共查询到20条相似文献，搜索用时 140 毫秒
1.
青海南山侵入体岩石类型为二长花岗岩、花岗闪长岩及英云闪长岩,具俯冲型花岗岩类的地球化学特征。通过高精度的LA-ICP-MS(激光剥蚀等离子体质谱)单颗粒锆石微区U-Pb同位素年龄测定,分别在二长花岗岩、花岗闪长岩及英云闪长岩中获得446.1±3.5Ma、447.2±5.3Ma、443.6±8.6Ma的锆石U-Pb年龄值,为成岩年龄,代表了加里东运动在祁连造山带的地质记录。3种不同岩石类型的成岩年龄可能代表了拉脊山造山带向南俯冲的时代。青海南山地区俯冲型侵入体的形成时代及构造环境的确定,对研究拉脊山造山带的构造演化及动力学机制具有重要意义。 相似文献
2.
甘肃黑石山早古生代埃达克质岩的发现及其构造动力学意义 总被引：11，自引：6，他引：11
笔者近期在甘肃黑石山地区早古生代火成岩的研究中发现了埃达克质岩,埃达克质岩的岩石类型为奥长花岗岩、花岗闪长岩及花岗癍岩,侵入于北祁连东段的白银陆缘弧火山岩中。岩石具高Sr低Y,Sr／Y>40;富钠贫钾(Na2O／K2O>2), 富SiO,但含量变化不大;富集LREE,亏损重稀土元素,La／Yb>20,无Eu负异常或轻微正异常(δEu=1．0-1．19)。与典型的俯冲板块熔融的埃达克岩比较,黑石山埃达克质岩具有更高的SiO2含量和更低的MgO、Mg#(-46)、Cr(均11．6μg／g)、Ni(均 6．52μg／g),未显示出初始埃达克质熔体与地幔橄榄岩明显的交代过程,因而不大可能由俯冲板块直接熔融形成的;与中国东部燕山期高钾钙碱性埃达克岩相比,具有较高的Na2O(Na2O>4．0％;Na2O／K2O=1．97-2．59),但类似Cordilera Blanca岩基的(非板片熔融成因的埃达克质岩),推测形成于加厚的陆缘弧中基性下地壳的部分熔融。黑石山埃达克质岩的发现表明, 在早古生代晚期,北祁连东段经历了洋盆闭合、板块碰撞、陆缘弧地壳加厚、玄武质岩浆底侵作用及下地壳再造作用的构造演化过程。同时指出,在本区寻找与埃达克质岩有关的斑岩型铜、金矿可能是一个新的有希望的找矿方向。 相似文献
3.
《矿物岩石地球化学通报》2015,(4)
长园带状杂岩体主要由长园石英二长闪长岩、官山石英二长岩、沙峪斑状花岗岩和西后峪花岗岩4个侵入体构成。长园石英二长闪长岩富镁贫铁,准铝质,属高钾钙碱性系列;具弱的Eu负异常,Sr/Y值较高,是中性埃达克质岩。官山石英二长岩富碱富镁,Sr/Y和(La/Yb)N值高,具弱的Eu负异常,是典型的"C型埃达克岩"。沙峪和西后峪花岗岩属高钾钙碱性系列岩石,稀土元素总量低,具负Eu异常。长园石英二长闪长岩和官山石英二长岩是高Sr的基性原始岩浆在中等压力(0.8~1.2GPa)条件下分离结晶的产物。沙峪斑状花岗岩和西后峪花岗岩则是由幔源岩浆与地壳岩石发生相互作用的产物。长园带状杂岩体的实例表明,埃达克质岩起源或形成的压力可以相对较低(1.2 GPa)。 相似文献
4.
北祁连早古生代花岗质岩浆作用及构造演化 总被引：29，自引：14，他引：15
北祁连山中段花岗岩锆石SHRIMP定年结果表明,柯柯里岩体的斜长花岗岩和石英闪长岩的年龄分别为512Ma和501 Ma,野马咀和金佛寺花岗岩的年龄分别为508Ma和424Ma。结合区内其它花岗岩体的定年资料,根据花岗岩的岩石地球化学特征及岩体产出的构造位置、区域地质资料等,我们认为,早古生代北祁连洋板块向南俯冲,至少引发了两期花岗质岩浆作用,第一次岩浆作用形成柯柯里斜长花岗岩(512Ma)、野马咀花岗岩(508Ma)和柯柯里石英闪长岩(501 Ma),第二次花岗质岩浆作用形成牛心山花岗岩(477Ma)。由于往南俯冲的板块受到柴达木板块向北俯冲的影响,俯冲受阻,继而俯冲极性发生变化,转向北俯冲,形成了民乐窑沟(463Ma)等花岗岩侵入体。大约440Ma之后,洋盆闭合,柴达木陆块和阿拉善陆块对接碰撞,形成北祁连造山带。由于造山带根部岩石圈发生折沉作用,造山带上不同的块体伸展、滑塌,形成一系列碰撞后花岗岩如金佛寺花岗岩(424Ma)及牛心山岩体的石英闪长岩(435Ma)等。 相似文献
5.
八达岭基性岩和高Ba—Sr花岗岩地球化学特征及成因探讨：华北和大别—苏鲁造山带中生代岩浆岩的对比 总被引：27，自引：15，他引：27
八达岭杂岩侵位于华北北部，由辉长闪长岩岩、石英闪长岩、石英二长岩、二长闪长岩、二长花岗岩、碱长花岗岩和石英正长岩等组成，主要属高钾钙碱性系列。除了含V-Ti磁铁矿的堆晶辉长闪长岩，整套岩石的主量元素变化范围较大，SiO2=46.5%-75.3%,MgO=5.6%-0.2%，中酸性岩石的K2O/NaO为0.59-1.09。碱长花岗岩和少数石英二长岩Ba和Sr含量较低，且具有明显（Eu）负异常。大多数中酸性岩石（高Ba-Sr花岗岩）具有如下显著的微量元素地球化学特征：Ba,Sr和轻稀土（LREE）富集，Y和重稀土（HREE）亏损，LREE/HREE强烈分离，Sr/Y和La/Yb比值较高；在原始地幔标准化的蛛网图中具有显著的Nb,Ta和Ti亏损，不具明显的Sr和Eu亏损。在Harker图解中，基性岩石和高Ba-Sr花岗岩的主量元素相关性明显，两者还具有相似的微量元素和稀土（REE）分配特征，并且，REE,Y,Sr,P和Ti含量从基性到酸性逐渐降低。辉长闪长岩和高Ba-Sr花岗岩的Sr-Nd同位素初始值呈EMI特征（Isr=0.7051-0.7068,εNdi=-8.2-20.2），大致呈负相关。地球化学特征表明基性岩浆为富集的大陆岩石圈地幔部分熔融形成，而高Ba-Sr花岗岩则为基性岩浆通过陆壳混染和结晶分离形成；富P和Ti的副矿物（如磷灰石和的榍石）的分离结晶导致了REE,P和Ti丰度的逐渐降低。另外，华北板块内部和大别-苏鲁造山带基性岩和高Ba-Sr花岗岩分别具有相似的地球化学特征，这表明，上述地区燕山期大规模岩浆活动具有相似的地球动力学机制，大别-苏鲁造山带岩浆岩的地球化学特征并不反映其地幔源区一定受到过来自深俯冲的扬子板块的流体的富集作用。岩石圈的拆沉和减簿作用可能导致了华北板块和大别-苏鲁造山带下古老岩石圈地幔的部分熔融，岩石圈地幔的富集作用可能主要性发生于元古代。 相似文献
6.
阿尔金山西端似埃达克岩的地球化学特征及构造背景 总被引：4，自引：0，他引：4
阿尔金山西端发现的一套中性-中酸性侵入岩，主要岩石类型为石英闪长岩，英云闪长岩和花岗闪长岩，详细的岩石矿物学，岩石化学，岩石地球化学及同位素地球化学研究表明，该套岩石为钙碱性系列，其岩石地球化学特征与经典的埃达克岩十分相似，相当于张旗划分的O型埃达克岩，其成因与板块的消减作用或玄武岩底侵作用有关，这些岩石因为分布于较古老的造山带-阿尔金造山带与青藏高原北缘接合部位，故暂称其为似埃达克岩，花岗闪长岩全岩Rb-Sr等时线年龄为575Ma，应为晚震旦世的产物，其形成的构造背景与洋壳俯冲作用有关。 相似文献
7.
埃达克岩(Adakite)的特殊性及其科学和现实意义广泛地吸引着地球科学工作者。位于青藏高原东北缘的祁连山早古生代造山带是新中国地学界认识板块构造的摇篮。本文研究了北祁连造山带中段毛藏寺地区侵入岩的岩石学和地球化学特征,结果表明:毛藏寺地区加里东期中酸性侵入岩具有较高的SiO2、Al2O3、Na2O含量及Na2O/K2O值,MgO较低; LREE强富集,HREE明显亏损,L/H比值>15; 岩石Th、Sr、Ba具显著的正异常,Sr含量一般在507×10-6 以上,具有高Sr/Y、La/Yb比值和较高的Cr、Ni含量; 岩石σ值一般为1.45～2.76,A/CNK值为0.83～1.15,多数<1.0,主体属于钙碱性岩系列,偏铝质花岗岩类。岩石化学特征指向埃达克岩。在(La/Yb)N-YbN和Sr/Y-Y判别图上,样品落入埃达克岩范围; 在SiO2-Mg#图解上,岩体处在"板片来源的埃达克岩"区域,表明毛藏寺地区侵入岩属于"O"型埃达克岩,岩浆起源于俯冲洋壳的部分熔融。毛藏寺"O"型埃达克岩的识别表明,在早古生代中期,北祁连中段经历了洋壳俯冲、岛弧发育和壳幔共同作用的构造演化过程,为祁连山造山带的板块构造演化历史提供了新资料,为祁连山地区寻找和勘查与埃达克岩相关的矿产资源提供了一个可能的方向。 相似文献
8.
北淮阳中生代adakite岩石地球化学特征及成因讨论 总被引：18，自引：9，他引：18
大别山造山带后缘的北淮阳带发育大面积的中生代岩浆岩.其中,晚侏罗世至早白垩世早期(150～130Ma)的岩体具有与adakite类似的地球化学特征,SiO2＞56%,高铝(SiO2＞70%时,A12O3≥15%)、高锶(Sr＞400μg/g)、钠质(Na2O3.34%～4.75%,Na2O/K2O＞1)、低Y和Yb(Y≤18μg/g),Sr/Y＞20～40,La/Yb＞20,Eu无明显异常,Sr正异常.Adakite岩石类型为(石英)闪长岩、二长闪长岩-花岗闪长岩-二长花岗岩-花岗岩.矿物成分以更长石、微斜长石或正长石、镁质黑云母、石英为主,副矿物为磁铁矿+榍石+锆石+磷灰石组合,岩石含富云质和闪长质包体,属Ⅰ型花岗岩类.而早白垩世晚期＜130Ma的岩体,属A型花岗岩,为非adakites花岗岩类.北淮阳adakites的形成可能与底侵到下地壳的玄武质岩石部分熔融有关,部分熔融比例在10%～＞20%,并且在岩浆演化中有AFC过程. 相似文献
9.
青海南山东段花岗岩类岩石类型为二长花岗岩、花岗闪长岩及英云闪长岩。通过高精度LA-ICP-MS锆石U-Pb同位素测年,获得二长花岗岩、花岗闪长岩的年龄分别为241±3Ma、245±2Ma和249±3Ma,可代表其成岩年龄。花岗岩类构造环境判别图显示,岩石具俯冲型花岗岩类特征,可能代表早三叠世宗务隆洋的北向俯冲过程。通过对青海南山东段侵入岩体形成时代、岩石成因、构造环境等的研究,为青海宗务隆造山带在印支期的构造环境演化和动力学机制提供了重要的依据。 相似文献
10.
《新疆地质》2017,(4)
通过对天山造山带古生代侵入岩岩石类型、岩石地球化学特征及年代学研究,初步厘定不同构造带侵入岩浆序列及形成构造环境。天山地区古生代侵入岩主要包括奥陶—志留纪俯冲期钙碱性花岗岩、泥盆纪后碰撞型正长花岗岩、石炭纪中早期俯冲型钙碱性花岗岩、石炭纪晚期后碰撞型正长花岗岩、石炭纪末后碰撞型镁铁-超镁铁质岩、二叠纪早期后造山型碱性花岗岩及洋壳残片等。俯冲期侵入岩主要为花岗闪长岩-石英二长闪长岩-石英闪长岩组合;同碰撞期为花岗闪长岩-二长花岗岩组合;后碰撞期为组成花岗岩-二长花岗岩组合;后造山期为正长花岗岩-碱性花岗岩组合。认为该地区古生代侵入岩与Terskey洋、北天山洋、南天山洋等洋盆演化密切相关,并建立了天山地区古生代构造演化模式图。 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.
14.
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
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.
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
17.
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
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.
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