Deformation features of garnet-bearing granites from Huwan,western Dabie Mountains  

作　　者：YANG KunGuang LIU Qiang XIE JianLei DAN Wei SHE ZhenBing MA ChangQian 

机构地区：[1]Key Laboratory of Tectonic and Petroleum Resources,Ministry of Education,China University of Geosciences,Wuhan 430074,China [2]Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China

出　　处：《Science China Earth Sciences》2009年第1期55-65,共11页中国科学（地球科学英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos.40802046 and 40334037);the Project of Science & Technology Research and Development from Sinopec (Grant No.P02009)

摘　　要：Foliated garnet-bearing granite,usually associated with high pressure and ultrahigh-pressure(UHP) metamophic rocks,is a particular rock-type extensively exposed in the Mesozoic Dabie-Sulu orogenic belt of China.This study focuses on deformation features and SHRIMP zircon dating of foliated garnet granite in a high-pressure metamorphic unit from Huwan,western Dabie Mountains in order to resolve discrepancies in current versions of its petrogenesis and structural evolution.SHRIMP dating reveals a zircon age of 762 ± 15 Ma(MSWD=1.7) for Huwan granites,representing the Middle to Late Neoproterozoic age of intrusion and crystallization.Field and microstructural studies show that the Huwan granite body underwent multiple-stage deformation.The deformation was manifested by an early stage of rootless folding and imposition of relict foliation(S1);an Indosinian main stage marked by imposition of north-dipping penetrative gneissosity(S2) and development of ductile shear zones under NNE-SSW directed compression;and a final Indosinian stage of southward thrusting of the Huwan high-pressure unit.Shallow level extension prevailed after the Late Triassic,giving rise to south-dipping thrust faults and north-dipping normal faults.Foliated garnet-bearing granite, usually associated with high pressure and ultrahigh -pressure (UHP) metamophic rocks, is a particular rock-type extensively exposed in the Mesozoic Dabie-Sulu orogenic belt of China. This study focuses on deformation features and SHRIMP zircon dating of foliated garnet granite in a high-pressure metamorphic unit from Huwan, western Dabie Mountains in order to resolve discrepancies in current versions of its petrogenesis and structural evolution. SHRIMP dating reveals a zircon age of 762 ± 15 Ma (MSWD=1.7) for Huwan granites, representing the Middle to Late Neoproterozoic age of intrusion and crystallization. Field and microstructural studies show that the Huwan granite body underwent multiple-stage deformation. The deformation was manifested by an early stage of rootless folding and imposition of relict foliation (S1); an Indosinian main stage marked by imposition of north-dipping penetrative gneissosity (S2) and development of ductile shear zones under NNE-SSW directed compression; and a final Indosinian stage of southward thrusting of the Huwan high-pressure unit. Shallow level extension prevailed after the Late Triassic, giving rise to south-dipping thrust faults and north-dipping normal faults.

关 键 词：SHRIMP DATING structural analysis foliated GARNET GRANITES Huwan DABIE OROGEN 

分 类 号：P597.3[天文地球—地球化学]