Compressional origin of the Aegean Orogeny,Greece  

作　　者：Michael P.Searle Thomas N.Lamont 

机构地区：[1]Dept Earth Sciences,Oxford University,South Parks Road,Oxford,OX13AN,UK [2]School of Earth and Environmental Sciences,University of St Andrews,St Andrews,KY169AL,UK

出　　处：《Geoscience Frontiers》2022年第2期383-404,共22页地学前缘（英文版）

基　　金：Natural Environment Research Council grant NE/L0021612/1;NERC Isotope Geoscience Laboratory grant IP-1597-1115 for funding。

摘　　要：The Aegean Sea area is thought to be an actively extending back-arc region,north of the present day Hellenic volcanic arc and north-dipping subduction zone in the Eastern Mediterranean.The area shows extensive normal faulting,ductile‘extensional’shear zones and extensional S-C fabrics throughout the islands that have previously been related to regional Aegean extension associated with slab rollback on the Hellenic Subduction Zone.In this paper,we question this interpretation,and suggest the Cenozoic geodynamic evolution of the Aegean region is associated with a Late Cretaceous-Eocene NE-dipping subduction zone that was responsible for continentcontinent collision between Eurasia and Adria-Apulia/Cyclades.Exhumation of eclogite and blueschist facies rocks in the Cyclades and kyanite-sillimanite grade gneisses in the Naxos core complex have pressures that are far greater than could be accounted for purely by lithospheric extension and isostatic uplift.We identify four stages of crustal shortening that affected the region prior to regional lithospheric extension,herein called the Aegean Orogeny.This orogeny followed a classic Wilson cycle from early ophiolite obduction(ca.74 Ma)onto a previously passive continental margin,to attempted crustal subduction with HP eclogite and blueschist facies metamorphism(ca.54-45 Ma),through crustal thickening and regional kyanite-sillimanite grade Barroviantype metamorphism(ca.22-14 Ma),to orogenic collapse(<14 Ma).At least three periods of‘extensional’fabrics relate to:(1)Exhumation of blueschists and eclogite facies rocks showing tight-isoclinal folds and top-NE,base-SW fabrics,recording return flow along a subduction channel in a compressional tectonic setting(ca.50-35 Ma).(2)Extensional fabrics within the core complexes formed by exhumation of kyanite-and sillimanite gneisses showing thrust-related fabrics at the base and‘extensional’fabrics along the top(ca.18.5-14 Ma).(3)Regional ductile-brittle‘extensional’fabrics and low-angle normal faulting related to the

关 键 词：CYCLADES OPHIOLITE High-pressure metamorphism Core complex Compressional tectonics 

分 类 号：P587[天文地球—岩石学] P542[天文地球—地质学]