大别山东部超高太变质带北侧的花岗片麻岩及其构造背景  

THE GRANITIC GNEISSES AND ITS TECTONIC SETTING FROM THE NORTHERN PART OF ULTRA HIGH PRESSURE METAMORPHIC BELT IN EASTERN DABIE SHAN

作　　者：吴维平[1] 徐树桐[1] 江来利[1] 刘贻灿[1] 苏文[1] 石永红[1] 范高红 陈金苗[2] 沈欢喜[2] 

机构地区：[1]安徽省地质科学研究所 [2]安徽省地矿局311地质队

出　　处：《安徽地质》1998年第1期28-35,共8页Geology of Anhui

基　　金：国家自然科学基金;安徽省地矿局资助

摘　　要：大别山东部超高压变质带北侧的花岗片麻岩有下列特征。（１）化学成分富硅、富碱，一般ＳｉＯ２＜７５％，Ｋ２Ｏ＋Ｎａ２Ｏ＞８％，且Ｋ２Ｏ＞Ｎａ２Ｏ。（２）与变质表壳岩有侵入接触关系，有异源、深源包体。（３）主要为鳞片花岗变晶结构，有残留的岩浆结构，普遍具片麻状构造，钾长石常以眼球状巨晶出现，剪切带中发育Ｌ＞Ｓ型变形组构。（４）变质作用为角闪岩相，变质矿物为黑云母、角闪石以及少量石榴石、白云母、绿帘石等。。（５）锆石的乙—Ｐ６同位素年龄值为６２９Ｍａ。上述特征与超高压变质带中的含霓石变质花岗岩有明显的区别，因此，它可能是杨子大陆板块的俯冲基底。The main characteritics of the granitic gneisses from the northern Dabie Shan are as follows: (1) rich in SiO 2<75%,K 2O+Na 2O>8%,and K 2O>Na 2O. (2) intrusive conact with the metamorphic crustal rocks, contain antilogues and typhonic inclusions. (3) lepide-granoblastic texture with relic magmatic texture, gneissic structure with augen of K-feldspar and L>S type shape-fabric in shear zone. (4)amphibolite facies metamorphism. With some metamorphic mineral such as biotite, hornblende and a few garnet, muscovite, epidote,ect. (5) 629Ma (zircon U-Pb). These indicate that the granitic gneisses are different from the aegirine-bearing meta-granitoid in the ultrahigh pressure metamorphic belt. So, the former may be the underthrust basement of the Yangtze continental plate.

关 键 词：花岗片麻岩 构造背景 超高压变质带 大别山东部 

分 类 号：P588.345[天文地球—岩石学]