title: (40)Ar/(39)Ar dating, paleomagnetism, and tephrochemistry of Pliocene strata of the hominid-bearing Woranso-Mille area, west-central Afar Rift, Ethiopia.
abstract: (40)Ar/(39)Ar dating of tuffs and mafic lavas, tephra geochemistry, and paleomagnetic reversal stratigraphy have been used to establish the chronostratigraphy of the Pliocene hominid-bearing fossiliferous succession at Woranso-Mille, a paleontological study area in the western part of the central Afar region of Ethiopia. The succession in the northwestern part of the study area ranges in (40)Ar/(39)Ar age from 3.82-3.570 Ma, encompassed by paleomagnetic subchron C2Ar (4.187-3.596 Ma). One of the major tuff units, locally named the Kilaytoli tuff, is correlative on the basis of age and geochemistry to the Lokochot Tuff of the Turkana Basin. A hominid partial skeleton (KSD-VP-1) was found in strata whose precise stratigraphic position and age is still under investigation, but is believed to correspond to the later part of this interval. Woranso-Mille fills a significant gap in the fossil record of northeastern Africa at the time of the lower to middle Pliocene transition, when many extant species lineages of African fauna were established.
authors.affiliation: Berkeley Geochronology Center, Berkeley, CA 94709, USA. al@bgc.org
authors.forename: Alan L
authors.initials: AL
authors.lastname: Deino
authors.forename: Gary R
authors.initials: GR
authors.lastname: Scott
authors.forename: Beverly
authors.initials: B
authors.lastname: Saylor
authors.forename: Mulugeta
authors.initials: M
authors.lastname: Alene
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Angelini
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Haile-Selassie
mesh_terms: D000818:Animals; D001128:Argon / Q000032:analysis*; D005002:Ethiopia; D005580:Fossils; D019015:Geologic Sediments / Q000032:analysis*; D005898:Glass / Q000032:analysis; D015186:Hominidae; D008280:Magnetics; D011868:Radioisotopes / Q000032:analysis*; D055110:Radiometric Dating; D013057:Spectrum Analysis
chemical_list: D011868:Radioisotopes; D001128:Argon