塑性岩体与逆冲构造变形关系讨论——库车坳陷西部实例分析   总被引：5，自引：0，他引：5  

张明山  姚宗惠  陈发景 《地学前缘》2002,9(4):371-376

在冲断构造分析过程中 ,常常把塑性岩体仅仅作为滑脱层看待 ,忽略了一些地区塑性变形与冲断构造变形的复合作用。根据露头、钻井、地震等资料 ,应用平衡剖面等技术对库车坳陷西部的构造变形进行了恢复分析 ,发现库车坳陷西部的下第三系盐、膏、泥等塑性体受重力和构造应力联合作用发生了复杂的变形。以往单纯用冲断构造模式分析其成因机制 ,没能科学地反映中生界与新生界之间的变形缩短量的差异 ,通过塑性体的底辟变形和滑脱变形依存关系的剖析 ,能够恢复库车坳陷西部构造演化过程 ,进而为油气勘探提供指导。  相似文献   

Topography as a major factor in the development of arcuate thrust belts: insights from sandbox experiments   总被引：2，自引：0，他引：2  

F. O. Marques  P. R. Cobbold 《Tectonophysics》2002,348(4)

We have used sandbox experiments to investigate and to illustrate the effects of topography upon the development of arcuate thrust belts. In experiments where a sand pack shortened and thickened in front of an advancing rectilinear piston, the geometry of the developing thrust wedge was highly sensitive to variations in surface topography. In the absence of erosion and sedimentation, the surface slope tended to become uniform, as predicted by the theory of critical taper. Under these conditions, the wedge propagated by sequential accretion of new thrust slices. In contrast, where erosion or sedimentation caused the topographic profile to become irregular, thrusts developed out of sequence. For example, erosion throughout a hinterland caused underlying thrusts to remain active and inhibited the development of new thrusts in the foreland. Where initial topography was irregular in plan view, accreting thrusts tended to be arcuate. They were convex towards the foreland, around an initially high area; concave towards the foreland, around an initially low area. Initial plateaux tended to behave rigidly, while arcuate thrust slices accreted to them. Thrust motions were radial with respect to each plateau. Within transfer zones to each side, fault blocks rotated about vertical axes and thrust motions were oblique-slip. At late stages of deformation, the surface slope of the thrust wedge tended towards a uniform value. Initial mountains of conical shape (representing volcanoes) also escaped deformation, except at depth, where they detached. Arcuate thrust slices accreted to front and back. Where a developing thrust wedge was subject to local incision, accreting thrust slices dipped towards surrounding areas of high topography, forming Vs across valleys.Arcuate structural patterns are to be found around the three highest plateaux on Earth (Tibet, Pamirs and Altiplano) and around the Tromen volcanic ridge in the Neuquén Basin of northern Patagonia. We infer that these areas behaved in quasi-rigid fashion, protected as they were by their high topography.  相似文献   

A rifted inside corner massif on the Mid-Atlantic Ridge at 5°S     

T. J. Reston  W. Weinrebe  I. Grevemeyer  E. R. Flueh  N. C. Mitchell  L. Kirstein  C. Kopp  H. Kopp  participants of Meteor / 《Earth and Planetary Science Letters》2002,200(3-4):255-269

The structure of the Mid-Atlantic Ridge at 5°S was investigated during a recent cruise with the FS Meteor. A major dextral transform fault (hereafter the 5°S FZ) offsets the ridge left-laterally by 80 km. Just south of the transform and to the west of the median valley, the inside corner (IC – the region bounded by the ridge and the active transform) is marked by a major massif, characterized by a corrugated upper surface. Fossil IC massifs can also be identified further to the west. Unusually, a massif almost as high as the IC massif also characterizes the outside corner (OC) south of the inactive fracture zone and to the east of the median valley. This OC massif has axis-parallel dimensions identical to the IC massif and both are bounded on their sides closest to the spreading axis by abrupt, steep slopes. An axial volcanic ridge is well developed in the median valley both south of the IC/OC massifs and in an abandoned rift valley to the east of the OC massif, but is absent along the new ridge-axis segment between the IC and OC massifs. Wide-angle seismic data show that between the massifs, the crust of the median valley thins markedly towards the FZ. These observations are consistent with the formation of the OC massif by the rifting of an IC core complex and the development of a new spreading centre between the IC and OC massifs. The split IC massif presents an opportunity to study the internal structure of the footwall of a detachment fault, from the corrugated fault surface to deeper beneath the fault, without recourse to drilling. Preliminary dredging recovered gabbros from the scarp slope of the rifted IC massif, and serpentinites and gabbros from the intersection of this scarp with the corrugated surface. This is compatible with a concentration of serpentinites along the detachment surface, even where the massif internally is largely plutonic in nature.  相似文献   

Models of passive margin inversion: implications for the Rhenohercynian fold-and-thrust belt, Belgium and Germany     

Y Vanbrabant  J Braun 《Earth and Planetary Science Letters》2002,202(1):15-29

Positive tectonic inversion is related to the transmission of compressional stresses along a décollement into the foreland of an orogenic zone. This stress and strain concentration in regions remote from the main orogenic front is commonly related to the presence of pre-existing rheological heterogeneities such as normal syn-depositional faults. During inversion, these pre-existing normal faults are reactivated as reverse faults. Tectonic inversion in the Rhenohercynian fold-and-thrust belt during the Variscan Orogeny shows that inversion is likely synchronous with the onset of collision in the hinterland. Here, we present the results of a simplified thermo-mechanical model (STM) which allows one to study strain partitioning between two orogenic zones. We show that, if the two orogenic zones have the same mechanical properties, the viscosity of the décollement, which links them, controls the initial strain partitioning. During subsequent finite shortening, erosional processes determine the partitioning of strain rate. The presence of a weak structure in the inverted zone and of a low-viscosity décollement leads to initial strain concentration in the inverted track rather than in the collision zone and a progressive decrease in strain partitioning between the two orogenic zones. The STM results are in good agreement with results of a 2D finite-element model. We conclude that, in the western part of the Rhenohercynian Massif, simultaneous uplift and deformation within the Mid-German Crystalline Rise (the main collision zone) and the Ardenne Anticlinorium (the inverted zone) lead to interpreting this orogenic event as a case of vice tectonic rather than the propagation of a ‘wave of folding’ towards the Variscan front, as suggested by previous authors.  相似文献   

Late Caledonian Ductile Thrusting Deformation in the Central East Kunlun Belt, Qinghai, China and Its Significance: Evidence from Geochronology   总被引：5，自引：0，他引：5  

WANG Guocan  CHEN Nengsong  ZHU Yunhai  ZHANG Kexin Faculty of Earth Sciences  China University of Geosciences  Wuhan  Hubei  E-mail: wgcan@cug.edu.cn Ren Xifei  Liu Ruixun  Xie Guanglian 《《地质学报》英文版》2003,77(3)

A high-angle ductile thrusting deformation with top-to-the-north movement penetratively developed in the Proterozoic-Early Paleozoic metamorphic rocks along the Central East Kunlun belt. The deformed rocks suffered epidote-amphibolite facies metamorphism. On the basis of our previous study, we present more data in this paper to further support that the ducdle thrust deformation occurred in the later Caledonian and more detailed information about the deformation. A zircon U-Pb concordant age of 446±2.2 Ma of a deformed granodiorite in the ductile thrust zone was obtained and can be interpreted as the lower limit of the deformation. A syntectonically crystallized and also strongly deformed hornblende Ar/ Ar dating gives an Ar/Ar plateau age of 426.5±3.8 Ma, which represents the deformation age. A strongly orientated muscovite gives an Ar/Ar plateau age of 408±1.6Ma, representing the cooling age after the peak temperature, constraining the upper limit of the ductile thrust deformation. This ductile thru  相似文献   

煤层底板突水系数计算公式的探讨   总被引：12，自引：1，他引：12  

段水云 《水文地质工程地质》2003,30(1):96-99

根据从诸多濒临带压开采威胁的煤矿中得到大量的第一手资料,运用多元统计分析方法,揭示出了煤层底板突水这种地质现象的演化和特征的内在联系和规律,建立了矿压对煤层底板破坏深度的计算式。通过对以往煤层底板突水系数计算公式进行对比、分析、推理和总结,克服了以往计算公式的不足,继承和发展了公式的优点,得出了考虑因素较全面和较科学的突水系数计算式,从而为解决煤层底板隔水岩柱薄弱地带或断裂陷落柱薄弱地带的煤矿安全生产提供了一套行之有效的解决方法。这套公式在太原西峪煤矿和晋城矿务局(西区)得到了应用,证明是一种行之有效的方法。  相似文献   

烃类垂向微渗漏及其地表异常显示   总被引：8，自引：3，他引：8  

蒋涛  陈浙春 《物探与化探》2003,27(2):92-96

烃类以微泡、水动力、扩散和渗透方式向地表迁移过程中,其效能、方式与油气藏的盖层、断裂与裂隙系统、储层的流体性质、地层压力等地质因素密切相关.通过对塔里木盆地雅克拉凝析气田上的地表、井中化探资料与地质资料的综合分析,认为该气田的井中垂向地球化学特征、控制烃类垂向微渗漏地质因素、地表化探异常显示之间呈现出很好的内在联系.  相似文献   

Flexural subsidence by 29 Ma on the NE edge of Tibet from the magnetostratigraphy of Linxia Basin, China   总被引：43，自引：0，他引：43  

Xiaomin Fang  Carmala Garzione  Rob Van der Voo  Jijun Li  Majie Fan 《Earth and Planetary Science Letters》2003,210(3-4):545-560

This study provides a detailed magnetostratigraphic record of subsidence in the Linxia Basin, documenting a 27 Myr long sedimentary record from the northeastern edge of the Tibetan Plateau. Deposition in the Linxia Basin began at 29 Ma and continued nearly uninterruptedly until 1.7 Ma. Increasing rates of subsidence between 29 and 6 Ma in the Linxia Basin suggest deposition in the foredeep portion of a flexural basin and constrain the timing of shortening in the northeastern margin of the plateau to Late Oligocene–Late Miocene time. By Late Miocene–Early Pliocene time, a decrease in subsidence rates in the Linxia Basin associated with thrust faulting and a 10° clockwise rotation in the basin indicates that the deformation front of the Tibetan plateau had propagated into the currently deforming region northeast of the plateau.  相似文献   

Regional Fault Systems of Qaidam Basin and Adjacent Orogenic Belts   总被引：4，自引：0，他引：4  

ZhangBingshan TangLiangjie JinZhijun DaiJunsheng ZhangMingli ZhangBingshan 《中国地质大学学报(英文版)》2003,14(1):65-72

The purpose of this paper is to analyze the regional fault systems of Qaidam basin and ad-jacent orogenic belts. Field investigation and seismic interpretation indicate that five regional fault sys-tans occurred in the Qaidam and adjacent nment.qin belts, controlling the development and evolution of the Qaidam basin. These fault systems are: (1)north Qaidam-Qilian Mountain fault system; (2) south Qaidam-East Kunhm Mountain fault system;（3）Altun strike-slip fault system; (4) Elashan strike-slip fault system, and (5) Gansen-Xiaochaidan fault system. It is indicated that the fault systems controlled the orientation of the Qaidam basin, the formation and distribution of secondary faults within the basin,the migration of depocenters and the distribution of hydrocarbon accmnulation belt.  相似文献   

渤海湾盆地区燕山期构造特征与原型盆地   总被引：11，自引：7，他引：11  

周立宏  李三忠  刘建忠  高振平 《地球物理学进展》2003,18(4):692-699

结合近几年来渤海湾盆地区深层地震勘探与解释的成果，重点论述了渤海湾盆地区燕山期构造特征与盆地原型，提出燕山期构造变形样式总体在纵向上可分为三个构造层，分别称为上部、中部和下部；横向上总体可分为三个构造带，西部为向西逆冲的薄皮逆冲带，中部为冲断—走滑带，东部为厚皮褶皱—冲断带，主体由两期挤压方向皆为NW—SE向的褶皱—逆冲变形形成；并将其演化分为三个阶段：燕山早期、燕山中期和燕山晚期。但是，渤海湾盆地区燕山期的构造变形特征和原型盆地有所变化，其空间上的差异是基底构造格局及其空间差异叠合的结果。综合其它研究结果还表明，渤海湾盆地区燕山期构造是在西太平洋大陆边缘弧的挤压构造背景下，陆内壳下拆沉和壳内挤出逃逸构造的综合动力作用下形成的。  相似文献