Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision

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	Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision
	Song, Shuguang ; Niu, Yaoling ; Su, Li ; Wei, Chunjing ; Zhang, Lifei
刊名	GEOCHIMICA ET COSMOCHIMICA ACTA
	2014
卷号	130 页码:42-62
通讯作者	Song, SG (reprint author), Peking Univ, Sch Earth & Space Sci, MOE Key Lab Orogen Belts & Crustal Evolut, Beijing 100871, Peoples R China.
英文摘要	Modern adakite or adakitic rocks are thought to result from partial melting of younger and thus warmer subducting ocean crust in subduction zones, with the melt interacting with or without mantle wedge peridotite during ascent, or from melting of thickened mafic lower crust. Here we show that adakitic (tonalitic-trondhjemitic) melts can also be produced by eclogite decompression during exhumation of subducted and metamorphosed oceanic/continental crust in response to continental collision, as exemplified by the adakitic rocks genetically associated with the early Paleozoic North Qaidam ultra-high pressure metamorphic (UHPM) belt on the northern margin of the Greater Tibetan Plateau. We present field evidence for partial melting of eclogite and its products, including adakitic melt, volumetrically significant plutons evolved from the melt, cumulate rocks precipitated from the melt, and associated granulitic residues. This "adakitic assemblage" records a clear progression from eclogite decompression and heating to partial melting, to melt fractionation and ascent/percolation in response to exhumation of the UHPM package. The garnetite and garnet-rich layers in the adakitic assemblage are of cumulate origin from the adakitic melt at high pressure, and accommodate much of the Nb-Ta-Ti. Zircon SHRIMP U-Pb dating shows that partial melting of the eclogite took place at similar to 435-410 Ma, which postdates the seafloor subduction (>440 Ma) and temporally overlaps the UHPM (similar to 440-425 Ma). While the geological context and the timing of adakite melt formation we observe differ from the prevailing models, our observations and documentations demonstrate that eclogite melting during UHPM exhumation may be important in contributing to crustal growth. (C) 2014 Elsevier Ltd. All rights reserved.
学科主题	Geochemistry & Geophysics
收录类别	SCI
语种	英语
WOS记录号	WOS:000332405700004
公开日期	2015-06-11
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/23791]
专题	海洋研究所_海洋地质与环境重点实验室
推荐引用方式 GB/T 7714	Song, Shuguang,Niu, Yaoling,Su, Li,et al. Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2014,130:42-62.
APA	Song, Shuguang,Niu, Yaoling,Su, Li,Wei, Chunjing,&Zhang, Lifei.(2014).Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision.GEOCHIMICA ET COSMOCHIMICA ACTA,130,42-62.
MLA	Song, Shuguang,et al."Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision".GEOCHIMICA ET COSMOCHIMICA ACTA 130(2014):42-62.