Unique coesite-bearing zircon from allanite-bearing gneisses: U-Pb, REE and Lu-Hf properties and implications for the evolution of the Sulu UHP terrane, China

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	Unique coesite-bearing zircon from allanite-bearing gneisses: U-Pb, REE and Lu-Hf properties and implications for the evolution of the Sulu UHP terrane, China
	Liu, FL (Liu, Fulai); Gerdes, A (Gerdes, Axel); Liou, J (Liou, Jahnguang); Liu, PH (Liu, Pinghua)
刊名	EUROPEAN JOURNAL OF MINERALOGY
	2009
卷号	21 期号:6 页码:1225-1250
关键词	coesite allanite zircon U-Pb dating REE Hf isotope gneiss Sulu UHP terrane
ISSN号	0935-1221
英文摘要	Zircon from allanite-bearing para- and ortho-gneisses provides a unique insight into the geologic evolution of the Sulu ultrahigh-pressure (UHP) terrine in eastern China. Laser Raman, cathodoluminescence (CL) imaging combined with trace-element, U-Pb, and Lu-Hf isotope data indicate that zircon grains consist of three distinct zones. Inherited magmatic core records a Neoproterozoic protolith age, the coesite-bearing mantle reveals a UHP metamorphic age of 230 +/- 7 Ma, and the low-P mineral-bearing rim retains an age of 210 +/- 3 Ma for the amphibolite-facies retrogression. Positive epsilon Hf(t) values for the inherited cores reflect involvement of juvenile materials in the protolith. Low (176)Lu/(177)Hf ratios of coesite-bearing mantles indicate their formation during / after garnet crystallization. Their (176)Hf/(177)Hf ratios are homogenous and more radiogenic than those of the inherited cores, implying fractionation of the Lu-Hf system during isotope equilibration within the metamorphic mineral assemblage. Moreover, coesite-bearing mantles show geochemical characteristics that are distinctly different from those of previous studies (1) The chondrite-normalized pattern shows a steep slope from HREE (heavy rare earth elements) to LREE (light rare earth elements) with a moderately negative Eu anomaly (mean Eu/Eu* = 0.53). Such a pattern requires that phases enriched in LREE (e.g., allanite) and europium (e.g., K-feldspar) were stable during UHP conditions. (2) The positive Cc anomaly is very pronounced (Ce/Ce* of 612-657), e.g., about seven to eight times higher than that of the inherited core; (3) The uranium content is very low (6-25 ppm) and the Th/U ratio elevated (0.52-2.83). These data for the coesite-bearing mantle are distinctly different from those of previous studies We interpret the data to suggest high O fugacity during the UHP and retrograde metamorphic evolution, which also played a critical role in restraining diamond growth in Sulu-Dabie UHP rocks.
学科主题	变质岩岩石学
WOS关键词	PRESSURE METAMORPHIC ROCKS ; EAST-CENTRAL CHINA ; SUBDUCTED CONTINENTAL-CRUST ; SCIENTIFIC-DRILLING PROJECT ; DORA-MAIRA MASSIF ; STABLE-ISOTOPE GEOCHEMISTRY ; BROSSASCO-ISASCA UNIT ; QINLING-DABIE OROGEN ; ULTRAHIGH-PRESSURE ; ECLOGITE-FACIES
WOS研究方向	Mineralogy
语种	英语
出版者	E SCHWEIZERBARTSCHE VERLAGS
WOS记录号	WOS:000274438400010
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38940]
专题	中国地质调查局
作者单位	Stanford Univ, Dept Geol & Environm Sci, Stanford, CA 94305 USA
推荐引用方式 GB/T 7714	Liu, FL ,Gerdes, A ,Liou, J ,et al. Unique coesite-bearing zircon from allanite-bearing gneisses: U-Pb, REE and Lu-Hf properties and implications for the evolution of the Sulu UHP terrane, China[J]. EUROPEAN JOURNAL OF MINERALOGY,2009,21(6):1225-1250.
APA	Liu, FL ,Gerdes, A ,Liou, J ,&Liu, PH .(2009).Unique coesite-bearing zircon from allanite-bearing gneisses: U-Pb, REE and Lu-Hf properties and implications for the evolution of the Sulu UHP terrane, China.EUROPEAN JOURNAL OF MINERALOGY,21(6),1225-1250.
MLA	Liu, FL ,et al."Unique coesite-bearing zircon from allanite-bearing gneisses: U-Pb, REE and Lu-Hf properties and implications for the evolution of the Sulu UHP terrane, China".EUROPEAN JOURNAL OF MINERALOGY 21.6(2009):1225-1250.