To better understand the Paleo-to Mesoproterozoic tectonic evolution of the Dabie Orogen in the northern margin of Yangtze Block,we present geochronological data for metasedimentary and metavolcanic rocks in the Huwan...To better understand the Paleo-to Mesoproterozoic tectonic evolution of the Dabie Orogen in the northern margin of Yangtze Block,we present geochronological data for metasedimentary and metavolcanic rocks in the Huwan complex.A total of 385 detrital zircon LA-ICP-MS analyses for metasedimentary rocks yielded three^(207)Pb/^(206)Pb age populations:1.50-1.80 Ga,1.81-1.87 Ga and 1.93-2.0 Ga,providing a maximum depositional timing of ca.1.50 Ga;while metafelsic volcanic gneisses yielded protolith U-Pb ages of 1893±54 Ma.The peak ages are remarkably consistent with the tectonothermal events that occurred in the northern Yangtze Block,indicating the presence of Paleo-to Mesoproterozoic magmatism in the Dabie Orogen.The age range of 1.93-2.0 Ga correlates with the Paleoproterozoic collision;the age range of 1.81-1.87 Ga coincides with the period of the post-orogenic extension;and the age range of 1.50-1.80 Ga is interpreted to associate with an extensional regime.Zircon cores with age of 1732-1965 Ma haveε_(Hf)(t)values ranging from-11.70 to-2.47,indicating that juvenile crust involved in their magma sources.Owing to the similar age spectra,we proposed that the nucleus of the Dabie Orogen was close to the Yangtze Block since the Paleoproterozoic.The Huwan complex has an intimate affiliation to the Yangtze Block,and implies multiple orogenic cycles.It was not only experienced the Paleo-Tethys ocean subduction and collision,but also recorded Paleo-to Mesoproterozoic tectono-magmatic events in the Dabie Orogen.展开更多
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granted by National Natural Science Foundation of China(Grant No.42172103)China Geological Survey(DD20221645)Hubei Geological Bureau(KJ2023-11,KCDZ2022-06,KCDZ2023-01)。
文摘To better understand the Paleo-to Mesoproterozoic tectonic evolution of the Dabie Orogen in the northern margin of Yangtze Block,we present geochronological data for metasedimentary and metavolcanic rocks in the Huwan complex.A total of 385 detrital zircon LA-ICP-MS analyses for metasedimentary rocks yielded three^(207)Pb/^(206)Pb age populations:1.50-1.80 Ga,1.81-1.87 Ga and 1.93-2.0 Ga,providing a maximum depositional timing of ca.1.50 Ga;while metafelsic volcanic gneisses yielded protolith U-Pb ages of 1893±54 Ma.The peak ages are remarkably consistent with the tectonothermal events that occurred in the northern Yangtze Block,indicating the presence of Paleo-to Mesoproterozoic magmatism in the Dabie Orogen.The age range of 1.93-2.0 Ga correlates with the Paleoproterozoic collision;the age range of 1.81-1.87 Ga coincides with the period of the post-orogenic extension;and the age range of 1.50-1.80 Ga is interpreted to associate with an extensional regime.Zircon cores with age of 1732-1965 Ma haveε_(Hf)(t)values ranging from-11.70 to-2.47,indicating that juvenile crust involved in their magma sources.Owing to the similar age spectra,we proposed that the nucleus of the Dabie Orogen was close to the Yangtze Block since the Paleoproterozoic.The Huwan complex has an intimate affiliation to the Yangtze Block,and implies multiple orogenic cycles.It was not only experienced the Paleo-Tethys ocean subduction and collision,but also recorded Paleo-to Mesoproterozoic tectono-magmatic events in the Dabie Orogen.
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.
