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1.
内蒙古白云鄂博地区晚古生代闪长质-花岗质岩石年代学框架及其地质意义 总被引：12，自引：6，他引：6
华北克拉通北缘的内蒙古白云鄂博地区分布着由辉长岩、辉长闪长岩、花岗闪长岩、二长花岗岩、黑云母花岗岩及钾长花岗岩等基性-中酸性-碱性花岗岩组成的闪长质-花岗质杂岩体,它们曾被认为是泥盆纪至侏罗纪多期次侵位的产物,而新的年代学资料揭示这些侵入体都是在晚古生代形成的.白云鄂博地区15件不同岩性的锆石LA-ICP-MS U-Pb测年表明,其侵位年龄具有很好的一致性,仅发生在263～281Ma狭窄时间段内,峰期年龄269Ma.这表明白云鄂博矿床的形成与这些闪长质-花岗质岩石的侵入活动没有直接的成因联系,也为重新认识华北克拉通北缘晚古生代构造环境及演化史提供了新的年代学资料. 相似文献
2.
冀北红旗营子杂岩的锆石、独居石年代学及地质意义 总被引：19，自引：0，他引：19
较为详细的SHRIMP、LA-ICPMS锆石U-pb年代学和独居石电子探针Th-U-b化学法定年揭示，隆化-山地块的石英闪长质片麻岩和石榴黑云二长花岗质片麻岩分别形成于2484Ma和2180Ma，同时存在3164～2553Ma的锆石记录和约1854Ma的变质改造事件；细粒二长花岗岩形成于413Ma，独居石内核记录了约628Ma的继承年龄。凤山-宁地块的钾长花岗质糜棱片麻岩、角闪黑云石英闪长质片麻岩和黑云母二长花岗岩分别形成于1876Ma、1838Ma和1810Ma，其中存在2042-1904Ma的捕获锆石，遭受了1756Ma、1694Ma和313．5Ma的多期改造，其中晚古生代的构造-浆-质事件的改造尤为强烈。赤城-礼地块的角闪黑云花岗闪长质片麻岩分别形成于2535Ma和2529-2480Ma，石榴英云闪长质片麻岩和石榴黑云斜长变粒岩分别形成于1871Ma和1841Ma，发现有约2602Ma的继承锆石，并记录了从古元古代到晚古生代多阶段的改造事件，尤其清楚地记录了343-320Ma的地质事件。结合前人的年代学资料，综合分析上述地质年代学的特征，认为红旗营子杂岩从东到西可能由不同来源的微陆块组成，这些微陆块都经历了晚古生代的构造-岩浆-变质事件，可能在古生代晚期才与华北克拉通北缘拼贴。 相似文献
3.
分布在华北克拉通北缘中段崇礼—赤城地区的红旗营子(岩)群主要由变质表壳岩、晚古生代的闪长质—石英闪长质片麻岩和古元古代—新太古代的变质岩残片或残块组成。利用SHRIMP和LA-ICPMS法对红旗营子(岩)群变质表壳岩的锆石同位素年代学研究表明,变质表壳岩样品中除大量古元古代—新太古代的锆石年龄信息外,还有许多中元古代—晚古生代的锆石,且均有晚古生代甚至早中生代的多阶段变质作用的记录。这些证据表明红旗营子(岩)群并非早前寒武纪岩石建造,而是一套晚古生代的变质杂岩。红旗营子(岩)群周围侵入体的锆石U-Pb测年表明岩浆作用与变质作用具有较好的相关性,它们与中亚造山带多阶段的俯冲、碰撞造山和后造山伸展事件相关。由于红旗营子杂岩中含有晚古生代退变榴辉岩和变质方辉橄榄岩,这可能意味着华北克拉通北缘的冀北地块在晚古生代早期曾经从华北克拉通上裂开,在中亚造山带古亚洲洋板块俯冲作用的影响下又重新拼合,红旗营子杂岩代表华北克拉通北缘的冀北地块与华北克拉通在晚古生代重新拼合的俯冲碰撞拼贴带。 相似文献
4.
内蒙古毕力赫含金花岗岩类侵入岩锆石U-Pb年龄及地质意义 总被引：4，自引：2，他引：2
毕力赫大型斑岩型金矿位于华北克拉通北缘白乃庙-哈达庙铜-钼-金矿化集中区。矿区侵入岩包括以花岗闪长斑岩为主的含金次火山侵入杂岩体和地表广泛出露的钾长花岗斑岩。次火山杂岩体SiO2含量61.5%～71.4%,属亚碱性钙碱性系列,岩石REE配分具LREE富集型,弱Eu负异常,相对富集大离子亲石元素(LILEs)、亏损高场强元素(HFSEs)和Ba,具壳幔混源特征,除亏损Ba之外总体类似陆缘弧花岗岩。LA-ICP-MS锆石U-Pb测年获得含金次火山侵入杂岩体和钾长花岗斑岩成岩年龄分别为283.8±4.2Ma～279.9±6.8Ma和264.2Ma,为早、中二叠世,与野外地质体穿插关系吻合。哈达庙-白乃庙地区晚古生代中-早二叠世的大规模构造-岩浆-成矿作用,与白云鄂博-西拉木伦缝合带两侧大陆对接碰撞的时间一致,受同碰撞构造环境制约。 相似文献
5.
抚顺南部早前寒武纪变质杂岩的地质事件序列 总被引：8，自引：7，他引：1
抚顺南部早前寒武纪变质杂岩是华北克拉通北缘辽北-吉南早前寒武纪变质地块的一个重要组成部分,主要由浑南群石棚子组角闪岩相变质火山岩、火山碎屑岩及相伴生的沉积岩等表壳岩系和侵位于其中的石英闪长质片麻岩、英云闪长质-奥长花岗质-花岗闪长质(TTG)片麻岩和花岗闪长岩-二长花岗岩-钾长花岗岩岩石组合组成。LA-ICP-MS锆石U-Pb同位素分析结果显示,侵位于表壳岩中的石英闪长质片麻岩样品12LN39-3的岩浆结晶年龄为2571±7Ma,指示存在老于该年龄的表壳岩系。英云闪长质片麻岩样品12LN04-1和奥长花岗质片麻岩样品13LB49-3的岩浆结晶年龄分别为2544±4Ma和2550±10Ma,记录了一期重要的英云闪长质-奥长花岗质片麻岩侵位事件。斜长角闪岩(样品12LN25-2)的岩浆结晶的最小年龄为2530±5Ma,指示另一火山喷发阶段。晚期钾长花岗岩样品12LN01-1和奥长花岗质片麻岩样品12LN27-1分别侵位于2522±4Ma和2518±23Ma,说明它们的岩浆作用发生于同一时期。而采自于晚期未变形侵入体的石英闪长岩样品12LN30-2的岩浆结晶年龄为2496±18Ma,与上述表壳岩和深成侵入体的主要变质作用(2510~2470Ma)同期发生。这些年代学结果表明,抚顺南部地区新太古代大规模的铁镁质火山喷发作用在大于2571±7Ma已经发生,紧接着2571±7Ma发生石英闪长质岩浆侵位,在2550±10Ma~2544±4Ma之间发生英云闪长质-奥长花岗质岩浆侵位。接下来铁镁质火山再度喷发(~2530±5Ma),随后为钾长花岗岩和奥长花岗质岩浆的侵位(2522±4Ma~2518±23Ma)。晚期为角闪岩相变质作用时期(2510~2470Ma),伴随一定规模的石英闪长岩侵位。 相似文献
6.
阿拉善变质基底中的早二叠世岩浆热事件——来自同位素年代学的证据 总被引：11，自引：3，他引：8
在阿拉善变质基底中发现了大量的早二叠世的弱变形花岗岩类。采自阿拉善东部的闪长质片麻岩(AL0705-1)、含石榴英云闪长质片麻岩(AL0709-1)、英云闪长岩(AL0718-1)、条痕状黑云斜长片麻岩(AL0822-1)和片麻状花岗岩(AL0822-3)的锆石U-Pb年龄分别为270±1.6Ma、276±1.8Ma、269±2.4Ma、276±2.4Ma和287±2.5Ma。采自阿拉善变质基底西部的花岗闪长质片麻岩(AL0805-1)、闪长质片麻岩(AL0805-4)、粗粒花岗闪长质片麻岩(AL0810-1)和中粒闪长质片麻岩(AL0810-2)的锆石LA-ICP-MSU-Pb年龄分别为284±3Ma、289±3Ma、276±2Ma和279±2Ma。尽管早二叠世花岗岩的岩石类型和化学成分不同,但它们都形成于269～289Ma一个较短的时间范围,属于同一期岩浆热事件的产物。早二叠世花岗岩的形成年龄与基底变质岩中角闪石39Ar-40Ar的坪年龄277～288Ma近于一致,表明这期岩浆热事件对基底变质岩石产生了改造,使角闪石等变质矿物的Ar-Ar同位素体系发生了重置。在阿拉善变质基底中大量早二叠世花岗岩类侵入体的发现表明,阿拉善变质基底在古生代晚期受到中亚造山带碰撞造山作用的强烈影响和改造。 相似文献
7.
本文对华北克拉通北缘中段内蒙古化德地区二叠纪—三叠纪5个花岗质侵入体进行了岩相学、地球化学、锆石U Pb年代学以及Sr Nd Hf同位素研究。结果表明本次所研究的岩体主要起源于华北克拉通古老下地壳的部分熔融,八音察汗岩体形成于早二叠世（276±1 Ma）,在岩浆上升过程中发生了岩浆混合作用;白音特拉岩体形成于中二叠世（270±1 Ma）,为地壳加厚作用下变质杂砂岩部分熔融形成的S型花岗岩;毛忽庆岩体形成于晚二叠世（254±1 Ma）,为I型花岗岩;张万良岩体与康家地岩体分别形成于早三叠世（248±1 Ma）和晚三叠世（229±1 Ma）,两者均为A型花岗岩。综合前人研究,本文认为研究区在早二叠世—晚三叠世经历了古亚洲洋向华北板块俯冲、俯冲 同碰撞、持续碰撞以及造山后的伸展4个阶段,古亚洲洋东段在研究区的闭合时间应为中二叠世晚期。 相似文献
8.
该区花岗质岩石主要岩性为石英闪长岩、英云闪长岩、花岗闪长岩、二长花岗岩和正长花岗岩。通过对石英闪长岩锆石SHRIMP U-Pb定年[1],所获得年龄为(313±5)Ma～(323±4)Ma,属于晚石炭世侵入体;前进场和达青二长花岗岩各单元岩体均侵入了该区早二叠世寿山沟组海陆交互相碎屑沉积岩,侵入接触关系明确,红柱石角岩发育。测得前进场岩体和达青岩体锆石SHRIMP U-Pb年龄分别为(280.8±3.6)Ma和(281.5±0.5)Ma,说明岩体形成于早二叠世晚期;乌兰陶勒盖正长花岗岩岩体获得了259Ma、羊角林高勒二长花岗岩为246～216Ma的U-Pb同位素年龄,说明在晚二叠世—三叠世又有一次侵入高峰。石炭—二叠纪裂谷发育时期,部分跨入三叠纪,先后有3次侵入高峰,即晚石炭世的石英闪长岩、早二叠世的英云闪长岩—二长花岗岩、晚二叠世—三叠纪的二长花岗岩-正长花岗岩。 相似文献
9.
为了探讨华北板块北缘晚古生代的隆升历史和古亚洲洋的闭合过程,利用碎屑岩的锆石U-Pb年代学、Hf同位素和锆石微量元素组成对北京周口店太平山南坡晚石炭世-早二叠世地层进行物源分析,并判定源区的大地构造背景.5件样品的碎屑锆石U-Pb年龄主要分布在3个时代:显生宙（285~425 Ma）、古元古代（1 700~2 450 Ma）和新太古代（2 500~2 747 Ma）.前寒武纪的锆石年龄主要集中在2.5 Ga和1.8 Ga,与华北克拉通的前寒武纪基底岩石相似.显生宙的锆石年龄主要集中在308~297 Ma,最年轻的峰值年龄在299~291 Ma,在误差范围内与地层沉积年龄相似,因此这些最年轻的碎屑锆石属于早二叠世同沉积锆石.29颗同沉积锆石的Hf同位素结果显示,原始176Hf/177Hf比值介于0.282 021~0.282 318,εHf（t）值介于-20.1~-9.6.显生宙锆石的年龄谱特征以及Hf同位素组成与内蒙古隆起同期的岩浆锆石特征十分相似,因此显生宙碎屑锆石可能来源于内蒙古隆起,并伴随有少量来自北侧兴蒙造山带南部的早古生代岛弧碎屑的输入.二叠纪同沉积锆石的微量元素特征表明锆石结晶的岩浆源区具有大陆岛弧的构造属性.上述数据表明:（1）华北板块北缘在晚石炭世-早二叠世为活动大陆边缘;（2）晚古生代古亚洲洋向华北北缘的持续俯冲消减导致了内蒙古隆起的快速隆升;（3）古亚洲洋闭合的时间应晚于早二叠世. 相似文献
10.
华北陆块北缘崇礼-赤城地区晚古生代花岗岩类的锆石年龄和Sr-Nd-Hf同位素组成 总被引：7，自引：5，他引：2
本文报道冀北崇礼-赤城地区晚古生代花岗岩类岩石的锆石U-Pb年龄和Sr-Nd-Hf同位素组成特征.它们出露在华北陆块北缘的构造单元内,侵位于中高级变质基底岩石红旗营子群中.锆石LA-ICP-MS定年结果表明,海流图花岗岩岩体记录了两期岩浆作用,即299±3Ma和254±11Ma;镇宁堡片麻状二长花岗岩和白花沟片麻状黑云母石英二长闪长岩分别形成于287±1Ma和252±3Ma.这些晚古生代花岗岩类岩石具有较低的初始~(87)Sr/~(86)Sr值(0.7062～0.7076)、低的ε_(Nd)(t)值(-18.1至-9.6)和古老的Nd亏损地幔模式年龄(2.49～1.87Ga).其锆石的ε~(Hf)(t)值变化在-13.2至-7.4之间,Hf平均地壳模式年龄值(T_(DM)~C)在2.15Ga至1.79Ga之间.锆石Hf同位素特征与全岩Nd同位素特征指示古老的华北陆块地壳物质是花岗岩浆的主要物源.在形成时代和地球化学特征上,崇礼-赤城地区晚古生代花岗岩与出露在东部丰宁-承德地区的花岗岩类岩石既有相似性,又有不同之处,可能代表华北陆块北缘不同构造背景下岩浆作用的产物. 相似文献
11.
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
12.
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
13.
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
14.
15.
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
16.
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
17.
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
18.
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
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
20.
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