation of important ecological spaces.(2)From 1980 to 2018,the area of ecological land in important ecological spaces shrank but the rate of reduction was lower than the national average,which shows the positive effect of regulating construction in natural ecological spaces.The restorative effects of ecological projects to convert farmland into forests and grasslands have been prominent.The expanded ecological land is mainly distributed in areas where such projects have been implemented,and the reduced area is concentrated in grain-producing areas of the Northeast China Plain and agricultural oases of Xinjiang.In the future,the government should focus on strength-ening the management and control of these areas.(3)The area ratio of ecological land was the highest in national nature reserves.The rate of reduction in its area was the lowest and the trend of reduction was the smallest in national nature reserves,which reflects differences in the status of ecological protection among different spaces.(4)The ratio of ecological land to important ecological spaces was higher than that in the surrounding external space,and the rate of reduction in it was lower.Thus,the effects of internal and external protection had clear differences in terms of gradient.  相似文献   

煤层气储层可改造性评价——以郑庄区块为例     

姚艳斌  王辉  杨延辉  刘大锰  鲁秀芹  曹路通 《煤田地质与勘探》2021,49(1):119-129

我国煤层气资源探明率与动用率“双低”,导致煤层气增产显著放缓,已经成为制约我国煤层气产业发展的瓶颈问题。常规煤储层评价较少考虑煤储层的可改造性潜力,导致发现的优质储量偏少,已发现的储量动用率偏低,因此,迫切需要开展煤储层可改造性评价研究。以沁水盆地南部郑庄区块为例,系统开展了岩心与大样物理模拟实验、测井与地震反演分析等;通过对比分析典型井储层地质特征与微地震水力压裂裂缝监测结果,指出影响煤储层可改造性的关键地质因素为煤体结构、宏观煤岩类型、煤层构造变形、煤层地应力、煤层与顶底板的抗拉强度之差,建立了煤储层可改造性综合定量评价模型;并对郑庄区块煤储层可改造性进行了评价分区,其结果得到了区内千余口产气井的验证。研究成果可用于指导尚未动用储量区的煤层气建产和已动用储量区的开发方案优化调整,根据不同区块储层地质特点选择适应性的工程技术与改造方案,以实现地质工程一体化,是我国煤层气“增储上产”的关键。   相似文献   

流体参与下的岩石破裂机制及其分形特征   总被引：1，自引：0，他引：1  

杨果岳  张家生 《地质与勘探》2006,42(3):107-110

流体参与下的岩石破裂机制一般分为爆发作用、流化作用和液压致裂等,其分维值大小一般遵循爆发作用→流化作用→液压致裂.通过对凤凰山铜矿II号矿体不同地段的角砾岩进行分形统计分析,判明其属于液压致裂角砾岩,验证了分维值的大小与致裂能量之间的正相关关系.  相似文献