A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans

We propose that such pulses of episodic silicic volcanism would have drastically remodelled landscapes and ecosystems occupied by early hominin populations

William Hutchison

2016

Scholarcy highlights

  • The Ethiopian Rift Valley hosts the longest record of human co-existence with volcanoes on Earth, current understanding of the magnitude and timing of large explosive eruptions in this region is poor
  • Aluto and Corbetti are two major silicic volcanoes located in the central Main Ethiopian Rift
  • Aluto is situated within the Ziway–Shala basin, a tectonically controlled drainage basin that formed a single connected lake in the Late Pleistocene, while Corbetti is located at the northern end of the Lake Awasa basin
  • The Gademotta stratigraphy represents an independent record of Pleistocene volcanism and testifies that several major explosive eruptions occurred during the flare-up period, but that significant volumes of tephra were dispersed across and along the rift
  • The new geochronological constraints and volume estimates provide the first robust evidence for flare-up activities in the CMER between 320 and 170 ka, and support the hypothesis of Mohr et al. who first proposed a pulse of volcanism at this time
  • The record of volcanism in the CMER from the middle-Pleistocene to recent is consistent with a ‘pulsed model’ of silicic magma productivity characterized by episodes of major ignimbrite eruptions, and by significant hiatuses
  • To obtain a first-order approximation of the volume of silicic magma produced at each volcano through time we consider their eruptive histories to be comprise three main phases: a pre-collapse edifice; caldera collapse; and post-caldera volcanism

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