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1.
中国蓝闪片岩相的变质作用 总被引：7，自引：1，他引：7
本文论述了中国蓝闪片岩的分布、变质条件及其构造位置。中国的蓝闪片岩从中晚元古代开始,各变质期均有出现。根据矿物组合,可分为两类:第一类蓝闪片岩常含有高压矿物,如硬柱石、硬玉和文石以及蓝闪石、绿纤石、黑硬绿泥石、多硅白云母、红帘石等,属高压亚绿片岩相,称蓝闪—硬柱石片岩相,形成温度约250—350℃,压力大于500—800MPa,甚至可达1200MPa。此类蓝闪—硬柱石片岩相多代表海洋板块古消减带。第二类蓝闪片岩的常见矿物为蓝闪石、青铝闪石或镁钠闪石、黑硬绿泥石、红帘石和绿片岩相中的绿帘石、阳起石、绿泥石、白云母、有时还有黑云母、铁铝榴石和钠质辉石。形成温度约350—450℃,压力500—800MPa。此类蓝闪绿片岩相虽处于活动带,但与板块构造没有直接关系。我国西藏南部和内蒙温都尔庙属第一类,但大部分蓝闪片岩带属第二类。 相似文献
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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
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通过对澜沧江杂岩带小黑江-上允地区蓝片岩的岩相学、地球化学、成因矿物学以及相平衡模拟的综合研究,阐述蓝片岩的原岩以及变质演化过程。地球化学分析结果显示,蓝片岩具有一致的稀土元素配分模式,具弱Eu正或负异常,稀土元素和微量元素特征与OIB相似,其原岩可能为OIB型玄武岩。详细矿物学研究表明,本区蓝片岩记录了俯冲峰期蓝片岩相变质和峰期后绿片岩相变质两个变质阶段,其矿物组合分别为蓝闪石+钠长石+多硅白云母+绿泥石+绿帘石和蓝闪石+钠长石±阳起石+绿泥石+绿帘石。通过Na_2O-Ca O-Fe O-MgO-Al_2O_3-SiO_2-H_2O-O体系相平衡计算,得到两个阶段的压力范围分别约为0.95 GPa和0.40 GPa。 相似文献
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新疆西南天山蓝片岩的变质作用pTDt轨迹及构造演化 总被引：31，自引：1，他引：31
西南天山蓝片岩的变质作用ｐＴＤｔ轨迹显示进变质作用为快速升压过程，退变质作用为近等热降压过程。自俯冲杂岩进入俯冲带到形成蓝片岩后抬升出露于造山带，变质作用经历了浊沸石相（４１５Ｍａ？）→硬柱石－蓝闪片岩相（４０８Ｍａ？）→蓝闪绿片岩相（３４５Ｍａ）→０绿片岩相（３１４Ｍａ）连续渐变演化的过程。蓝片岩中现存主要蓝闪绿片岩相矿物组合并非峰期变质矿物组合。造山运动晚期的大规模韧性推覆作用促成蓝片岩快速抬 相似文献
5.
陕甘川交界区碧口群的变质作用及其地质意义 总被引：4，自引：1，他引：4
碧口群由一套中晚元古代的变质双峰式火山岩及复理石型深积岩组成，其变质作用分为蓝片岩相和绿片岩相。据其野外分布及白云母ｂ０值的变化可分成Ａ、Ｂ、Ｃ三个变质带。蓝片岩相以钠质闪石＋绿帘石共生为特征，在Ａ带的大面积绿片岩中呈条带或残片状分布。对区内的角闪石、绿泥石、绿帘石及白云母等矿物及其间的交代关系研究表明蓝片岩和绿片岩并非同一物理化学条件下的产物。蓝片岩相的温度为３００－４００℃，压力为０．５－０． 相似文献
6.
北祁连山硬柱石蓝片岩p-T条件相平衡计算及其岩石学意义 总被引：2，自引：0，他引：2
北祁连硬柱石蓝片岩主要分布在甘肃省肃南县九个泉一带,是目前中国唯一报道的、确切地含有硬柱石的蓝片岩。文中在详细的岩石学和矿物学研究基础上,根据矿物共生组合的不同,将北祁连低温蓝片岩进一步划分为绿纤石蓝片岩、硬柱石蓝片岩和绿帘石蓝片岩。绿纤石蓝片岩的特征变质矿物组合为蓝闪石(>40%)+绿纤石(30%)+绿泥石(10%)+钠长石(8%)+石英(5%)+硬柱石(<3%)±方解石/文石(<1%)。硬柱石蓝片岩的矿物组合为蓝闪石(35%~40%)+硬柱石(35%~40%)+绿泥石(10%)+钠长石(10%)+石榴石(1%~2%)+黝帘石/斜黝帘石(<2%)+石英(<1%),副矿物有磷灰石和榍石,总含量小于2%。绿帘石蓝片岩的矿物组合为蓝闪石(30%~35%)+黝帘石/斜黝帘石/绿帘石(~30%)+绿泥石(15%)+钠长石(15%)+石榴石(2%)+石英(<2%),副矿物有金红石、磷灰石和磁铁矿,总含量小于2%。利用矿物内部一致性热力学数据和Domino/Theriak软件计算了这三种类型的蓝片岩形成的峰期温压条件,它们分别是绿纤石蓝片岩为320~350℃,0.75~0.85GPa;硬柱石蓝片岩为335~355℃,0.8~0.95GPa;绿帘石蓝片岩为345~375℃;0.75~0.85GPa。北祁连低温蓝片岩带由硬柱石蓝片岩相到绿帘石蓝片岩相的转化代表了俯冲变质过程中的递进变质过程。 相似文献
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黑龙江杂岩主要由蓝闪石片岩构成,蓝闪石片岩主要包括绿帘石、绿泥石、钠长石、钠质角闪石、多硅白云母和石英以及为数不多的榍石、钛铁矿和黑硬绿泥石。其中,钠质角闪石包括蓝闪石和镁质钠闪石。变质条件的压力（P）温度（T）评价条件为400－425℃和0.69－0.86 MPa,对应岩相为绿帘蓝闪石片岩相。黑龙江杂岩蓝闪石片岩的地球化学研究表明,其原岩是可与洋岛型（OIB）玄武岩和一些洋中脊型（E-MORB）玄武岩相对比的大洋玄武岩,这说明黑龙江杂岩蓝闪石片岩的玄武岩原岩是在海底山或者在大洋隆起条件下由富集源形成的;具有洋岛型玄武岩地球化学特征的变质玄武岩以及富锰的变质燧石、大理石、变质硬砂岩和蛇绿岩鳞片的加入证明黑龙江杂岩是消减—增生杂岩,它含有变形洋壳的碎块和在被改造的前震旦纪佳木斯岩体西边缘上形成于侏罗纪的增生楔岩石;黑龙江杂岩在原岩成分上可与活动大陆边缘许多增生的杂岩相当。 相似文献
10.
安徽张八岭蓝片岩带的矿物分带 总被引：5，自引：1，他引：5
皖中张八岭蓝片岩带含硬玉和石英组合，位于扬子地块北缘，是我国蓝片岩带压力最高的地区。以矿物共生组合为基础，将蓝片岩带划分为５个矿物带：黑硬绿泥石－白云母带；红帘石－白云母带；蓝闪石－青铝闪石带；阳起石带；白云母带。阐述了蓝片岩可能在板底垫托作用下抬升至地表的机制。 相似文献
11.
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
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
12.
高压、超高压变质作用是地学研究的热点，它能很好地反映深部地质作用特征和恢复地质历史演化的过程。当前高压、超高压变质作用研究中有几个值得注意的动向：（１）高压变质作用中流体性状和物理化学特点的研究是解决高压变质作用成因的关键；（２）高压变质矿物流变学研究是揭示变质过程的有效途径；（３）超高压变质岩的发现是８０年代地学领域中的一场“革命”，其动力学模式为探讨大陆动力学开辟了新的思路。文中介绍了产生超高压变质的柯石英榴辉岩亚相组合的六种动力学模式。 相似文献
13.
Wei Chunjing 《《地质学报》英文版》1995,8(1):53-68
Abstract The Bikou Group on the Shaanxi-Gansu-Sichuan border is composed of Mid-Late Proterozoic metamorphosed bimodal volcanic rocks and flysch sediments. Its metamorphism may be divided into the blueschist and greenschist facies. Three metamorphic zones, i.e. zones A, B, and C, may be distinguished on the basis of the field distribution of metamorphic rocks and the variation of b0 values of muscovite. Blueschists are characterized by coexistence of sodic amphiboles and epidote and occur as stripes or relict patches in extensive greenschists of zone A. Studies of metamorphic minerals such as amphiboles, chlorite, epidote and muscovite and their textural relationships indicate that blueschists and greenschists were not formed under the same metamorphic physico-chemical conditions. The blueschist facies was formed at temperatures of 300-400°C and pressures of 0.5–0.6 GPa. The greenschist facies in zones A and B has similar temperatures but its pressure is only 0.4 GPa or so. The transition from the blueschist to greenschist facies is a nearly isothermal uplift process. The rock and mineral assemblages of the Bikou Group indicate that the blueschist facies metamorphism of the group might be related to crustal thickening or A-subduction accompanying the closure of an intracontinental small ocean basin. 相似文献
14.
皖中张八岭群"蓝片岩"中钠质角闪石及其变质p-T条件分析 总被引：2，自引：0，他引：2
对张八岭地区管店附近含角闪石片岩的岩相学、矿物成分分析和p-T条件的初步估计表明,该地区片岩中的角闪石为钠质闪石类的镁钠闪石,其中氧化物平均含量Al2O3=3.97%,Fe2O3=20.57%,相应的Al3 ,IV=0.54,Fe3 =1.34,指示的变质温压条件为t=500~600℃,p≤0.3 GPa,显示了低压变质相系的特征。结合前人对张八岭地区的“蓝闪石”的研究资料,并对比作者等对天山昭苏、库车地区和西藏羌塘地区的蓝闪石分析数据,认为张八岭地区并没有真正意义上的蓝闪石存在,张八岭群中“蓝片岩”是否存在以及是否经历低温高压变质作用需要进一步的详细研究。 相似文献
15.
The Blkou Group on the Shaanxi-Gansu-Sichuan border is composed of Mid-Late Proterozoic metamorphosed bimodal volcanic rocks and flysch sediments. Its metamorphism may be divided into the blueschist and greenschist facies. Three metamorphlc zones, i.e. zones A, B, and C, may be distinguished on the basis of the field distribution of metamorphlc rocks and the variation of b0 values of muscovite. Blueschists are characterized by coexistence of sodic amphiboles and epidote and occur as stripes or relict patches in extensive greenschists of zone A. Studies of metamorphic minerals such as amphiboles, chlorite, epidote and muscovite and their textural relationships indicate that blueschists and greenschists were not formed under the same metamorphic physico-chemical conditions. The blueschist facies was formed at temperatures of 300-400℃ and pressures of 0.5-0.6 GPa. The greenschist facies in zones A and B has similar temperatures but its pressure is only 0.4 GPa or so. The transition from the blueschist to 相似文献
16.
Metamorphism and tectonic evolution of the Lancang paired metamorphic belts, south-western China 总被引：10，自引：0，他引：10
RUYUAN ZHANG BOLIN CONG SHIGE MARUYAMA† J. G. LIOU‡ 《Journal of Metamorphic Geology》1993,11(4):605-619
Abstract The Lancang metamorphic terrane consists of an eastern low- P/T belt and a western high- P/T belt divided by a N–S-trending fault. Protoliths of both units are mid–late Proterozoic basement and its cover. The low- P/T belt includes the Permian Lincang batholith, related amphibolite facies rocks of the Damenglong and Chongshan groups, and Permo-Triassic volcanic and volcaniclastic rocks. Most whole-rock Rb–Sr isochron and U–Pb zircon ages of the Lincang batholith are in the range 290–279 and 254–212 Ma, respectively. Metamorphism of the low- P/T belt reaches upper amphibolite with local granulite facies (735°C at 5 kbar), subsequently retrogressed at 450–500°C during post-Triassic time. The high- P/T rocks grade from west to east from blueschist through transitional blueschist/greenschist to epidote amphibolite facies. Estimated P–T conditions follow the high- P intermediate facies series up to about 550–600°C, at which oligoclase is stable. The 40 Ar/39 Ar plateau age of sodic amphibole in blueschist is 279 Ma.
The paired metamorphic belts combined with the spatial and temporal distribution of other blueschist belts lead us to propose a tentative tectonic history of south-east Asia since the latest Precambrian. Tectonic juxtaposition of paired belts with contrasting P–T conditions, perhaps during collision of the Baoshan block with south-east Asia, suggests that an intervening oceanic zone existed that has been removed. The Baoshan block is a microcontinent rifted from the northern periphery of Gondwana. Successive collision and amalgamation of microcontinents from either Gondwana or the Panthalassan ocean resulted in rapid southward continental growth of c. 500 km during the last 200 Ma. Hence, the Lancang region in south-east Asia represents a suture zone between two contrasting microcontinents. 相似文献
The paired metamorphic belts combined with the spatial and temporal distribution of other blueschist belts lead us to propose a tentative tectonic history of south-east Asia since the latest Precambrian. Tectonic juxtaposition of paired belts with contrasting P–T conditions, perhaps during collision of the Baoshan block with south-east Asia, suggests that an intervening oceanic zone existed that has been removed. The Baoshan block is a microcontinent rifted from the northern periphery of Gondwana. Successive collision and amalgamation of microcontinents from either Gondwana or the Panthalassan ocean resulted in rapid southward continental growth of c. 500 km during the last 200 Ma. Hence, the Lancang region in south-east Asia represents a suture zone between two contrasting microcontinents. 相似文献
17.
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
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