Regional metamorphic belts of the Japanese Islands   总被引：1，自引：0，他引：1  

Takashi  Nakajima 《Island Arc》1997,6(1):69-90

Abstract An overview of the regional metamorphic belts of Japan is given in the context of the tectonic evolution of the Japanese Islands. The Japanese Islands were situated on an active margin of the Eurasian continent or its constituent landmass before their assembly during the Phanerozoic. The Japanese Islands are composed mainly of metamorphosed and unmetamorphosed accretionary complexes, granitoids and their effusive equivalents that were formed by the Cordilleran-type orogeny. The metamorphic belts are regarded essentially as a deep-seated portion of an accretionary complex. In spite of continuous subduction of oceanic plates beneath the continents, these orogenic rocks were formed quite episodically, as evidenced by discontinuous matrix ages of the accretionary complexes and a striking concentration of isotopic ages of the granitoids. A systematic along-arc age shift of Cretaceous large-scaled granitic magmatism and regional metamorphism suggests a tectonic control such as ridge subduction, which triggered the episodic orogeny. A tectonic model based on the paired metamorphic belts, combined with the non-steady tectonic control, works well to explain this magmatism and metamorphism in a single arc-trench system as a continental margin process. However, the juxtapositional process of the paired metamorphic belts is still a problem. Two possible cases, namely transcurrent displacement and back-arc overthrusting are discussed.  相似文献   

3D MODEL STUDY ON FOG OVER COMPLEX TERRAIN-PART Ⅱ:NUMERICAL EXPERIMENT^*     

Li Zihuam  Shi Chun''e  Lu Taoshi 《Acta Meteorologica Sinica》1997,11(1):88-94

A series of numerical sensitivity experiments on Chongqing fog are made using the 3D fog model over complex terrain.Some factors affecting Chongqing fog are studied.  相似文献   

辽西元古宙旧庙基性杂岩的地球化学特征及物源区讨论     

孙景贵 《吉林大学学报(地球科学版)》1997,(3)

辽西旧庙基性杂岩主要由二辉辉石岩、辉长苏长岩和角闪辉长岩组成。它们是由同源岩浆演化分离结晶作用为主形成的拉斑玄武系列。痕量元素、ＲＥＥ及Ｓｒ同位素的特征表明岩浆起源于富集型地幔源区。低的Ｎｉ、较高的Ｈ２Ｏ，说明初始岩浆起源于富含Ｈ２Ｏ的富集型地幔源区，在相对较低的温度下熔融形成。ｗ（Ｒｂ）／ｗ（Ｂａ）、ｗ（Ｒｂ）／ｗ（Ｓｒ）值变化较大，表明岩浆形成演化与下地壳物质曾发生强烈的混合  相似文献   

Study on fluid-rock equilibrium systems of Fuping gneiss complex, Taihang Mountains   总被引：5，自引：0，他引：5  

Shuwen Liu 《中国科学D辑(英文版)》1997,40(3):239-245

The characters of fluid compositions and fluid-rock equilibrium system of the Archean Fuping gneiss complex, Taihang Mountains are first determined by fluid-rock equilibrium thermodynamics calculations and microthermometry of fluid inclusions. These investigations suggest that the X(H₂0) is generally less than 0.05 in fluids equilibrating with the granulite facies metamorphic mineral assemblage of Fuping gneiss complex, and fluid-rock interaction is chiefly controlled by C0₂-rich fluid infiltration. Project supported by thc National Natural Science Foundation of China.  相似文献   

桐柏─大别山西段的伸展构造   总被引：7，自引：2，他引：7       下载免费PDF全文

金维浚  宋鸿林 《地质科学》1997,32(2):156-164

桐柏─大别造山带经历了两阶段的伸展作用。早阶段伸展形成了局限海,并且形成了桐柏─大别山变质核杂岩的雏形。二郎坪岩群、龟山岩组、南湾岩组沉积在局限海中,沉积层序表现为从北向南的迁移。宽坪岩群和二郎坪岩群以低压高温的拉张变质作用为特征。晚期伸展对桐柏─大别山变质核杂岩的最后成型起着重要作用,并产生了中生代的花岗岩侵入和混合岩化。  相似文献   

北京四合堂花岗质杂岩的两种演化趋势     

Liu Shuwen 《吉林大学学报(地球科学版)》1990,(2)

北京密怀隆起西部的石城片麻岩、皂树片麻岩和云蒙山北部的片麻状花岗闪长岩是太古代同源岩浆演化形成的古深成侵入体,本文称之为四合堂花岗质杂岩。该杂岩中的石城片麻岩,皂树片麻岩的闪长质、石英门长质片麻岩—英云间长质片麻—脉状的奥长花岗岩构成了英云间长岩—奥长花岗岩演化趋势,片麻岩中的石英闪长质片麻岩与花岗间长岩—二长花岗岩构成了钙碱性演化趋势。这两个演化趋势是在不同的条件下分离的矿物相不同所致。  相似文献   

尉犁蛭石矿床的地质特征及成因探讨   总被引：5，自引：1，他引：5  

陈国耀 《新疆地质》1989,(1)

新疆尉犁蛭石矿是个大型矿床,含矿岩体为晚元古代超基性杂岩,长4Km,宽200—600m,具分带性,外带为透辉岩,内带为金云母岩和碳酸岩.蛭石矿主要分布在岩体内带.近地表10m品位极富.矿石质量以膨胀Ⅰ级品为主,膨胀10—21倍,最大31.9倍;下部品位贫,膨胀性差,金云母为岩浆晚期结晶而成.蛭石由金云母风化而来.  相似文献   

不同样式的剥离断层控矿研究   总被引：10，自引：1，他引：10  

傅昭仁  李先福 《地球科学》1991,16(6):627-634

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宁芜火山杂岩中标准岩石的研究和意义     

赵玉琛 《矿物岩石》1991,11(4):12-21

宁芜中生代火山杂岩覆盖面积约1200km~2,累计厚度1920m左右,分五组,经筛选得出各组的标准岩石共22块,分别从矿物学特征和岩石化学判据上建立了区分各火山岩组的判别模型。在此基础上,用“标准岩石-阶段成图法”测制的岩性图、相图和组图,能较准确地反映出古火山岩地喷构造特征。  相似文献   

辽东半岛南部早白垩世变质核杂岩时空分布及动力学特征     

仲米山  张国仁  杨中柱  高福亮  吴子杰  潘玉啟  高永钊  王煊  王然 《地质与资源》1992,29(5):411-418

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