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41.
Jesús Galindo-Zaldivar Francisco Gonzalez-Lodeiro Antonio Jabaloy 《Geodinamica Acta》2013,26(1):73-85
AbstractThe present contact caused by the superposition of the Alpujarride complex over that of the Nevado-Filabride in the western area of Sierra Nevada and Sierra de Filábres corresponds to a detachment. The deformation in the footwall associated with this contact, produced mylonitic fabrics with a significant stretching-lineation, over which brittle structures are superimposed. The deformation in the hanging wall associated with this contact is, on the other hand, essentially brittle. These deformations are subsequent to a series of syn-to post-metamorphic structures related to thrust phases.The micro- and meso-structures indicate that the hanging wall has moved towards the west-south-west.Other brittle structures, which began during the same extensional regime, are superimposed on the detachment and have continued to develop up to the present time. These structures were produced in an extensional regime with a non-coaxial deformation component and suggest the possibility of a tectonic evolution similar to that described for core complexes in the USA. 相似文献
42.
宫同伦 《地球科学与环境学报》1993,(4)
本文在构造控制金矿床理论的基础上,进一步提出了断裂构造控制金矿床的思想,主张是断裂构造控金,而非褶皱构造控金;是脆性断裂带控金,而非韧性剪切带控金。文中阐述了动力作用为何能形成金矿床和如何形成金矿床,同时强调了动力作用可使原有的各类金矿体富化,形成富矿体。 相似文献
43.
Shear and extensional veins formed during the reactivation of the Magdala shear system at Stawell in western Victoria, Australia,
contribute to the formation of the auriferous Central and Basalt Contact lodes. Within this shear system is a range of fault
rocks accompanied by steep-dipping (>65°) quartz-rich laminated shear veins and relatively flat-lying extensional veins. Both
vein sets appear to have been a primary source for the host rock permeability during fluid flow in a regime of significant
deviatoric stresses. The macro- and microstructures suggest that the dilatancy, that produced mineralized veins, formed under
conditions of overpressure generated by fluid infiltration late in a tectonic regime. A new microfabric analysis technique
is used to investigate the quartz-rich veins, which allows rapid integration of the microstructure with the crystallographic
preferred orientations (CPOs). Both the shear and extensional quartz veins have a random CPO with ∼120° dihedral angles between
the quartz–quartz grains, which is typical of a metamorphic equilibrium microfabric. The microstructures indicate that the
quartz has undergone extensive grain adjustment in the solid-state, with grain shape and size affected by interfacial solution
(pressure solution) effects. These features are consistent with inferences from experimental rock deformation studies, where
grain boundary migration is enhanced in a water-rich environment. The onset of solution-transfer processes (pressure solution)
developed as the quartz microfabric stabilized and continued to modify the CPO and microstructure significantly. It is concluded
that grain growth and pressure solution are coupled diffusive mass transfer processes, related to fluctuations in pore fluid
pressures in a region undergoing deformation at near lithostatic pressures. 相似文献
44.
断层滑动分析与古应力恢复研究综述 总被引：8，自引：1，他引：7
对遭受脆性变形（尤其是断裂作用）的岩层进行古构造应力恢复是进行地壳构造变形历史和动力学研究的重要手段之一。对带有擦痕线理的断层进行大量观测,不仅便于精确描述断层几何学,而且还可使地球上部脆性地壳的构造模式与应力状态相关联,从而再现构造应力场在时空上的演化特征。对脆性构造研究中的断层滑动分析与古应力恢复这一方法的研究历史与现状、原理假设、数学方法以及如何把反演结果与野外地质认识相结合进行构造变形期次的研究进行了介绍和评述,并指出这种方法不仅有利于认识盆地与造山带在构造应力场上的同一性,而且有利于从动力学上去探讨盆山之间的关系,在目前盆山耦合的构造研究中有其自身的优越性。 相似文献
45.
This study involves the development of the auxiliary stress approach for producing elastically-homogeneous lattice models of damage in geomaterials. The lattice models are based on random, three-dimensional assemblages of rigid-body-spring elements. Unlike conventional lattice or particle models, the elastic constants of a material (e.g., Young’s modulus and Poisson’s ratio) are represented properly in both global and local senses, without any need for calibration. The proposed approach is demonstrated and validated through analyses of homogeneous and heterogeneous systems under uni- and tri-axial loading conditions. Comparisons are made with analytical solutions and finite element results. Thereafter, the model is used to simulate a series of standard laboratory tests: (a) split-cylinder tests, and (b) uniaxial compressive tests of sedimentary rocks at the Horonobe Underground Research Laboratory in Hokkaido, Japan. Model inputs are based on physical quantities measured in the experiments. The simulation results agree well with the experimental results in terms of pre-peak stress-strain/displacement responses, strength measurements, and failure patterns. 相似文献
46.
Brittle faulting-related shear heating is important in petroleum geosciences, tectonics and seismic studies. Temporal variation of shear heat related temperature rise for rotational and roto-translational faults are investigated in this work. For planar fault planes, devoid of gouge and any secondary faulting, temperature rise is proportional to the coefficient of friction, and rate of (angular) slip. Tectonically realistic physical parameters for rotational faults, especially prolonged faulting, can significantly increase temperature by shear heating at shallow crustal depth, capable of thermal maturity of hydrocarbons. 相似文献
47.
CCSD主孔中发育有十分丰富的脆性变形现象,按其充填特征大致可划分有石英和方解石充填的微破裂、有矿物薄膜的微破裂和既无矿物充填、又无矿物簿膜的微破裂等3大类.石英微破裂脉和方解石微破裂脉次生包裹体的均一温度分别为110℃～215℃和90℃～190℃,表明前者的形成要早于后者,按现代地热梯度23.4℃/km估算,两者的形成深度分别为4.7～9.2km和3.8～8.1km,9.2km大致可作为宏观上岩石圈发生脆性变形的最大深度或岩石圈由韧性变形域向脆性变形域过渡的界线.片麻岩、榴辉岩和超基性岩微破裂脉的次生包裹体均一温度显示三者由韧性变形域向脆性变形域过渡的深度是不一致的,依次为9.2km、8.5km和8.1km,反映主孔主要岩石类型的脆性变形行为存在有一定差异.根据微破裂的充填物特征和相互切割关系,大致可确定主孔中脆性破裂的形成深度和先后关系:石英微破裂脉,形成最早,深度为4.7～9.2km,方解石微破裂脉的形成深度为3.8～8.1km,8.1km以上开始出现有矿物薄膜的微破裂,既无矿物充填、又无矿物簿膜的微破裂则是地壳深度3.8km以上的主要脆性变形构造类型.可见,微破裂次生包裹体的均一温度或许可作为宏观上建立CCSD主孔脆性变形构造剖面的重要依据之一. 相似文献
48.
The NW-SE oriented Sorgenfrei–Tornquist Zone (STZ) has been thoroughly studied during the last 25 years, especially by means of well data and seismic profiles. We present the results of a first brittle tectonic analysis based on about 850 dykes, veins and minor fault-slip data measured in the field in Scania, including paleostress reconstruction. We discuss the relationships between normal and strike-slip faulting in Scania since the Permian extension to the Late Cretaceous–Tertiary structural inversions. Our paleostress determinations reveal six successive or coeval main stress states in the evolution of Scania since the Permian. Two stress states correspond to normal faulting with NE-SW and NW-SE extensions, one stress state is mainly of reverse type with NE-SW compression, and three stress states are strike-slip in type with NNW-SSE, WNW-ESE and NNE-SSW directions of compression.The NE-SW extension partly corresponds to the Late Carboniferous–Permian important extensional period, dated by dykes and fault mineralisations. However extension existed along a similar direction during the Mesozoic. It has been locally observed until within the Danian. A perpendicular NW-SE extension reveals the occurrence of stress permutations. The NNW-SSE strike-slip episode is also expected to belong to the Late Carboniferous–Permian episode and is interpreted in terms of right-lateral wrench faulting along STZ-oriented faults. The inversion process has been characterised by reverse and strike-slip faulting related to the NE-SW compressional stress state.This study highlights the importance of extensional tectonics in northwest Europe since the end of the Palaeozoic until the end of the Cretaceous. The importance and role of wrench faulting in the tectonic evolution of the Sorgenfrei–Tornquist Zone are discussed. 相似文献
49.
一条特殊的超浅成脆—韧性剪切带：湘西白沙镇含油瘤状灰岩带 总被引：7，自引：0，他引：7
湘西泸阳县白沙镇西发育了一条特殊的脆韧性剪切带。该剪切带中除了发育了许多脆性变形外，还发育了许多韧性剪切的标志：如Ｓ－Ｃ组构，方解石鱼、核幔构造、方解石ｅ双晶、方解石波状消光、钙质糜棱岩条带以及（光学）各向异性体。经研究发现该剪切带的形成深度不超过３．０ｋｍ，其中的大量石油也与脆韧性剪切作用有一定关系。 相似文献
50.
F. Purtscheller T. Pirchl G. Sieder V. Stingl T. Tessadri P. Brunner O. Ennemoser P. Schneider 《Environmental Geology》1995,26(1):32-38
The identification of extremely high indoor radon concentrations in the village Umhausen (Tyrol, Austria) initiated a scientific program to get information about the source and distribution of this noble gas. The high concentrations can not be related to U anomalies or large-scale fault zones. The nearby giant landslide of Koefels, with its highly fractured and crushed orthogneisses, are the only possible source of radon, despite the fact that the U and Ra content of the rocks is by no means exceptional. The reasons for the high emanation rates from the landslide are discussed and compared to results gained from a similar examination of the giant landslide of Langtang Himal (Nepal). The exceptional geologic situation in both cases, as well as the spatial distribution of different concentration levels, indicate that both landslides must be considered as the production sites of radon. Independent of the U and Ra contents of the rocks, the most important factors producing high emanation rates are the production of a high active surface area and circulation pathways for Rn-enriched soil air by brittle deformation due to the impact of the landslidemass. 相似文献