Tracing the protolith, UHP metamorphism, and exhumation ages of;orthogneiss from the SW Sulu terrane (eastern China): SHRIMP U-Pb dating;of mineral inclusion-bearing zircons

doi:10.1016/j.lithos.2004.08.001

	Tracing the protolith, UHP metamorphism, and exhumation ages of;orthogneiss from the SW Sulu terrane (eastern China): SHRIMP U-Pb dating;of mineral inclusion-bearing zircons
	Liu, FL; Xu, ZQ; Xue, HM
刊名	LITHOS
	2004
卷号	78 期号:4 页码:411-429
关键词	orthogneiss mineral inclusion in zircon UHP metamorphism SHRIMP U-Pb dating Chinese Continental Scientific Drilling Project
ISSN号	0024-4937
DOI	10.1016/j.lithos.2004.08.001
英文摘要	Orthogneisses are the major country rocks hosting eclogites in the Sulu UHP terrane, eastern China. All of the analyzed orthogneiss cores from the main drilling hole of the Chinese Continental Scientific Drilting Project (CCSD-MH) have similar major and trace element compositions and a granite protolith. These rocks have relatively high LREE/HREE ratios, strong negative Eu anomalies (Eu/Eu=0.20-0.39), and negative Ba anomalies (Ba/Ba=0.25-0.64). Coesite and coesite-bearing UHP mineral assemblages are common inclusions in zircons separated from orthogneiss, paragneiss, amphibolite, and (retrograded) eclogite of the CCSD-MH. This suggests that the eclogite, together with its country rocks, experienced in situ ultrahigh-pressure (UHP) metamorphism. Laser Raman spectroscopy and cathodoluminescence (CL) images show that zircons from the orthogneisses are zoned and that they have distinct mineral inclusions in the different zones. Most zircons retain early magmatic cores with abundant low-pressure mineral inclusions, which are mantled with metamorphic zircon-containing inclusions of coesite and other UHP minerals. The outermost rims on these grains contain low-pressure mineral inclusions, such as quartz and albite. SHRIMP U-Pb dating of the zoned zircons gives three discrete and meaningful groups of ages: Proterozoic ages for the protolith, 227+/-2 Ma for the coesite-bearing mantles, and 209+/-3 Ma for the amphibolite facies retrograde rims. The widespread occurrence of UHP mineral inclusions in zircons from the Sulu metamorphic belt dated at about 227 Ma suggests that voluminous continental crust experienced late Triassic subduction to depths of at least 120 km and perhaps more than 200 km. Eighteen million years later, the terrane was rapidly exhumed to midcrustal levels, and the UHP rocks were overprinted by amphibolite facies metamorphism. The exhumation rate deduced from the zircon age data and previously obtained metamorphic P-T data is estimated to be 5.6-11.0 km/Ma. Such rapid exhumation of the Sulu UHP terrane may be due to the buoyancy forces produced by subduction of low-density continental material into the deep mantle. (C) 2004 Elsevier B.V. All rights reserved.
学科主题	变质岩岩石学
WOS关键词	ULTRAHIGH-PRESSURE METAMORPHISM ; JIANGSU-PROVINCE ; LU TERRANE ; DABIE ; MOUNTAINS ; ISOTOPE GEOCHEMISTRY ; QINGLONGSHAN OXYGEN ; GARNET ; PERIDOTITES ; ULTRAMAFIC ROCKS ; KOKCHETAV MASSIF ; YANGTZE CRATONS
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000225181700005
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/37735]
专题	中国地质科学院地质研究所
作者单位	Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China.
推荐引用方式 GB/T 7714	Liu, FL,Xu, ZQ,Xue, HM. Tracing the protolith, UHP metamorphism, and exhumation ages of;orthogneiss from the SW Sulu terrane (eastern China): SHRIMP U-Pb dating;of mineral inclusion-bearing zircons[J]. LITHOS,2004,78(4):411-429.
APA	Liu, FL,Xu, ZQ,&Xue, HM.(2004).Tracing the protolith, UHP metamorphism, and exhumation ages of;orthogneiss from the SW Sulu terrane (eastern China): SHRIMP U-Pb dating;of mineral inclusion-bearing zircons.LITHOS,78(4),411-429.
MLA	Liu, FL,et al."Tracing the protolith, UHP metamorphism, and exhumation ages of;orthogneiss from the SW Sulu terrane (eastern China): SHRIMP U-Pb dating;of mineral inclusion-bearing zircons".LITHOS 78.4(2004):411-429.