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1.
通过对青峰韧性剪切带中糜棱岩的磁性组构研究,同时与常规主应变分析方法所测结果比较,表明岩石磁化率各向异性椭球体与应变椭球体之间有一定的对应关系。磁性组构的特征为构造岩变形机制,以及断裂带的运动学、动力学等的研究提供了一种比较可靠、准确、方便的方法。 相似文献
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衡山岩体西缘韧性剪切带磁性组构研究 总被引：1，自引：1，他引：1
本文对采自衡山花岗岩体西缘韧性剪切带的标本进行了岩石磁性组构研究,并将其与常规应变分析方法所得结果予以比较,表明了岩石磁化率各向异性椭球体与应变椭球体之间有一定的对应关系,岩石磁化率各向异性技术可望成为构造地质学的一种新手段。岩石磁性组构资料可应用于变形岩石的应变分析,特别是在没有宏观应变标志或者通常的岩石组构分析方法太费时间的情况下更显出其优越性。 相似文献
3.
岩石的磁性组构及其在岩石变形分析中的应用 总被引：17，自引：0，他引：17
文本总结了对采自巴彦乌拉山韧性剪切带的部分标本进行岩石组构数据测定的分析结果,并将其与用常规应变分析方法所得结果予以比较,表明了岩石磁化率各向异性椭球体能够反映总的应变椭球体,证明岩石磁化率各向异性技术做为一种岩石组构因素的研究是有发展前景的。岩石磁性组构资料可应用于变形岩石的应变分析,特别是在通常的岩石组构分析技术太费时间和粗糙的情况下更显示了其优越性。 相似文献
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We use new (micro-)structural, petrofabric, strain and vorticity data to analyze the deformation path in a mesoscopic quartz mylonite zone. The mylonite zone resulted from the complete transposition of a stretching lineation-parallel isoclinal fold. Symmetric cleft-girdle quartz c-axis fabrics were recorded in the middle domain, which occupies the inner limbs of the precursor isoclinal fold, while asymmetric cleft- and crossed-girdle fabrics were observed in the upper and lower domains that represent the outer limbs. Constrictional strain, with increasing k values towards the middle domain, is inferred from petrofabric and 3D strain data. Oblique grain shape fabrics yield vorticity estimates of 0.72–0.90 in the zone. However, in the middle domain, pure shear dominated deformation is suggested by orthorhombic crystallographic fabrics. Strain rate is constant throughout the zone; a strain decrease towards the zone center implies that deformation ceased earlier in the middle domain. The data indicates that fold transposition and subsequent mylonitization started as pure-shear-dominated constrictional deformation and progressively changed to simple-shear-dominated, plane strain. During this flow path the asymmetric quartz c-axis fabrics likely developed by depopulation of cleft-girdle maxima rather than from the synthetic rotation of fabric maxima itself. 相似文献
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中国显微构造地质学的回顾 总被引：3，自引：0，他引：3
我国的显微构造与组构研究始于20世纪30年代。已故何作霖教授把“岩组学”由德语文献介绍到中国，王嘉荫教授实测了国内岩石的岩组图，研究了矿物形成与变化的构造作用因素，他们把这一领域的研究与构造地质分析结合起来，结合构造地质分析引入了显微镜方法。不过在以后的30多年里，显微构造与组织分析只局限于少数学术单位和少数学者。从20世纪70年代中期开始，随着地 质工作的发展和国际交往的带动，显微构造与组构在我国得到较快速的发展。许多高校地质系开设了相关课程，在矿业开发、工程地质、环境与灾害地质等方面也得到有成效的应用。 相似文献
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Application of magnetic susceptibility anisotropy technique to the study of geological structures in the Armorican massif, France 总被引：1，自引：0，他引：1
Magnetic susceptibility anisotropy analyses have been carried out on 300 samples of rock from various metamorphosed regions of Normandy and Brittany, within the northern half of the Armorican massif, to test the ability of the magnetic fabric method (in a relatively complex region where structures have been well charted) to delineate regional structures. The two major structural directions to emerge from the study were a ENE—WSW striking magnetic foliation plane, conforming to a Variscan direction of the Bocaine syncline in the Granville region of Normandy and a ESE—WNW striking magnetic foliation plane conforming to the Armorican direction in the Chateaulin syncline region of Brittany. The magnetic fabric of sites elsewhere confirmed localised structures and minor synclinal structures.
The major advantages of the technique of studying magnetic fabric over petrofabric are the speed at which magnetic fabric can be measured (2 minutes per sample compared with up to 24 h using X-ray goniometry techniques) and the sensitivity of the magnetic fabric to very slight stresses. 相似文献
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AbstractThe fabric and the anisotropy of magnetic susceptibility of the Cabo Ortegal eclogite (NW Spain) are studied. These mafic rocks were metamorphosed and deformed under high pressures and temperatures between 390 and 370 Ma in a subduction/collision tectonic setting. Massive eclogite slices and deformed eclogite in shear zones have bulk magnetic susceptibilities of 31 to 82·10?5 S.I. and 28 to 75·10?5 S.I., respectively. The paramagnetic mineral fraction is the principal magnetic susceptibility carrier. This fraction includes notably garnet and clinopyroxene as matrix minerals, and ilmenite and rutile as accessory constituents. Though magnetic anisotropy degree varies between 3.1 % and 6.6 %, variations of this parameter in each rock type are marked. In the deformed eclogite, magnetic lineation (Kmax) and the pole to the magnetic foliation (Kmin) are coaxial and coincident with macroscopic petrofabric elements (foliation and lineation). In the massive eclogite, the magnetic fabric is dispersed along the principal structural planes and inversions are associated with samples with small degrees of anisotropy. The anisotropy of magnetic susceptibility is interpreted as being due to the crystallographic preferred orientation and spatial organisation of the polymineralic aggregate. Relating the evolution of the symmetry of magnetic fabric to the symmetry of petrofabric or deformation is rather precluded since susceptibility has multiple origins and bulk magnetic fabric is due to minerals of different symmetry. © Elsevier, Paris 相似文献
8.
《Geodinamica Acta》1998,11(6):271-283
The fabric and the anisotropy of magnetic susceptibility of the Cabo Ortegal eclogite (NW Spain) are studied. These mafic rocks were metamorphosed and deformed under high pressures and temperatures between 390 and 370 Ma in a subduction/collision tectonic setting. Massive eclogite slices and deformed eclogite in shear zones have bulk magnetic susceptibilities of 31 to 82 · 10−5 S.I. and 28 to 75 · 10−5 S.I., respectively. The paramagnetic mineral fraction is the principal magnetic susceptibility carrier. This fraction includes notably garnet and clinopyroxene as matrix minerals, and ilmenite and rutile as accessory constituents. Though magnetic anisotropy degree varies between 3.1 % and 6.6%, variations of this parameter in each rock type are marked. In the deformed eclogite, magnetic lineation (Kmax) and the pole to the magnetic foliation (Kmin) are coaxial and coincident with macroscopic petrofabric elements (foliation and lineation). In the massive eclogite, the magnetic fabric is dispersed along the principal structural planes and inversions are associated with samples with small degrees of anisotropy. The anisotropy of magnetic susceptibility is interpreted as being due to the crystallographic preferred orientation and spatial organisation of the polymineralic aggregate. Relating the evolution of the symmetry of magnetic fabric to the symmetry of petrofabric or deformation is rather precluded since susceptibility has multiple origins and bulk magnetic fabric is due to minerals of different symmetry. 相似文献
9.
The 616 ± 3 Ma (Ediacaran) Egersund doleritic dike swarm cuts across the Rogaland anorthosite province and its granulitic country rocks, in SW Norway. The structure of eight out of eleven main dikes of the swarm was investigated using the anisotropy of magnetic susceptibility (AMS) technique. Thermomagnetic data and values of the bulk magnetic susceptibility reveal a magnetic mineralogy dominated by Ti-poor titanomagnetite. Magnetic fabric and global petrofabric are coaxial, except in sites strongly affected by hydrothermal alteration, as demonstrated through image analysis. Asymmetrical dispositions of the magnetic foliation and lineation support the existence of a syn-emplacement, sinistral strike-slip shearing resolved on dike walls. Such asymmetrical fabrics are attributed to a transtension tectonic regime, in a context of oblique extension during the continental rifting phase which preceded the opening of the Iapetus Ocean along the SW margin (present-day orientation) of Baltica. 相似文献
10.
研究了枞树板铅锌矿区的磁组构特征。结果表明,在变形较弱及无应变标志体的地区,利用磁组构进行构造变形分析是非常有效的,其结果不仅与其它方法的结果大体一致,而且能够获得用其它方法难以获得的认识（如变形类型问题）。据此可以分析控矿构造的变形性质及演化,查明构造控矿的规律。 相似文献
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New kinematic and structural data from the tectonic windows of eastern Crete and the Dodecanese Islands combined with strain and quartz fabric analysis have enabled us to determine a detailed structural evolution of the region and to present a plate tectonic scenario for the southeast Hellenides. During the Early Mesozoic, the southeastern part of Apulia was separated from North Africa and the adjacent microplates by WNW‐trending rift zones and NE‐trending transfer faults. Displacement along the transfer faults has locally reoriented these rift zones into an ENE–WSW direction. Finite strain and quartz fabric asymmetry data indicate that in Late Cenozoic time, NNW‐directed nappe movements caused a nearly coaxial deformation along the ENE–WSW trending rift segments and non coaxial top‐to‐the‐southeast shearing along the WNW‐trending rift segments, as well as along the pre‐existing NE‐trending transfer faults. Tectonic style along the margin varies in response to the obliquity of the principal shortening direction with respect to the margin. These variations could be due to the pre‐convergence geometry of the southern margin of Eurasia and to local strain partitioning effects. Furthermore, a tectonic model is presented in which syncompressional uplift and vertical buoyancy of the subducted crustal slice caused the rapid exhumation of metamorphic units in the south Hellenides. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(5):499-503
A combination of magnetostratigraphic studies and magnetic fabric investigations in the Cretaceous-Tertiary transition section at Cerbara in the Umbrian Apennine (Italy) produced consistent results indicating local tectonic movements affecting the orientation of characteristic remanent magnetization as well as the magnetic fabric. The comparison of the data shows that a simple tilt correction is not sufficient to adjust the characteristic remanence directions. There remains a scatter in the declination that can be reduced by means of additional corrections by taking into account further local tectonic movements that affected the section. Different models are presented where anisotropy of magnetic susceptibility was used as a tool to correct for tectonic complications. 相似文献
16.
湖南郴州枞树板铅锌矿X光组构分析 总被引：1，自引：0，他引：1
作者通过对湖南郴州枞树板铅锌矿围岩及含矿构造带岩石的X光岩组分析,认为在构造变形过程中,原岩粒度越细,对变形的反映越敏感。在相同的变形条件下,较细的变质砂岩石的石英定向组构比较粗的变质砂岩内明显,板岩和粉砂质板岩的定向组构最明显。枞树板地区近EW向褶皱变形组构表现强烈,近SN向褶皱变形组构较弱。矿化热液的蚀变作用破坏了岩石中早期褶皱变形组构,但铅锌矿脉内的石英没有明显的生长组构,说明在矿化和含矿石英脉成生过程中没有明显的张性充填结晶表现,而是一种以交代为主的矿化形式。这与从其它地质地球化学研究取得的关于本 相似文献
17.
A.M. Bell 《Journal of Structural Geology》1979,1(2):163-167
Strain analysis using deformed objects is already well established. The more sophisticated techniques can resolve tectonic strains and indicate the nature of any pre-tectonic fabric. Methods that analyse in two dimensions can produce problems of incomparability when results from three faces of one sample are combined.A method for factorizing finite, non-coaxial strains is presented which overcomes these problems by analysing in three dimensions. Published data from deformed lapilli tuff from the English Lake District have been used to test the method.Results are as valid as those obtained originally from the data, and the technique enables strain analysis to be extended to areas which give imprecise results using existing methods. 相似文献
18.
怀安地区构造变形强烈,是研究华北克拉通形成和演化的重要窗口。通过对该区基底变质岩系构造形迹进行研究,结合区域地质资料及同位素年龄数据,将该区早前寒武纪构造变形序列划分为4期: 新太古代阜平晚期(D1),桑干岩群韧性变形,形成片麻理、无根褶皱和韧性剪切带; 新太古代五台晚期(D2),在新太古代TTG/花岗岩中形成区域性片麻理和条带状构造,并在桑干岩群中形成近EW向的复式背形和向形构造; 古元古代吕梁中期(D3),集宁岩群沙渠村岩组形成区域性片麻理,并形成与片麻理一致的NE向韧性剪切带,在新太古代地质体中叠加近SN向的开阔复式背形和向形构造; 古元古代吕梁晚期(D4),红旗营子岩群太平庄岩组形成片理和片麻理,尚义—平泉断裂形成。建立了该区早前寒武纪构造演化模式,并将其划分为新太古代陆壳增生阶段和古元古代碰撞造山阶段,对理解华北克拉通的形成及演化具有重要意义。 相似文献
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Changes in the coordinates of 38 stations, 32 of which were common to three historical triangulation surveys (1889–1905, 1927–1930 and 1950–1970) in central Greece were computed based on conventional adjustment techniques and the assumption of a nearly fixed baseline length. Some of the calculated coordinate changes are significant against the a posteriori network adjustment errors and are likely to indicate tectonic motions consistent with those deduced from geological and geophysical data and other geodetic studies (comparison of the first survey network with GPS data).
More explicitly, the historical geodetic data confirm the rotational character of the deformation in the area, but they show that the strain pattern is likely to have changed after 1930: between 1890 and 1930 strain was changing smoothly, as if no strain discontinuities existed, while the Peloponnesus was under contraction from the northeast, probably reflecting accommodation of strain from the arc. Significant left-lateral shear in the gulf of Corinth and N-S extension in the whole of the study area were observed only after 1930. Estimates of strain are consistent with those deduced from comparison of historical triangulation and GPS data, corrected for the scale error that exists in the terrestrial geodetic data in Greece, and estimates of strain from seismological data. The change in the kinematic pattern after 1930 seems to be confirmed by changes in the shear strain computed directly from changes in observed angles between stations and from changes in the seismicity rates; such changes, although not unusual in the geological record, are not easy to explain, but may reflect elastic rebound effects in area with an extremely complicated tectonic fabric or hysteresis in the accommodation of E-W compression from the arc by N-S stretching. 相似文献
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用X射线鉴定地质构造和古构造应力场,是从微观上研究地壳构造运动的新途径,能解决一些宏观方法所难以解决的问题,并补充后者之不足。 迁西地区,有两翼东西延伸的山字型,成条带式分布的南北向,东西向,北东向,北北东向,北西向和北北西向构造,从它们的走向上看,对研究构造运动有一定代表性。 相似文献