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1.
本文讨论了韦特尔茄尔斯地区海克拉霍克岩系褶皱构造的特征:早期是一系列不同级别的平卧褶皱,并伴生有轴面片理S_1;晚期褶皱表现为不同时代、不同方向、不同类型的叠加褶皱,轴面近直立,有时伴有轴面劈理。叠加褶皱的类型有共轴和横轴重褶构造、两类不同横跨构造和被限制构造。该区经历了六个构造形变期,以相当于主加里东期的第二期(D_2)与喜马拉雅期的第五期(D_5)形变期最为重要。所有的构造形变均与基底断裂,尤其是与西侧滨外的斯匹茨卑尔根断裂带的活动有关。  相似文献   

2.
通过对东昆仑祁漫塔格岩浆弧带构造变形特征研究,指出该区至少经历了三期变形及后期脆性断裂的改造。三期主要变形包括顺层流劈理及局部顺层掩卧褶皱、韧性剪切带(或劈理化带)、区域规模的褶皱构造。除此之外,还发育有大量的NE及SN向的断裂构造及后期推覆构造。这些构造的形成与东昆仑造山带古生代以来的构造演化密切相关。  相似文献   

3.
剪切褶皱及其所赖以形成的滑动面──轴面劈理的成因是长期以来颇有争议的问题。本文在对剪切褶皱详细的宏微观观察的基础上,系统论述了滑动面所具有的挤压和剪切的双重力学性质,并首次运用递进单剪变形理论解释劈理的成因,指出劈理作为一个物质面,其初始和最终的发育均垂直于应变椭球体的最小应变主方向,而在变形过程中二者发生斜交,从而很好的解释了劈理的双重力学性质。在此基础上本文进一步探讨了剪切褶皱的形成模式,把剪切褶皱的形成分为六个主要阶段。该模式指出剪切褶皱并。是单纯的与层面斜交的剪切作用产物,而是在纵弯褶皱作用的基础上形成的。纵弯褶皱作用形成初始褶皱,在褶皱转折端部位由于压扁作用形成与褶皱轴面平行的劈理,而在褶皱翼部则发生递进单剪变形而形成与轴面斜交的劈理,这些劈理在变形后期由于挤压而逐渐转至与轴面平行。岩层沿轴面劈理发生依次错动形成剪切褶皱。因此,剪切褶皱是纵弯和剪切两种机制联合作用的产物。  相似文献   

4.
由褶皱和剪切带联合控制的金厂峪金矿床   总被引:1,自引:0,他引:1  
金厂峪经历了四期大的构造形变。每期褶皱形都伴有相应的剪切带产生。韧性剪切带是本区断裂的一种主要表现形式。它与褶皱的部位以及轴面劈理等具有密切的空间展布关系。  相似文献   

5.
通常发育在变质岩系中的层内褶皱近年来在北京西山的沉积岩层中广为发现。其特征表明,它们系构造成因,而非同沉积褶皱。通过层内褶皱的构造分析,尤其是它与大型褶皱特殊关系的查明,以及变形标志体的有限应变分析,北京西山的层内褶皱是大型纵弯背斜之上重力垂向压缩及侧向扩展的产物。  相似文献   

6.
结合三维变形理论,在Transpression变形模型基础上,提出了"剪切方向物质挤出模型",并从三维有限应变角度定量探讨剪切方向物质(体积)挤出对剪切带宏观组构样式、转变的影响及其与运动学涡度的关系。变形过程中剪切方向物质挤出对韧性剪切带构造组构样式影响显著:在减薄型三维变形中,当竖直(z)方向体积挤出量小于剪切运动(x)方向挤出量(两者比值a<1或a=1)时,发生"拉长-减薄剪切变形",剪切带发育稳定的竖直面理和水平线理,运动学涡度数(ωk)对面理和线理组合不产生影响;当a>1时,发生"加宽-减薄剪切变形",剪切带组构样式取决于2个因素:运动学涡度数(ωk)和剪切带收缩量(k),可能的组构组合类型为"竖直面理和水平线理"或"竖直面理和竖直线理"。根据剪切方向物质挤出模型,得到结论:同一运动性质的韧性剪切带可形成不同取向的拉伸线理;拉伸线理方向不一定和变形的简单剪切组分方向一致。  相似文献   

7.
西昆仑山南侧沿北西向分布的变质复理石海相碎屑岩系,其时代主要属晚三叠世,是巴颜喀喇山群的西延部分。它的东段和西段岩石变质程度、构造样式和变形机制的不同,是同一构造带中不同构造层次构造的反映。东段属下部构造层次,西段属深部构造层次和深熔花岗岩。它们形成于晚三叠世昆仑地块南缘的陆缘盆地,印支期褶皱变质,燕山期和喜山期的挤压、抬升和剥蚀,使东西两段出露了于不同深度构造层次形成的构造。  相似文献   

8.
通过对变质岩区地层特征的分析,认为在变质地层中存在着大量的结晶片理、变形分异条带与片麻理条带、构造透镜体、顺层褶皱及近水平韧性剪切带,其分别为纵向构造置换或横向构造置换的结果。为多期变形的产物。在这些地区开展构造测量需考虑采用构造—地层学方法。此工作方法可进一步指导对变质岩老矿山的重新认识与评价。  相似文献   

9.
位于川滇南北构造带北部的泸定断裂带内发育糜棱面理、拉伸线理、"A"型褶皱、鞘褶皱、糜棱岩系列的断层构造岩等,它们是原岩和矿物在地壳较深处,在高温、高压环境中,经过晶格位错滑移、位错蠕变、动态重结晶等方式发生强烈韧性变形而形成.该断裂带属于一条典型的韧性剪切带.剪切带内发育的旋转碎斑系、不对称显微揉皱以及书斜构造等指示剪切带上盘下滑移的运动学特征.该韧性剪切带仅发育在古元古界康定群之中,而未见其影响上覆的古生代-新生代的地层,可能形成于元古代的晋宁期-澄江期.泸定韧性剪切带在几何学特征、断层岩类型、变形环境、变形层次、变形机制、运动学特征、动力学特征以及形成时期上与该区发育的其他南北向脆性断层迥然不同,它们不属于同一构造成分.  相似文献   

10.
结合三维变形理论,在Transpression变形模型基础上,提出了“剪切方向物质挤 出模型”,并从三维有限应变角度定量探讨剪切方向物质(体积)挤出对剪切带宏观组构样 式、转变的影响及其与运动学涡度的关系。变形过程中剪切方向物质挤出对韧性剪切带构造 组构样式影响显著:在减薄型三维变形中,当竖直(z)方向体积挤出量小于剪切运动(x)方向挤出量(两者比值a<1或a=1)时,发生“拉长-减薄剪切变形”,剪切带发育 稳定的竖直面理和水平线理,运动学涡度数(ωk)对面理和线理组合不产生影响; 当a>1时,发生“加宽-减薄剪切变形”,剪切带组构样式取决于2个因素:运动学涡度 数(ωk)和剪切带收缩量(k),可能的组构组合类型为“竖直面理和水平线理 ”或“竖直面理和竖直线理”。根据剪切方向物质挤出模型,得到结论:同一运动性质的韧 性剪切带可形成不同取向的拉伸线理;拉伸线理方向不一定和变形的简单剪切组分方向一致。  相似文献   

11.
Hydroxyl induced eclogite fabric and deformation mechanism   总被引:9,自引:0,他引:9  
Eclogites from orogens often show strong plastic deformation and high hydroxyl content. We have studied the correlation between crystallographic preferred orientations of garnet and omphacite from natural eclogites with their hydroxyl contents using the electron back-scattered diffraction technique. The results show: 1) Omphacite has typical L-type or SL-type crystrallographic preferred orientations, that is, [001] is distributed in a girdle in the foliation plane with a maximum parallel to lineation; (010) is distributed in a girdle normal to tbe lineation with a maximum parallel to the foliation plane, suggesting a shear dominant deformation regime. Omphacite fabrics do not vary significantly with hydroxyl content, although the hydrous component may cause lower flow strength. 2) Hydroxyl can influence significantly flow properties of garnet in eclogite. Garnets behave as rigid bodies under low temperature and dry conditions. Grain boundary processes will dominate the deformation and lower the flow strength of garnet under high water fugacity conditions. Garnets show no crystallographic preferred orientation in both cases.These results may have important implications for a better understanding of deformation mechanisms and associated fluid activities during deep subduction and exhumation processes.  相似文献   

12.
胶东地区星载合成孔径雷达图象具有丰富的转换构造信息。ERS-1SAR和JERS-1SAR的图象纹理以及图象处理分析结果,在胶东地区准确碍定了与转换作用有关的定性构造纹理,为动力学和运动学研究提供了极为重要的直观依据。  相似文献   

13.
The mylonitic granitic plutons are extended in line-shape (L) and parallel to the regional extensional shear foliation. After being unstrained, the primary shapes of these plutons are also nearly sheet-like (S). Their fabrics are of S-L or L type. Various kinds of shear marks indicate top-to-south shear. The plutons of various stages are different in deformation intensity; however, the foliation and lineation of these rocks have the same shear sense, which suggests progressive ductile shearing. The development mechanisms of the fabrics include magmatic flow, high-temperature solidstate flow and mid-low temperature solid-state flow. All this demonstrates that these plutons are probably early synextensional tectonic plutons. Their structural features and ages suggest that the low- and mid-crustal extensional detachments might have occurred at the early stage of the development of the metamorphic core complex in the early Mesozoic. These deformations are much deeper at levels and much older than those formed at the final formation stage.  相似文献   

14.
A set of metamorphic suites, previously known as the Precambrian metamorphic basement in Kuda, western Kunlun has been determined as a large nappe ductile shear zone which develops penetrative foliation, oriented stretching lineation, various but consistent kinematic indicators of thrusting from north to south. The microstructure and the supermicrostructure also display the ductile deformation characteristics, and the paleotectonic differential stress is obtained. The metamorphic age is 426–451 Ma dated by40Ar/39Ar method. According to tectonic background, it is a product of early Paleozoic accretionary wedge orogenesis in western Kunlun.  相似文献   

15.
本文对有向循环图 G(N;1.S_2,S_3)的直径下界进行了讨论,并且在两种特殊情形下,得到了新的直径下界.  相似文献   

16.
The Yalashangbo dome, located at the eastern end of North Himalayan domes zone, has a geometry and structure similar to those of a metamorphic core complex. Ductile shear zones formed the detachment system around the dome and these zones are composed of garnet-bearing phyllonite, mylonitic schist, mylonitic gneiss and mylonitic granite. Ductile shear fabrics developed well in mylonitic rocks, and penetrative lineation and foliation were formed by stretched quartz and feldspar and preferred orientation of mica. Polar Mohr diagram method is used to calculate the kinematic vorticity numbers of the shear zones in the detachment system. Results indicate that the shear zone is a thinned shear zone (thinning of 23%) in an extensional setting which underwent a general shear dominated by simple shear. Comparison of the vorticity numbers between the northern and southern flanks of the Yalashangbo dome shows that the dome is an asymmetric system formed by a north-northwest-directed detaching unanimously. Statistical fractal analysis shows that the shapes of dynamically recrystallized quartz grains in the mylonites have characteristics of self-similarity, with fractal numbers ranging from 1.05 to 1.18. From these fractal numbers, the strain rate of the rock was deduced from 10-9.2 S-1 to 10-7.3 S-1, the differential paleao-stress was 13.7-25.6 MPa during the deformation happened at a temperature over 500 ℃. The ductile shear zones in the detachment system around Yalashangbo dome were formed under a high green-schist grade condition or happened simultaneously with the intrusion of granite.  相似文献   

17.
合成了有机锡配合物(4-FC6H4CH2)2Sn(Cl)S2CNC2H4O用X-射线单晶衍射测定了该化合物的晶体结构,结果表明,在该配合物的晶体中,锡原子呈五配位畸变三角双锥构型。  相似文献   

18.
本文以碗豆根尖为材料,测定了Na_2S_2O_5和1萘胺的诱变作用。结果表明,Na_2S_2O_5(0.2%)和1—萘胺(0.2%)有明显的诱变效果,说明Na_2S_2O_5和1—萘胺有使染色体发生畸变的作用。  相似文献   

19.
东濮凹陷文留地区沙三~(3-4)亚段成岩作用模式   总被引:2,自引:0,他引:2  
描述了东濮凹陷文留地区沙三~(3-4)亚段的主要成岩事件,对成岩阶段进行了划分,讨论了埋藏深度、砂体类型、构造位置、断层活动、有机质演化与油气运移、埋藏历史等因素对成岩作用的影响,在分析成岩作用历史的基础上,总结出文留地区沙三~(3-4)亚段的成岩演化模式,讨论了构造位置、砂体微相和成岩相对储层储集性能的影响,指出了有利的勘探方向.  相似文献   

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