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1.
黔中隆起的形成时间及形成机制探讨 总被引：6，自引：0，他引：6
黔中隆起经历了水下和陆上两个发育阶段;都匀运动是这一发育转变的成因。问题的焦点是水下隆起的开始时间和都匀运动发生的具体时间。根据沉积相研究,受郁南运动控制,黔中隆起在下奥陶统桐梓组沉积期间已具雏形。对贵阳乌当发现的珊瑚化石Plasmoporella、Heliolites、Amsassia等重新厘定后认为黔中隆起大规模露出水面的时间为晚奥陶世五峰组沉积期结束之时,这也是都匀运动发生的时间。都匀运动本身,受到自南而北方向的滇桂—北越地块的挤压和南东—北西方向的加里东造山运动的挤压,因此在黔中及周缘地区形成了以黔中背斜、乌当—二比向斜为代表的东西向构造和以麻江背斜为代表的南北向构造并存的地质现象。 相似文献
2.
四川盆地加里东期经历了桐湾、郁南、都匀、广西等多期次构造运动，于盆地中西部和西北部分别形成了川中古隆起和川西北古隆起。重建加里东期川中古隆起和川西北古隆起形成演化过程及其关联性可以为四川盆地中西部和西北部深层海相层系下一步油气勘探部署提供新思路。本文通过对四川盆地已有钻井和地震资料的分析，开展了不同构造区的震旦系—早古生代地层对比分析，识别出四川盆地加里东期古隆起各套地层尖灭点分布范围、不整合削截点和上超点。利用地震、连井剖面相结合的方法，重塑了川中和川西北地区古隆起的形成演化过程。综合研究认为，加里东期古隆起的构造形态在晚奥陶世—早志留世初步形成，在晚志留世广西运动中经历了细微调整，古隆起在早志留世达到最大展布范围，于二叠纪沉积前定型，郁南运动和都匀运动对加里东期古隆起的变形起着重要作用；二者总体经历了“隆-凹”分异阶段(Z—∈1m)、隆起定型阶段(∈<sub>1q—S1)、联合隆升阶段(S2—C)、稳定埋藏阶段(P—T2)等4个阶段。 相似文献
3.
黔东北地区与黔中隆起相邻，受黔中隆起影响与控制，该区自古生代以来经历了郁南运动、都匀运动、广西运动和燕山运动。早古生代早期发育在奥陶系下统红花园组(O1h)和桐梓组(O1t)脆性灰岩中的NW向裂隙是黔东北萤石矿床的容矿构造，而NE向断层属于导矿构造。本文通过区域构造研究，典型矿区的构造解析，面理、线理、节理等统计与赤平投影分析，对黔东北地区构造变形与萤石矿床的成因关系开展了研究。结果表明，寒武纪末-早奥陶世早期的郁南运动、晚奥陶世-早志留世都匀运动形成了容矿与导矿构造。早古生代末期的广西运动使得黔东北长期(石炭纪-二叠纪)处于隆升暴露，在此期间，在下古生界形成了以正断层为特点的断层组合，发育了地垒式、地堑式、阶梯状、放射状、羽裂状等多种断层组合，这些组合断层在上覆上古生界的地层中不发育。同时，下古生界还发育了切割寒武系-志留系地层的NW向断层，这些NW断层不是控矿断层，在上述研究基础上，拟定了该区控矿和不控矿的NW向断层的特征。燕山运动在黔东北形成隔槽式褶皱组合，早期断层在此期间大多反转或平移，少数继承性再活动切穿上覆二叠系-三叠系地层。总体... 相似文献
4.
"黔中隆起"是雏形于晚寒武世郁南运动的东西向平缓隆起,经历了都匀运动水下隆起向陆上隆起的转化发展阶段。通过对比沉积岩相与古地理研究,黔中隆起水陆转换开始于晚奥陶世涧草沟期,即都匀运动发生的时间,鼎盛时期发育在晚奥陶世五峰期至早志留世龙马溪期。广西运动期间,受到来自南部云开地块与桂滇-北越地块的挤压和南东向华夏地块与扬子板块汇聚、碰撞脉动式收缩的远程效应,出现了以黔中背斜、乌当-二比向斜为代表的东西向构造带和以麻江背斜为代表的南北向构造带共存的现象,之后,"黔中隆起"作为独立意义的构造单元消失,与"江南古陆"相连接进入联合发展时期。东吴运动和峨眉山玄武岩的喷发改变了黔中隆起控制东西走向的沉积古地理格架,变为近南北向,黔中隆起与上扬子地区的构造演化彻底融为一体,标志黔中隆起演化的彻底结束。黔中隆起南缘边界的镇远—贵阳断裂中的钾镁煌斑岩单颗粒锆石U-Pb同位素年龄为(261.3±8.0)Ma,很好地指示了黔中隆起作为独立单元发展的最后年限。 相似文献
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广西历来被认为是我国加里东运动的典型地区,志留纪末的造山运动使早泥盆世莲花山组砾岩不整合于下伏地层之上。但是,实际上莲花山组只分布于广西中部的大明山－大瑶山地区和东北部扬子地块边缘,并且,它不具备同造山期磨拉石沉积特征,而是古陆剥蚀面上新海侵序列底部的滨海相沉积。广西西部的晚古生代台地相区,泥盆系底部为泥岩或粉砂岩,超覆于寒武系台地相沉积层之上。滇东南和越南北部邻区情况类似。推测在早古生代时它们属于一个地块,可称为“桂滇－北越地块”。早奥陶世云开地块和桂滇－北越地块、扬子地块的会聚和挤压,形成了大明山－大瑶山地体寒武系东西向的线形褶皱带。这是广西加里东运动的主幕。晚奥陶世-早志留世华夏地块和扬子地块的碰撞带在广西仅限于它的东北部,表现为震旦系-下志留统近南北向的线形褶皱带。志留纪末并无造山运动的证据。早泥盆世开始,可能由于地幔柱活动而使桂滇－北越地块裂解,形成北越地块、靖西台地和其他更小的块体。 相似文献
6.
扬子克拉通南华纪-早古生代的构造-沉积旋回 总被引：5，自引：3，他引：2
根据影响克拉通盆地演化的板块活动所经历的威尔逊旋回,扬子克拉通南华纪-早古生代的构造-沉积旋回可分为5期,即南华纪-震旦纪的均衡调整期、寒武纪的扩张期、早-中奥陶世的汇聚期、中-晚奥陶世的碰撞期和志留纪新一轮的均衡调整期。发生在晚奥陶世的中加里东运动是加里东期最强烈的一次造山运动,而发生在晚志留世的晚加里东运动是一次地壳上升运动;相应的扬子古板块志留纪盆地的构造背景为造山期后的裂谷伸展环境,其原型盆地表现为周缘裂谷盆地与弱伸展的克拉通内盆地相间发育的格局。 相似文献
7.
贵州太康运动的地层学效应：兼论“黔中古陆”的形成 总被引：2，自引：1，他引：2
太康运动是发生在中奥陶世末期的一次全球规模的地壳运动,相应地在贵州又称为都匀运动。由此而形成的贵州南部的早、中奥陶世及志留纪地层间的平行不整合,以及不整合面上、下的古地质特征是太康运动在贵州的主要地层学效应。 太康运动使中奥陶世以前的北东—南西向的古地理构局转变为南北向的格局。由于太康运动形成的地壳抬升,使榕江—天柱一带隆起成江南古陆,黔中地区的修文—瓮安一带隆起形成黔中古陆。 本文以太康运动的地层学效应为基础,着重讨论了黔中古陆的形成。 相似文献
8.
黔中隆起何时形成?认识不一。有认为:寒武纪末期,因黔中地区湄潭组页岩覆于娄山关群白云岩之上;奥陶、志留系地层沿黔中隆起向北渐次分布。有认为:加里东末期,因奥陶、志留系地层缺少边缘相(滨岸碎屑岩)沉积。上述认识,已逐渐被越来越多的资料所否定,如在娄山关群大套白云岩顶部,发现桐梓、红花园组的三叶虫。笔者在遵义南新站核桃窝附近,湄潭组页岩之下的白云岩,顶部为生物碎屑白云岩,内碎屑白云岩及鲕粒白云岩, 相似文献
9.
晚奥陶世与早志留世之间的都匀运动，使滇中古隆起与黔中古隆起成为一整体隆起带（习惯上称黔中古陆），把滇东南和黔南与滇东北-黔北-川南分隔为南、北两个不同的构造沉积域。南侧的曲靖一带出露下、中寒武统，其上分别与中、上志留统和下泥盆统呈假整合，其间缺失奥陶纪和早志留世的沉积物。北侧的禄劝－武定一带，下古生界的沉积序列与之相反，有完整的奥陶纪沉积组合，上与泥盆系假整合，其间无志留纪的沉积。这表明黔中古陆两侧的沉积域各为独立的系统。中晚志留世，黔中古隆起南侧应归属于上扬子与滇黔桂地块前陆挠曲盆地的一部分，由曲靖向北东经赫章哑都-贵阳南转向湘西，向南则与云南的绿春海相连，黔中古隆起北侧的沉积域则为上扬子前陆（川南-黔北）盆地的边缘相。 相似文献
10.
江南隆起上的下古生界缺失带──华南加里东前陆褶冲带的标志 总被引：12，自引：0，他引：12
华南的主造山事件发生在加里东期。由于中生代同一方向薄皮冲断作用的叠加和改造，早古生代的碰撞构造格局已不清楚。江南隆起核部存在一下古生界缺失带，它平行隆起走向线状分布，空间上分开了西北的扬子型地层和东南的江南型地层区，晚古生代浅海碳酸盐平缓超覆其上。由于早古生代时江南隆起位于扬子陆块东南的大陆斜坡部位，当时曾普遍接受沉积，上述线状地层缺失带应属造山变形产物，可能标示着加里东期造山带的前陆褶冲带的位置。 相似文献
11.
Guboglo M. N. 《GeoJournal》1980,4(1):53-58
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen. 相似文献
12.
Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″. 相似文献
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14.
Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated. 相似文献
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摩擦桩基桩土间极限摩阻力取值问题探讨 总被引：1，自引：0，他引：1
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。 相似文献
17.
位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。 相似文献
18.
某高速公路下伏煤矿采空区稳定性分析 总被引：10，自引：0，他引：10
在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。 相似文献
19.
The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time. 相似文献
20.
Michel Westphal Mikhail L. Bazhenov Jean Paul Lauer Diamar M. Pechersky Jean-Claude Sibuet 《Tectonophysics》1986,123(1-4)
We first re-examined the apparent polar wander curves for stable Eurasia and Africa since the Triassic. These curves were then combined together with curves of North and South America according to the kinematics of the Atlantic ocean and a synthetic polar wander curve was given. Then, most of the paleomagnetic results from the Tethys mobile belt, from the Atlantic to the Pamirs, were analysed.Several groups of plates, microplates and blocks can be seen. First, relatively stable regions like Maghreb and Sicily, which have not moved much. Then we have a group formed by Iberia, Sardinia, Italy and, to a lesser extent, Corsica and the Western and Central Alps. For these blocks, movements are anticlockwise rotations chiefly driven by the anticlockwise rotation of Africa, but they are sometimes stronger.To the east, a major change takes place. The north of the Aegean Sea and the Ionian zone are clockwise rotated and these rotations are recent: Oligocene-Miocene for the first part, Pliocene to the present for the second part.A major problem arises in Turkey, Caucasus and Iran. Paleomagnetic results indicate a position far to the south of Eurasia, and, at the same time, geological evidence is in favour of a position close to Eurasia. We discuss these discrepancies. 相似文献