U-Pb zircon geochronology of coesite-bearing eclogites from the southern Dulan area of the North Qaidam UHP terrane, northwestern China  spatially and temporally extensive UHP metamorphism during continental subduction

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	U-Pb zircon geochronology of coesite-bearing eclogites from the southern Dulan area of the North Qaidam UHP terrane, northwestern China spatially and temporally extensive UHP metamorphism during continental subduction
	Zhang, JX (Zhang, J. X.)5; Mattinson, CG (Mattinson, C. G.); Yu, SY (Yu, S. Y.); Li, JP (Li, J. P.); Meng, FC (Meng, F. C.)
刊名	JOURNAL OF METAMORPHIC GEOLOGY
	2010
卷号	28 期号:9 页码:955-978
关键词	coesite-bearing eclogite Dulan area North Qaidam Mountains protolith UHP metamorphism U-Pb geochronology
ISSN号	0263-4929
英文摘要	Coesite-bearing eclogites from > 100 km2 in the southern Dulan area, North Qaidam Mountains (NQM) of western China, contain zircon that records protolith crystallization and ultra high pressure (UHP) metamorphism. Sensitive High-Resolution Ion Microprobe (Mass Spectrometer) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry U-Pb analyses from cathodoluminescence (CL)-dark zircon cores in a coesite-bearing eclogite yield an upper intercept age of 838 +/- 50 Ma, and oscillatory zoned cores in a kyanite-bearing eclogite gave a weighted mean 206Pb/238U age of 832 +/- 20 Ma. These zircon cores yield steep heavy rare earth element (HREE) slopes and negative Eu anomalies that suggest a magmatic origin. Thus, c. 835 Ma is interpreted as the eclogite protolith age. Unzoned CL-grey or -bright zircon and zircon rims from four samples yield weighted mean ages of 430 +/- 4, 438 +/- 2, 446 +/- 10 and 446 +/- 3 Ma, flat HREE patterns without Eu anomalies, and contain inclusions of garnet, omphacite, rutile, phengite and rare coesite. These ages are interpreted to record 16 +/- 5 Myr of UHP metamorphism. These new UHP ages overlap the age range of both eclogite and paragneiss from the northern Dulan area, suggesting that all UHP rock types in the Dulan area belong to the same tectonic unit. Our results are consistent with slow continental subduction, but do not match oceanic subduction and diapiric exhumation UHP model predictions. These new data suggest that, similar to eclogites in other HP/UHP units of the NQM and South Altyn Tagh, protoliths of the eclogites in the Dulan area formed in a continental setting during the Neoproterozoic, and then subducted to mantle depth together with continental materials during the Early Palaeozoic.
学科主题	地质年代学
WOS关键词	ULTRAHIGH-PRESSURE METAMORPHISM ; TRACE-ELEMENT GEOCHEMISTRY ; WESTERN CHINA ; NW CHINA ; GARNET PERIDOTITES ; TIBETAN PLATEAU ; XITIESHAN AREA ; EASTERN CHINA ; TECTONIC SIGNIFICANCE ; GRANITIC GNEISS
WOS研究方向	Geology
语种	英语
出版者	WILEY-BLACKWELL
WOS记录号	WOS:000283728000004
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39179]
专题	中国地质调查局
作者单位	1.[Zhang, J. X. 2.Yu, S. Y. 3.Li, J. P. 4.Meng, F. C.] Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China [Mattinson, C. G.] Cent Washington Univ, Dept Geol Sci, Ellensburg, WA 98926 USA 5.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Zhang, JX ,Mattinson, CG ,Yu, SY ,et al. U-Pb zircon geochronology of coesite-bearing eclogites from the southern Dulan area of the North Qaidam UHP terrane, northwestern China spatially and temporally extensive UHP metamorphism during continental subduction[J]. JOURNAL OF METAMORPHIC GEOLOGY,2010,28(9):955-978.
APA	Zhang, JX ,Mattinson, CG ,Yu, SY ,Li, JP ,&Meng, FC .(2010).U-Pb zircon geochronology of coesite-bearing eclogites from the southern Dulan area of the North Qaidam UHP terrane, northwestern China spatially and temporally extensive UHP metamorphism during continental subduction.JOURNAL OF METAMORPHIC GEOLOGY,28(9),955-978.
MLA	Zhang, JX ,et al."U-Pb zircon geochronology of coesite-bearing eclogites from the southern Dulan area of the North Qaidam UHP terrane, northwestern China spatially and temporally extensive UHP metamorphism during continental subduction".JOURNAL OF METAMORPHIC GEOLOGY 28.9(2010):955-978.