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柴达木北缘滩间山群时代及其地质意义 总被引：4，自引：1，他引：4
滩间山群是柴北缘早古生代重要的火山-沉积建造。基于野外地质特征、古生物组合、同位素年龄、构造-热事件等的综合分析,本文认为滩间山群形成于早-晚奥陶世,时限496~440Ma,与该区超高压变质作用不同步,后者时限545~485Ma。新的滩间山群火山-沉积建造序列表明,柴北缘从新元古代-早古生代可能存在两次构造开合演化过程。 相似文献
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详细的地球化学研究表明,柴北缘旺尕秀辉长杂岩(包括辉长岩、辉绿岩和斜长岩)具有岛弧火山岩的特征,形成于岛弧环境。对辉长岩中锆石的阴极发光图像和微量元素的研究显示,所有的锆石均具有相对宽缓的振荡环带结构和轻稀土元素亏损、重稀土元素明显富集的典型基性岩浆锆石的特征。通过锆石LA-ICP-MS U-Th-Pb同位素分析,得到206Pb/238U加权平均年龄468 Ma±2 Ma,同时得到一个最大的谐和年龄522 Ma±9 Ma,表明旺尕秀辉长杂岩的形成时代应介于468~522 Ma之间。岛弧型旺尕秀辉长杂岩时代的确定,结合本区已有的研究成果,表明柴北缘确实存在古生代洋盆事件,至少从中奥陶世开始发生板块的俯冲消减作用,从侧面说明柴北缘陆壳深俯冲的时代不应早于460 Ma。 相似文献
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青海锡铁山矿区滩间山群新认识 总被引：4，自引：0，他引：4
锡铁山滩间山群是重要的含矿火山-沉积建造.基于野外地质特征、古生物组合、同位素年龄、构造-热事件和火山-沉积演化等的综合分析,文章认为滩间山群形成于早-晚奥陶世,并重新厘定了4个(构造-)岩石地层单位.新建层序反映柴北缘早古生代经历了大陆裂谷开合演化过程. 相似文献
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详细的地球化学研究表明,柴北缘旺尕秀辉长杂岩（包括辉长岩、辉绿岩和斜长岩）具有岛弧火山岩的特征,形成于岛弧环境。对辉长岩中锆石的阴极发光图像和微量元素的研究显示,所有的锆石均具有相对宽缓的振荡环带结构和轻稀土元素亏损、重稀土元素明显富集的典型基性岩浆锆石的特征。通过锆石LA—ICP—MSU-Th-Pb同位素分析,得到^206Pb／^238U加权平均年龄468Ma＋2Ma,同时得到一个最大的谐和年龄522Ma＋9Ma．表明旺尕秀辉长杂岩的形成时代应介于468-522Ma之间。岛孤型旺尕秀辉长杂岩时代的确定,结合本区已有的研究成果,表明柴北缘确实存在古生代洋盆事件,至少从中奥陶世开始发生板块的俯冲消减作用．从侧面说明柴北缘陆壳深俯冲的时代不应早于460Ma。 相似文献
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秦岭造山带商南-西峡地区富水杂岩的变辉长岩中斜锆石与锆石U-Pb同位素年龄的差异 总被引：9，自引：4，他引：9
秦岭造山带富水杂岩体的一些变辉长岩含有粒度较大且U、Pb含量较高的斜锆石和锆石,是U-Pb同位素测年的极好矿物.对该杂岩体的中粗粒角闪黑云辉长岩中的斜锆石和锆石分别进行了SHRIMP法和TIMS法U-Pb同位素年龄测定,获得斜锆石和锆石的U-Pb同位素年龄分别为501.4 Ma±1.2 Ma和480.0 Ma±3.4Ma,两者相差约20 Ma.对该岩石中部分斜锆石向锆石转化的现象及锆石的成因进行了初步研究,认为斜锆石的U-Pb同位素年龄应解释为秦岭富水杂岩中基性岩石的形成时代,而锆石的成因及其U-Pb同位素系统在变质作用过程中的变化比较复杂,对其U-Pb同位素年龄地质意义的合理解释需做进一步的研究. 相似文献
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柴达木盆地北缘滩间山群新厘定 总被引：12，自引：0，他引：12
滩间山群是柴达木盆地北缘早古生代重要的火山-沉积建造,总体为一套绿片岩相和强烈变形岩石。基于野外地质特征、古生物组合、同位素年龄、构造-热事件和火山-沉积演化等的综合分析,笔者认为滩间山群形成于早—晚奥陶世,同位素年龄在496~440Ma。重新厘定的滩间山群从老到新岩石地层单位有:早—中奥陶世火山-碎屑岩组;晚奥陶世沉积岩组;晚奥陶世熔岩-次火山岩组。原滩间山群c岩组(紫色砂砾岩组)变质微弱,仅达千枚岩相,与晚奥陶世熔岩-次火山岩组间呈角度不整合接触。其中的泥质岩Rb-Sr等时线年龄为313±1.0Ma(代表其千枚岩相的变质年龄),将其从滩间山群中剥离,归属早志留世。新的层序总体反映柴北缘早古生代经历了大陆裂谷开合的演化过程。 相似文献
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青海柴达木山岩体LA-ICP-MS锆石U-Pb定年
及Hf同位素特征 总被引：3，自引：1，他引：2
柴达木山岩体是柴北缘地区最大的岩体之一。为确定柴达木山岩体成因及其与柴北缘早古生代造山作用的关系,采用LA-ICP-MS方法对柴达木山眼球状花岗岩和花岗闪长岩中的锆石进行了U-Th-Pb同位素及Hf同位素研究。柴达木山眼球状花岗岩及花岗闪长岩206Pb/238U年龄加权平均值分别为436.9Ma±2.8Ma及440.8Ma±7.3Ma,Th/U值均大于0.2,代表了岩浆的形成年龄。眼球状花岗岩和花岗闪长岩锆石Hf同位素地球化学特征相近,45个锆石Hf同位素分析值中42个锆石176Lu/177Hf值均介于0.000735~0.002786之间,176Hf/177Hf值变化范围为0.282264~0.282439,εHf(t)变化于-8.5~-2.5之间,Hf同位素两阶段模式年龄为1.44~1.77Ga。研究表明,柴达木山岩体形成于437~446Ma,具有多期侵位特点,其原岩来自柴达木板块基底下地壳;结合柴北地区缘早古生代构造演化特点认为,柴达木山岩体为陆陆碰撞的产物。 相似文献
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柴达木盆地北缘都兰地区旺尕秀辉长杂岩的锆石LA-ICP-MS U-Pb年龄及地质意义 总被引：1，自引：0，他引：1
详细的地球化学研究表明,柴北缘旺尕秀辉长杂岩(包括辉长岩、辉绿岩和斜长岩)具有岛弧火山岩的特征,形成于岛孤环境.对辉长岩中锆石的阴极发光图像和微量元素的研究显示,所有的锆石均具有相对宽缓的振荡环带结构和轻稀土元素亏损、重稀土元素明显富集的典型基性岩浆锆石的特征.通过锆石LA-ICP-MS U-Th-Pb同住素分析,得到~(206)pb/~(238)U加权平均年龄468 Ma±2 Ma,同时得到一个最大的谐和年龄522 Ma±9 Ma,表明旺尕秀辉长杂岩的形成时代应介于468～522 Ma之间.岛弧型旺尕秀辉长杂岩时代的确定,结合本区已有的研究成果,表明柴北缘确实存在古生代洋盆事件,至少从中奥陶世开始发生板块的俯冲消减作用,从侧面说明柴北缘陆壳深俯冲的时代不应早于460 Ma. 相似文献
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东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。 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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郯庐断裂南段研究进展与断裂性质讨论 总被引：13，自引：3，他引：13
据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。 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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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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Dean S. Oliver 《Mathematical Geology》1998,30(7):911-933
In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix. 相似文献
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Jiayu Rong Michael Melchin S. Henry Williams Tatyana N. Koren Jacques Verniers 《《幕》》2008,31(3):315-318
The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs. 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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Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base. 相似文献