Preservation of ancient Os isotope signatures in the Yungbwa ophiolite (southwestern Tibet) after subduction modification

doi:10.1016/j.jseaes.2011.08.010

	Preservation of ancient Os isotope signatures in the Yungbwa ophiolite (southwestern Tibet) after subduction modification
	Liu, Chuan-Zhou; Wu, Fu-Yuan; Chu, Zhu-Yin; Ji, Wei-Qiang; Yu, Liang-Jun; Li, Ji-Liang
刊名	JOURNAL OF ASIAN EARTH SCIENCES
	2012-07-07
卷号	53 页码:38-50
关键词	Re-Os isotopes Highly siderophile elements The Yungbwa ophiolite Indus-Yarlung Zangbo Suture The Tibetan Plateau
ISSN号	1367-9120
DOI	10.1016/j.jseaes.2011.08.010
文献子类	Article
英文摘要	Both spinel and plagioclase harzburgites from the Yungbwa ophiolite, southwestern Tibet, have been studied for highly siderophile elements (HSEs) and Re-Os isotopes. The spinel harzburgites can be subdivided into low-Cr# and high-Cr# groups, according to the spinel Cr#. The low-Cr# harzburgites have been estimated to experience with ca. 13% degrees of partial melting, whereas the high-Cr# harzburgites have been subjected to 16-18% degrees of melting. Clinopyroxenes in the low-Cr# harzburgites show depleted REE patterns, indicating they have been negligibly modified by melts. In contrast, both high-Cr# and plagioclase harzburgites have been metasomatized to different extents, as evidenced by the variable enrichment of LREE in their clinopyroxenes. Compositions of the metasomatic agents are of affinities to the subduction-related magmas. The low-Cr# harzburgites have equilibrium temperatures higher than both high-Cr# and plagioclase harzburgites. We explain that the low-Cr# harzburgites represent mantle residues after melt extraction at mid-ocean ridge (MOR), whereas both high-Cr# and plagioclase harzburgites were originated from the supra-subduction zone (SSZ) settings. These different types of mantle peridotites were tectonically juxtaposed during the emplacement of the Yungbwa ophiolite. The low-Cr# harzburgites display consistent highly siderophile element (HSE) patterns with suprachondritic Ru/Ir and Pd/Ir ratios, whereas both high-Cr# and plagioclase harzburgites show fractionated HSE patterns. A high-Cr# harzburgite, GHP-86, is strongly depleted in both Pd and Re. The Yungbwa harzburgites have variable Os-187/Os-188 ratios ranging from 0.12228 to 0.12876. Sample GHP-86 has the less radiogenic Os-187/Os-188 ratio, giving a depletion age (T-RD) of similar to 1 Ga. The Re-Os isotope compositions of different types of the Yungbwa harzburgites suggest that their Os-187/Os-188 ratios have not been remarkably modified by subduction-related melts. Furthermore, subduction modification has not erased the ancient Os signatures in the Yungbwa peridotites. The reason is probably because the primary unradiogenic Os in the Yungbwa harzburgites had not been significantly reduced during the metasomatism. The asthenospheric mantle beneath the Neo-Tethys Ocean, from which the Yungbwa ophiolite was derived, had heterogeneous Os isotope compositions and contained some ancient mantle domains. (C) 2011 Elsevier Ltd. All rights reserved.
WOS关键词	ZANGBO SUTURE ZONE ; HIGHLY SIDEROPHILE ELEMENTS ; MID-ATLANTIC RIDGE ; SOUTHERN TIBET ; UPPER-MANTLE ; ABYSSAL PERIDOTITES ; XIGAZE OPHIOLITE ; ORTHO-PYROXENE ; OCEANIC LITHOSPHERE ; 4-PHASE LHERZOLITES
WOS研究方向	Geology
语种	英语
出版者	PERGAMON-ELSEVIER SCIENCE LTD
WOS记录号	WOS:000306246700005
资助机构	National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; National Natural Science Foundation of China(40873024) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130) ; State Key Laboratory of Lithospheric Evolution, IGGCAS(10801130)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/84370]
专题	中国科学院地质与地球物理研究所
通讯作者	Liu, Chuan-Zhou
作者单位	Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Liu, Chuan-Zhou,Wu, Fu-Yuan,Chu, Zhu-Yin,et al. Preservation of ancient Os isotope signatures in the Yungbwa ophiolite (southwestern Tibet) after subduction modification[J]. JOURNAL OF ASIAN EARTH SCIENCES,2012,53:38-50.
APA	Liu, Chuan-Zhou,Wu, Fu-Yuan,Chu, Zhu-Yin,Ji, Wei-Qiang,Yu, Liang-Jun,&Li, Ji-Liang.(2012).Preservation of ancient Os isotope signatures in the Yungbwa ophiolite (southwestern Tibet) after subduction modification.JOURNAL OF ASIAN EARTH SCIENCES,53,38-50.
MLA	Liu, Chuan-Zhou,et al."Preservation of ancient Os isotope signatures in the Yungbwa ophiolite (southwestern Tibet) after subduction modification".JOURNAL OF ASIAN EARTH SCIENCES 53(2012):38-50.