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1.
柴达木北缘超高压变质带形成与折返的时限及机制 总被引：49，自引：7，他引：42
位于青藏高原北缘的祁连山加里东造山带的形成是阿拉善板块、祁连微板块及柴达木一东昆仑板块在加里东期间汇聚和碰撞的结果。祁连微板块和柴达木一东昆仑板块之间的柴(达木)北缘超高压变质带形成于495～440Ma,是继南祁连洋壳向北俯冲于祁连微板块下形成增生的柴北缘火山岛弧带之后,陆壳深俯冲的产物。柴北缘超高压变质带是在祁连微板块及柴达木一东昆仑板块之间的“正向陆内俯冲”向“斜向陆内俯冲”转化过程中“斜向挤出”机制下折返的,开始折返年龄为470～460Ma,最后的折返时间为400～406Ma。折返构造很好地保存在超高压变质岩石中,并且记录了广泛的退变质作用。 相似文献
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祁连造山带位于东特提斯北缘,蛇绿混杂岩带、(超)高压变质岩和弧岩浆岩等广泛发育,是前新生代华北克拉通与柴达木古地块之间多期次俯冲、碰撞和造山形成的复合造山带。现今的祁连山是青藏高原北缘高原隆升与扩展的关键构造带,具有复杂的陆内变形构造和深部结构,记录了新生代高原生长过程中不同阶段的构造变形和盆-山演化历史。本文在区域地质研究资料的综合分析基础上,讨论祁连造山带元古宙变质基底属性、新元古代—古生代古海洋演化和中—新生代构造变形特征,探讨祁连(山)造山带的构造演化过程和陆内变形历史。祁连造山带发育新元古代早期和早古生代两期岩浆弧,分别代表了古祁连洋和(南、北)祁连洋的俯冲-碰撞事件;亲华北的基底属性指示了祁连洋实属陆缘海。新生代青藏高原东北缘发育两阶段构造变形和盆-山演化,在中新世完成了由新生代早期以逆冲断裂活动为主向走滑断裂和逆冲断裂共同作用的转变,随着东昆仑山的快速隆起将古近纪大盆地隔开成两个盆地,即现今的柴达木盆地和可可西里盆地。中新世中晚期以来,青藏高原东北缘的构造格局主要受控于东昆仑和海原两个近乎平行的大型转换挤压构造系统的发育、顺时针旋转和侧向生长。大型走滑断裂系统在造山带内的... 相似文献
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青藏高原东北缘印支期宗务隆造山带 总被引：42，自引：9，他引：33
位于柴达木地块北缘构造带（柴北缘构造带）与南祁连造山带间的宗务隆构造带发育晚古生代、早中三叠世地层以及石炭纪蛇绿岩地体和具有岛弧性质的二叠纪—早三叠世中酸性火山岩。三个侵入宗务隆带南侧的海西—印支期花岗岩（246Ma天峻南山花岗岩、238Ma青海湖南山花岗岩和215Ma二郎洞花岗岩）分别与俯冲和后碰撞相关。两期明显的构造变形为印支期造山构造和第三纪陆内构造活动印记,前者以300余千米长的韧性剪切带为代表,后者以大规模指向南的逆冲推覆作用为特征。宗务隆构造带经历了由陆内裂陷、洋盆发育和俯冲—碰撞造山的演化过程,既不同于其南侧的柴北缘构造带也不属于北侧的南祁连造山带,而是一在柴北缘和南祁连造山带共同构建的加里东陆块上发育起来的、具有完整板块旋回的印支期造山带。 相似文献
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柴北缘尕秀雅平东和红柳沟北镁铁-超镁铁质岩体锆石U-Pb年龄及其找矿意义 总被引：1，自引：0，他引：1
位于柴达木地块北缘构造带内欧龙布鲁克微陆块东缘的2个镁铁-超镁铁质岩体——含Cu-Ni的尕秀雅平东岩体和含Ti-Fe的红柳沟北岩体,前者的LA-ICP-MS锆石U-Pb年龄为408.0±1.5Ma,属早泥盆世;后者的SHRIMP锆石U-Pb年龄为418.3±2.8Ma,属晚志留世。区域地质资料研究表明,东昆仑地区、柴北缘在晚志留世—晚泥盆世处于后造山伸展阶段,尕秀雅平东岩体和红柳沟北岩体正是拉张环境下幔源岩浆活动的产物。在东昆仑地区、柴北缘发现的铜镍矿床和铜镍矿点(除夏日哈木有争议外)基本都形成于晚志留世—晚泥盆世。结合区域成矿年代学研究,认为晚志留世—晚泥盆世期间,东昆仑造山带和祁连造山带之间的柴达木地块、欧龙布鲁克微陆块,以及位于这两大造山带内部的微型古陆块区,是形成岩浆铜镍硫化物矿床和钛铁氧化物矿床的有利环境。 相似文献
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通过柴达木盆地西部茫崖-赛什腾山地表地质、航磁、重力、大地电磁测深和地震资料的综合分析,认为柴达木盆地夹持在昆北地块与赛什腾构造带之间,其中包括柴达木地块与祁连地块南缘2个一级构造单元和昆北地体北缘,柴达木盆地,赛什腾构造带和祁连地块南部的苏干湖盆地等4个二级构造单元。盆地的总体结构表现为东昆仑山和祁连山相向向盆地挤压对冲,盆地中部沉降的构造格局。盆地内部的构造样式以自盆地边缘至中心以此形成背斜构造为显著特征,背斜两翼多发育逆断层,构成“两断夹-隆”的构造格局。挤压应力主要来自南西方向、北东方向起阻挡作用。在两侧造山带的强烈挤压作用下,侏罗纪时期在祁连造山带南缘形成并不典型的前陆盆地,古近纪至新近纪时期则在祁连造山带与昆仑造山带之间形成双侧前陆盆地,第四纪属挤压坳陷盆地。 相似文献
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《吉林大学学报(地球科学版)》2015,(Z1)
<正>1地质概况阿尔金造山带位于新疆、青海、甘肃省区的交界地带,是塔里木、柴达木以及东西昆仑、天山、柴北缘、北祁连和北山构造带的衔接地带,其阿尔金南缘断裂是一条左型走滑深大断裂带,至今还在活动。斜长花岗岩及辉长岩位于阿尔金南缘断裂带中段的清水泉一带,属于前人划分的阿南茫崖构造混杂岩带单元 相似文献
7.
东昆仑纳赤台群晚二叠世孢粉化石的发现及其意义 总被引：5，自引：0，他引：5
东昆仑造山带是我国西部一条规模宏大的造山带,它的形成时代及其演化格局涉及青藏高原构造格架和隆升机制研究的重要基础地质问题。它北隔柴达木盆地与祁连造山带相望,南与可可西里—羌塘地块为邻,西与西昆仑造山带相连,东与秦岭—大别造山带相接,地质位置极为重要。对东昆仑造山带形成的时代一直存在着不同的观点和认识,有人将其划为加里东期,也有人划为华力西期,造成这些分歧的关键是对纳赤台群的时代认识问题(李光岑等,1982)。纳赤台群是位于昆中断裂与昆南断裂之间的一套非均匀变质的地层,主要由灰绿色浅变质的复理石相的砂板岩、变砂岩和 相似文献
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东昆仑造山带花岗岩及地壳生长 总被引：65，自引：0，他引：65
东昆仑造山带是青藏高原内可与冈底斯相媲美的又一条巨型构造岩浆岩带。该带内的花岗岩形成可以划分为4个时段,分别与4个造山旋回相对应：前寒武纪（元古宙）;早古生代;晚古生代—早中生代;晚中生代—新生代。其中,以晚古生代—早中生代（或称华力西—印支旋回）、特别是三叠纪的花岗岩最为发育。东昆仑造山带基底主要形成于古元古代晚期。其早古生代构造-岩浆事件序列与北祁连造山带可以对比,属祁连—东昆仑加里东造山系统的一部分。到晚古生代—早中生代时东昆仑卷入古特提斯构造体制,属于古特提斯造山系统的北缘。华力西—印支是一个完整的造山旋回,与西南“三江”古特提斯的演化历史相似。昆南缝合带是当时中国南北大陆的主要构造分界线。新生代印度—欧亚大陆的碰撞,使东昆仑造山带又卷入了青藏大陆碰撞造山系统,但对东昆仑的影响是一种远程效应。
东昆仑造山带大陆地壳主要形成于古元古代晚期,但在显生宙还有新生地壳 （juvenile crust） 产生,与兴蒙、冈底斯、安第斯等造山带相似。东昆仑花岗岩带中丰富的幔源岩浆底侵作用与壳-幔源岩浆混合作用的证据,以及花岗岩类的Nd、Sr同位素成份（87Sr/ 86Sr初始值多数小于0.710;εNd（t ）值变化于－9.2和＋3.6之间）,说明
地幔物质的注入及其与地壳物质的混合,对显生宙地壳的形成演化起着重要作用,是显生宙东昆仑地壳生长的重要方式。根据花岗质寄主岩、镁铁质暗色微粒包体（MME）及底侵辉长岩的锆石SHRIMP U-Pb定年,东昆仑造山带在显生宙发生过两次大规模的底侵作用与岩浆混合作用,一次在早-中泥盆世（394~403 Ma）,另一次在中三叠世（239～242 Ma）,分别相当于加里东旋回、华力西-印支旋回的俯冲结束/碰撞开始阶段。 相似文献
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正1区域地质概况1.1大地构造祁连造山带北邻华北板块西南缘,与秦岭、昆仑一起构成中国大陆中部的秦祁昆巨型造山带,是我国重要的造山带之一。祁连造山带位于我国秦祁昆中央造山系西段,南以武山一临夏一贵德一青海湖南山断裂为界,与西秦岭造山带相邻,北以河西走廊断裂为界,与华北古陆的阿拉善地块相邻,西北端被北东东向的阿尔金走滑断裂截切,与塔里木 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
12.
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
13.
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
14.
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
15.
Fouad N. Ibrahim Dr. 《GeoJournal》1988,17(1):133-141
Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators. 相似文献
16.
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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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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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