浅谈高温高压区域变质岩——榴辉岩.docx

浅谈高P/T区域变质岩—榴辉岩相摘要：高P/T区域变质岩产于海沟带和大陆碰撞带，是地壳俯冲的标志，有很重要的构造意义。典型的高P/T区域变质相系列为Z—LA—BS—E。在一些过渡型高P/T变质区，如日本三波川出现BS—EA—角闪岩相系列。LA（硬柱石—钠长石—绿泥石相）、BS（蓝片岩相）和E（榴辉岩相）是高P/T变质地体特有的三个变质相。本次报告主要针对其中的E（榴辉岩相）进行描述，因为榴辉岩相为高温高压区域变质岩的典型代表，并且在我国秦岭、大别山、苏鲁一带分布明显，其为陆壳岩石可以深俯冲到地幔深处提供了证据，且对于超高压变质矿物（柯石英、金刚石）、超高压变质岩的全球分布及其剖露机制均有重要意义。由于本人学识有限，如有不当之处，还请老师批评指正。关键词： 高P/T区域变质岩榴辉岩相 俯冲Abstract: high P/T regional metamorphic rocks in trench belt and continental collision zone, is a sign of crustal subduction, tectonic significance. High P/T regional metamorphism typical phase series for Z - LA - BS - E. In some transitional type high P/T metamorphic zone, such as Japans three wave in BS - EA - amphibolite facies series. LA (lawsonite - albite, chlorite facies), BS (blueschistfacies) and E (eclogitefacies) is high P\/T metamorphic terrane of three unique metamorphic facies. This report mainly on the E (eclogitefacies) is described, as a typical representative of eclogitefacies for high temperature and high pressure metamorphic rocks, and in Chinas Qinling Mountains, fasten hill greatly, Su Lu area distribution significantly, which may be of deep subduction of continental crust to the deep mantle provides evidence, and the ultra high pressure metamorphism mineral (coesite, diamond), important global distribution and partition of the ultra-high pressure metamorphic rocks are exposed mechanism.Due to my limited knowledge, such as inappropriate, please criticism.Keywords: High P/T regional metamorphic rocksEclogiteSubduction1．主要特征榴辉岩，呈深灰绿色，块状或片麻状构造，以块状为主，少数具面理和线理构造，粒状变晶结构。主要矿物由石榴石和绿辉石组成，二者之和大于75％。次要矿物有角闪石、石英、金红石、榍石、帘石、钠长石等。石榴石呈红褐色，镜下无色，高正突起，粒状，粒径d=0.3-0.5mm，发育裂纹，并有由粒状(d=0．03mm±)斜长石，细小粒状角闪石组成的冠状边。石榴石核部矿物包体发育，本身有时也作为包体包于石英等矿物之中。绿辉石呈短柱状，粒径d=0.3—1.0mm，浅绿色，颜色不均匀，具有弱多色性：浅绿色-无色。部分在边部退变为斜长石和透辉石或角闪石后成合晶。高正突起，具辉石式解理，干涉色达II级中部，二轴晶正延性，2v(+)。绿辉石中发育石英、角闪石、帘石等细小矿物包体，角闪石呈柱状或不规则形状，粒径d=0.lmm左右，具明显多色性：Ng=蓝绿色，Np=浅黄绿色。具角闪式解理．垂直(O1O)纵切面平行消光，其它纵切面斜消光，消光角Ng“c=30°-20°，干涉色达II级蓝。角闪石多以嵌边形式分布于绿辉石和石榴石边部或以细粒状分布于它们之间，具退变质成囚的结构特征。金红石多为粒状、不