Petrogenesis and tectonic significance of the late Triassic mafic dikes and felsic volcanic rocks in the East Kunlun Orogenic Belt, Northern Tibet Plateau

CORC > 海洋研究所 > 中国科学院海洋研究所 > 海洋地质与环境重点实验室

	Petrogenesis and tectonic significance of the late Triassic mafic dikes and felsic volcanic rocks in the East Kunlun Orogenic Belt, Northern Tibet Plateau
	Hu, Yan1 ; Niu, Yaoling 1,2,3; Li, Jiyong1 ; Ye, Lei 4; Kong, Juanjuan 1; Chen, Shuo 1; Zhang, Yu 4; Zhang, Guorui 4
刊名	LITHOS
	2016-02-15
卷号	245 页码:205-222
关键词	Alkaline mafic dikes Felsic volcanic rocks Subcontinental lithospheric mantle Crustal anatexis Post-collision East Kunlun Orogenic Belt
英文摘要	We present zircon U-Pb ages and geochemical data on the late Triassic mafic dikes (diabase) and felsic volcanic rocks (rhyolite and rhyolitic tuffs) in the East Kunlun Orogenic Belt (EKOB). These rocks give a small age window of 228-218 Ma. The mafic dikes represent evolved alkaline basaltic melts intruding similar to 8-9 Myrs older and volumetrically more abundant A-type granite batholith. Their rare earth element (REE) and multi-element patterns are similar to those of the present-day ocean island basalts (OIBs) except for a weak continental crustal signature (i.e., enrichment of Rb and Pb and weak depletion of Nb, Ta and Ti). Their trace element characteristics together with the high Sr-87/Sr-86 (0.7076-0.7104), low epsilon(Nd(t)) (-2.18 to 3.46), low epsilon(Hf(t)) (-2.85 to -4.59) and variable Pb isotopic ratios are consistent with melts derived from metasomatized subcontinental lithospheric mantle with crustal contamination. The felsic volcanic rocks are characterized by high LREE/HREE (e.g., [La/YI](N) of 5.71-17.00) with a negative Eu anomaly and strong depletion in Sr and P, resembling the model upper continental crust (UCC). Given the high Sr-87/Sr-86 (0.7213-0.7550) and less negative epsilon(Nd(t)) (-3.83 to -5.09) and epsilon(Hf(t)) (-3.06 to -3.83) than the UCC plus the overlapping isotopes with the mafic dikes and high Nb-Ta rhyolites, the felsic volcanic rocks are best interpreted as resulting from melting-induced mixing with 45-50% crustal materials and 50-55% mantle-derived mafic melts probably parental to the mafic dikes. Such mantle-derived melts underplated and intruded the deep crust as juvenile crustal materials. Partial melting of such juvenile crust produced felsic melts parental to the felsic volcanic rocks in the EKOB. We hypothesize that the late Triassic mafic dikes and felsic volcanic rocks are associated with post-collisional extension and related orogenic collapse. Such processes are probably significant in causing asthenospheric upwelling, decompression melting, induced melting of the prior metasomatized mantle lithosphere and the existing crust. This work represents our ongoing effort in understanding the origin of the juvenile crust and continental crustal accretion through magmatism in the broad context of orogenesis from seafloor subduction to continental collision and to post-collisional processes. (C) 2015 Elsevier B.V. All rights reserved.
收录类别	SCI
语种	英语
WOS记录号	WOS:000371945200016
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/126204]
专题	海洋研究所_海洋地质与环境重点实验室
作者单位	1.Chinese Acad Sci, Inst Oceanol, 7 Nanhai Rd, Qingdao 266071, Peoples R China 2.Univ Durham, Dept Earth Sci, Durham DH11 3LE, England 3.China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China 4.Lanzhou Univ, Sch Earth Sci, Lanzhou 730000, Peoples R China
推荐引用方式 GB/T 7714	Hu, Yan,Niu, Yaoling,Li, Jiyong,et al. Petrogenesis and tectonic significance of the late Triassic mafic dikes and felsic volcanic rocks in the East Kunlun Orogenic Belt, Northern Tibet Plateau[J]. LITHOS,2016,245:205-222.
APA	Hu, Yan.,Niu, Yaoling.,Li, Jiyong.,Ye, Lei.,Kong, Juanjuan.,...&Zhang, Guorui.(2016).Petrogenesis and tectonic significance of the late Triassic mafic dikes and felsic volcanic rocks in the East Kunlun Orogenic Belt, Northern Tibet Plateau.LITHOS,245,205-222.
MLA	Hu, Yan,et al."Petrogenesis and tectonic significance of the late Triassic mafic dikes and felsic volcanic rocks in the East Kunlun Orogenic Belt, Northern Tibet Plateau".LITHOS 245(2016):205-222.