Yipeng FENG, Genhou WANG, Shulai WANG, Dian LI, Huan WANG, Yang LU, Han LIU, Peilie ZHANG
{"title":"郭学普剪切带的构造、40Ar/39Ar地质年代和流变特征分析:澜沧江北部地区吉塘变质复合体的迹象","authors":"Yipeng FENG, Genhou WANG, Shulai WANG, Dian LI, Huan WANG, Yang LU, Han LIU, Peilie ZHANG","doi":"10.1111/1755-6724.15119","DOIUrl":null,"url":null,"abstract":"<p>The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural-lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro- and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top-to-the-southeast. The presence of various deformation features and quartz C-axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (έ) ranging from 9.77×10<sup>–14</sup> s<sup>–1</sup> to 6.52×10<sup>–16</sup> s<sup>-1</sup>. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a <sup>40</sup>Ar-<sup>39</sup>Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike-slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene.</p>","PeriodicalId":7095,"journal":{"name":"Acta Geologica Sinica ‐ English Edition","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Structural, 40Ar/39Ar Geochronological and Rheological Feature Analysis of the Guoxuepu Shear Zone: Indications for the Jitang Metamorphic Complex in the Northern Lancangjiang Zone\",\"authors\":\"Yipeng FENG, Genhou WANG, Shulai WANG, Dian LI, Huan WANG, Yang LU, Han LIU, Peilie ZHANG\",\"doi\":\"10.1111/1755-6724.15119\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural-lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro- and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top-to-the-southeast. The presence of various deformation features and quartz C-axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (έ) ranging from 9.77×10<sup>–14</sup> s<sup>–1</sup> to 6.52×10<sup>–16</sup> s<sup>-1</sup>. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a <sup>40</sup>Ar-<sup>39</sup>Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike-slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene.</p>\",\"PeriodicalId\":7095,\"journal\":{\"name\":\"Acta Geologica Sinica ‐ English Edition\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2023-10-28\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Geologica Sinica ‐ English Edition\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/1755-6724.15119\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Geologica Sinica ‐ English Edition","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/1755-6724.15119","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Structural, 40Ar/39Ar Geochronological and Rheological Feature Analysis of the Guoxuepu Shear Zone: Indications for the Jitang Metamorphic Complex in the Northern Lancangjiang Zone
The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural-lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro- and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top-to-the-southeast. The presence of various deformation features and quartz C-axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (έ) ranging from 9.77×10–14 s–1 to 6.52×10–16 s-1. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar-39Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike-slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene.
期刊介绍:
Acta Geologica Sinica mainly reports the latest and most important achievements in the theoretical and basic research in geological sciences, together with new technologies, in China. Papers published involve various aspects of research concerning geosciences and related disciplines, such as stratigraphy, palaeontology, origin and history of the Earth, structural geology, tectonics, mineralogy, petrology, geochemistry, geophysics, geology of mineral deposits, hydrogeology, engineering geology, environmental geology, regional geology and new theories and technologies of geological exploration.