Re-Os isotopes of Dali picrite (Yunnan): New constraints on the formation of Emeishan Large Igneous Province

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	Re-Os isotopes of Dali picrite (Yunnan): New constraints on the formation of Emeishan Large Igneous Province
	Hao, YL (Hao YanLi); Huang, QS (Huang QiShuai); Zhang, XR (Zhang XiaoRan); Shi, RD (Shi RenDeng)
刊名	ACTA PETROLOGICA SINICA
	2011
卷号	27 期号:10 页码:2937-2946
关键词	Picrite Interaction of crust-mantle Re-Os isotopes Emeishan Large igneous Province Dali
ISSN号	1000-0569
英文摘要	Dali picrite in Yunnan Province occurs at the bottom of Emeishan basalt in the inner zone of Emeishan Large Igneous Province (ELIP). The picrite is highly porphyritic with 20% similar to 40% euhedral-subhedral olivine and clinopyroxenite phenocrysts, and the groundmass with diabasic texture is composed of microcrystalline olivine, clinopyroxenite and plagioclase with minor spinel. SiO(2) content of most picrites ranges from 45. 94% to 46. 37%, lower than 47%, except for one sample, whose SiO(2) content is up to 47. 35%. In all picrite samples, MgO is higher than 18%, varying between 19. 01% and 23. 77%, and total NO(2)O + K(2)O is lower than 2%, ranging narrowly from 1. 52% to 1. 97%, which indicates the features of typical picrites. Whole-rock Re content shows a narrow range from 0. 349 x 10(-9) to 0. 424 x 10(-9) while Os has a wide range from 0. 889 x 10(-9) to 4. 276 x 10(-9); in addition, the whole-rock (187)Re/(188)Os and (187)Os/(188)Os ratios vary from 0.437 +/- 0.012 to 2. 708 +/- 0.025 and from 0. 1283 +/- 0.0002 to 0. 1354 +/- 0.0004, respectively. The estimated (187)Os/(188)Os ratios of the matrix range from 0. 1380 to 0. 1415 by the Mass Balance Calculation. By contrast, all Re (0. 030 x 10(-9) similar to 0. 049 x 10(-9)) and Os (0. 625 x 10(-9) similar to 0. 757 x 10(-9)) values of the olivines separated from the picrites are lower than those of whole-rock data, and the (187)Os/(188)Os ratio of the olivines ranges from 0. 1254 +/- 0. 0005 to 0. 1268 +/- 0. 0005, lower than that of the whole-rock. The spinel separated from the picrites has the highest Os content up to 80. 6 x 10(-9) and the lowest (187)Os/(188)Os ratio down to 0. 1252 +/- 0. 0003. Compared with features of the Primitive Upper Mantle (PUM), the matrix Re-Os isotopes have the crust lava affinity, while the olivine and spinel show residual mantle features. gamma Os values of the separated minerals (olivine and spinel) are between - 2. 01 and - 2. 59, indicating that the rock-forming materials might have originated from the depleted sources instead of from such rich or fertile areas as the boundary of the core-mantle, while the gamma Os values of whole-rock vary from -1. 11 to -3.24, obviously the mixing result of olivine, spinel and matrix. It is inferred that the formation of ELIP should be attributed to the interaction between the crust and the mantle.
学科主题	火成岩岩石学
WOS关键词	PERMIAN-TRIASSIC BOUNDARY ; FLOOD-BASALT PROVINCE ; LITHOSPHERIC MANTLE ; ABYSSAL PERIDOTITES ; YANGTZE PLATFORM ; SW CHINA ; GEOCHEMISTRY ; SYSTEMATICS ; INSIGHTS ; ORIGIN
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000296655800013
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39415]
专题	中国地质调查局
作者单位	Chinese Acad Sci, Inst Tibetan Plateau Res, Beijing 100085, Peoples R China
推荐引用方式 GB/T 7714	Hao, YL ,Huang, QS ,Zhang, XR ,et al. Re-Os isotopes of Dali picrite (Yunnan): New constraints on the formation of Emeishan Large Igneous Province[J]. ACTA PETROLOGICA SINICA,2011,27(10):2937-2946.
APA	Hao, YL ,Huang, QS ,Zhang, XR ,&Shi, RD .(2011).Re-Os isotopes of Dali picrite (Yunnan): New constraints on the formation of Emeishan Large Igneous Province.ACTA PETROLOGICA SINICA,27(10),2937-2946.
MLA	Hao, YL ,et al."Re-Os isotopes of Dali picrite (Yunnan): New constraints on the formation of Emeishan Large Igneous Province".ACTA PETROLOGICA SINICA 27.10(2011):2937-2946.