Early Cretaceous potassic volcanic rocks in the Jiangnan Orogenic Belt, East China: Crustal melting in response to subduction of the Pacific-Izanagi ridge?

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	Early Cretaceous potassic volcanic rocks in the Jiangnan Orogenic Belt, East China: Crustal melting in response to subduction of the Pacific-Izanagi ridge?
	Zhao, Liang; Guo, Feng; Fan, Weiming; Zhang, Qingwen; Wu, Yangming; Li, Jingyan; Yan, Wen
刊名	CHEMICAL GEOLOGY
	2016
卷号	437 页码:30-43
关键词	Potassic lavas Crustal melting Ridge subduction Early Cretaceous Jiangnan Orogenic Belt South China
通讯作者	Guo, F (reprint author), Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China.
中文摘要	Eastern China is characterized by widespread Mesozoic magmatism that was closely related to subduction of the Paleo-Pacific Plate, but the genetic relationship between magmatism and subduction is not always clear. The Jiangnan Orogenic Belt (JOB) is a Neoproterozoic collisional belt between the Yangtze and Cathaysian blocks. Early Cretaceous felsic magmas from the Tianmushan basin in the eastern JOB forma >3000 m thick volcanic sequence erupted within an extremely short period of time (132-130 Ma). These rocks are potassic (K2O=3.86-6.05%) and peraluminous (A/CNK = 1.0-1.23), and are compositionally similar to experimental melts derived from predominantly clay-poor and K-rich metasediments or granodiorites at crustal conditions. They are LILE-and LREE-enriched ((La/Yb)(CN)=9.0-14.6) and display variable Eu anomalies and Nb-Ta depletion. The weakly variable and negative whole-rock epsilon(Nd)(t) (-5.4 to-2.5) and heterogeneous zircon epsilon(Hf)(t) values (-6.7to+3.5) of these rocks are similar to those of basement rocks beneath the JOB, suggesting a genetic relationship with basement. No magmas with clear subduction-related composition occurred at this time in the area and the compositions of the potassic rocks more closely resemble high-temperature melts of extensively thinned crust in continental rift environments. Our data favors a model that the Early Cretaceous potassic magmas formed as subduction of the Pacific-Izanagi ridge resulted in upwelling asthenosphere, providing the high temperatures required to extensively melt the lower-middle crust in the eastern JOB. (C) 2016 Elsevier B.V. All rights reserved.
学科主题	Geochemistry & Geophysics
内容类型	期刊论文
源URL	[http://ir.scsio.ac.cn/handle/344004/15315]
专题	南海海洋研究所_中科院边缘海地质重点实验室
推荐引用方式 GB/T 7714	Zhao, Liang,Guo, Feng,Fan, Weiming,et al. Early Cretaceous potassic volcanic rocks in the Jiangnan Orogenic Belt, East China: Crustal melting in response to subduction of the Pacific-Izanagi ridge?[J]. CHEMICAL GEOLOGY,2016,437:30-43.
APA	Zhao, Liang.,Guo, Feng.,Fan, Weiming.,Zhang, Qingwen.,Wu, Yangming.,...&Yan, Wen.(2016).Early Cretaceous potassic volcanic rocks in the Jiangnan Orogenic Belt, East China: Crustal melting in response to subduction of the Pacific-Izanagi ridge?.CHEMICAL GEOLOGY,437,30-43.
MLA	Zhao, Liang,et al."Early Cretaceous potassic volcanic rocks in the Jiangnan Orogenic Belt, East China: Crustal melting in response to subduction of the Pacific-Izanagi ridge?".CHEMICAL GEOLOGY 437(2016):30-43.