福建省区域地质构造特征   总被引：1，自引：0，他引：1  

韦德光  揭育金  黄廷淦 《地质通报》1997,(2)

福建自晚太古代以来经受了多次造山运动影响，尤以燕山期构造—岩浆活动最为强烈和频繁，以致省内华夏古陆不断发生裂解及增生。省内的北北东—北东东、北西—东西及南—北走向断裂十分发育，形成大小不同的断块（地体）。最突出的是南平—宁化（北东）断裂带与政和—大埔（北北东）构造—岩浆带相交汇，将福建省割切为闽西北、闽西南及闽东３个地体。本文对主要断裂及三大地体的构造—岩浆活动、变质—变形、岩浆侵入与喷发、地体的分离与拼接的演化历史进行概略阐述。总之，福建省是经多期造山作用由不同地体或断块拼接而成的复合造山带  相似文献   

Unconformity-like Reflection Pattern under the Moho in the Sulu Area   总被引：1，自引：0，他引：1  

YANG Wencai 《Continental Dynamics》1997,(1)

1.IntroductionSincethediscoveryofcoesiteandndcrodiamond,theDabie-Suluultra-highPressure(UHP)meta-morphicbelthasbeenattractingworldwideattentionsofgeoscientists.Studyingthisoutstandinggeologicalregionmaygreatlyenhanceourunderstandingofmetamorphism,deepeffectsofcontinentalcollisionandgeodynandcsinconvergentplateboundaries.Thestudymayalsobeveryhelpfultoprovideevidencetorevealinteractionbetweenthecrustandthemantle,andtheformationofnewtypesofdiamonddeposits.EncouragedbytheinternationalContinenta…  相似文献   

Geochemical evolution within a Devonian intra-oceanic island arc: The Gamilaroi terrane, southern New England orogen, Australia     

James M. C.  Stratford Jonathan C.  Aitchison 《Island Arc》1997,6(2):213-227

Abstract Geochemical analyses of volcanic rocks in the Gamilaroi terrane reveal several phases of arc activity within an intra-oceanic island-arc terrane. Felsic volcanic rocks at the base of the section have rare earth element (REE) and trace element compositions which indicate that they were derived from an island-arc source. Basalts immediately overlying the felsic volcanic rocks have a distinctive geochemical signature with low levels of Ti and Y and high levels of Ni, Cr and Mg. Low concentrations of REE and trace elements relative to mid-ocean-ridge basalts (MORB) indicate that they were also derived from an intra-oceanic island-arc source. Extensive basalts and basaltic andesites among the youngest rocks of the terrane have typically flat to enriched REE and trace element compositions, indicating a transitional arc-back-arc source. The change in basalt compositions indicates that rifting had occurred by this stage in the evolution of the arc. Confirmation of an intra-oceanic setting for this terrane enables a more detailed comparison with similar intra-oceanic rocks in the northern New England orogen. This study of the Gamilaroi terrane is an example of the potential use of geochemical data to identify other ancient intra-oceanic island-arc-rift suites.  相似文献   

新疆北部古生代大陆增生构造   总被引：35，自引：2，他引：35  

舒良树  卢华复  印栋浩  马瑞士  夏飞  卢汉 《新疆地质》2001,19(1):59-63

古生代亚洲中部是一幅两陆夹一洋、洋中多地体的构造图案，大地构造框架与现代西南太平洋格局十分相似。中亚造山带是晚古生代复杂地体的拼贴带。新疆北部古生代存在4类成因的8个地体构造。它们以裂解陆块地层块体、海山和火山弧的形式散布在中蒙大洋中，诸地体间是一系列的小洋盆。晚古生代，这些地体开始彼此拼贴并导致强烈推覆作用。石炭纪末－二叠纪初，中蒙大洋闭合，散布其中的诸地体分别增生到塔里木大陆北缘和西伯利亚大陆南缘。北天山－准噶尔地区6条蛇绿岩带记录了诸地体间碰撞事件。  相似文献   

Preliminary report on Lower Jurassic radiolaria of Gondwana origin from the Kawhia coast, New Zealand     

R. S. Hori  Y. Aita  J. A. Grant-Mackie   《Island Arc》1996,5(2):104-113

Abstract Well-preserved radiolarians from the Newcastle Group in southwest Kawhia, New Zealand, constitute the first record of Lower Jurassic radiolarians from in situ deposits in high latitudes of the Southern Hemisphere on the margin of Gondwana. The radiolarians were extracted from carbonate nodules from five horizons in the Rewarewa Formation and the lower part of the Arawhero Formation, in the Murihiku Terrane. The radiolarian-bearing sequence, which lies within the upper part of the type section of the local Aratauran Stage, is roughly datable as Hettangian-Sinemurian from rare ammonite occurrences. The radiolarian assemblages consist, on average, of 80–90% spumellarians and 10–20% nassellarians. Spumellarians include species of the following genera: Archaeotriastrum, Crucella, Emiluvia (?) Homeoparo-riaella, Orbictilifomaa, Pantanellium, Paronaella (?), Pseudocrucella, PseIIdoheliodiscus, Spon-gostaurus and Spongotrochus. Nassellarians are composed of species of Ragotum, Bipedis, Droltus, Jams (?) Perispyridium (?) Raoultius, Riedelius, Saitoum and Thetis. From data of Lower Jurassic radiolarian faunas of Europe, North America and Japan, the New Zealand fauna shows stronger affinity with those of the European Tethys such as Turkey (e.g. De Wever 1982) and the Northern Alps (Kozur & Mostler 1990) than with faunas from other areas of the circum-Pacific. This connection between the European Tethyan and New Zealand faunas is not well explained by presently accepted continental reconstructions (Smith et al. 1994) for the Early Jurassic.  相似文献   

北祁连地体古地磁新数据及古生代地体南向位移事件的发现     

杨惠心  董学斌  李鹏武 《吉林大学学报(地球科学版)》1996,(1)

格尔木－额济纳旗地学断面古地磁学研究工作中，在北祁连地体上获得了８个古生代、中生代古地磁新数据。研究结果在明北祁连地体在古生代一直处于北纬低纬度（１０°～１７°Ｎ）地区，并且表现出于古生代明显的南向位移过程。南移幅度为５．５°左右。这与北祁连地区原始陆壳在中奥陶世的强烈拉张及其后期洋壳闭合作用有关。  相似文献   

华北晚太古代－早元古代高级变质区的变质PTt轨迹及其地壳热动力学演化模式   总被引：4，自引：1，他引：4  

金巍  李树勋 《岩石学报》1996,12(2)

华北高级变质区是早前寒武纪下地壳的组成部分，经历复杂的地质演化。根据变质ＰＴｔ轨迹和变质矿物冷却年龄研究，确定高级变质区ＰＴｔ演化具有两种基本形式：（１）逆时针ＩＢＣ型轨迹和（２）顺时针ＩＴＤ型轨迹。前者属晚太古代末期变质事件，反映在相对稳定环境中地壳的缓慢冷却过程，下地壳冷却速率较小（＜０．３℃／Ｍａ）。后者代表早元古代变质事件，形成于地壳的构造隆升过程，下地壳冷却速率明显加快（２．４～３．７℃／Ｍａ）。高级变质区地壳热动力学状态由晚太古代末期重力均衡条件下的稳定状态转变为早元古代增厚地壳的构造隆升状态。这种转变起因于早元古代大陆增厚（造山）作用  相似文献   

地层特征对比研究在地体解析中的意义   总被引：2，自引：0，他引：2  

张庆龙  水谷伸法 《地层学杂志》1996,20(1):70-75

不同地区地层特征的对比研究,是地体解析的重要方法之一。在对中国那丹哈达地区和日本美浓地区出露的地层、岩石等进行对比研究后认为,在老第三纪日本海尚未形成之前它们是连在一起的统一的地体。三叠纪时它们在赤道附近生成,侏罗纪—白垩纪时随板块运动增生于亚洲东部大陆边缘,白垩纪—老第三纪时左行剪切北移,新第三纪时因日本海的扩张而分裂移动到现今的位置。  相似文献   

Geochemistry of eclogites from the Dabie–Sulu terrane, eastern China: New insights into protoliths and trace element behaviour during UHP metamorphism     

Hong-Feng Tang  Cong-Qiang Liu  Shun''ichi Nakai  Yuji Orihashi 《Lithos》2007,95(3-4):441-457

The major and trace element compositions of nine eclogites from the Dabie–Sulu ultrahigh pressure (UHP) metamorphic terrane in eastern China were determined for both whole rock and the main constituent minerals, garnet and clinopyroxene. The results indicate that the eclogite protoliths originated from a basaltic magma, which formed in a continental setting as shown by isotopic and immobile element data. Based on the garnet REE characteristics, the eclogites can be roughly divided into two groups. Group 1 has LREE enrichment with no Eu anomaly for whole rock, and smooth LREE depletion but HREE enrichment pattern for garnet, whereas group 2 shows a depletion of LREE with a pronounced positive Eu anomaly and flat HREE pattern for both whole rock and garnet. From these features, we suggest that the protoliths for group 2 are Fe–Ti–gabbros with relatively high cumulus plagioclase and Fe–Ti oxide, whereas the group 1 eclogites are probably from basalts. Therefore, the unusual garnet REE pattern observed in group 2 can be considered as an important signature for identifying gabbro protoliths for eclogites. The identification of gabbro protoliths from the eclogites in the Dabie–Sulu terrane provides evidence for Neoproterozoic rift magmatism in the northern margin of the Yangtze craton. During ultrahigh pressure metamorphism in the Dabie–Sulu terrane, LILEs (including Ba, Rb, Th, U, K) had high mobility, but REEs and HFSEs were immobile, and trace element distribution equilibrium was approached between garnet and clinopyroxene. An estimate of mass balance indicates that garnet and clinopyroxene host the majority of HREEs and Y, and clinopyroxene is a significant host for Sr, but minor and accessory minerals predominantly account for LREEs, Th, U, and Zr.  相似文献   

川西老君沟和孟通沟花岗岩的地球化学特征、成因机制及对松潘-甘孜地体基底性质的制约   总被引：5，自引：5，他引：5  

赵永久 袁超周美夫  颜丹平龙晓平 李继亮 《岩石学报》2007,23(5):995-1006

老君沟岩体和孟通沟岩体是位于松潘-甘孜地体东部的中生代花岗岩,为碰撞过程中岩浆作用的产物,包含有地壳基底性质的重要信息。两岩体具有中等至较高的SiO_2含量(63.9～75.0wt%),具有准铝质和轻微过铝质(ACNK=0.86～1. 08)特征,属于中钾到高钾钙碱性系列。其中,老君沟岩体富Al_2O_3(14.2～16.0wt%)、K_2O(2.88～4.36wt%),贫MgO(0.38～1.98wt%),并具有高Sr(307～697ppm)低Y(12.2～21.0ppm)特征以及中等至较高的稀土分馏((La/Yb)_N>10),这些特征非常类似于下地壳熔融形成的埃达克岩。孟通沟岩体的主微量元素特征类似于老君沟岩体,但具有相对低的Sr(110～397 ppm)、稍高的Y(12.2～21.0ppm)和明显较低的Sr/Y比值(5～32)。两岩体均具有地壳特征的Nd-Sr同位素组成(ε_(Nd)(T)= -6.02～-3.11;I_(Sr)=0.7053～0.7075),排除了直接来自地幔岩浆的可能性,表明其可能来自于石榴石稳定区地壳物质的部分熔融。两岩体富含Rb(106～202ppm)、Cs(3.79～25.6ppm)而K_2O/Na_2O(0.56～1.12)比值较高,显示其可能来自黑云母的脱水熔融。由于黑云母的脱水熔融温度较高而剪切生热所能达致的温度较低,同造山的滑脱构造难以导致上述两个岩体的形成,地幔岩浆的底侵作用可能是导致下地壳物质部分熔融的主要原因。两岩体的源区成分和Nd模式年龄(T_(DM(Ⅱ))=1.23～1.44 Ga)均反映松潘-甘孜地体具有类似于扬子板块的中元古陆壳基底。  相似文献