The Evolution of Mantle Plumes in East Africa
The Evolution of Mantle Plumes in East Africa
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DOI：
10.1029/2020jb019929
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发表时间：
2020-11
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影响因子：
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通讯作者：
Sung‐Joon Chang;E. Kendall;A. Davaille;A. Ferreira
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文献类型：
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作者：
Sung‐Joon Chang;E. Kendall;A. Davaille;A. Ferreira
全球层析成像模型显示出一个巨大的低速异常，从南非下方的核心地幔边界（CMB）延伸到东非的上地幔。尽管人们认为这种异常与控制非洲大陆关键表面特征的地幔上升流有关，但其起源和演化仍然存在争议。在这里，我们汇集了地球化学和地震学约束以及来自新地震分析和地球动力学实验室实验的信息，提出目前阿法尔和肯尼亚下方至少存在两个起源于宇宙微波背景的不同羽流头。肯尼亚和阿法尔之间的第三个羽流可能导致了埃塞俄比亚-也门的 30 Ma 气旋，现在与阿法尔羽流合并。我们推断，阿法尔羽流目前与宇宙微波背景分离，可能是因为与俯冲的特提斯板片相互作用，并且它很可能是垂死的羽流。这可能意味着埃塞俄比亚主裂谷沿线的裂谷将因热源的丧失而失败，从而阻碍大陆分裂。
Global tomography models show a large low‐velocity anomaly extending from the core‐mantle boundary (CMB) beneath South Africa to the upper mantle in East Africa. Although it is believed that this anomaly is linked to mantle upwellings that control key surface features of the African continent, its origin and evolution are still debated. Here we assemble geochemical and seismological constraints along with information from new seismic analyses and geodynamic laboratory experiments to propose that presently there are at least two different plume heads beneath Afar and Kenya that originated at the CMB. A third plume between Kenya and Afar may have caused the Ethiopia‐Yemen traps 30 Ma, now merging with the Afar plume. We infer that the Afar plume is presently detached from the CMB probably because of an interaction with the subducted Tethyan slab and that it is likely a dying plume. This may imply that rifts along the Main Ethiopian Rift would fail by the loss of thermal sources, which consequently hampers continental breakup.