气候变化领域集成服务门户(CCPortal): Eocene supra-subduction zone mafic magmatism in the Sibumasu Block of SW Yunnan: Implications for Neotethyan subduction and India-Asia collision

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DOI	10.1016/j.lithos.2014.08.012
	Eocene supra-subduction zone mafic magmatism in the Sibumasu Block of SW Yunnan: Implications for Neotethyan subduction and India-Asia collision
	Wang, Yuejun; Zhang, Limin; Cawood, Peter A.; Ma, Liyan; Fan, Weiming; Zhang, Aimei; Zhang, Yuzhi; Bi, Xianwu
通讯作者	Wang, YJ (通讯作者)
发表日期	2014
ISSN	0024-4937
EISSN	1872-6143
起始页码	384
结束页码	399
卷号	206
英文摘要	Geochemical and isotopic data for metabasic rocks in NW Yunnan constrain the nature of the mantle source beneath the East Himalayan Syntaxis during the Neotethyan subduction and the timing of initial collision between India and Asia. Our results indicate that these mafic rocks crystallized at 50-55 Ma and were metamorphosed at similar to 39 Ma, contemporaneous with magmatic flare-ups and high-grade metamorphism in South Tibet. The mafic rocks in NW Yunnan are divisible into three groups. Group 1, from Nabang, shows geochemical affinity to a MORB-like source modified by the recycled component with epsilon(Nd)(t) of +5.1 to +9.5 and epsilon(Hf)(t) of +5.1 to +11.6, and resembles back-arc basin basalt. Group 2 is mainly from Jinzhouzhai and Tongbiguan to the east of Group 1, and is marked by high Al2O3, enrichment in LILEs and depletion in HFSEs, along with negative epsilon(Nd)(t) (-1.1 to -5.6) and epsilon(Hf)(t) (-4.6 to -0.9) values. Group 2 is interpreted to have originated from the lithospheric mantle modified by input from a slab-derived component in a continental arc setting. Group 3, from Nanjingli, is located a considerable distance east from Group 1, and exhibits negative epsilon(Nd)(t) (-6.7 to -7.6) and epsilon(Hf)(t) (-7.1 to -2.2), and is inferred to be derived from the Tengchong lithospheric mantle but with limited involvement of a slab-derived component. Overall Nd-Hf isotopic compositions show a sharp decrease from Group 1 to Group 2 and then a more subdued decrease to Group 3, with the three groups corresponding to an overall spatial distribution from west to east. Our results suggest that early Eocene magmatism in NW Yunnan represents the eastward continuation of the Gangdese magmatic belt and that the Neotethyan subduction continued until similar to 50 Ma followed by the India-Asia collision. It is proposed that at least two eastward-dipping subduction zones are involved in the Neotethyan suprasubduction system prior to 55 Ma. The sudden decrease in convergence rate in the early Eocene (55-50 Ma), together with the inferred positive buoyancy of the Tengchong lithosphere, stimulated rollback of down-going slab and induced melting of heterogeneous mantle sources to result in a flare-up in magmatic activity. (C) 2014 Elsevier B.V. All rights reserved.
关键词	ZIRCON U-PB SOUTHERN TIBET IMPLICATIONS STRENGTH ELEMENT ENRICHMENT TECTONIC EVOLUTION GANGDESE BATHOLITH GEOCHEMICAL CHARACTERISTICS AR-40/AR-39 GEOCHRONOLOGY ISOTOPIC CHARACTERISTICS CONTINENTAL COLLISION OPHIOLITE OBDUCTION
英文关键词	Early Eocene mafic rocks; Mantle source; Geochronological and geochemical constrains; Gangdese belt; Neotethyan suprasubduction; NW Yunnan
语种	英语
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
WOS类目	Geochemistry & Geophysics ; Mineralogy
WOS记录号	WOS:000343336100025
来源期刊	LITHOS
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/258398
推荐引用方式 GB/T 7714	Wang, Yuejun,Zhang, Limin,Cawood, Peter A.,et al. Eocene supra-subduction zone mafic magmatism in the Sibumasu Block of SW Yunnan: Implications for Neotethyan subduction and India-Asia collision[J]. 中国科学院青藏高原研究所,2014,206.
APA	Wang, Yuejun.,Zhang, Limin.,Cawood, Peter A..,Ma, Liyan.,Fan, Weiming.,...&Bi, Xianwu.(2014).Eocene supra-subduction zone mafic magmatism in the Sibumasu Block of SW Yunnan: Implications for Neotethyan subduction and India-Asia collision.LITHOS,206.
MLA	Wang, Yuejun,et al."Eocene supra-subduction zone mafic magmatism in the Sibumasu Block of SW Yunnan: Implications for Neotethyan subduction and India-Asia collision".LITHOS 206(2014).