西天山山脉多期次隆升-剥露的裂变径迹证据

磷灰石的裂变径迹法已经广泛地应用于限定山脉的隆升剥露历史研究。天山山脉的隆升历史一直存在争议,西天山山脉的构造隆升研究则相对更为缺乏。野外系统采集三个横穿西天山察汗乌苏山剖面的花岗岩、火山岩等样品,挑选磷灰石开展了裂变径迹测试分析工作。测试结果表明,西天山可能存在多期次的构造隆升事件;进一步利用实测的磷灰石裂变径迹年龄数据和径迹长度,开展了磷灰石的温度时间反演模拟研究。模拟结果结合区域性的地质资料分析推断,西天山山脉自中生代以来存在4个阶段构造隆升剥露事件,分别为:三叠纪末—早侏罗纪(220～180Ma)、侏罗纪中期(170～140Ma)、白垩纪中期(110～80Ma)和晚新生代(24Ma以来)。     

西天山隆升-剥露过程初步研究

天山造山带是在古生代造山基础上,在新生代由于印亚碰撞的远程效应而陆内再造成山。本文主要用磷灰石裂变径迹测年分析来限定西天山的隆升-剥露过程。野外系统采集西天山山脉及其伊犁盆地钻孔中的样品,挑选磷灰石进行了裂变径迹测试分析工作,着重开展了磷灰石的温度-时间反演模拟研究。根据温度-时间模拟结果推断,西天山在中新生代期间共发生了3期次的快速冷却作用,分别为早侏罗纪(200～180Ma)、白垩纪中期(115～95Ma)和新生代期间(24Ma以来);根据样品位置分析表明,西天山的隆升-剥露作用并不均一,开始于侏罗纪早期的山脉抬升范围有限,仅局限于中天山;白垩纪中期(115～95Ma),整个西天山山脉和伊犁盆地一起发生整体的抬升和剥露;新生代24Ma以来,西天山的山体块体抬升与山间盆地的断陷同时发育。     

天山北缘侏罗系地层热历史演化及其地质意义：磷灰石裂变径迹和镜质体反射率证据

对天山北缘石场-玛纳斯、安集海河和四棵树河地区18个样品进行了磷灰石裂变径迹年龄测定,同时测定了中生界地层10件裂变径迹样品相应煤层的镜质体反射率。结果表明地层由老到新镜质体反射率逐渐增加,磷灰石裂变径迹中值年龄逐渐降低。石场-玛纳斯地区,下部三叠系煤层镜质体反射率 R_o 值较低,为O.56%,磷灰石裂变径迹中值年龄较大,为125.3±9.1Ma;八道湾组煤层 R_o 为0.53%～0.64%,磷灰石裂变径迹中值年龄介于81.3±4.7～87.8±5.9Ma;上部西山窑组煤层 R_o 最高,达到0.81%,磷灰石裂变径迹中年龄较低,为44.0±5.4～11.8±1.8Ma;相同层位,东部石场-玛纳斯一带 R_o比西部四棵树地区高,磷灰石裂变径迹年龄刚好相反。磷灰石裂变径迹模拟结果表明中生界三叠系、下侏罗统地层的埋藏深度相对较浅,上覆沉积持续的时间到晚侏罗世到早白垩世基本上已经结束,然后保持在基本不变的深度,直至中新世,不整合在三叠系之下的花岗岩的模拟结果也支持这样的认识。晚侏罗世—早白垩世的冷却降温事件可能是地温梯度变化和隆升作用的共同结果;中侏罗统地层埋藏增温过程持续时间较长,在玛纳斯地区直至渐新世末期。所有样品中磷灰石裂变径迹模拟都记录了10Ma 左右的快速冷却过程,近4～5km 的地壳表层物质被剥蚀,平均剥蚀速率400～500m/Ma。这一剥蚀过程应该与天山地区的快速隆升,以及向北的冲断推覆作用相对应。天山地区山前带的变形应不早于10Ma,这一认识与野外地质证据一致。     

阿齐山—雅满苏地区中-新生代构造隆升裂变径迹 证据:兼论构造活动对核废选址场的意义

构造活动性是核废处置场评价的一项基本判别要素。文中通过对东天山阿齐山—雅满苏地区磷灰石裂变径迹测年及 构造隆升剥蚀过程的模拟来评价核废处置场的构造活动性。结果表明阿齐山—雅满苏地区样品磷灰石裂变径迹年龄集中分 布在81.7~51.4 Ma之间,反映出东天山地区晚白垩世—始新世存在一次明显的构造冷却事件,这与天山地区晚白垩世的抬 升剥露事件相一致。磷灰石裂变径迹长度介于13.60±0.11~14.36±0.10 μm之间,其长度标准差为0.98~1.22 μm,显示该区 磷灰石径迹形成后没有发生过明显的退火作用。根据地温梯度计算得到晚白垩世—始新世东天山阿齐山—雅满苏地区隆升 剥蚀速率为270~580 m/Ma。现有地质资料及热史模拟结果表明,东天山阿齐山—雅满苏地区在晚白垩世—始新世(84~49 Ma)期间经历了强烈的构造隆升—剥露事件,自始新世以后50 Ma以来,地壳处于稳定状态,新生代构造活动不明显,其 活动强度明显有别于天山其他地段。东天山阿齐山—雅满苏地区现在的构造地貌基本继承了晚白垩世的特征,处于构造活 动平稳期,符合核废处置场选址的构造要求。     

东天山地区中—新生代隆升-剥露过程:来自磷灰石裂变径迹的证据

前人已经对西天山及邻区以及阿尔金断裂带进行了大量中—新生代隆升-剥露的研究工作,但对东天山地区的研究工作很少。天山造山带中—新生代期间的隆升-剥露过程是否具有均一性,目前仍没有确切的认识。为了获得东天山地区中生代以来的隆升-剥露信息,对吐哈盆地东南缘雅满苏地区磷灰石裂变径迹进行了研究。研究表明,在不同构造位置采集的花岗岩、砂岩、火山岩样品年龄集中分布在81~53Ma,样品年龄记录了东天山地区晚白垩世—古新世发生的冷却事件。磷灰石裂变径迹平均长度为13.60~14.36μm,接近于磷灰石初始径迹长度约14.5μm,表明径迹形成后没有发生过明显的退火作用。根据地温梯度计算得到东天山晚白垩世以来的平均隆升速率约为4.31×10-2 mm/a。进一步的热史模拟表明,晚白垩世—古新世(80~50Ma)期间东天山地区经历了一次隆升-剥露事件;始新世以后(50 Ma),东天山地区地壳处于稳定状态,东天山隆起带现在的构造面貌基本继承了中生代的特征。     

新疆博格达--哈尔里克山白垩纪以来剥露历史的裂变径迹证据

对新疆博格达-哈尔里克山火山岩和花岗岩的15个磷灰石样品和5个锆石样品的裂变径迹年龄测定表明,磷灰石的裂变径迹年龄变化于109.3～11.9 Ma之间,锆石的裂变径迹年龄变化于81.7～56.8 Ma之间.矿物对法计算得到,该地区晚白垩世至新生代中期的视剥露速率为0.157～0.222 mm/a.热史模拟结果表明,博格达-哈尔里克山自白垩纪以来经历了多期冷却剥露,分别是早白垩世(119～105 Ma)、晚白垩世晚期(67～65 Ma)、新生代早中期(47～31 Ma)和新生代晚期(12～7 Ma).白垩纪以来的天山变形作用,与亚洲南缘多期的地体碰撞增生有关.     

西天山白垩纪隆升-剥露的裂变径迹证据

白垩纪的隆升-剥露事件在新疆不同构造单元广泛发育。本文主要是通过磷灰石裂变径迹测年技术,结合温度-时间热模拟反演的研究,探讨西天山北段和中段白垩纪的隆升-剥露过程。17个样品分别采自西天山北段的博罗科鲁山、依连哈比尔尕山以及西天山中段的独库公路附近的花岗岩体。裂变径迹测试结果显示,样品的径迹年龄介于45.4±3.2~81.6±4.9 Ma,平均径迹长度介于12.62±0.17~13.53±0.14μm之间。进一步根据温度-时间的模拟结果推断,西天山北段和中段在晚白垩世都经历了快速隆升-剥露过程。在时间上,西天山北段样品记录的快速隆升的时间主要集中在50~70 Ma之间,西天山中段样品记录的快速隆升时间集中在70~90Ma之间。结合相应的地质证据,认为从晚白垩世开始,西天山地区开始出现差异性的隆升剥露过程,伊犁盆地从早中白垩世隆升剥蚀状态转变为晚白垩世接受沉积,其两侧山脉继续处于快速隆升剥蚀的状态。导致这种隆升-剥露事件的动力学机制是受多因素综合控制的,印亚碰撞的远程效应可能是该期事件的主要动力来源,但天山不同地段的热-流变性质的差异性及不同块体之间的相互作用是导致差异性隆升-剥蚀的主要因素。     

龙门山冲断隆升及其走向差异的裂变径迹证据

大量的低温年代学研究用来讨论龙门山晚新生代的隆升,但很少涉及其走向差异和中生代隆升。本文分别沿龙门山北、中、南段3条剖面进行了锆石和磷灰石裂变径迹测试,结合已有的热年代学数据,以期揭示整个中-新生代期间龙门山隆升历史及其时空变化。中生代以来,龙门山主要有印支期(约200 Ma)、早白垩世末(约100 Ma)、早新生代(65～30 Ma)以及晚中新世(15～9 Ma)等或快或慢的冷却事件,总体上经历了中生代至早新生代的缓慢冷却和晚新生代快速冷却2个阶段,快速剥露开始于15～9 Ma,剥蚀速率由早期的0.1 mm/a增加到0.15～0.3 mm/a左右,局部可达0.9 mm/a左右。走向上,龙门山北段相对偏小的锆石裂变径迹年龄和相对偏大的磷灰石裂变径迹年龄反映其在中生代较中、南段隆升更快,而裂变径迹年龄总体上从北段向中、南段减小,表明中、南段在新生代发生了更快的隆升。倾向上,多种热年代学数据显示新生代期间在北川断裂和彭灌断裂两侧存在明显的差异剥露,这种差异在中、南段表现比北段更为突出。龙门山晚新生代快速隆升和剥露是青藏高原区域隆升背景上叠加的冲断活动所致,而非下地壳流动驱动。     

阿尔泰山南缘白垩纪以来的剥露历史和古地形恢复

应用裂变径迹技术研究阿尔泰山南缘中新生代以来的隆升剥露历史,并对古地形进行恢复。对所获得的11个磷灰石样品的裂变径迹年龄分析表明,裂变径迹年龄变化分布于99.1~43.7 Ma之间。该地区晚白垩世以来平均视剥露速率为0.050 mm/a。热史模拟结果表明,阿尔泰山南缘自白垩纪以来经历了多期冷却剥露历史:早白垩世至晚白垩世晚期(约120~75 Ma),剥露速率为0.044 mm/a;晚白垩世晚期至始新世(约75-70~50 Ma),剥露速率为0.070 mm/a;中新世以来(约20-15 Ma~现今),剥露速率为0.081 mm/a。对研究区进行古地形恢复显示,自白垩纪(120 Ma)至今,平均剥露幅度达约5 km,古地形海拔降低约0.8 km。阿尔泰山南缘白垩纪以来古地形海拔仅在17.5~50 Ma期间保持基本稳定,其他阶段均有降低的趋势。早白垩世的构造抬升与蒙古-鄂霍茨克海最后阶段的闭合以及西伯利亚板块和中朝-蒙古板块的最终收敛和碰撞有关;晚白垩世晚期至始新世的构造活动则是受拉萨地块、Kohistan-Dras岛弧增生的远距离影响;中新世以来快速隆升可能与印度板块与欧亚板块碰撞的远程效应有关。     

秭归盆地中新生代构造-热演化的裂变径迹约束

通过磷灰石裂变径迹年龄的测定以及时间-温度热历史的反演,揭示了秭归盆地中新生代构造-热演化过程。结果表明:秭归盆地自120 Ma左右开始缓慢隆升,主要经历了3个强烈的隆升阶段:(1)晚白垩世100~80 Ma开始强烈隆升,是燕山期造山运动在该地区作用的结果,也可能是黄陵背斜晚白垩世强烈抬升向西延伸的响应;(2)晚始新世40 Ma的强烈隆升,可能是印度板块和亚欧板块碰撞初期作用的远程响应;(3)中新世中期到末期10~5 Ma的强烈隆升,是青藏高原东部边界向东扩展及亚洲季风气候变化的响应。秭归盆地内部自白垩纪以来一直隆升剥蚀,展现出与盆地边缘构造-热演化的差异。通过与黄陵背斜东部的当阳盆地构造-热事件的对比,暗示了黄陵背斜在晚白垩世已隆升剥露至地表,分割了两个盆地。晚侏罗世—早白垩世,秦岭大规模挤压变形逆冲推覆构造作用使得米仓山—汉南隆起和黄陵背斜地区成为中上扬子地区磷灰石裂变径迹年龄相对最大的区域,江南—雪峰陆内造山作用向西北方向的扩展使得湘鄂西地区向川东地区磷灰石裂变径迹年龄具有整体变年轻的趋势。晚白垩世以来太平洋板块俯冲挤压效应使得川东褶皱带周缘及川东北磷灰石裂变径迹年龄自南东向北西方向减小,江汉盆地、当阳盆地及龙泉山以西记录的年轻的磷灰石裂变径迹年龄则与青藏高原隆升及其向南东方向构造逃逸的挤压作用和亚洲季风等气候变化的影响有关。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

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.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

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″.     

Global repeating events in the history of the Earth and the motion of the Sun in the Galaxy

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.     

摩擦桩基桩土间极限摩阻力取值问题探讨

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。     

从榴辉岩与围岩的关系论苏鲁榴辉岩的形成与折返

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。     

某高速公路下伏煤矿采空区稳定性分析

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。      

On the consistency of proposed models for the Pyrenees with the structure of the eastern parts of the belt

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.     

Paleomagnetic implications on the evolution of the tethys belt from the atlantic ocean to the pamirs since the triassic

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.