Petrological, geochemical and chronological constraints for the tectonic setting of the Dongco ophiolite in Tibet

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	Petrological, geochemical and chronological constraints for the tectonic setting of the Dongco ophiolite in Tibet
	Bao, PS (Bao PeiSheng); Xiao, XC (Xiao XuChang); Su, L (Su Li); Wang, J (Wang Jun)
刊名	SCIENCE IN CHINA SERIES D-EARTH SCIENCES
	2007
卷号	50 期号:5 页码:660-671
关键词	Dongco ophiolite geochemistry SHRIMP U-Pb dating for zircon whole-rock dating of Ar-39/Ar-40 Bangong-Nujiang suture zone
ISSN号	1006-9313
英文摘要	The Dongco ophiolite occurred in the middle-western segment of the Bangong-Nujiang suture zone. The thickness of the ophiolite suite is more than 5 km, which is composed, from bottom to top, of the mantle peridotite, mafic-ultramafic cumulates, basic sills (dykes) and basic lava and tectonically emplaced in Jurassic strata (Mugagongru Group). The Dongco cumulates consist of dunitetroctolite-olivine-gabbro, being a part of DTG series of mafic-ultramafic cumulates. The basic lavas are characterized by being rich in alkali (Na2O + K2O), TiO2, P2O5 and a LREE-rich type pattern dipping right with [La/Yb]=6.94-16.6 as well as a trace elements spider-diagram with normal anomaly of Th, Nb, Ta, Hf. Therefore, the Dongco basic lavas belong to ocean-island basalt (0113) and distinctly differ from mid-ocean ridge basalt (MORB) and island-arc basalt (IAB) formed in the plate convergence margin. The basic lavas have higher Sr-87/Sr-86 (0.704363-0.705007), lower Nd-143/Nd-144 (0.512708-0.512887) and epsilon(Nd)(t) from +2.7-+5.8, indicating that they derive from a two-components mixing mantle source of depleted mantle (DM) and enriched mantle (EMI). From above it is ready to see that the Dongco ophiolite forms in oceanic island (OIB) where the mantle source is replaced by a large amount of enriched material, therefore it distinctly differs from these ophiolites formed in island-arc and mid-oecan ridge. Newly obtained SHRIMP U-Pb dating for zircon of the cumulate troctolite is 132 +/- 3 Ma and whole-rock dating of Ar-39/Ar-40 for the basalt is 173.4 +/- 2.7 Ma and 140.9 +/- 2.8 Ma, indicating that the Dongco ophiolite formed at Early Cretaceous and the middle-western segment of the Bangong-Nujiang oceanic basin was still in the developing and evolving period at Early Cretaceous.
学科主题	火成岩岩石学
WOS关键词	BASALTIC VOLCANISM ; NORTH ARCH ; PLUME ; PB ; PETROGENESIS ; MANTLE ; ROCKS ; LAVAS ; PROVINCE ; ORIGIN
WOS研究方向	Geology
语种	英语
出版者	SCIENCE CHINA PRESS
WOS记录号	WOS:000247177900003
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38519]
专题	中国地质调查局
作者单位	Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China China Univ Geol, Expt Ctr, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Bao, PS ,Xiao, XC ,Su, L ,et al. Petrological, geochemical and chronological constraints for the tectonic setting of the Dongco ophiolite in Tibet[J]. SCIENCE IN CHINA SERIES D-EARTH SCIENCES,2007,50(5):660-671.
APA	Bao, PS ,Xiao, XC ,Su, L ,&Wang, J .(2007).Petrological, geochemical and chronological constraints for the tectonic setting of the Dongco ophiolite in Tibet.SCIENCE IN CHINA SERIES D-EARTH SCIENCES,50(5),660-671.
MLA	Bao, PS ,et al."Petrological, geochemical and chronological constraints for the tectonic setting of the Dongco ophiolite in Tibet".SCIENCE IN CHINA SERIES D-EARTH SCIENCES 50.5(2007):660-671.