Zircon U-Pb age and O isotope evidence for Neoproterozoic low-(18)O magmatism during supercontinental rifting in South China: Implications for the snowball Earth event

doi:10.2475/04.2008.04

	Zircon U-Pb age and O isotope evidence for Neoproterozoic low-(18)O magmatism during supercontinental rifting in South China: Implications for the snowball Earth event
	Zheng, Y. F.1; Gong, B.1; Zhao, Z. F.1; Wu, Y. B.2; Chen, F. K.3
刊名	AMERICAN JOURNAL OF SCIENCE
	2008-04-01
卷号	308 期号:4 页码:484-516
ISSN号	0002-9599
DOI	10.2475/04.2008.04
文献子类	Review
英文摘要	Identification of Neoproterozoic low delta(18)O igneous rocks is a key to demonstrate that high-T water-rock interaction and low-(18)O magmatism in rift tectonic zones can serve as an efficient interface to transport heat and material from the Earth's interior to exterior at the onset of the snowball Earth event. Low delta(18)O values of - 10.9 to +4.4 permil characteristic of meteoric origin were observed, on an areal extent over 30,000 km(2), for mid-Neoproterozoic metaigneous zircons from the ultrahigh-pressure eclogite-facies metamorphic belt of Triassic ages along the Dabie-Sulu orogenic belt, China. Although the zircon O isotope system could be reset to acquire its low delta(18)O values by exchange with matrix minerals during "wet" eclogite-facies metamorphism, the abnormal (18)O depletion is confirmed by occurrence of Neoproterozoic low delta(18)O zircons in low-grade metaigneous rocks in the same belt. Cathodoluminscence imaging of zircons from low-grade metagranitoid and metavolcanic rocks shows preservation of the internal structures of oscillatory zoning typical of magmatic origin. Hornblende from two granites of low delta(18)O zircons gave Ar-Ar plateau ages of 747 +/- 6 and 776 +/- 12 Ma, ruling out that Phanerozoic metamorphism effected mineral 0 isotope values. Two groups of U-Pb ages were measured at 756 +/- 5 Ma and 782 +/- 5 Ma, respectively, for the low delta(18)O zircons. This indicates that low delta(18)O zircons crystallized during two episodes of low-(18)O magmatism in response to tectonic evolution from supercontinental rifting at similar to 780 Ma to breakup at similar to 750 Ma. The second episode of low-(18)O magmatism is contemporaneous with the continental Kaigas iceage. A plate-rift model is advanced to account for the tectonic connection between the low-(18)O magmatism, the continental glaciation and the supercontinental. rifting during the Cryogenian period. High-T meteoric water-rock interaction occurred prior to low-(18)O magmatism in rift tectonic zones, and caldera collapse was responsible for melting of hydrothermally altered low delta(18)O rocks during rifting of the South China Block from the Rodinia supercontinent.
WOS关键词	PRESSURE METAMORPHIC ROCKS ; EAST-CENTRAL CHINA ; LOW DELTA-O-18 GRANITES ; NORTHERN VOLCANIC ZONE ; OXYGEN-ISOTOPE ; DABIE MOUNTAINS ; SULU OROGEN ; CONTINENTAL-CRUST ; YANGTZE BLOCK ; LOW-DELTA-O-18 RHYOLITES
WOS研究方向	Geology
语种	英语
出版者	AMER JOURNAL SCIENCE
WOS记录号	WOS:000258131900004
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/69744]
专题	中国科学院地质与地球物理研究所
通讯作者	Zheng, Y. F.
作者单位	1.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China 2.China Univ Geosci, Fac Earth Sci, State Key Lab Geol Proc & Mineral Resources, Wuhan 430074, Peoples R China 3.Chinese Acad Sci, Inst Geol & Geophys, State Kay Lab Lithosphere Evolut, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Zheng, Y. F.,Gong, B.,Zhao, Z. F.,et al. Zircon U-Pb age and O isotope evidence for Neoproterozoic low-(18)O magmatism during supercontinental rifting in South China: Implications for the snowball Earth event[J]. AMERICAN JOURNAL OF SCIENCE,2008,308(4):484-516.
APA	Zheng, Y. F.,Gong, B.,Zhao, Z. F.,Wu, Y. B.,&Chen, F. K..(2008).Zircon U-Pb age and O isotope evidence for Neoproterozoic low-(18)O magmatism during supercontinental rifting in South China: Implications for the snowball Earth event.AMERICAN JOURNAL OF SCIENCE,308(4),484-516.
MLA	Zheng, Y. F.,et al."Zircon U-Pb age and O isotope evidence for Neoproterozoic low-(18)O magmatism during supercontinental rifting in South China: Implications for the snowball Earth event".AMERICAN JOURNAL OF SCIENCE 308.4(2008):484-516.