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Non-plume flood basalt volcanism before the emplacement of the Afar mantle plume head
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  • Yutaka Yoshimura,
  • Osamu Ishizuka,
  • Toshitsugu Yamazaki,
  • Hyeon-Seon Ahn,
  • Tesfaye Kidane,
  • Yuhji Yamamoto,
  • Shun Sekimoto,
  • Yo-Ichiro Otofuji
Yutaka Yoshimura
Kyushu University

Corresponding Author:[email protected]

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Osamu Ishizuka
Geological Survey of Japan
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Toshitsugu Yamazaki
The University of Tokyo
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Hyeon-Seon Ahn
Korea Institute of Geoscience and Mineral Resources
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Tesfaye Kidane
University of KwaZulu Natal
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Yuhji Yamamoto
Kochi University
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Shun Sekimoto
Kyoto University
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Yo-Ichiro Otofuji
Kobe University
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The Ethiopia-Yemen flood basalts are spatially zoned with progressively lower TiO2 lavas from near the Afar depression toward the margins. The timing and rate of emplacement of low TiO2 (LT) lavas are poorly known compared with the ultra-high TiO2 (HT2) lavas. We measured two high-precision 40Ar/39Ar ages of 29.63 ± 0.14 and 30.02 ± 0.22 Ma (2σ) from basalts of the 2-km-thick LT lava sequence at the Afar plume head margin. Using our eruption age model constructed from our and previous 40Ar/39Ar ages with the paleomagnetic directions, we estimate that the LT lava eruption continued over Chrons C12r-C12n-C11r. The eruption of the plume head margin started earlier than the plume head axis emplacement in C12n. Also, the eruption rate was low at the margin, high at the axis. We estimate that the LT lavas are induced by the edge-driven convection, the result of a plume-lithosphere interaction, not a plume head.