气候变化领域集成服务门户(CCPortal): Macro- and microstructural analysis of the Zhujiafang ductile shear zone, Hengshan Complex: Tectonic nature and geodynamic implications of the evolution of Trans-North China orogen

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DOI	10.1130/B35672.1
	Macro- and microstructural analysis of the Zhujiafang ductile shear zone, Hengshan Complex: Tectonic nature and geodynamic implications of the evolution of Trans-North China orogen
	He L.; Zhang J.; Zhao G.; Yin C.; Qian J.; Liu J.; Liu X.; Zhao C.
发表日期	2021
ISSN	167606
起始页码	1237
结束页码	1255
卷号	133 期号:2021-05-06
英文摘要	In worldwide orogenic belts, crustal-scale ductile shear zones are important tectonic channels along which the orogenic root (i.e., high-grade metamorphic lower-crustal rocks) commonly experienced a relatively quick exhumation or uplift process. However, their tectonic nature and geodynamic processes are poorly constrained. In the TransNorth China orogen, the crustal-scale Zhu-jiafang ductile shear zone represents a major tectonic boundary separating the upper and lower crusts of the orogen. Its tectonic nature, structural features, and timing provide vital information into understanding this issue. Detailed field observations showed that the Zhujiafang ductile shear zone experienced polyphase deformation. Variable macro- and microscopic kinematic indicators are extensively preserved in the highly sheared tonal-ite-trondhjemite-granodiorite (TTG) and su-pracrustal rock assemblages and indicate an obvious dextral strike-slip and dip-slip sense of shear. Electron backscattered diffraction (EBSD) was utilized to further determine the crystallographic preferred orientation (CPO) of typical rock-forming minerals, including hornblende, quartz, and feldspar. EBSD results indicate that the hornblendes are characterized by (100) <001> and (110) <001> slip systems, whereas quartz grains are dominated by prism and prism slip systems, suggesting an approximate shear condition of 650-700 °C. This result is consistent with traditional thermobarometry pressure-temperature calculations implemented on the same mineral assemblages. Combined with previously reported metamorphic data in the Trans-North China orogen, we suggest that the Zhujiafang supracrustal rocks were initially buried down to -30 km depth, where high differential stress triggered the largescale ductile shear between the upper and lower crusts. The high-grade lower-crustal rocks were consequently exhumed upwards along the shear zone, synchronous with extensive isothermal decompression metamorphism. The timing of peak collision-related crustal thickening was further constrained by the ca. 1930 Ma metamorphic zircon ages, whereas a subsequent exhumation event was manifested by ca. 1860 Ma syntectonic granitic veins and the available Ar-Ar ages of the region. The Zhujiafang ductile shear zone thus essentially record an integrated geodynamic process of initial collision, crustal thickening, and exhumation involved in formation of the Trans-North China orogen at 1.9-1.8 Ga. © 2021 Geological Society of America. All Rights Reserved.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184682
作者单位	Guangdong Provincial Key Laboratory of Mineral Resources & Geological Processes, School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519000, China; Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong
推荐引用方式 GB/T 7714	He L.,Zhang J.,Zhao G.,et al. Macro- and microstructural analysis of the Zhujiafang ductile shear zone, Hengshan Complex: Tectonic nature and geodynamic implications of the evolution of Trans-North China orogen[J],2021,133(2021-05-06).
APA	He L..,Zhang J..,Zhao G..,Yin C..,Qian J..,...&Zhao C..(2021).Macro- and microstructural analysis of the Zhujiafang ductile shear zone, Hengshan Complex: Tectonic nature and geodynamic implications of the evolution of Trans-North China orogen.Bulletin of the Geological Society of America,133(2021-05-06).
MLA	He L.,et al."Macro- and microstructural analysis of the Zhujiafang ductile shear zone, Hengshan Complex: Tectonic nature and geodynamic implications of the evolution of Trans-North China orogen".Bulletin of the Geological Society of America 133.2021-05-06(2021).