Mantle upwelling and initiation of rift segmentation beneath the Afar Depression

James O S Hammond, J-M Kendall, G W Stuart, C J Ebinger, Ian D Bastow, D Keir, A Ayele, M Belachew, Berhe Gezahegn, G Ogubazghi, T J Wright

Research output: Contribution to journalArticle (Academic Journal)peer-review

62 Citations (Scopus)

Abstract

The Afar Depression, at the northern end of the East African Rift, is the only place on land where the transition from a plume-induced continental breakup to seafloor spreading is active today. New images of seismic velocity structure, based on exceptional new data sets, show that the mantle plume that initiated rifting in Africa is absent beneath Afar today. The images are dominated by a major low-velocity feature at similar to 75 km depth closely mimicking the abrupt changes in rift axis orientation seen at the surface. This is likely associated with passive upwelling beneath the rift. Additional focused low-velocity anomalies show that small diapiric upwellings are present beneath major off-axis volcanoes. These multiple melting sources can explain the wide range of geochemical signatures seen in Afar. These images suggest that passive upwelling beneath Afar marks the initiation of rift segmentation as continental breakup progresses to seafloor spreading.

Original languageEnglish
Pages (from-to)635-638
Number of pages4
JournalGeology
Volume41
Issue number6
DOIs
Publication statusPublished - 8 Jan 2013

Keywords

  • PLATE DRIVING FORCES
  • EAST-AFRICA
  • PLUME
  • MAGMATISM
  • CENTERS
  • ORIGIN
  • GULF

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