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拉鸡山造山带的蛇绿岩套及古构造环境 总被引：2，自引：3，他引：2
传统认为蛇绿岩套由超基性岩，含枕状构造的基本熔岩和硅质岩组成，是大洋岩石圈的碎片，具有完整的５个或４个层序，但经深入研究发现，蛇绿岩有不同的类型，可产在不同的构造环境区。从层序，岩性、岩性组合特征来看，拉鸡山存在蛇绿岩套。拉鸡山蛇岩套厚度小，层序不全、岩性变化大、不是大洋中脊产物，其岩石学特点与初始洋盆蛇绿岩套相同。拉鸡山 绿岩套是中寒武世陆间裂谷拉张到最宽时的小洋盆中形成的，属于陆间裂谷型小洋盆 相似文献
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拉鸡山裂谷带特征及演化 总被引：1，自引：0，他引：1
拉鸡山构造带东西长逾 6 50km ,展布于由元古宇组成的结晶地块内部 ,是一条早古生代火山岩极为发育的构造带。通过作者在拉鸡山多年的野外调查工作和研究 ,认为该地区无论在区域地质学、岩石学、构造变形学还是大地构造演化方面 ,其早古生代构造演化史皆具典型的裂谷带特征。晚古生代以来 ,区内经历了陆内多阶段造山过程。新生代早更新世 ,拉鸡山巨型断裂带发生左旋走滑运动 ,导致断裂带弧形转折部位强烈崛起 ,形成雄伟高山。 相似文献
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拉鸡山断裂带位于祁连山褶皱带内,呈北西-南东向延伸.后者构成青藏高原的东北边缘,由三个主要构造单元组成:北部是一条早古生代的板块缝合带,中部是一个元古代的结晶地块,南部由一套晚古生代到三叠纪的被动大陆边缘沉积物组成.对拉鸡山及其邻区的构造研究结果表明,祁连山褶皱带在古生代加里东期发生过大规模的缩短,北祁连的早古生代蛇绿岩和岛弧火山岩沿祁连山中央冲断层向南,陆内俯冲到中祁连元古界变质杂岩之下.由于发生在晚古生代和晚中生代的陆内变形,位于中祁连之下的北祁连的蛇绿岩和岛弧火山岩发生褶皱,并被抬升到地表.到新生代,由于印度板块和欧亚大陆之间的碰撞和陆内汇聚作用,拉鸡山断裂带再次活动,这些下古生界蛇绿岩和岛弧火山岩通过冲断作用快速抬升,将中祁连地块一分为二.因此,拉鸡山是一个抬升的构造窗,不是一个中祁连结晶地块中的早古生代大陆裂谷. 相似文献
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新疆博格达山东段石炭系火山岩发育。本文通过对该地区石炭系火山岩分布和岩石组成特征的调研,结合以往对该区火山岩地球化学研究,对博格达构造带的构造属性和造山机制进行了探讨,提出博格达构造带具有坳拉谷的基本特征,即具有一端连接大洋(哈尔里克)、一端伸向和尖灭于陆块(准噶尔地块)内,拉张阶段堆积裂谷型双峰式火山岩建造,造山阶段没有俯冲而直接抬升,造山末期有巨量辉绿岩泄出,表明地幔柱在博格达坳拉谷发生和发展过程中的主导作用。 相似文献
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华北燕山造山带结构要素组合 总被引：19，自引：0，他引：19
采用造山带结构要素组合的概念,对华北燕山造山带进行了研究。燕山造山带各演化阶段的结构要素组合特征如下：前造山和初始造山幕(J1),早侏罗世早期为前造山伸展构造,结构要素组合有：三又式裂谷带、板内型玄武岩、含煤建造;早侏罗世晚期为初始造山收缩构造,结构要素组合有：向北倾伏的褶曲与逆冲、九龙山组类磨拉石建造,硬绿泥石一十字石一蓝晶石为标志的低温、中一高压变质带。早期造山幕(J2),中侏罗世早期为同造山伸展构造,结构要素组合有：岩石圈上隆伸展有关的火山盆地及可能的同期侵入岩,火山岩线型分布;中侏罗世晚期为收缩构造,有关的结构要素组合为：逆冲推覆和褶曲变形、磨拉石建造、同构造侵入体和角闪岩相变质岩。峰期造山幕(J3),晚侏罗世早期同构造伸展构造,结构要素组合有：岩石圈上隆伸展有关的火山盆地与同期侵入岩,火山岩面型分布,火成岩组合中出现高压粗面岩类,较大量的流纹岩;晚侏罗世晚期收缩构造有关结构要素组合为：逆冲推覆和褶曲变形、磨拉石建造、同构造侵入体和角闪岩相变质岩,侵入岩中出现高压正长岩类。早白垩世早期(K1^1)晚造山幕有关的结构要素组合为：收缩变形分布较局限,湖相沉积建造替代磨拉石建造,侵入岩组合中出现过碱性石英正长岩,大晶洞构造的花岗岩及科马提质辉长岩等。早白垩世晚期(K1^2)后造山幕伸展有关的结构要素组合为：正断层、变质核杂岩、双峰式岩墙辟、典型的过碱性花岗岩和含煤建造。 相似文献
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湘东北燕山晚期花岗岩构造环境判别 总被引：12，自引：1，他引：12
在湘东北中生代多期陆内花岗岩浆活动中，燕山晚期花岗岩占有重要地位，燕山晚期大规模花岗岩侵入代表一种特殊的构造环境。本文通过湘东北主要燕山晚期花岗岩的岩石化学和微量元素来判别成岩构造环境，认为该期花岗岩属于富碱质的钙碱性花岗岩，为陆内拉张环境下的产物，进一步进行构造环境分类，判别其属于后造山PA型花岗岩，形成于造山作用后期的拉张环境，与陆内裂谷长期拉张的构造环境明显不同。在区域构造演化分析的基础上，提出湘东北燕山晚期花岗岩形成于印支－燕山早期陆内挤压－走滑剪切造山作用后期的构造松弛阶段拉张环境，燕山晚期PA型花岗岩的出现标志着陆内活化由挤压向拉张的构造转折，同时也反映湘东北的陆内活化至少经历了陆内挤压和陆内拉张两个演化阶段。 相似文献
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兴蒙陆内造山带 总被引：21，自引：9，他引：12
本文提出了"兴蒙陆内造山带"的新概念(Xing-Meng Intracontinent Orogenic Belt,XMIOB),从大地构造、沉积建造、岩浆作用和变质作用等方面论述了XMIOB从晚古生代到中生代初的陆内伸展及陆内造山过程,为探讨晚古生代构造演化提供了新模式。根据对内蒙古中西部晚古生代构造格局的总体认识,可将XMIOB划分为五个构造单元即:早石炭世二连-贺根山裂谷带、晚石炭世陆表海盆地、早二叠世艾力格庙-二连伸展构造带、早-中二叠世盆岭构造带和晚二叠世索伦山-乌兰沟伸展构造带。晚石炭世末-二叠纪在兴蒙造山带基底上发育三期伸展构造:第一期见于内蒙古北部二连-艾力格庙地区,形成陆内裂谷盆地及其盆缘三角洲沉积,发育时代为302～298Ma;第二期在内蒙古中西部广泛分布,以隆起与凹陷相间分布的盆岭构造为特征,发育时代为290～260Ma;第三期见于内蒙古南部索伦山到温都尔庙乌兰沟一带,形成主动裂谷背景下的红海型小洋盆,发育时代为260～250Ma。晚古生代与伸展过程有关的岩浆活动可分四期:1)早石炭世贺根山期:以蛇绿岩为主,发育于具有前寒武纪古老基底和早古生代造山带年轻基底的陆壳伸展区; 2)晚石炭世达青牧场期:主要沿北造山带分布,以基性和酸性岩浆构成的双峰式侵火成岩为特征; 3)早二叠世大石寨期:形成的岩石种类多样,分布广泛,包括双峰式火山岩、双峰式侵入岩和碱性岩; 4)二叠纪末-三叠纪初索伦山期:形成陆缘型蛇绿岩或基性岩-超基性岩组合,产生于软流圈上涌造成的主动裂谷背景。兴蒙陆内造山带的构造变形可分为两期,第一期为晚古生代地层大范围褶皱变形,造成盆-岭构造带的缩短;第二期为沿盆-岭构造的边界强烈剪切变形,产生向东逃逸的挤出构造,其构造背景是北部蒙古-鄂霍茨克造山带和南部大别-秦岭中央造山带的远距离效应引起的被动闭合作用。兴蒙陆内造山带的变质作用分为两个阶段,早期变质作用主要表现为石炭纪期间与陆内伸展有关的低压高温变质,晚期为二叠纪末到三叠纪初区域大面积的低压绿片岩相变质以及沿构造边界的局部中-低压型低温变质。 相似文献
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燕山陆内造山作用的深部制约因素 总被引：13，自引：2，他引：11
中生代燕山陆内造山带是在克拉通软弱带上发育起来的。陆内造山作用受到深部条件的制约是与陆缘造山的主要区别。深部制约表现在:(1)继承性的构造活动;(2)断块的差异升降;(3)主动裂谷盆地演化;(4)岩石圈剧烈的构造变动。其中,岩石圈剧烈的构造变动和主动裂谷盆地演化直接受制于上地幔的影响,而断块差异升降是深部作用的间接反映。继承性的构造活动贯穿于燕山运动各个时期,其表现形式可以不同。这些深部影响因素随着时间是有变化的,存在交叉叠置,但是构造-岩浆活动的深度总的来说趋于越来越浅。与其他陆缘、陆间造山带对比,可以看到深部热体制调整在燕山陆内造山作用中是最重要的因素。陆内造山作用是上部地壳对岩石圈不同深度层次剧烈变动的响应,地壳以及岩石圈的加厚和随后的变薄是其实质性的构造过程,不仅导致岩石的变形,而且也引起了山脉的隆升。 相似文献
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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
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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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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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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
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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
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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
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The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning. 相似文献
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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