TY - JOUR
T1 - Geological summary of the Busidima Formation (Plio-Pleistocene) at the Hadar paleoanthropological site, Afar Depression, Ethiopia
AU - Campisano, Christopher
N1 - Funding Information:
This project was funded by grants from the National Science Foundation , the National Geographic Society , the Institute of Human Origins (ASU) , and the Center for Human Evolutionary Studies (Rutgers University) to both the author and directors of the Hadar Research Project (Kimbel, Johanson, Hovers). Craig Feibel provided essential help and advice on the tephrostratigraphic work discussed here and previously published. For helpful discussions that provided vital information, ideas, and clarification pertaining to the geology outside Hadar over the last several years, I thank Jay Quade, Ramon Arrowsmith, Erin DiMaggio, and especially Jonathan Wynn. For logistical and field support I would like to thank Bill Kimbel, Don Johanson, Erella Hovers, Gerry Eck, the Institute of Human Origins, the National Museum of Ethiopia, the Ethiopian A.R.C.C.H., and especially our field crew and friends from the Eloaha region.
Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 2012/3
Y1 - 2012/3
N2 - The Hadar paleoanthropological site in Ethiopia preserves a record of hominin evolution spanning from approximately 3.45Ma to 0.8Ma. An angular unconformity just above the ca. 2.95Ma BKT-2 complex divides the sediments into the Hadar Formation (ca. 3.8-2.9Ma) and the Busidima Formation (ca. 2.7-0.15Ma). The unconformity is likely a response to a major tectonic reorganization in the Afar Depression, and activation of the As Duma fault near the Ethiopian Escarpment (west of Hadar) created a half-graben in which the Busidima Formation was deposited. The pattern and character of sedimentation in the region changed dramatically above the unconformity, as cut-and-fill channel conglomerates and silt-dominated paleosols that comprise the Busidima Formation stand in sharp contrast to the underlying deposits of the Hadar Formation. Conglomerate deposition has been related to both the perennial, axial paleo-Awash and ephemeral, escarpment-draining tributaries. Overbank silts have yielded fossils attributed to early Homo and Oldowan stone tools. Numerous tuffaceous deposits exist within the Busidima Formation, but they are often spatially limited, fine-grained, and reworked. Recent work on the tephrostratigraphic framework of the Busidima Formation at Hadar has identified at least 12 distinct vitric tephras and established the first geochemical-based correlations between Hadar and the neighboring project areas of Gona and Dikika. Compared to Gona and Dikika, where Busidima Formation sediments are exposed over large areas, the highly discontinuous sediments at Hadar comprise less than 40m in composite section and are exposed over an area of <20km2, providing only snapshots into the 2.7-0.15Ma window. The stratigraphic record at Hadar confirms the complex depositional history of the Busidima Formation, and also provides important details on regional stratigraphic correlations and the pattern of deposition and erosion in the lower Awash Valley reflective of its tectonic history.
AB - The Hadar paleoanthropological site in Ethiopia preserves a record of hominin evolution spanning from approximately 3.45Ma to 0.8Ma. An angular unconformity just above the ca. 2.95Ma BKT-2 complex divides the sediments into the Hadar Formation (ca. 3.8-2.9Ma) and the Busidima Formation (ca. 2.7-0.15Ma). The unconformity is likely a response to a major tectonic reorganization in the Afar Depression, and activation of the As Duma fault near the Ethiopian Escarpment (west of Hadar) created a half-graben in which the Busidima Formation was deposited. The pattern and character of sedimentation in the region changed dramatically above the unconformity, as cut-and-fill channel conglomerates and silt-dominated paleosols that comprise the Busidima Formation stand in sharp contrast to the underlying deposits of the Hadar Formation. Conglomerate deposition has been related to both the perennial, axial paleo-Awash and ephemeral, escarpment-draining tributaries. Overbank silts have yielded fossils attributed to early Homo and Oldowan stone tools. Numerous tuffaceous deposits exist within the Busidima Formation, but they are often spatially limited, fine-grained, and reworked. Recent work on the tephrostratigraphic framework of the Busidima Formation at Hadar has identified at least 12 distinct vitric tephras and established the first geochemical-based correlations between Hadar and the neighboring project areas of Gona and Dikika. Compared to Gona and Dikika, where Busidima Formation sediments are exposed over large areas, the highly discontinuous sediments at Hadar comprise less than 40m in composite section and are exposed over an area of <20km2, providing only snapshots into the 2.7-0.15Ma window. The stratigraphic record at Hadar confirms the complex depositional history of the Busidima Formation, and also provides important details on regional stratigraphic correlations and the pattern of deposition and erosion in the lower Awash Valley reflective of its tectonic history.
KW - Afar
KW - Busidima Formation
KW - Hadar Formation
KW - Oldowan
KW - Tephrostratigraphy
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U2 - 10.1016/j.jhevol.2011.05.002
DO - 10.1016/j.jhevol.2011.05.002
M3 - Article
C2 - 21762952
AN - SCOPUS:84858075174
SN - 0047-2484
VL - 62
SP - 338
EP - 352
JO - Journal of human evolution
JF - Journal of human evolution
IS - 3
ER -