蓝片岩及其有关高压变质带研究的新进展   总被引：5，自引：0，他引：5  

魏春景 《地学前缘》1994,(Z1)

通常认为蓝片岩主要分布在中新生代的造山带中，其成因与大洋板块的俯冲作用有关；而大陆上的蓝片岩一般与蛇绿岩和混杂岩伴生代表了古板块的缝合线。但近来研究发现，蓝片岩的矿物组合、时空分布和原岩建造多种多样。归纳起来可分为两种类型：科迪勒拉型和大陆内部型。不同的蓝片岩是在不同的大地构造环境下由不同的成因机制形成的，还是仅在洋壳俯冲环境中，由于不同的物质卷入俯冲带，引起俯冲过程中动力学机制变化形成的，是当前蓝片岩研究中至为重要的问题。  相似文献   

秦岭——大别高压超高压变质带构造特征及构造演化   总被引：7，自引：0，他引：7  

杨巍然  游振东 《高校地质学报》1995,1(2):53-64

秦岭－大别高压超高压变质带是地中海全球近纬向活动带的组成部分，地中海活动带具有长期活动历史，高压超高压变质岩发育在不同时代的褶皱带中。秦岭－大别高压超高压变带以丹凤－商南－信阳－桐城对拉带为界分为秦岭和鄂北－桐柏－大别两个高压超高压块体，前者分为南北两个高压变质带，后者进一步划分为蓝片岩带、高压低温榴辉岩带、超高压榴辉岩带、高压中温榴辉岩带和盆榴辉岩带。它们均具有前准对称展布特征。不同地区高压超高  相似文献   

滇西澜沧变质带中白云母b_0值特征及其多期变质作用意义     

赵靖  钟大赉  王毅 《矿物岩石》1993,(1)

滇西澜沧变质带中199件白云母b_0值分析结果表明,b_0值均在0.9020nm以上。与澜沧变质带遭受蓝片岩相高压变质作用的事实相吻合。此外,白云母b_0值的统计规律显示,澜沧变质带经历了多期变质作用,一期为高压变质作用,另一期为中压变质作用,这也与已知的地质现象相符。由此可见,白云母b_0值可以很好地反映多期变质作用。  相似文献   

A deep section of accretionary complex: Susunai Complex in Sakhalin Island, Northwest Pacific Margin     

Gaku  Kimura Masayuki  Sakakibara Hisashi  Ofuka Hideo  Ishizuka Sumio  Miyashita Makoto  Okamura Olex A.  Melinikov Vilera  Lushchenko 《Island Arc》1992,1(1):166-175

Abstract A deep section of accretionary complex, the metamorphosed Susunai Complex, is observed on Sakhalin Is., Russia. High pressure part of pumpellyite-actinolite facies metavolcanics, metacherts and metapelites are well exposed and constitute a tectonic pile preserving primary structures related to underplating of the oceanic crust. Three stages of deformation, D₁ through D₃, suggest successive deformation during subduction, underplating and exhumation of the complex. Oceanic material in the complex is more abundant than other well documented ancient accretionary complexes (e.g. the Shimanto Belt in southwest Japan and the Ghost Rocks Formation in Alaska), which were shallowly underplated. At Susunai, deep down-stepping of a décollément has scraped off the upper part of the oceanic crust, primarily the pillowed basalt horizon. This down-stepping results from crustal weakening as overpressured water is released from the fractured oceanic crust during metamorphism.  相似文献   

Lawsonite growth in the epidote blueschists from the Ile de Groix (Armorican Massif, France): a potential geobarometer   总被引：2，自引：0，他引：2  

M. Ballevre  P. Pitra  M. Bohn 《Journal of Metamorphic Geology》2003,21(7):723-735

Abstract The garnet blueschists from the Ile de Groix (Armorican Massif, France) contain millimetre‐ to centimetre‐sized pseudomorphs consisting of an aggregate of chlorite, epidote and paragonite. The pseudomorphed phase developed at a late stage of the deformation history, because it overgrows a glaucophane–epidote–titanite foliation. Garnet growth occurred earlier than the beginning of the ductile deformation, and thus garnet is also included in the pseudomorphs. Microprobe analyses show that garnet is strongly zoned, with decreasing spessartine and increasing almandine and pyrope contents from core to rim. Grossular content is higher in garnet cores (about 35 mole%) compared to garnet rims (about 30 mole%). Blue amphibole has glaucophane compositions with a low Fe³⁺ content and become more magnesian when inclusions in garnet (X_Mg = 0.62–0.65) are compared with matrix grains (X_Mg = 0.67–0.70). Matrix epidote has a pistacite content of about 50 mole%. On the basis of their shape and the nature of the breakdown products, the pseudomorphs are attributed to lawsonite. A numerical model (using Thermocalc ) has been developed in order to understand the reactions controlling both the growth and the breakdown of lawsonite. Lawsonite growth could have taken place through the continuous hydration reaction Chl + Ep + Pg + Qtz + Vap = Gln + Lws, followed by the fluid‐absent reaction Chl + Ep + Pg = Grt + Gln + Lws. Peak P–T conditions are estimated at about 18–20 kbar, 450 °C. This indicates that lawsonite growth took place at increasing P and T, hence can be used as a geobarometer in the buffering assemblage garnet–glaucophane–epidote. The final part of the history is recorded by lawsonite breakdown, after cessation of the ductile deformation, and recording the earliest stages of the exhumation.  相似文献   

Glaucophane-bearing assemblage overprinted by greenschist-facies metamorphism in the Variscan Kaczawa complex, Sudetes, Poland   总被引：1，自引：0，他引：1  

R. KRYZA  A. MUSZYNSKI  D. VIELZEUF 《Journal of Metamorphic Geology》1990,8(3):345-355

An Early Palaeozoic (Ordovician ?) metamudstone sequence near Wojcieszow, Kaczawa Mts, Western Sudetes, Poland, contains numerous metabasite sills, up to 50 m thick. These subvolcanic rocks are of within-plate alkali basalt type. Primary igneous phases in the metabasites, clinopyroxene (salite) and kaersutite, are veined and partly replaced by complex metamorphic mineral assemblages. Particularly, the kaersutite is corroded and rimmed by zoned sodic, sodic–calcic and calcic amphiboles. The matrix is composed of actinolite, pycnochlorite, albite (An ≤ 0.5%), epidote (Ps 27–33), titanite, calcite, opaques and, occasionally, biotite, phengite and stilpnomelane. The sodic amphiboles are glaucophane to crossite in composition with Na^B from 1.9 to 1.6. They are rimmed successively by sodic–calcic and calcic amphiboles with compositions ranging from magnesioferri-winchite to actinolite. No compositions between Na^B= 0.92 and Na^B= 1.56 have been ascertained. The textures may be interpreted as representing a greenschist facies overprint on an earlier blueschist (or blueschist–greenschist transitional) assemblage. The presence of glaucophane and no traces of a jadeitic pyroxene + quartz association indicate pressures between 6 and 12 kbar during the high-pressure episode. Temperature is difficult to assess in this metamorphic event. The replacement of glaucophane by actinolite + chlorite + albite, with associated epidote, allows restriction of the upper pressure limit of the greenschist recrystallization to <8 kbar, between 350 and 450°C. The mineral assemblage representing the greenschist episode suggests the P–T conditions of the high-pressure part of the chlorite or lower biotite zone. The latest metamorphic recrystallization, under the greenschist facies, may have taken place in the Viséan.  相似文献   

甘肃玉门昌马地区的蓝闪片岩     

吴汉泉  冯益民  霍有光  左国朝 《西北地质科学》1991,(2)

蓝闪片岩产于一套含放射虫硅质岩、硅质大理岩、板岩、变质基性火山岩中,与此相伴的超基性岩块,以一系列向南逆冲的断片产出。蓝闪片岩中的蓝闪石往往和黑硬绿泥石、钠长石、绿泥石以及钠钙闪石(蓝透闪石、冻蓝闪石等)、钙闪石(阳起石等)共存。据钠角闪石、绿泥石计算的生成压力是0.65GPa至0.8GPa,略大于美国佛兰西斯科的瓦尔德溪蓝片岩中该矿物对生成的压力。稀土元素分析证明蓝片岩的原岩是典型洋底(中脊)玄武岩和岛弧玄武岩,这是蓝片岩沟-弧俯冲-碰撞的证据之一。  相似文献   

Studies on the Blueschist Belt in the Shuanghu Region, Central Northern Tibet and Its Tectonic Implications   总被引：4，自引：0，他引：4  

BAO Peisheng  XIAO Xuchang  WANG Jun 《Continental Dynamics》1999,(2)

l.IntroductionThebIueschistblocksextenddiscontinuouslyover3oOkintrendinginE-WinthecentTalnorthernTibetfromtheeastemQageIelatown,l3kmwestofShuanghu,XiyaergangineasternTibet,throughNaro,Jiaomuri,GuoganjianianShan(GuoganjianianMt.)towesternGangmarCo-LungmuCo.Theblueschistblocksoccurinasuiteofassemblageofclasticrock,basalticrock,diamictiteandpebblysandyslate(namedBulannisedimentsbefore).TheageisprobablytheMiddle-LateCarboniferous-LatePermianepochinthelightofthecoldwaterfauna-Eurydesmaan…  相似文献   

内蒙古头道桥地区蓝闪石片岩和相关变质岩石岩石学特征及其构造意义     

赵立敏  刘永江  滕加雨  李伟民 《吉林大学学报(地球科学版)》2018,48(2):534-544

内蒙古头道桥地区出露了一套经高压变质形成的岩石组合。本次研究通过岩相学和矿物化学分析,根据矿物组合的不同,识别出蓝片岩、绿片岩两种不同类型的岩石类型。其中,蓝片岩的矿物组合为角闪石（蓝闪石、蓝透闪石）+绿帘石+钠长石+绿泥石+石英+赤铁矿±多硅白云母±方解石±榍石;绿片岩的矿物组合为绿泥石+钠长石+石英±绿帘石±角闪石（阳起石、镁角闪石、蓝透闪石、冻蓝闪石等）±多硅白云母±赤铁矿。确定了蓝片岩的峰期变质级别为绿帘-蓝闪片岩相,峰期变质温度为400~600℃,压力为1.2~1.4 GPa。绿片岩的峰期变质级别为绿帘-角闪岩相。结合前人研究成果,认为蓝片岩和绿片岩的形成与额尔古纳地块和兴安地块的碰撞拼合有关。  相似文献   

结合实测光谱的ASTER TIR数据岩性划分与构造样式分析:以新疆阿克苏蓝片岩为例     

张志  管志超  王少军 《吉林大学学报(地球科学版)》2018,48(1):334-342

常见造岩矿物的特征谱带位于热红外区域,因此热红外遥感在岩石地层划分与构造样式分析方面有巨大的应用潜力,并且精细岩石地层划分是构造样式分析的基础。新疆阿克苏蓝片岩被认为是目前世界范围内保存最好的前寒武纪蓝片岩之一。本文对该地质体中采集的不同类型岩石样品进行了室内热红外发射光谱测试,发现白云母石英片岩类残余辐射特征（restrahlen features,RF）位于波长8.55、9.16和9.60 μm处,绿泥绿帘片岩类RF位于波长9.60、10.50和11.66 μm处。按照ASTER TIR波段位置将样品的发射率光谱曲线重采样,利用ASTER TIR数据计算基性指数I_b和白云母指数I_m。依据I_b和I_m得到不同岩性段分布图,该图能反映蓝片岩地质体中不同基性程度岩石、后期侵入的基性岩墙群以及白云母石英片岩单元的空间分布。从岩性区域分布特征看,我们认为新疆阿克苏蓝片岩地质体平面构造样式表现为褶皱,其轴迹线为NE—SW向,这一结果与前人对其划分的单斜地层结构有较大的差异。另外,褶皱出现在地质体南部,说明其北部所受压力较南部小,与前人认识一致。研究结果体现了热红外遥感结合实测光谱可有效探测矿物岩石信息的优势,该方法可为相关研究提供参考。  相似文献