A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in the...A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in thecourse of the Caledonian-Indosinian ductilc and brittle-ductile reworking. The study on their petrography. va-riations in composition and conditions of formation is conducive to revealing the metamorphism-deformationhistory of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its evo-lution.展开更多
Based on the deformation characteristics of the ductile shear zones in Sumdo （松多） Group, the quartz fabric by EBSD （electron backscatter diffraction）, the data of muscovite 40Ar-39Ar geochronology （220-230 Ma）...Based on the deformation characteristics of the ductile shear zones in Sumdo （松多） Group, the quartz fabric by EBSD （electron backscatter diffraction）, the data of muscovite 40Ar-39Ar geochronology （220-230 Ma） from ductile shear zones and the zircon SHRIMP U-Pb chronology （190 Ma） of granites in Sumdo region, Lhasa （拉萨） terrane is thought to have experienced an important Indosinian orogenic event at 220-230 Ma, which caused the closure of the paleo-Tethys Ocean along the tectonic zone of eclogite and the collision between northern part and southern part of the Lhasa terrane. The zircon SHRIMP U-Pb chronology of 190 Ma for biotite adamellite, with the distributing characteristics of the granite massif intruding in Sumdo Group, indicates that the biotite adamellite should be the late orogenic or post-orogenic granite resulting from the Indosinian orogenesis. The discovery of Indosinian orogenic belt in Lhasa terrane expansed the southern boundary of Indosinian orogenic belt in Qinghai （青海）-Tibet plateau to Lhasa terrane from Qiangtang （羌塘） terrane, which changed the understanding about the distribution of Indosinian orogenic belt in Qinghai-Tibet plateau and extended the ＂T＂ type Indosinian orogenic belt in China. The study is very important for the formation and distribution of paleo-Tethys Ocean in Tibet. The ancient terrane framework and evolution of Qinghai-Tibet plateau need further research.展开更多
文摘A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in thecourse of the Caledonian-Indosinian ductilc and brittle-ductile reworking. The study on their petrography. va-riations in composition and conditions of formation is conducive to revealing the metamorphism-deformationhistory of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its evo-lution.
基金supported by the Geological Survey Program of China Geological Survey (No. 1212010610105)
文摘Based on the deformation characteristics of the ductile shear zones in Sumdo （松多） Group, the quartz fabric by EBSD （electron backscatter diffraction）, the data of muscovite 40Ar-39Ar geochronology （220-230 Ma） from ductile shear zones and the zircon SHRIMP U-Pb chronology （190 Ma） of granites in Sumdo region, Lhasa （拉萨） terrane is thought to have experienced an important Indosinian orogenic event at 220-230 Ma, which caused the closure of the paleo-Tethys Ocean along the tectonic zone of eclogite and the collision between northern part and southern part of the Lhasa terrane. The zircon SHRIMP U-Pb chronology of 190 Ma for biotite adamellite, with the distributing characteristics of the granite massif intruding in Sumdo Group, indicates that the biotite adamellite should be the late orogenic or post-orogenic granite resulting from the Indosinian orogenesis. The discovery of Indosinian orogenic belt in Lhasa terrane expansed the southern boundary of Indosinian orogenic belt in Qinghai （青海）-Tibet plateau to Lhasa terrane from Qiangtang （羌塘） terrane, which changed the understanding about the distribution of Indosinian orogenic belt in Qinghai-Tibet plateau and extended the ＂T＂ type Indosinian orogenic belt in China. The study is very important for the formation and distribution of paleo-Tethys Ocean in Tibet. The ancient terrane framework and evolution of Qinghai-Tibet plateau need further research.
