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鄂尔多斯盆地南部地区加里东运动的形变特征主要有三种表现形式：即在盆缘地带形成较宽缓褶皱，逆冲推覆构造、上、下古生界呈角度不整合接触，并构成具造山性质的加里东构造带，向盆地内部依次为和缓隆起，高角度断裂，中、下奥陶统不同层位与上覆上古生界不同层位呈微角度不整合接触；整体抬升、下奥陶统与石炭系不同层位与上覆上古生界不同层位呈微角度不整合接触；整体抬升，下奥陶统与石炭系不同层位呈平行不整合接触，加里东运 相似文献
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辽河盆地与伸展作用有关的构造动力学分析 总被引：1，自引：1，他引：0
辽河盆地是中生代大陆的裂谷盆地,以伸展作用为主,同时受到后期走滑作用的改造,构造形式复杂,裂谷盆地的形成,演化是在伸展活动发生复杂而有规律的运动中进行的,表现为水平伸展运动,垂直升降运动,掀斜或翘倾运动等,这是裂谷盆地的主要特征。 相似文献
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在分析滚石运动形式的基础上,简化斜坡滚石运动模型,从运动学角度出发,推导出一套计算斜坡滚石运动特征的方程。该数理模型符合滚石运动的规律,可用于斜坡区滚石运动特征的预测,并可作为斜坡区滚石灾害防治的依据。 相似文献
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段绪省 《陕西地质科技情报》1996,21(2):37-50
根据（１）脆性断裂的主构造面产状与擦痕，阶步要素或韧性断裂的主面理与ａ线理要素：（２）韧性断裂的Ｓｃ面理与Ｓｓ面理或主构面与片理面产状要素，定量推算其上盘运动的空间方向，并附Ｃａｓｉｏ ｆｘ－４０００Ｐ计算器用程序。 相似文献
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根据几年来对嵩山地区的考察和研究，通过对夷平面，河流阶地，串珠状洪积扇等诸多地貌现象的分析，论述了嵩山地区新构造运动以间竭性抬升运动和掀斜运行为主的特征。 相似文献
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从板缘碰撞到陆内造山:华南东南缘早古生代造山作用演化 总被引：2，自引：0，他引：2
华南的广西运动被认为是发生在早古生代的陆内造山作用,然而触发陆内变形的地球动力学机制仍然不清.广西运动形成了泥盆系与下伏岩石之间广泛的不整合面以及分布在局部地区的下古生界内部的多个不整合面.广西运动期间的构造热事件和古生物响应时间在460~380 Ma,时间上对应于奥陶系和泥盆系之间的多个不整合,而分布在华南南缘的寒武系和奥陶系之间的不整合面（郁南运动）仅与少量的530~480 Ma之间的变质事件相当,但是却同步于广泛分布在东冈瓦纳北缘的造山事件.华南南部寒武系-奥陶系不整合面上下的碎屑锆石年代学研究表明,早古生代华南与印度北缘相连,而三亚地块在寒武纪是澳大利亚西缘的一部分,直到奥陶纪才与华南拼合,同步于冈瓦纳最终的聚合.郁南运动之后,华夏板块处于冈瓦纳内部,来自冈瓦纳东缘造山作用的应力向大陆内部传播,在具有弱流变学性质的南华盆地聚集,导致盆地构造反转,触发了广西运动.早古生代的华南经历了从板缘碰撞（郁南运动）到陆内造山（广西运动）的演化过程. 相似文献
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斜坡破坏后滑体的运动学研究 总被引：3，自引：0，他引：3
提出和介绍在某些复杂条件下的滑坡运动计算公式 ,分析滑体变质量运动、变滑面坡角等因素对滑坡运动的影响 ,提出滑坡的运动特征参数的确定和应用。研究结果对滑坡灾害的调查、研究、预测评价有着重要的理论和实际意义 相似文献
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叙述了地体相对运动与绝对运动的古地磁方法。这些方法在地体构造演化研究方面发挥了重要的作用，同时指出了这些方法的不足之处。方法包括：相对于热点系的运动，块体间的相对运动，板块绝对运动的真极移模式，相对于热点的绝对运动和利用板块边界或海沟位置确定单一板块的绝对运动，其中板块绝对运动的研究是古地磁学研究的热点。 相似文献
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板块构造理论形成以来,不同板块之间的相对作用得到深入阐述,但对多板块聚合的运动过程的研究常被忽略。依据全球古地磁数据和古板块再造,可以获得板块运动轨迹,这些板块轨迹指示全球主要大陆在志留纪(约443Ma)-二叠纪(约250Ma)期间发生向北半球中纬地区的汇聚,具体表现为在泛大陆的形成过程中,全球板块运动具有顺时针旋转的特征,并且大板块(南美、波罗的、西伯利亚、澳大利亚等)纬向移动速率和板块自转速率明显高于小陆块的(华北、塔里木、扬子陆块等)。一些主要陆块显示不对称的"e"型顺时针旋转的漩涡轨迹,汇聚中心在中亚地区,以哈萨克斯坦马蹄形的最终形成和保留为标志。板块聚合的涡旋状运动轨迹,受控于上地幔流动过程产生长期的漩涡运动。这种对流运动在一定时间内(晚古生代)保持相对稳态的流动形式,导致泛大陆的形成。 相似文献
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The high seismicity of portions of the Indian peninsula, together with the high density of population and industrial growth,
results in a significant seismic risk in many parts of the subcontinent. Large construction projects throughout the peninsula
require an adequate basis for earthquake-resistant design. Thus, as well as strong scientific arguments, there are major practical
reasons why a substantial programme to record strong seismic ground motion should be carried out in India. This paper first
reviews the history of strong motion instrumental recording, beginning with the important accelerograms obtained in the Koyna
earthquake of 11 December 1969 through the recent increase in strong motion instrumentation, particularly in association with
construction of large dams. It is argued that there is a pressing need for further extension of strong motion accelerograph
coverage of India, especially along the seismically active regional thrust faults of the Himalayan region. Such programme
expansion should follow deliberate strategies of site selection, designed to optimize the scientific and practical returns,
given the requirements of minimum costs, reliable maintenance and accessible data. 相似文献
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N. C. Stevens 《Australian Journal of Earth Sciences》2013,60(1):37-39
Two ring‐structures, one a ring‐dyke complex, the other a solitary ring‐dyke, have intruded gently‐dipping Mesozoic sedimentary rocks at Mt. Alford, S.S.W. of Brisbane. In the ring‐dyke complex, a central stock of porphyritic microdiorite with closely associated granophyre has dragged up the surrounding sandstones and tilted them to a vertical position around its northern margin. Narrow, steeply‐dipping ring‐dykes of rhyolite and trachyte have intruded the upturned sediments and andesite has invaded the stock, probably as a result of cauldron subsidence. Further dyke intrusions of rhyolite and trachyte and explosive activity were followed by a basaltic dyke swarm. The complex is adjoined on the south and east by stocks of rhyolite, a neck of bedded breccia with centroclinal dips and a ring‐dyke of alkaline rhyolite. It is suggested that the alternation of acid and basic magma is due to tapping of a magma reservoir which rises and falls in the crust, deriving acid magma from the sial. The present highest point in the complex is thought to be below the original surface at the time of intrusion (probably early Tertiary). 相似文献
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We use paleomagnetic data to map Mesozoic absolute motion of North America, using paleomagnetic Euler poles (PEP). First, we address two important questions: (1) How much clockwise rotation has been experienced by crustal blocks within and adjacent to the Colorado Plateau? (2) Why is there disagreement between the apparent polar wander (APW) path constructed using poles from southwestern North America and the alternative path based on poles from eastern North America? Regarding (1), a 10.5° clockwise rotation of the Colorado Plateau about a pole located near 35°N, 102°W seems to fit the evidence best. Regarding (2), it appears that some rock units from the Appalachian region retain a hard overprint acquired during the mid-Cretaceous, when the geomagnetic field had constant normal polarity and APW was negligible.We found three well-defined small-circle APW tracks: 245–200 Ma (PEP at 39.2°N, 245.2°E, R=81.1°, root mean square error (RMS)=1.82°), 200–160 Ma (38.5°N, 270.1°E, R=80.4°, RMS=1.06°), 160 to 125 Ma (45.1°N, 48.5°E, R=60.7°, RMS=1.84°). Intersections of these tracks (the “cusps” of Gordon et al. [Tectonics 3 (1984) 499]) are located at 59.6°N, 69.5°E (the 200 Ma or “J1” cusp) and 48.9°N, 144.0°E (the 160 Ma or “J2” cusp). At these times, the absolute velocity of North America appears to have changed abruptly.North America absolute motion also changed abruptly at the beginning and end of the Cretaceous APW stillstand, currently dated at about 125 and 88 Ma (J. Geophys. Res. 97 (1992b) 19651). During this interval, the APW path degenerates into a single point, implying rotation about an Euler pole coincident with the spin axis.Using our PEP and cusp locations, we calculate the absolute motion of seven points on the North American continent. Our intention is to provide a chronological framework for the analysis of Mesozoic tectonics. Clearly, if APW is caused by plate motion, abrupt changes in absolute motion should correlate with major tectonic events. This follows because large accelerations reflect important changes in the balance of forces acting on the plate, the most important of which are edge effects (subduction, terrane accretion, etc.). Some tectonic interpretations: (1) The J1 cusp may be associated with the inception of rifting of North America away from land masses to the east; the J2 cusp seems to mark the beginning of rapid spreading in the North Atlantic. (2) The J2 cusp signals the beginning of a period of rapid northwestward absolute motion of western North America; motion of tectonostratigraphic terranes in the westernmost Cordillera seems likely to have been directed toward the south during this interval. (3) The interval 88 to 80 Ma saw a rapid decrease in the paleolatitude of North America; unless this represents a period of true polar wander, terrane motion during this time should have been relatively northward. 相似文献
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本文研究了转动物台椭圆偏光的运动规律,并用公式和图解表示椭圆偏光运动轨迹,导出的椭圆偏光方程式集中反映了各公式之间的关系。为解决椭圆偏光长轴运动轨迹,推导出计算椭圆长轴(a)和视旋转角(Ar)两个新公式,使最大视旋转角所对应的物台转角的研究有新的进展。本文重点讨论不透明矿物反射光的椭圆偏光的性质,但对透明矿物透射光的椭圆偏光也有一定意义。 相似文献
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G. Bouckovalas A. Anagnostopoulos A. Kapenis T. Karantoni 《Geotechnical and Geological Engineering》1996,14(2):111-128
Summary On 26 March, 1993, a moderate magnitude earthquake (M
s=5.5) occurred at 3 km epicentral distance from the town of Pyrgos, in Southern Greece, causing extensive damage to masonry houses. To explain the variability of seismic intensity over the town and to propose measures against future seismic activity, a microzonation study was undertaken which combined geological, geophysical and geotechnical investigations, site specific analyses of seismic ground response and detailed recording of structural damage. The analytical predictions of ground response are correlated to soil conditions and then used to identify (micro-)zones of sites with similar seismic response. Furthermore, they are compared to quantitative estimates of damage distribution over the town. It is concluded that the peak ground acceleration, normalized against the input peak seismic acceleration, is a function of the local soil conditions as well as the seismic excitation characteristics. Hence, it cannot be defined uniquely at a site, without reference to the seismic excitation. However, the normalized peak ground velocity and the acceleration response spectra are mainly functions of the soil conditions and can be used as criteria for the practical definition of (micro-)zones. The distribution of damage in various parts of the town is at least partially attributable to local soil effects. The small epicentral distance of the earthquake, connected with the direction of the fault rupture, as well as the quality and techniques of construction, are additional factors that may have influenced the extent and distribution of damage. 相似文献
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ISOTOPE EFFECT OF PRECIPITATION AND MOTION REGULARITY OF RAINFALL CLOUD IN THE SOUTH TIBET 相似文献