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1.
青藏高原中部发育有一系列独立的内流断陷湖盆,其中位于南亚季风区边缘的错鄂湖盆发育了巨厚的湖泊沉积,是研究高原内部地质环境变迁与构造-气候旋回的理想场所。本文对青藏高原中部错鄂孔197m沉积岩心Sr、Rb、Zr含量及其比值以及沉积物有机质δ^13C、TOC含量进行了分析,同时结合岩性、粒度、粘土矿物组成,初步建立了青藏高原中部2．8Ma来岩石化学风化的相对强度和古环境演化过程。结果表明,2．8Ma来青藏高原中部经历了三次剧烈的环境演化过程：在约2．8～2．5Ma期间,低Sr含量,高Rb／Sr和Zr／Rb值记录了较弱的化学风化过程, 相似文献
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青藏高原中部2.8Ma以来的化学风化与环境演化的湖泊沉积记录 总被引：2，自引：0，他引：2
对采自青藏高原中部错鄂湖泊钻孔近200m以上深处、形成于2.8Ma以来的沉积岩岩芯中Sr,Rb,Zr含量变化及Rb/Sr,Zr/Rb比进行了研究,并结合其岩性、粒度、粘土矿物组成,分析了该地区2.8Ma来化学风化的相对强度和古环境演化过程。研究表明,2.8Ma来青藏高原中部的环境经历了3个演化阶段：在深约197－170m(2.8-2.5Ma)岩性段,低Sr含量,高Rb/Sr和Zr/Rb比揭示的是较弱的化学风化过程,反映了与当时强烈的高原隆升运动有关;在约170－38.5m（约2.5-0.8Ma)段,高Sr含量,低Rb/Sr和Zr/Rb比记录的是该流域较强的化学风化阶段,与高原在稳定期中部总体处于温湿或凉湿的环境下的结论吻合;在38.5-0m（约0.8-0Ma)段,总体Sr含量处于相对低值,Rb/Sr比相对较高,化学风化相对较弱,表明高原中部处于较寒冷的环境之中,高原整体已隆升到4000m以上。 相似文献
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湖泊沉积物记录的藏中地区2.8Ma以来的环境演变历史 总被引：4，自引：0，他引：4
对青藏高原中部错鄂钻孔岩芯湖泊沉积物δ13C、总有机碳(TOC)、总氮(TN)、C/N和Rb/Sr比值等进行了分析,并结合岩性、孢粉组合特征等,建立了2.8Ma以来藏中地区的环境演化序列、区域构造活动和湖盆演化过程.研究显示,大约在2.8Ma,错鄂构造成盆,2.6Ma的构造运动之后,湖泊扩张,夏季风降水增加,湖泊沉积物以青灰色泥为主,藏中地区总体上处于温湿或凉湿的环境下;约0.78Ma后,沉积岩性明显变粗,湖盆快速充填,反映了强烈的构造隆升运动,并使高原中部整体隆升到4000m以上,δ13C和TOC反映藏中地区环境具明显的高寒特点;高原剧烈隆升时期,化学风化较弱,而在高原相对稳定的剥蚀夷平阶段,化学风化较强,说明藏中地区的化学风化在受气候强烈影响的同时,又受高原阶段性的构造隆升所控制. 相似文献
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Late Cenozoic Chemical Weathering and Environmental Changes Recorded in the Co Ngoin Sediments,Central Qinghai-Tibet Plateau 总被引：1，自引：2，他引：1
CHEN Shiyue JIN Zhangdong WANG Sumin SHEN Ji Nanjing Institute of Geography Limnology Chinese Academy of Sciences Nanjing Jiangsu School of Environment Planning Liaocheng University Liaocheng Shandong Institute of Earth Environment Chinese Academy of Sciences Xi’an Shaanxi 《《地质学报》英文版》2005,79(3):384-391
A series of faulted inland basins were developed in the central Qinghai-Tibet Plateau, among which the Co Ngoin Basin containing thick lacustrine sediments is located in the peripheral area of the Indian monsoon. In this paper, we present the weathering history and paleoclimatic changes in the last 2.8 Ma based on studies of high-resolution temporal distributions of Sr, Rb and Zr concentrations, Rb/Sr and Zr/Rb ratios and δ ^13C and TOC for the Co Ngoin sediments, in combination with the sediment properties, grain size distribution and clay mineralogy. The sedimentary records indicate three environmental stages in the last 2.8Ma. At the core depth of 197-170m (about 2.8-2.5Ma), low-intensity chemical weathering in the Co Ngoin catchment was experienced under warm-dry to cool-wet climate conditions with relatively low Sr concentration and high Rb/Sr and Zr/Rb ratios. The sudden occurrence of both subalpine coniferous forest and coarses and and gravel sediments in the Co Ngoin core reflects a strong tectonic uplift. The high Sr concentrations and low Rb/Sr and Zr/Rb ratios reflect a relatively strong chemical weathering between 2.5Ma and 0.8Ma (at the core depth of 170-38.5m) under a temperate/cool and wet climate, characterized by mud and silt with fine sand, probably indicating a stable process of denudation and planation of the plateau. Above the depth of 38.5m (about 0.8-0Ma), the coarsening of sediments indicates a strong tectonic uplift and a relatively low intensity of chemical weathering as supported by the record of sediments having relatively low Sr concentrations and high Rb/Sr and Zr/Rb ratios. Since then, the plateau has taken the shape of the modern topographic pattern above 4000m a.s.l. 相似文献
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粒度分组:提取古环境变化信息的一种有效方法 总被引：3，自引：0，他引：3
对南京老虎山黄土-古土壤剖面全样和三个粒级组分(《2 μm、2～45μm和》45 μm)的Rb/Sr比值进行了系统研究.结果表明,Rb/Sr比值是衡量黄土和古土壤化学风化强度的良好地球化学指标;粒度分组是利用Rb/Sr比值研究古环境变化的有效方法.通过粒度分组,可以排除不同粒度组分之间由于Rb/Sr初始比值不同造成的互相干扰.《2 μm粒级的(Rb/Sr)-Sr反相关图的R2值最大(达0.97),说明该粒级指示化学风化作用的灵敏度最高,研究Rb/Sr比值这一地球化学指标最理想. 相似文献
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哈尔滨城市道路表土记录的痕量元素在不同粒级中的分布特征 总被引：1，自引：1，他引：0
将城市道路表土样品进行粒度分级(全样、＞63μm、63～30μm、30～11μm和＜11μm),测定了各粒级组分的微量元素和稀土元素组成.结果显示,微量元素在不同粒级组分中的变化程度按照以下顺序依次递增:Sr＜Rb＜Ga＜Y＜V＜Zn＜Nb＜Cr＜Zr＜Cu＜Ni,Sr和Rb受粒度影响较小,Zr、Cu和Ni受粒度影响很大.绝大部分微量元素(V、Cr、Cu、Zn、Sr、Y、Zr、Nb)随粒度的变细含量趋于增加,而Rb则相反,Ni和Ga与粒度不存在明确的相关关系.Rb/Sr比值是一个基本不受粒度分选作用影响的化学风化指标,Zr/Rb、Cu/Zn、V/Cr和Ni/V比值受粒度的影响很大,Zr/Rb比值随粒度变细而明显增高.所有REE在不同粒级组分中的分布规律和波动幅度高度一致,趋向于在细颗粒物质中富集.δEu明显受粒度的影响,随粒度变细,Eu从正异常向负异常演化.δCe在不同粒级组分中的变化不大,显示受粒度的影响较小. 相似文献
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对大别山北麓0.78 Ma以来的黄土-古土壤样品的磁化率及Rb和Sr的地球化学特征研究表明,相对高的w(Rb)和w(Rb)/w(Sr)值及低w(Sr)值指示夏季风占优势的湿润时期,对应古土壤层;相对低的w(Rb)和w(Rb)/w(Sr)值及高w(Sr)值指示冬季风占优势的干旱期,磁化率相对较低,对应黄土层。剖面的w(Rb)/w(Sr)值自下至上降低反映大别山北麓地区的风化作用逐渐减弱,也揭示自0.78 Ma以来气候具有由湿向干的趋势;磁化率与w(Rb)/w(Sr)值的对比分析表明,它们的变化曲线存在显著不同,原因可能是由于磁化率在古土壤中的增强机制比较复杂所致,w(Rb)/w(Sr)值作为气候替代指标比磁化率更灵敏。与洛川剖面相比,大别山黄土-古土壤的w(Rb)较高而w(Sr)较低及Rb、Sr较强的分异能力特征反映了大别山气候整体较为温湿,沉积物遭受的风化程度更强。 相似文献
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湖泊沉积物不同粒级组分的元素含量特征及其环境指示意义①——以内蒙古黄旗海为例 总被引：1，自引：0，他引：1
黄旗海湖泊柱状沉积物的全样、77~20 μm、<20 μm粒级的钛(Ti)、锰(Mn)、锶(Sr)、銣(Rb)、钡(Ba)、锆(Zr)等元素含量分析表明,元素在湖泊沉积物各粒级组分的丰度存在较大差异:Ti、Zr倾向于在粗颗粒中富集,Mn、Sr、Rb倾向于在细颗粒中富集,Ba的富集粒级不明显。Ti、Zr与Mn、Rb的颗粒粒级富集倾向可能是其硅酸盐矿物颗粒碎化过程的结果,而Sr则与湖泊自生碳酸盐有关。元素比值Zrc/（Rbc+Bac）、Zrc/Rbc与Ti、Zr的粒度效应Tic/Tif、Zrc/Zrf指示了沉积物重、轻矿物的相对比率,是流域侵蚀强度与湖泊涨缩的信息指示;Ba、Rb与Sr在细粒级的含量之比Baf/Srf、Rbf/Srf指示了硅酸盐与碳酸盐矿物的相对含量,是流域风化、侵蚀搬运强度与湖泊过程（包括物理/化学/生物）等混合信息指示,没有明确的环境指向性。 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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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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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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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