Heterogeneity of a plume axis: Bulk-rock geochemical evidence from;picrites and basalts in the Emei large igneous province, southwest China

	Heterogeneity of a plume axis: Bulk-rock geochemical evidence from;picrites and basalts in the Emei large igneous province, southwest China
	Hou Zengqian 3; Lu Jiren ; Lin Shengzhong
刊名	INTERNATIONAL GEOLOGY REVIEW
	2006
卷号	48 期号:12 页码:1087-1112
ISSN号	0020-6814
英文摘要	In order to document the chemical characteristics of sources of a continental flood basalt (CFB) and to understand its origin, we studied four typical picrite-basalt flows and three picritic intrusions in the Emeishan picrite-cluster field (5 x 10(4) 1112 area), located in the southwestern part of the Ernei large igneous province. Major and trace elements, and Sr-Nd-Pb isotopic compositions, are reported for picrites and associated basalts in the picrite-cluster field, regarded as the axial area of the Emei mantle Plume. These rocks exhibit a range of MgO contents (4.2-27.2%), variable degrees of LREE enrichment (La-N/Yb-N = 2.7-29.0), and heterogeneous isotopic ratios (epsilon(Nd(t)) = 4.84 to -4.00; initial Sr-87/Sr-86 = 0.7023-0.7064; Pb-206/Pb-204) = 18.034-20.641). Nd, Sr, and Pb isotopic covariations are similar to at least three groups of the picrites and basalts. Ontong Java-like lavas yielded low (Sr-87/86Sr), (< 0.7045) high epsilon(Nd(t)) (> 2.5), and the lowest (Ce/Yb)(N) (similar to 4), La/Sm (similar to 3), Th/Nb (similar to 0.75), La/Nb (similar to 0.85), and Ba/Nb (similar to 8) ratios, suggesting a focus zone (FOZO)-like mantle source. Cook-Austral-like lavas have high Pb-206/Pb-204 (> 19.0) low (Sr-87/Sr-86)(i) (< 0.7045), and high Sm/Yb (> 4), Nb/Y (> 1) and Zr/Y (> 8), simular to the HIMU component. Heard-like lavas yielded high (Sr-87/Sr-86)(i) (0.7044 similar to 0.7060), low epsilon(Nd(t)) (1.7 to -3.0), Pb-206/Pb-204 (18.75-1.8.03) and Pb-208/Pb-204 (37.8-39.0), and high (Ce/Yb)(N) (> 10) Ba/Nb (> 30). and Tb/Nb (> 0.1), which might be explained by mixing of picritic magmas from the plume with lamproitic melt from continental lithospheric mantle. Three samples outside the three groups have Sr-Nd isotopic signatures similar to EM 1, and high Th/Nb (> 0.2). La/Nb (> 1.5). and low Nb/U (< 25), suggesting a pelagic sediment source component. The picritic intrusives have low epsilon(Nd(t)) (0.32-0.59), intermediate (Sr-87/Sr-86)(i) (0.7037-0.7042), very high Th/Nb (0.11-0.20). and low Nb/U (< 25), implying minor crustal assimilation. The trace elements and Sr-Nd-Pb isotope geochemistry of the Emei picrites and associated basalts reflect processes involving: (1) partial inciting of a heterogeneous, eclogite-bearing Source to produce picritic magmas; then (2) mixing with small amounts of melt from the continental lithospheric mantle; and (3) crustal assimilation during picritic magma ascent. The heterogeneity of this source is related to recycling of subducted oceanic crust and associated sediments into the deep upper mantle.
学科主题	火成岩岩石学
WOS关键词	CONTINENTAL FLOOD BASALTS ; PERMIAN-TRIASSIC BOUNDARY ; SOUTHERN ; INDIAN-OCEAN ; PB-ISOTOPE EVIDENCE ; MANTLE PLUMES ; ISLAND BASALTS ; TRACE-ELEMENT ; KERGUELEN ARCHIPELAGO ; MAJOR-ELEMENT ; SIBERIAN TRAP
WOS研究方向	Geology
语种	英语
出版者	V H WINSTON & SON INC
WOS记录号	WOS:000242519700003
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38314]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China. 2.Chinese Acad Geol Sci, Inst Mineral Resources, Beijing 100037, Peoples R China. 3.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Hou Zengqian,Lu Jiren,Lin Shengzhong. Heterogeneity of a plume axis: Bulk-rock geochemical evidence from;picrites and basalts in the Emei large igneous province, southwest China[J]. INTERNATIONAL GEOLOGY REVIEW,2006,48(12):1087-1112.
APA	Hou Zengqian,Lu Jiren,&Lin Shengzhong.(2006).Heterogeneity of a plume axis: Bulk-rock geochemical evidence from;picrites and basalts in the Emei large igneous province, southwest China.INTERNATIONAL GEOLOGY REVIEW,48(12),1087-1112.
MLA	Hou Zengqian,et al."Heterogeneity of a plume axis: Bulk-rock geochemical evidence from;picrites and basalts in the Emei large igneous province, southwest China".INTERNATIONAL GEOLOGY REVIEW 48.12(2006):1087-1112.