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Constraining late stage melt-peridotite interaction in the lithospheric mantle of southern Ethiopia: evidence from lithium elemental and isotopic compositions

文献类型：期刊论文

作者Alemayehu, Melesse1,2; Zhang, Hong-Fu1,3; Seitz, Hans-Michael4
刊名MINERALOGY AND PETROLOGY
出版日期2017-10-01
卷号111期号:5页码:777-792
关键词Dillo-Megado Mantle xenoliths Li isotope Melt-peridotite interaction
ISSN号0930-0708
DOI10.1007/s00710-017-0499-x
文献子类Article
英文摘要Lithium (Li) elemental and isotopic compositions for mineral separates of coexisting olivine, orthopyroxene and clinopyroxene of mantle xenoliths from the Quaternary volcanic rocks of southern Ethiopian rift (Dillo and Megado) reveal the influence of late stage melt-peridotite interaction on the early depleted and variably metasomatized lithospheric mantle. Two types of lherzolites are reported (LREE-depleted La/Sm-(N) = 0.11-0.37 x Cl and LREE-enriched, La/Sm-(N) = 1.88-15.72 x Cl). The depleted lherzolites have variable range in Li concentration (olivine: 2.1-5.4 ppm; opx: 1.1-2.3 ppm; cpx: 1.0-1.8 ppm) and in Li isotopic composition (delta Li-7 in olivine: -9.4 to 1.5aEuro degrees; in opx: -4.5 to 3.6aEuro degrees; in cpx: -17.0 to 4.8aEuro degrees), indicating strong disequilibrium in Li partitioning and Li isotope fractionation between samples. The enriched lherzolites have limited range in both Li abundances (olivine: 2.7-3.0 ppm; opx: 1.1-3.1 ppm; cpx: 1.1-2.3 ppm) and Li isotopic compositions (delta Li-7 in olivine: -1.3 to +1.3aEuro degrees; in opx: -2.0 to +5.0aEuro degrees; in cpx: -7.5 to +4.8aEuro degrees), suggest that the earlier metasomatic event which lead to LREE enrichment could also homogenize the Li contents and its isotopes. The enriched harzburgite and clinopyroxenite minerals show limited variation in Li abundances and variable Li isotopic compositions. The Li enrichments of olivine and clinopyroxene correlate neither with the incompatible trace element enrichment nor with the Sr-Nd isotopic compositions of clinopyroxene. These observations indicate that the metasomatic events which are responsible for the LREE enrichment and for the Li addition are distinct, whereby the LREE-enrichment pre-dates the influx of Li. The presence of large Li isotopic disequilibria within and between minerals of depleted and enriched peridotites suggest that the lithospheric mantle beneath the southern Ethiopian rift has experienced recent melt-peridotite interaction. Thus, the Li data set reported in this study offer new additional evidence for the existence of late stage metasomatism, which probably occurred at shallow depth briefly before and/or during entrainment and ascent of mantle xenoliths to the surface.
WOS关键词NORTH CHINA CRATON ; EAST-AFRICAN RIFT ; LI-ISOTOPE ; CARBONATITE METASOMATISM ; ULTRAMAFIC XENOLITHS ; OROGENIC ECLOGITES ; CONTINENTAL-CRUST ; WESTERN VICTORIA ; TANZANIAN CRATON ; TRACE-ELEMENT
WOS研究方向Geochemistry & Geophysics ; Mineralogy
语种英语
WOS记录号WOS:000410742800008
出版者SPRINGER WIEN
资助机构Chinese Academy of Sciences(2014FFBZ003) ; Chinese Academy of Sciences(2014FFBZ003) ; National Science Foundation of China(41450110429 ; National Science Foundation of China(41450110429 ; 91414301) ; 91414301) ; Chinese Academy of Sciences(2014FFBZ003) ; Chinese Academy of Sciences(2014FFBZ003) ; National Science Foundation of China(41450110429 ; National Science Foundation of China(41450110429 ; 91414301) ; 91414301) ; Chinese Academy of Sciences(2014FFBZ003) ; Chinese Academy of Sciences(2014FFBZ003) ; National Science Foundation of China(41450110429 ; National Science Foundation of China(41450110429 ; 91414301) ; 91414301) ; Chinese Academy of Sciences(2014FFBZ003) ; Chinese Academy of Sciences(2014FFBZ003) ; National Science Foundation of China(41450110429 ; National Science Foundation of China(41450110429 ; 91414301) ; 91414301)
源URL[http://ir.iggcas.ac.cn/handle/132A11/61928]  
专题地质与地球物理研究所_岩石圈演化国家重点实验室
通讯作者Alemayehu, Melesse
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, POB 9825, Beijing 100029, Peoples R China
2.Addis Ababa Sci & Technol Univ, Sch Earth Sci & Min Engn, Dept Earth Sci, POB 16417, Addis Ababa, Ethiopia
3.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China
4.Goethe Univ Frankfurt, Inst Geowissensch, Mineral, Altenhoferallee 1, D-60438 Frankfurt, Germany
推荐引用方式
GB/T 7714		 Alemayehu, Melesse,Zhang, Hong-Fu,Seitz, Hans-Michael. Constraining late stage melt-peridotite interaction in the lithospheric mantle of southern Ethiopia: evidence from lithium elemental and isotopic compositions[J]. MINERALOGY AND PETROLOGY,2017,111(5):777-792.
APA Alemayehu, Melesse,Zhang, Hong-Fu,&Seitz, Hans-Michael.(2017).Constraining late stage melt-peridotite interaction in the lithospheric mantle of southern Ethiopia: evidence from lithium elemental and isotopic compositions.MINERALOGY AND PETROLOGY,111(5),777-792.
MLA Alemayehu, Melesse,et al."Constraining late stage melt-peridotite interaction in the lithospheric mantle of southern Ethiopia: evidence from lithium elemental and isotopic compositions".MINERALOGY AND PETROLOGY 111.5(2017):777-792.

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