气候变化领域集成服务门户(CCPortal): Tectonic transition from oceanic subduction to continental collision: New geochemical evidence from Early-Middle Triassic mafic igneous rocks in southern Liaodong Peninsula, east-central China

CCPortal

DOI	10.1130/B35278.1
	Tectonic transition from oceanic subduction to continental collision: New geochemical evidence from Early-Middle Triassic mafic igneous rocks in southern Liaodong Peninsula, east-central China
	Fang W.; Dai L.-Q.; Zheng Y.-F.; Zhao Z.-F.; Ma L.-T.
发表日期	2020
ISSN	167606
起始页码	1469
结束页码	1488
卷号	132 期号:2021-07-08
英文摘要	In contrast to the widespread occurrence of mafic arc magmatism during oceanic subduction, there is a general lack of such magmatism during continental subduction. This paradigm is challenged by the discovery of Early-Middle Triassic mafic igneous rocks from the southeastern margin of the North China Block (NCB), which was subducted by the South China Block (SCB) during the Triassic. Zircon U-Pb dating for these mafic rocks yields 247 ± 2-244 ± 5 Ma for their emplacement, coeval with the initial collision between the two continental blocks. These Triassic mafic rocks generally exhibit ocean island basalt (OIB)-like trace element distribution patterns, intermediate (87Sr/86Sr)i ratios of 0.7057-0.7091, weakly negative εNd(t) values of-1.2 to-3.8, and εHf(t) values of-1.3 to-3.2. Such geochemical features indicate origination from a metasomatic mantle source with involvement of felsic melts derived from dehydration melting of the previously subducting Paleo-Tethyan oceanic crust. The syn-magmatic zircons of Triassic age show variable Hf-O isotopic compositions, indicating that the crustal component was composed of both altered basaltic oceanic crust and terrigenous sediment. High Fe/Mn and Zn/Fe ratios suggest that the mantle source would mainly consist of ultramafic pyroxenites. The melt-mobile incompatible trace elements were further fractionated relative to melt-immobile trace elements during partial melting of these pyroxenites, giving rise to basaltic melts with OIB-like geochemical signatures. The mafic magmatism may be caused by tectonic extension due to rollback of the subducting Paleo-Tethyan oceanic slab in response to the initial collision of the NCB and SCB in the Early Triassic. Therefore, the syn-subduction mafic magmatism provides new geochemical evidence for tectonic transition from oceanic subduction to continental collision in east-central China. © 2019 Geological Society of America.
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/184763
作者单位	CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; Center of Excellence in Comparative Planetology, Chinese Academy of Sciences (CAS), Hefei, 230026, China
推荐引用方式 GB/T 7714	Fang W.,Dai L.-Q.,Zheng Y.-F.,et al. Tectonic transition from oceanic subduction to continental collision: New geochemical evidence from Early-Middle Triassic mafic igneous rocks in southern Liaodong Peninsula, east-central China[J],2020,132(2021-07-08).
APA	Fang W.,Dai L.-Q.,Zheng Y.-F.,Zhao Z.-F.,&Ma L.-T..(2020).Tectonic transition from oceanic subduction to continental collision: New geochemical evidence from Early-Middle Triassic mafic igneous rocks in southern Liaodong Peninsula, east-central China.Bulletin of the Geological Society of America,132(2021-07-08).
MLA	Fang W.,et al."Tectonic transition from oceanic subduction to continental collision: New geochemical evidence from Early-Middle Triassic mafic igneous rocks in southern Liaodong Peninsula, east-central China".Bulletin of the Geological Society of America 132.2021-07-08(2020).