气候变化领域集成服务门户(CCPortal): Olivine chemistry reveals compositional source heterogeneities within a tilted mantle plume beneath Iceland

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DOI	10.1016/j.epsl.2019.116008
	Olivine chemistry reveals compositional source heterogeneities within a tilted mantle plume beneath Iceland
	Rasmussen M.B.; Halldórsson S.A.; Gibson S.A.; Guðfinnsson G.H.
发表日期	2020
ISSN	0012821X
卷号	531
英文摘要	High-Fo olivine (Fo = Mg/(Mg+Fe) mol%) is an ideal proxy for establishing the compositions of primary melts and their mantle sources. This has been exploited in establishing lithological variations in the mantle source regions of oceanic basalts, including in Iceland. However, previous studies on Icelandic olivine lack spatial and temporal coverage. We present high-precision in-situ major, minor and trace element analyses of Fo-rich olivine from a suite of 53 primitive basalts erupted in the neovolcanic rift and flank zones of Iceland, as well as in older regions of Quaternary and Tertiary crust. Most of these samples have previously been analysed for 3He/4He, which ranges from 6.7 to 47.8 RA, the largest span reported for any oceanic island. By combining trace elemental variability with 3He/4He, we assess the extent of lithological variability in the Icelandic mantle plume. Trace-element ratios that are likely to preserve information about mantle source regions (e.g., Mn/Fe, Ni/(Mg/Fe), Ga/Sc, Zn/Fe and Mn/Zn) suggest a peridotitic mantle source in all rift-related volcanic regions, as well as in the off-rift flank zones of Öræfajökull and Snæfellsnes. However, a signal of a more pyroxenitic mantle lithology is clearly visible in olivine from the South Iceland Volcanic Zone, which represents the southward propagation of the Eastern Rift Zone, while olivine from Tertiary lavas suggests a mixed peridotite-pyroxenite source composition. We are able to identify four components present in the Icelandic mantle: a lithologically heterogeneous plume component with 3He/4He >MORB; a depleted MORB-like peridotite; an isotopically enriched MORB-like peridotite; and a peridotitic component with 3He/4He
关键词	helium isotopes Iceland mantle heterogeneity olivine trace elements
英文关键词	Basalt; Lithology; Thermal plumes; Trace elements; Volcanoes; Contributing factor; Helium isotopes; Icelands; Isotopically enriched; Lithological variability; Mantle heterogeneity; Mantle source region; Minor and trace elements; Olivine; basalt; chemical composition; helium isotope; igneous geochemistry; mantle plume; mantle source; olivine; spatiotemporal analysis; trace element; Iceland
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202848
作者单位	Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, Reykjavik, 101, Iceland; Department of Earth Sciences, University of Cambridge, Downing St, Cambridge, CB2 3EQ, United Kingdom
推荐引用方式 GB/T 7714	Rasmussen M.B.,Halldórsson S.A.,Gibson S.A.,et al. Olivine chemistry reveals compositional source heterogeneities within a tilted mantle plume beneath Iceland[J],2020,531.
APA	Rasmussen M.B.,Halldórsson S.A.,Gibson S.A.,&Guðfinnsson G.H..(2020).Olivine chemistry reveals compositional source heterogeneities within a tilted mantle plume beneath Iceland.Earth and Planetary Science Letters,531.
MLA	Rasmussen M.B.,et al."Olivine chemistry reveals compositional source heterogeneities within a tilted mantle plume beneath Iceland".Earth and Planetary Science Letters 531(2020).