摘要:佛子岭群位于大别造山带最北缘，处于华北和扬子板块结合部位，是获取两大板块耦合过程和信息的重要岩石单元。由于佛子岭群一直被视为典型的“浅变质”复理石建造，故研究多是从沉积学角度展开，并籍此对其构造归属和动力学机制产生了不同的认识。为此，本文将从新的视角（变质地质学），解析佛子岭群岩石构成和变质作用，为充分探讨佛子岭群形成机制提供变质岩石学的支撑。野外调查和全面岩相学分析表明，佛子岭群主体是由各类片岩、石英岩和少量石榴云母片岩构成，但因后期构造作用，裹挟有少量的其他岩石单元的花岗质片麻岩和变基性岩块。对特征性岩石（石榴云母片岩）的主期变质PT条件估算显示，佛子岭群普遍经历了中-高压角闪岩相变质，温压范围为T = 550 ℃～620 ℃和P = 0.6～1.0 GPa。细致的野外露头观测和精细的岩相学研究表明，佛子岭群各类岩石均是由新生的变质矿物构成，普遍发育变晶结构，不具备任何沉积结构和构造。所谓的“沉积韵律”，可能是由不同变质矿物含量差异构成的成分层所致。对比前人研究成果，佛子岭群与庐镇关群存在一个0.9 GPa的压力差异，暗示了两者并非形成于相同的动力学背景，其可能为一个独立的微陆块。
关键词: 佛子岭群/
主期变质PT条件/
中-高压角闪岩相/
变晶结构/
沉积韵律
Abstract:The Foziling Group （FZG） located in the northernmost margin of the Dabie orogenic belt between the north and aouth plates, and is the critical litho-unit for gaining the coupling process and information of these plates. For a long time, the FZG has been defined as the typical ‘lower-metamorphic’ flysch formation, and usually investigated by means of the sedimentology, so that some different standpoints have been formed for its attribution and dynamic mechanism. In this study, the components and metamorphism of the FZG has been insight from a new view-metamorphic petrology. On the basis of the fieldtrip and the detail petrographic analysis, the FZG mainly consists of different kinds of schists, quartzite and a small quantity of garnet-mica schist. However, some granitic gneiss and metamorphic basic rocks from other litho-units have been juxtaposed as tectonic blocks in the FZG due to structure activity. The main metamorphic PT estimates for garnet-mica schists indicate that the FZG has been metamorphosed in the middle-high pressure amphibolite facies, universally, and arrive to T = 550 ℃～620 ℃和P = 0.6～1.0 GPa. Through the careful observation in the outcrop and the detail petrologic analysis, all kinds of rock from the FZG composed of metamorphic minerals, and develop conspicuous crystalloblastic structure, and have no any sedimentary structure and tectonic. The so called ‘sedimentary rhythm’ result from the content difference of metamorphic minerals. Compared with previous researches, a～0.9 GPa pressure discrepancy exists between the FZG and the Luzhenguan Group, which mplies that the two units have been formed in different dynamic setting, and the FZG could be an independent micro continent.
Key words:Foziling Group/
Main metamorphic PT conditions/
Middle-high pressure amphibolite facies/
Crystalloblastic structure/
Sedimentary rhythm
PDF全文下载地址:
http://www.dzkx.org/data/article/export-pdf?id=geology_11557
