Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia

dc.contributor.authorMcDougall, Ian
dc.contributor.authorBrown, F H
dc.contributor.authorFleagle, John
dc.date.accessioned2015-12-08T22:33:43Z
dc.date.issued2008
dc.date.updated2015-12-08T09:38:07Z
dc.description.abstractThe provenance and age of two Homo sapiens fossils (Omo I and Omo II) from the Kibish Formation in southern Ethiopia have been much debated. Here we confirm that Omo I and the somewhat more primitive-looking Omo II calvariae are from similar stratigraphic levels in Member I of the Kibish Formation. Based on 40Ar/39Ar age measurements on alkali feldspar crystals from pumice clasts in the Nakaa'kire Tuff, a tuffaceous bed in Member I just below the hominin levels, we place an older limit of 198 ± 14 ka (weighted mean age = 196 ± 2 ka) for the hominins. A younger limit of 104 ± 7 ka (weighted mean age = 104 ± 1 ka) is provided by feldspars separated from pumice clasts in the Aliyo Tuff in Member III. Geological evidence indicates rapid deposition of each member of the Kibish Formation, concurrent with deposition of sapropels in the Mediterranean Sea. The 40Ar/39Ar age measurements, together with correlations with sapropels, indicate that the hominin fossils are close in age to the older limit. Our preferred estimate of the age of the hominins is 195 ± 5 ka, making them the earliest well-dated anatomically modern humans yet described.
dc.identifier.issn0047-2484
dc.identifier.urihttp://hdl.handle.net/1885/34793
dc.publisherAcademic Press
dc.sourceJournal of Human Evolution
dc.subjectKeywords: aluminum silicate; argon; benzopyran derivative; potassium derivative; alkali feldspar; argon-argon dating; biostratigraphy; deposition; hominid; provenance; sapropel; animal; article; chemistry; Ethiopia; feldspar; fossil; history; human; humic substance 40Ar/39Ar dating; Ethiopia; Kibish Formation; Mediterranean sapropels; Modern hominins; Tephrostratigraphy
dc.titleSapropels and the age of hominins Omo I and II, Kibish, Ethiopia
dc.typeJournal article
local.bibliographicCitation.lastpage420
local.bibliographicCitation.startpage409
local.contributor.affiliationMcDougall, Ian, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationBrown, F H, University of Utah
local.contributor.affiliationFleagle, John, Stony Brook University
local.contributor.authoremailu6100426@anu.edu.au
local.contributor.authoruidMcDougall, Ian, u6100426
local.description.embargo2037-12-31
local.description.notesImported from ARIES
local.identifier.absfor040105 - Climatology (excl. Climate Change Processes)
local.identifier.absfor040311 - Stratigraphy (incl. Biostratigraphy and Sequence Stratigraphy)
local.identifier.absfor040303 - Geochronology
local.identifier.ariespublicationu4047674xPUB117
local.identifier.citationvolume55
local.identifier.doi10.1016/j.jhevol.2008.05.012
local.identifier.scopusID2-s2.0-50849101032
local.identifier.thomsonID000259912200005
local.identifier.uidSubmittedByu4047674
local.type.statusPublished Version

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