The geology of gona, afar, ethiopia

Jay Quade, Naomi E. Levin, Scott W. Simpson, Robert Butler, William C. McIntosh, Sileshi Semaw, Lynnette Kleinsasser, Guillaume Dupont-Nivet, Paul Renne, Nelia Dunbar

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Deposits in the Gona Paleoanthropological Research Project (GPRP) area in eastcentral Ethiopia span most of the last ∼6.4 m.y. and are among the longest and most complete paleoenvironmental and human fossil archives in East Africa. The 40Ar/39Ar and paleomagnetic dates and tephrostratigraphic correlations establish the time spans for the four formations present at Gona: the Adu-Asa (>6.4-5.2 Ma), Sagantole (>4.6-3.9 Ma), Hadar (3.8-2.9 Ma), and Busidima Formations (2.7 to <0.16 Ma). The volcano-sedimentary succession at Gona displays many classic tectono-sedimentary features of an evolving rift basin. The mixed volcanic and fluviolacustrine Adu-Asa Formation is the earliest expression of rifting at Gona, probably deposited in a small half-graben. The Sagantole and Hadar Formations were deposited in a much wave length larger half-graben bounded to the E-NE by an as-yet-unidentified normal fault. The Sagantole and Hadar Formations are both fluvial and lacustrine, reflecting periodic shallow impoundment of a low-gradient paleo-Awash River, perhaps by an accommodation zone north of the Ledi-Geraru project area. Starting at 2.9-2.7 Ma, the character of sedimentation changed dramatically throughout the Awash Valley as bed load coarsened and the meandering paleo-Awash River cyclically cut and filled. Unlike the Hadar Formation, the Busidima Formation thickens westward, suggesting deposition in a half-graben of the opposite polarity compared to Sagantole/Hadar time. Sedimentation rates decreased 5-fold, from 0.25 mm/yr in the Hadar Formation to 0.05 mm/yr in the Busidima Formation, perhaps in response to slowing extension rates and/or opening of the half-graben north of Gona.

Original languageEnglish (US)
Pages (from-to)1-31
Number of pages31
JournalSpecial Paper of the Geological Society of America
Volume446
DOIs
StatePublished - 2008

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graben
geology
sedimentary feature
impoundment
bedload
river
sedimentation rate
normal fault
rifting
volcano
sedimentation
fossil
fold
wavelength
valley
basin

Keywords

  • Adu-Asa
  • Busidima
  • Ethiopian Rift
  • Gona
  • Sagantole
  • Tephrostratigraphy

ASJC Scopus subject areas

  • Geology

Cite this

Quade, J., Levin, N. E., Simpson, S. W., Butler, R., McIntosh, W. C., Semaw, S., ... Dunbar, N. (2008). The geology of gona, afar, ethiopia. Special Paper of the Geological Society of America, 446, 1-31. https://doi.org/10.1130/2008.2446(01)

The geology of gona, afar, ethiopia. / Quade, Jay; Levin, Naomi E.; Simpson, Scott W.; Butler, Robert; McIntosh, William C.; Semaw, Sileshi; Kleinsasser, Lynnette; Dupont-Nivet, Guillaume; Renne, Paul; Dunbar, Nelia.

In: Special Paper of the Geological Society of America, Vol. 446, 2008, p. 1-31.

Research output: Contribution to journalArticle

Quade, J, Levin, NE, Simpson, SW, Butler, R, McIntosh, WC, Semaw, S, Kleinsasser, L, Dupont-Nivet, G, Renne, P & Dunbar, N 2008, 'The geology of gona, afar, ethiopia', Special Paper of the Geological Society of America, vol. 446, pp. 1-31. https://doi.org/10.1130/2008.2446(01)
Quade, Jay ; Levin, Naomi E. ; Simpson, Scott W. ; Butler, Robert ; McIntosh, William C. ; Semaw, Sileshi ; Kleinsasser, Lynnette ; Dupont-Nivet, Guillaume ; Renne, Paul ; Dunbar, Nelia. / The geology of gona, afar, ethiopia. In: Special Paper of the Geological Society of America. 2008 ; Vol. 446. pp. 1-31.
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