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 s...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.展开更多
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)
文摘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.
