共查询到20条相似文献，搜索用时 62 毫秒
1.
再论红旗营子群的时代问题 总被引：6，自引：0，他引：6
红旗营子群相当于单塔子群上部，为一套低角闪岩相火山沉积岩。该群上部刘营组的斜长变粒岩，测得单颗粒锆石Ｕ－Ｐｂ年龄为２４２３±２３Ｍａ；侵入该群的花岗岩锆石Ｕ－Ｐｂ年龄与以上数值相近。凤凰咀组上部的斜长角闪岩测得Ｓｍ－Ｎｄ全岩等时线年龄２５８７±１７８Ｍａ，２６３９±１７４Ｍａ。根据测定样品产于不同层位或岩石之中，经受后期变质与变形作用的改造亦有差异，对测定的年龄值所反映的地质意义进行了分析与对比。 相似文献
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泰山地区早前寒武纪主要地质事件与陆壳演化 总被引：24，自引：9，他引：24
通过详细的野外地质调查和岩石学、地球化学、同位素年代学工作，建立了鲁西泰山地区地质演化框架、晚太代早期表壳岩形成（２８４０￣２８２０Ｍａ），晚太古代早期望府山期英云闪长岩侵位和高角闪岩相变质变形改造（〉２７００Ｍａ）；晚太古代晚期绿岩建造形成和高绿片岩相－低角闪岩相变质变形改造（２７００￣２６００Ｍａ），晚太古代晚期大众桥期基性－中酸性岩侵位（２５６０￣２５３０Ｍａ）；晚太古代晚期傲徕山期二长花岗 相似文献
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西昆仑康西瓦西北部库尔良早古生代角闪闪长岩花岗闪长岩锆石ＳＨＲＩＭＰ Ｕ－Ｐｂ测年 总被引：1，自引：0，他引：1
依据１∶２５万康西瓦幅区域地质调查成果，重点对库尔良早古生代深成岩的同位素年代学进行了详细的研究，获得了裂解期细粒黑云母角闪闪长岩锆石ＳＨＲＩＭＰ Ｕ－Ｐｂ年龄均值５０６．８Ｍａ±９．８Ｍａ，中粒似斑状花岗闪长岩单颗粒锆石Ｕ－Ｐｂ法年龄５００．２Ｍａ±１．２Ｍａ，表明其形成时代均为中寒武世。该同位素年龄的获得，为进一步详细地研究库地－其曼于特早古生代构造－岩浆岩带的裂解时限提供了直接的时代证据。 相似文献
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海南岛前寒武纪花岗岩—绿岩系Sm—Nd同位素年龄及其地质意义 总被引：19，自引：2，他引：19
利用Ｓｍ－Ｎｄ同位素法测试了海南岛土外山金矿区花岗－绿岩系的１５个样品，７个为绿岩中的斜长角闪片岩，８个为花岗（质）岩，分别获得了１７００．９±２０Ｍａ和１３７９．７±１７Ｍａ的Ｓｍ－Ｎｄ等时年龄，各自代表了其原岩的成岩时代。同时对花岗（质）岩获得了与１７００．９０１３２２０Ｍａ相当的１６９０～１８００Ｍａ的Ｎｄ模式年龄。对斜长角门片岩则获得２３００～２７００Ｍａ的Ｎｄ模式年龄。这些反映了海南岛于２４００Ｍａ、１７００Ｍａ、１４００Ｍａ左右发生了三次重大构造岩浆热事件。 相似文献
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长城系团山子组火山岩颗粒锆石U－Pb年龄及其地质意义 总被引：46，自引：1，他引：46
蓟县中－上元古界典型剖面之邻区平谷县境内，长城系团山子组连续发育两层厚度各为１ｍ左右的富钾粗面安山岩，发育气孔构造和绳状构造。其中存在三种不同成因类型锆石，应用颗粒锆石Ｕ－Ｐｂ测定年龄技术，得到：（１）自生锆石，其Ｕ－Ｐｂ不一致上交点年龄为１６８３±６７Ｍａ，代表该火山岩形成年龄；（２）捕获锆石，多为原碎屑锆石，较年轻的一种捕获锆石的２０７Ｐｂ／２０６Ｐｂ表面年龄为１８２３±６８Ｍａ，这限定了长城系底界年龄应新于１８２３Ｍａ；（３）后生热液锆石，其Ｕ－Ｐｂ年龄为４６０Ｍａ左右，反映后期热液事件发生的时代。 相似文献
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招远—莱州地区花岗岩类继承锆石年龄及其意义 总被引：11，自引：0，他引：11
招远－莱州地区花岗岩类锆石ＳＨＲＩＭＰ研究表明,该区花岗岩类含有大量不同时代的继承锆石,３４４６±２Ｍａ～３１１４±４Ｍａ继承锆石的发现,表明鲁东地区存在古太古代硅铝核。大量印支期继续锆石的年龄（平均年龄２１９Ｍａ）与华南,华北克拉通碰撞时代一致,推测这些锆石极可能来自其源岩－华南,华北克拉碰撞造山花岗岩,从而否定了玲珑型花岗岩主要是由胶东岩群交代－重熔形成的传统认识,郭家岭型花岗闪长岩中含有较多 相似文献
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吉林南部太古代花岗岩Sm—Nd,Rb—Sr同位素年龄测定 总被引：8，自引：7，他引：8
吉林南部太古代花岗质岩石经同位素年龄测定，英云闪长质片麻岩类的Ｒｂ－Ｓｒ全岩等时年龄为２４１７±１２１Ｍａ，Ｓｍ－Ｎｄ全岩等时年龄为２４１６±１２７Ｍａ，模式年龄为２８４０Ｍａ；辉石花岗岩类的Ｒｂ－Ｓｒ全岩等时年龄为２３４６±２３２Ｍａ，Ｓｍ－Ｎｄ全岩等时年龄为２４４０±１５９Ｍａ，模式年龄为２７８０Ｍａ。反映这些岩石都是在太古宙晚期形成的，并且是在较短的时间间隔内完成的，其模式年龄与华北地台太古宙主体地壳的形成时代一致。 相似文献
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大巴－建设地区太古宙花岗质岩石由英云闪长岩、奥长花岗岩、花岗闪长岩组成，属ＴＴＧ岩系。地质、岩石学及地质化学特征表明，它们是古深成侵入体，变质程度属绿片岩相。同位素年龄为２４４３Ｍａ。岩浆来源于陆壳的部分熔融。 相似文献
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河南登封石牌河“变闪长岩体”的锆石SHRIMP年代学研究 总被引：8，自引：0，他引：8
河南登封石牌河"变闪长岩"包括闪长岩至英云闪长岩和花岗闪长岩两种岩类,它们是同一岩浆系列分异结果的产物.其结晶时代以往曾用锆石U-Pb等时线测得为2 520±17 Ma,这次采用SHRIMP法重测,获得锆石U-Pb年龄为2 493±7 Ma,比以前稍小,年龄更为精确.这次所测锆石均具有岩浆环带,锆石Th/U比为0.76～1.27,平均为1.03,具岩浆锆石特征,中心和边部测年结果一致,说明未受到明显的变质作用影响,故此年龄为岩浆的结晶/侵位年龄.根据野外地质、岩石学和地球化学等特征,这一岩体与山东鲁西泰山 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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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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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
19.
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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正Artemia cysts are an extremely important component of aquaculture diets.It is well established that the cultivation of fish and shellfish derive substantial health and growth advantages when Artemia are included in the diets of the 相似文献