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The 2004 tectonic and hydrothermal crisis in the Danakil depression: documenting the last continental step prior to oceanic spreading
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  • Daniel Mège,
  • Ernst Hauber,
  • Pascal Allemand,
  • Hugo Moors,
  • Mieke de Craen,
  • Hanjin Choe,
  • Jérôme Dyment
Daniel Mège
Centrum Badan Kosmicznych PAN

Corresponding Author:dmege@cbk.waw.pl

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Ernst Hauber
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Pascal Allemand
Laboratoire de Géologie de Lyon - OSU de Lyon
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Hugo Moors
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Mieke de Craen
Belgian Nuclear Research Centre
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Hanjin Choe
Kangwon National University
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Jérôme Dyment
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The Danakil depression in Ethiopia, at the end of the southern Red Sea, has been the locus of volcanic crises in 2004-10, with emplacement of 15 dykes: one, non-emergent, in Lake Asale next to Black Mountain and south of the Dallol dome during fall 2004, the others in the Dabbahu-Manda Hararo rift segment between September 2005 and May 2010. We report on a hydrothermal crisis that opened a 4.5 km long fissure in the ground, at the same time the Black Mountain dyke was intruding the crust 2 km away and parallel to it. The fissure, located north and south of Yellow Lake (Gaet’ale) and trending NNW-SSE, is still active. Its morphology is remarkably diversified, but surface evidence of the structural deformation has been lost over the years. Its formation is coeval with the intrusion of the Black Mountain dyke intrusion. It is suggested that after its documented propagation, the Black Mountain dyke propagated aseismically eastward as a sill, disrupting the stress equilibrium in the long-living Yellow Lake hydrothermal environment. The stress field was brought to rupture by the increased deviatoric stress, triggering the nucleation of a tensile fracture that propagated to the surface and released the far-field stress already released at depth by the emplacement of the dyke. This study documents the delicate intermingling of magmatic, tectonic, and hydrothermal processes at the ultimate step of continental rifting prior to the earliest stage of oceanic spreading.