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Titel |
The mantle sources beneath the Afar volcanic province and their interplay with extension |
VerfasserIn |
Raphaël Pik, Martin Stab, Marie-Anne Ancellin, Sarah Medynski, Christophe Cloquet, Dereje Ayalew, Gezahegn Yirgu, Gilles Chazot, Charlotte Vye-Brown, Nicolas Bellahsen, Sylvie Leroy |
Konferenz |
EGU General Assembly 2015
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 17 (2015) |
Datensatznummer |
250103690
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Publikation (Nr.) |
EGU/EGU2015-3928.pdf |
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Zusammenfassung |
The evolution of mantle sources beneath the Ethiopian volcanic province has long been discussed and debated with a long-lived controversy in identifying mantle reservoirs and locating them in the mantle. One interpretation of the isotopic composition of erupted lavas considers that the Afar mantle plume composition is best expressed by recent lavas from Afar and Gulf of Aden (e.g. Erta Ale, Manda Inakir and the 45°E torus anomaly on the Gulf of Aden) implying that all other volcanics (including other active segments and the initial flood basalt province) result from mixing of this plume component with additional lithospheric and asthenospheric components. A completely opposite view considers that the initial Oligocene continental flood basalts best represent the isotopic composition of the Afar mantle plume, which is subsequently mixed in various proportions with continental lithospheric mantle for generating some of the specific signature of Miocene and Quaternary volcanics.
The precise and correct identification of mantle components involved in the generation of magmas is of particular importance because this is the only way to document the participation of mantle during extension and its potential role in break-up processes. In this contribution we provide new isotopic data for central Afar and we revisit the whole data set of the Ethiopian volcanic province and African/Arabian intraplate volcanics in order to: (i) precisely identify the distinct mantle components implicated, (ii) discuss their location and evolution in space and time, and (3) link the evolution of mantle with extensional processes beneath the Afar province.
This new interpretation of geochemical data allows reconsidering the evolution of mantle in the course of rift evolution. In terms of mantle sources, two populations of active segments are frontally opposed in the volcanic province: those that share exactly the same composition with plume related CFBs (e.g. the Manda Hararo and the Main Ethiopian rift segments), and those that involve the participation of additional lithospheric mantle components (Erta Ale, Manda Inakir, Asal). We show that the material of the Afar mantle plume is not dispersed and attenuated laterally away from the centre of the province, but instead distributed and controlled spatially by rift segmentation. |
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