Multiple partial melting events in the Sulu UHP terrane: zircon U-Pb dating of granitic leucosomes within amphibolite and gneiss

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	Multiple partial melting events in the Sulu UHP terrane: zircon U-Pb dating of granitic leucosomes within amphibolite and gneiss
	Liu, FL (Liu, F. L.)3; Robinson, PT (Robinson, P. T.); Liu, PH (Liu, P. H.)
刊名	JOURNAL OF METAMORPHIC GEOLOGY
	2012
卷号	30 期号:8 页码:887-906
关键词	anatectic zircon granitic leucosome mineral inclusions multiple partial melting events REE Sulu UHP terrane U-Pb age
ISSN号	0263-4929
英文摘要	Thin layers and lenses of granitic leucosome are widely distributed within amphibolites, paragneisses and orthogneisses of the Sulu UHP terrane. They are parallel to, or cross-cut, foliations in the host rocks at different scales and show evidence of coalescence and migration to form centimetre- to decimetre-scale segregations. Variously migmatized rocks extend at least 350 km from SW Sulu (Maobei) to NE Sulu (Weihai), in a band at least 50 km wide. A combined study of mineral inclusions, cathoduluminescence (CL) images, UPb LA-ICP-MS dates, and in-situ trace element compositions of zircon provide clear evidence on the nature and timing of partial melting in these UHP rocks. Most zircon from the granitic leucosomes occurs as distinct overgrowths around inherited (igneous or metamorphic) cores or as new, euhedral crystals. The overgrowths and new crystals commonly show perfectly euhedral shapes, have pronounced oscillatory zoning and contain felsic mineral inclusions, such as Kfs + Pl + Qtz +/- Ilm +/- monazite (Mon). In contrast, the inherited igneous or metamorphic cores are rounded or irregular, contain low-P or UHP mineral inclusions and show clear dissolution textures. These data suggest that the new zircon is anatectic in origin and that it grew during partial melting of the UHP rocks. The REE patterns of the anatectic zircon show steep slopes from the HREE to LREE with strongly to moderately negative Eu anomalies (Eu/Eu* = 0.310.72) and pronounced positive Ce anomalies (Ce/Ce* = 6.826.5). Abundant UPb spot analyses of the anatectic zircon reveal two discrete and meaningful ages of partial melting within the Sulu UHP terrane. Anatectic zircon from 12 granitic leucosomes within amphibolites, paragneisses, and orthogneisses from Sulu UHP slices II and III yields consistent mean UPb ages of 219.0 +/- 1.2 to 218.3 +/- 1.6 Ma, 218.8 +/- 2.0 to 217.3 +/- 1.7 Ma and 218.2 +/- 1.4 to 215.0 +/- 1.5 Ma, respectively. In contrast, anatectic zircon from six granitic leucosomes within paragneisses and orthogneisses from Sulu UHP slice III records younger mean UPb ages of 151.9 +/- 1.3 to 151.1 +/- 1.8 Ma and 155.9 +/- 1.8 to 153.7 +/- 1.7 Ma, respectively. These data imply that the Sulu UHP terrane experienced two Mesozoic partial melting events. The first partial melting event (219215 Ma) was probably associated with a Late Triassic granulite facies stage of hot exhumation, whereas the second (156151 Ma) is interpreted as the result of Middle-Late Jurassic extension and thinning of the previously thickened crust of the Sulu UHP terrane. Both partial melting events induced extensive retrograde metamorphism of the eclogites and their country rocks.
学科主题	变质岩岩石学
WOS关键词	PRESSURE METAMORPHIC ROCKS ; QINLING-DABIE OROGEN ; TI-IN-ZIRCON ; EAST-CENTRAL CHINA ; ULTRAHIGH-PRESSURE ; HF ISOTOPE ; GREENLAND CALEDONIDES ; CONTINENTAL COLLISION ; MINERAL INCLUSIONS ; CENTRAL AUSTRALIA
WOS研究方向	Geology
语种	英语
出版者	WILEY-BLACKWELL
WOS记录号	WOS:000308295900007
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39641]
专题	中国地质调查局
作者单位	1.[Liu, F. L. 2.Liu, P. H.] Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China [Robinson, P. T.] Dalhousie Univ, Dept Earth Sci, Halifax, NS, Canada 3.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Liu, FL ,Robinson, PT ,Liu, PH . Multiple partial melting events in the Sulu UHP terrane: zircon U-Pb dating of granitic leucosomes within amphibolite and gneiss[J]. JOURNAL OF METAMORPHIC GEOLOGY,2012,30(8):887-906.
APA	Liu, FL ,Robinson, PT ,&Liu, PH .(2012).Multiple partial melting events in the Sulu UHP terrane: zircon U-Pb dating of granitic leucosomes within amphibolite and gneiss.JOURNAL OF METAMORPHIC GEOLOGY,30(8),887-906.
MLA	Liu, FL ,et al."Multiple partial melting events in the Sulu UHP terrane: zircon U-Pb dating of granitic leucosomes within amphibolite and gneiss".JOURNAL OF METAMORPHIC GEOLOGY 30.8(2012):887-906.