共查询到20条相似文献，搜索用时 78 毫秒
1.
The results of our new paleomagnetic investigations on 21 sites in the Cévennes and Lure regions as well as previous studies demonstrate that all Mesozoic marly limestones of SE France exhibit similar paleomagnetic behavior with remagnetization disputed in age. The studied areas have the particularity to have been folded before (Late Eocene), the Alpine folding (Oligo–Miocene). Samples (201 marly limestones) dated from Lower Jurassic to Lower Cretaceous have been demagnetized by thermal treatment. They all present a well-defined component with a normal polarity which was mostly obtained between 200 and 350 °C. Numerous arguments lead from pretectonic to syntectonic widespread remagnetization related to orogenic fluid circulation affecting the whole basin. An Eocene age (between 35 and 40 Ma) is obtained for this remagnetization thanks both to the comparison of the average inclination of all regional paleomagnetic studies (+54.9°/−1.5°) with the expected paleomagnetic inclination and the syntectonic character of remagnetization. 相似文献
2.
灰岩成因-结构分类的进展及其相关问题讨论 总被引：11，自引：0，他引：11
由Folk在1959，1962年及Dunham在1962年所提出的灰岩因－结构分类体系，具有划时代的意义，至今还得到极为广泛的应用，Embry和Klovan在1971年关于生物礁灰岩的成因－结构分类，即关于骨架灰岩，障积灰岩，粘结灰岩的成因－结构分类的第一次重要的补充，它解决了与生物作用有关的灰岩不符合Folk和Dunham的结构成熟度概念的矛盾，而对成岩作用及其产物的更深入研究，地质学家们发现了许多布成岩作用形成的泥晶化作用和颗粒化作用，由它们所形成的岩石也不符合Folk和Dunbam的结构成熟度概念，导致了Wright在1992年提出了一个更完整的灰岩成因－结构分类体系，把灰岩分为生物作用类，沉积作用类及成岩作用类三大类，即Folk和Dumban描述的分类均属于沉积作用类。要特别指出的是，在从松散沉积物到已石化的竖硬石头的成岩过程中，不但灰岩的结构会发生变化，而且组分也会发生变化，从而使灰岩的成因－结构分类变得更加复杂，关于这方面还存在许多有待进一步研究的问题。在审视Wright在1992年的分类体系时，有必要在沉积作用类中增加“非正常沉积作用亚类灰岩”，针对许多非礁相地层中发育的由生物礁岩石构成的生物层及生物丘，因而有必要对生物作用灰灰岩进行更进一步的分类。 相似文献
3.
《Journal of Structural Geology》1986,8(6):655-668
In the Morcles nappe (lowermost Helvetic nappe in western Switzerland) two phases of folding have been established. In this article the relationship between the calcite fabrics present in folded limestones and the folding history is analysed. Calcite fabrics around the first- and second-phase folds are related to the second phase of deformation. The following fabric patterns have been found. (1) The fabric geometry around a second-phase fold from the most internal part of the inverted limb of the nappe (locality Saillon) can be related to an overall simple shear deformation sequence, the sense of shear being related to the last advance of the Morcles nappe over the underlying autochthonous sedimentary cover of the Aiguilles Rouges massif. (2) In more external parts of the inverted limb (locality Petit Pré) the fabrics around a second-phase fold are interpreted as indicating a change in the deformation history from simple shear to a strain regime which can account for shortening along the first-phase cleavage by the formation of buckle folds. This change in the local strain regime could be related to a ‘locking’ of the frontal folds of the nappe during the last overthrust shear movements. (3) In the normal limb of the nappe the fabrics around a late second-phase kink fold (locality Neimia) are earlier than the folding event and appear to be rotated passively by the fold. (4) The fabrics around a first-phase fold (locality La Routia) are later than the folding event and overprint the fold. 相似文献
4.
苏皖辽地区新元古代微亮晶构造碳酸盐岩的沉积岩相与环境约束 总被引：7，自引：0，他引：7
国内外元古代碳酸盐岩中常见席状、透镜状、脉状和块状等形态的微亮晶碳酸盐岩。微亮晶体宏观、微观边界清晰,内部充填均一等粒结构的方解石微亮晶。宿主岩相以含泥质或粉砂质的细砂屑、粉泥屑灰岩为主,经常与风暴岩共生。微亮晶构造碳酸盐岩发育在缓坡型台地,沉积层序中常见潮汐流、风暴流侵蚀-充填和浪成交错层理与递变层理。微亮晶构造碳酸盐岩发育严格受沉积环境和岩相约束,形成于 (内缓坡深部-中缓坡浅部 )潮下带和环潮坪,风暴浪基面是其发育的最大深度。垂向序列由高频潮下带和环潮坪微层序加积而成,单个微层序顶部通常为环潮坪为纹层状含铁质有机质泥屑碳酸盐岩披盖层,是一个向上沉积动力减弱、沉积物变细和水体变浅的沉积旋回。 相似文献
5.
It is shown that the formation of borosilicate skarn in the Taukha metallogenic zone completes a series of successive stages of the formation and transformation of the folded sequences of the Taukha accretionary wedge. The Early Cretaceous sedimentary stage, including accumulation of detrital tourmaline-rich sedimentary rocks, was implemented in the marginal sea of the Paleopacific Sino-Korean segment. In the Turonian–Campanian, the boron-bearing folded sequences of the accretionary wedge were involved in anatexis to generate siliceous S-type boron-bearing melts. The thus-formed magmatic chambers were emptied during catastrophic volcanic eruptions. At the final Middle Campanian volcanic stage, fluid-magmatic differentiation of the melt in the residual chambers generated fluid flow. The infiltration interaction of the fluids, which inherited enrichment in boron, with limestones of the olistostrome sequence resulted in the formation of a giant zone of grossular–wollastonite skarns and danburite lodes. The boron potential of the Taukha boron–lead–zinc metallogenic zone may be considered as a reproduction of the Precambrian boron metallogeny of the eastern Eurasian margin, which was implemented in the Late Mesozoic during recycling of the continental crust. 相似文献
6.
To investigate the impacts of mineral composition on physical and mechanical properties of carbonate rocks, limestone specimens containing different contents in calcite and dolomite are selected to perform CO2-water-rock reaction experiments. The X-ray Diffraction (XRD) and Nuclear Magnetic Resonance (NMR) are carried out to examine the change characteristics of mineral dissolution and pore structure after reaction. The core flooding experiments with Fiber Bragg gratings are implemented to examine the stress sensitivity of carbonate rocks. The results show that the limestones containing pure calcite are more susceptible to acid dissolution compared to limestone containing impure dolomite. The calcite content in pure limestone decreases as the reaction undergoes. The dissolution of dolomite leads to the formation of calcite in impure limestone. Calcite dissolution leads to the formation of macropore and flow channels in pure limestone, while the effects of impure dolomite in impure limestone results in mesopore formation. When confining pressure is lower than 12 MPa, pure limestones demonstrate higher strain sensitivity coefficients compared to impure limestone containing dolomite after reaction. When confining pressure exceeds 12 MPa, the strain sensitivity coefficients of both pure and impure limestones become almost equal. 相似文献
7.
A. Angabini 《Engineering Geology》2003,67(3-4):353-372
Investigations of the engineering geological, physical and rock mechanical properties have been carried out on Carboniferous core samples of the research wells Geverik, Kastanjelaan and Heugem in South Limburg, The Netherlands over a total length of 2687 m. On the basis of a mathematical modeling of the deformation and anisotropy of the Variscan-folded Carboniferous, the following parameters were determined: density, porosity, water resumption and specific permeability for gas.
Dynamic, static and uniaxial compression tests were performed in order to obtain direction-dependent data like dynamic elasticity modulus, static elasticity modulus (Young's modulus), shear modulus and the Poisson's ratios. Additionally, the stress–strain behaviors were determined by uniaxial strength, tensile strength and shear strength tests. For the evaluation of the anisotropy of the rock mass caused by tectonic movements, ultrasonic measurements were of greatest importance. The results show that the ultrasonic velocities of p- and s-waves are dependent on the rock type, the tectonic configuration and the degree of saturation.
The stress–strain behavior of mud, sand and marly limestones shows an orthogonal anisotropy, while limestones and siliceous limestones are quasi-isotropic. The anisotropy is related and parallel to the main tectonic axis and also to the rock texture. 相似文献
8.
F. Moseley J.C. Cuttell E.W. Lange D. Stevens J.R. Warbrick 《Journal of Structural Geology》1981,3(3):237-251
The Pre-Betic is the most northerly of the Alpine zones forming the Betic Cordilleras of southern Spain. It consists of strongly folded and faulted Mesozoic and Tertiary rocks, the oldest of which are ferruginous and gypsiferous Triassic mudstones, followed by a predominantly carbonate facies of Cretaceous, Palaeogene and Miocene age. Although this sequence is interrupted by a number of minor unconformities, the major structures were formed during the middle or late Miocene. The highly incompetent Triassic rocks are the most strongly deformed, and form diapiric intrusions discordant to regional structural trends in the younger rocks. The latter are essentially of two facies: massive competent limestones which are deformed by relatively simple folds of large wavelength, and highly incompetent marl-limestone interbeds with complex disharmonic folds and crush belts. Faults include low-angle and high-angle thrusts, gravity slides and wrench faults. The regional tectonic strike is ENE to NE, but the diapiric intrusions mostly follow WNW and N directions. These intrusions have pushed the younger rocks aside, the result being polyphase structures of several trends.Less intense post-Miocene tectonics are mostly associated with continued diapirism and have resulted in the folding and tilting of the late Miocene to Quaternary elastic sediments. 相似文献
9.
N. M. Chumakov 《Stratigraphy and Geological Correlation》2016,24(2):212-217
This work describes clastic dikes which intruded along cleavage planes into Lower Vendian clay shales of the Barakun Formation (the eastern part of the Patom folded zone). Dikes are composed of sandstones, which are common in other parts of the Barakun Formation, or more often by thin intercalations of finely oolitic limestones in surrounding shales. It is evident that dikes were formed as a result of elision processes synchronous to the folding, the major system of cleavage planes, and dehydration of clayey rocks of the Dalnetaiginsky Group at the end of Early Vendian. This stage of folding can be considered as one of the first phases of the Baikal folding by N.S. Shatsky. 相似文献
10.
11.
Unconformity of red sandstones in north Vietnam: field evidence for Indosinian orogeny in northern Indochina? 总被引：1，自引：0，他引：1
We re-examine several unconformity sites in northwestern Vietnam where the Indosinian orogenesis has been defined. Field observations in the Black-River (Song Da) region, near Son La, demonstrate that red sandtones and conglomerates, reportedly of Cretaceous age, occur unconformably above schistosed epimetamorphic middle-Triassic sediments. A mesozoic unconformity thus really exists in this region, though the age of deformation is poorly contrained (upper Triassic to upper Cretaceous). In most places, however, the unconformity is strongly deformed, folded Triassic limestones are often thrusted onto the Cretaceous rocks. This implies that Tertiary deformations probably due to the India–Asia collision have been strong in the northern part of the Indochina block. 相似文献
12.
Subir Kumar Ghosh 《Tectonophysics》1974,21(3):249-272
Two series of experiments were carried out with soft model-materials in order to assess the relative importance of initial homogeneous strain, external rotation and late-stage strain in reorienting early lineations during superposed buckle-folding. In the first series cylindrical buckling folds were produced in embedded planar sheets containing a “lineation”. In the second series noncylindrical folds were produced by compression of a set of cylindrical folds. The experiments indicate that the ratio of buckle shortening to layer-parallel strain is much smaller when the principal extension is parallel to the fold-axis than in the case when the principal extension is perpendicular to the fold-axis. In very competent rocks, the reorientation of old lineations is mainly by external rotation and by the associated concentric longitudinal strain. In moderately competent rocks, the orientation of early lineations always changes by initial homogeneous strain before buckling becomes significant. Because of the unlike amounts of initial strain in layers of different competences, orientations of unrolled lineations may not be parallel in disharmonically folded layers of unlike competences. Under certain conditions the early lineation may become virtually parallel to the later fold-axis. The experiments indicate that the effects of late-stage strain in buckle-folding are largely restricted to the incompetent layers of a multilayer. Hence, if orientation data of early lineations in both competent and incompetent rocks are lumped together, the pattern of orientation may become quite complex. Even for a single competent layer, the pattern of early lineations can locally become complex because of the complex nature of concentric longitudinal strain (and strain resulting from stretching of middle surface of the layer), development of conical folds, development of shear strain along hinge zones of deformed early folds and also because of the development of different orders of folds in both the first and the second deformations. 相似文献
13.
构造应变与砂岩成岩的构造非均质性——以塔里木盆地库车坳陷研究为例 总被引：6，自引：2，他引：4
孔隙性砂岩在应变过程中首先发生应变局域化并形成肉眼不易识别的变形条带(deformation band),这与低孔隙性的碳酸盐岩的应变效应迥然不同.实例分析说明,天山南缘库车坳陷后期构造变形强烈,自白垩纪以来构造应变具有南北分带、东西分异的显著特征.结合盆地构造格架以及砂岩物性分布特征,本文提出了该区六类砂岩储层改造的构造样式,并描述了其中砂岩的构造非均质性.其中深层卷入型(3类)主要发育于盆地西部,而浅层卷入型发育于盆地东部,其分布受基底构造、盐煤等滑脱层、近南北向的调节断裂、盆山边界接触方式的控制.除变形条带外,研究发现本区最大埋深大于6500～7000m的白垩系致密砂岩的应变属性亲近灰岩,其由于后期抬升或深层次构造应变将容易导致裂隙的发育,这一点在有效储层预测中值得重视. 相似文献
14.
ABSTRACT Carboniferous speleothem calcites in un-metamorphosed limestones from South Wales exhibit crystal diminution (degrading neomorphism) textures. These textures result from processes which have been considered only important under metamorphic conditions. The textures are interpreted as the result of recrystallization associated with dislocation processes. These processes relate to low temperature creep associated with low strain rates extended over long periods of time. The textures described here occur in unusually large crystals but similar textures have been described in limestones from deep boreholes. Dislocation processes, recovery and recrystallization are likely to be important processes operating during deep burial diagenesis. 相似文献
15.
Two-dimensional analysis of folded surfaces oblique to the mechanical layering can shed light on the kinematic mechanisms that operated during the development of folds. A new version of the program ‘FoldModeler’, developed in the Mathematica™ environment, is used to obtain the deformed configuration of an initial pattern of oblique surfaces deformed by any combination of the most common kinematic folding mechanisms: flexural flow, tangential longitudinal strain, with or without area change and heterogeneous simple shear. The layer can also undergo any form of homogeneous strain at any moment of the folding process. The outputs of the program provide complete information about the strain distribution in the folded layer that includes graphs of the angle between the oblique surfaces as a function of the inclination of the layering through the fold. These graphs can be very useful to discriminate between the mechanisms that operate in the development of natural folds, and they have been obtained and discussed for the most common combinations of strain patterns. The program is applied to obtain theoretical folds that give a good fit of some natural examples of folded oblique surfaces. 相似文献
16.
Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC′ tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of “aseismic” behaviour. 相似文献
17.
《Journal of Structural Geology》1988,10(3):305-309
Cathodoluminescence petrography is a valuable tool for the analysis of strain microfabrics in deformed limestones. Finely banded growth zones in calcite cements, visible only in the cathodoluminescent mode, act as very sensitive displacement markers. They reveal the varied and heterogeneous nature of microstructures within the deformed calcite. 相似文献
18.
AbstractThe deformation behavior of fine grained limestones from the Monte Sirino area (Lucania region) of the southern Apennines has been analysed by constraining microstructural observations and crystallographic fabrics with data on the metamorphic conditions of deformation. X-ray and infrared analysis of clay minerals, together with illite ‘crystallinity’ data, suggest that the studied rocks underwent very low grade metamorphism in the deep diagenetic zone. The limestones consist of very fine grained (<10 μm) aggregates of micrite. Elliptically-shaped radiolarians, preserved as moulds with coarser (>20 μm) crystalline fillings, provide common strain markers. Optical microstructures and strain analysis indicate heterogeneous intracrystalline strain in the coarser (>50 μm) calcite. On the other hand, SEM and TEM observations, and crystallographic fabrics determined by X-ray texture goniometry, indicate a deformation involving not only intracrystalline slip, but also an important component of grain boundary sliding in the fine grained matrix. The inferred microscopic deformation mechanisms are compared with constitutive flow laws derived from experimental studies. For the maximum inferred temperature of deformation of 250 °C and geologic strain rates of 10?13?10?15 s?1, deformation mechanism maps for calcite suggest twinning and other glide mechanisms to be active in grains larger than about 5?10 μm. Smaller grains would be mostly deformed by grain size sensitive creep mechanisms, which include both diffusion mass transfer processes and grain boundary sliding. Deformation features observed in the study limestones are compatible with the prediction of such temperature-dependent mechanism maps. © 2001 Éditions scientifiques et médicales Elsevier SAS 相似文献
19.
《Geodinamica Acta》2001,14(4):213-230
The deformation behavior of fine grained limestones from the Monte Sirino area (Lucania region) of the southern Apennines has been analysed by constraining microstructural observations and crystallographic fabrics with data on the metamorphic conditions of deformation. X-ray and infrared analysis of clay minerals, together with illite ‘crystallinity’ data, suggest that the studied rocks underwent very low grade metamorphism in the deep diagenetic zone. The limestones consist of very fine grained (<10 μm) aggregates of micrite. Elliptically-shaped radiolarians, preserved as moulds with coarser (>20 μm) crystalline fillings, provide common strain markers. Optical microstructures and strain analysis indicate heterogeneous intracrystalline strain in the coarser (>50 μm) calcite. On the other hand, SEM and TEM observations, and crystallographic fabrics determined by X-ray texture goniometry, indicate a deformation involving not only intracrystalline slip, but also an important component of grain boundary sliding in the fine grained matrix. The inferred microscopic deformation mechanisms are compared with constitutive flow laws derived from experimental studies. For the maximum inferred temperature of deformation of 250 °C and geologic strain rates of 10–13–10–15 s–1, deformation mechanism maps for calcite suggest twinning and other glide mechanisms to be active in grains larger than about 5–10 μm. Smaller grains would be mostly deformed by grain size sensitive creep mechanisms, which include both diffusion mass transfer processes and grain boundary sliding. Deformation features observed in the study limestones are compatible with the prediction of such temperature-dependent mechanism maps. 相似文献
20.
N.E. Odling 《Journal of Structural Geology》1984,6(5):543-562
A quantitative structural analysis is presented for the Loch Tullie gneisses of the Lewisian complex outcropping at Gairloch. The gneisses and the dykes they contain are folded into a large antiformal structure known as the Tollic Antiform. Quartz aggregates in quartzo-feldspathic gneisses have been used as finite strain markers in eleven specimens across the antiform. Two models, using rotational strain (simple shear) and irrotational strain (pure shear), are used to reconstruct the strain path. Results show that only the rotational strain model satisfies the strain data and the field evidence, and indicates a steeply northeast (75°) dipping shear plane and moderately northwest (55°) plunging shear direction, with a southwest-side-down sense of shear. A strain profile is constructed for the Tollie gneisses using the model and the attitude of gneissose layering. This shows increasing shear strain to the southwest to a maximum gamma value of approximately 8. The strain profile indicates a horizontal dextral displacement of 4.7 km and a vertical displacement of 6.8 km for the Tollie gneisses. The Tollie Antiform thus lies on the northeast margin of a large-scale shear zone, the main zone of deformation of which can be traced southwestwards some 4 km. Such a shear zone presents a major tectonic boundary within the Lewisian of northwest Scotland. 相似文献