气候变化领域集成服务门户(CCPortal): Early Paleozoic oblique convergence from subduction to collision: Insights from timing and structural style of the transpressional dextral shear zone in the Qilian orogen, northern Tibet of China

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DOI	10.1130/B36947.1
	Early Paleozoic oblique convergence from subduction to collision: Insights from timing and structural style of the transpressional dextral shear zone in the Qilian orogen, northern Tibet of China
	Wu, Yawei; Zhang, Jianxin; Zhang, Bo; Mao, Xiaohong; Lu, Zenglong; Zhou, Guisheng; Teng, Xia; Guo, Qi
发表日期	2024
ISSN	0016-7606
EISSN	1943-2674
起始页码	136
结束页码	5-6
卷号	136 期号:5-6
英文摘要	Transpressional shear zones commonly occur in ancient and modern convergent plate boundaries to accommodate oblique plate convergence. The early Paleozoic Qilian orogen in northeastern Tibet records the subduction of Proto-Tethyan Ocean lithosphere and the accretion -collision of various magmatic arcs and continental terranes. This study focused on the Datong ductile shear zone, which represents the central part of the WNW-ESE-striking ductile shear zone along the northern margin of the Qilian block in the Qilian orogen. This structure bears key information about the evolution of oblique convergence during the early Paleozoic orogeny. The kinematics and timing of the Datong ductile shear zone were investigated via field based, microstructural, and mica 40 Ar/ 39 Ar dating analyses. Mesostructural and micro structural data showed predominantly dextral strike -slip shearing within the Datong ductile shear zone. Microstructural features and quartz c -axis crystallographic preferred orientation patterns indicated that dextral ductile shearing occurred under lower-amphibolite-facies conditions ( ' 500-550 degrees C and ' 5.6 kbar) within the shear zone. Microstructures of quartz showed subgrain rotation (SGR) and grain boundary migration (GBM), suggesting dislocation creep-dominated deformation. A strain rate of 10 - 12 s - and a differential stress of 25-39 MPa were estimated by the rheological flow law and quartz paleopiezometry. Finite strain measurements indicated that all deformed rocks of the Datong ductile shear zone exhibit weakly oblate ellipsoid near the plane strain. Kinematic vorticity (ranging 0.47-0.83) analysis suggested the coexistence of simple shear and pure shear strains within the Datong ductile shear zone, indicating a transpressional setting. Biotite and muscovite 40 Ar/ 39 Ar data showed that transpressional shearing deformation started in the Ordovician (before 453 Ma) and lasted to the Silurian (ca. 430 Ma). Our new data combined with regional geological data show that the deformation type, kinematics, and dynamics of the Datong ductile shear zone were controlled by the southward oblique subduction of the Paleo-Qilian Ocean (Proto-Tethyan Ocean) and the following oblique collision between the Qilian block and the Alxa block. The intensive transpressional deformation along the northern Qilian block may reflect strong coupling between the subducting Paleo-Qilian oceanic slab and the overriding Qilian block as well as a high degree of convergence obliquity during the ongoing early Paleozoic convergence.
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:001234721200001
来源期刊	GEOLOGICAL SOCIETY OF AMERICA BULLETIN
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/292338
作者单位	China Geological Survey; Chinese Academy of Geological Sciences; Institute of Geology, Chinese Academy of Geological Sciences; Ministry of Natural Resources of the People's Republic of China; Peking University
推荐引用方式 GB/T 7714	Wu, Yawei,Zhang, Jianxin,Zhang, Bo,et al. Early Paleozoic oblique convergence from subduction to collision: Insights from timing and structural style of the transpressional dextral shear zone in the Qilian orogen, northern Tibet of China[J],2024,136(5-6).
APA	Wu, Yawei.,Zhang, Jianxin.,Zhang, Bo.,Mao, Xiaohong.,Lu, Zenglong.,...&Guo, Qi.(2024).Early Paleozoic oblique convergence from subduction to collision: Insights from timing and structural style of the transpressional dextral shear zone in the Qilian orogen, northern Tibet of China.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,136(5-6).
MLA	Wu, Yawei,et al."Early Paleozoic oblique convergence from subduction to collision: Insights from timing and structural style of the transpressional dextral shear zone in the Qilian orogen, northern Tibet of China".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 136.5-6(2024).