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Geochronology and thermochronology by the [40]Ar/[39]Ar method
1. Historical introduction 2. Basis of the 40AR/39AR dating method 3. Technical aspects 4. 40AR/39AR data presentation and interpretation App.4.1 Isochron analysis 5. Diffusion theory andExpand
Stratigraphic context of fossil hominids from the Omo group deposits: northern Turkana Basin, Kenya and Ethiopia.
The chronometric framework developed for Plio-Pleistocene deposits of the northern Turkana Basin is reviewed in light of recent advances in lithostratigraphy, geochemical correlation, paleomagneticExpand
New four-million-year-old hominid species from Kanapoi and Allia Bay, Kenya
The mosaic of primitive and derived features shows this species to be a possible ancestor to Australopithecus afarensis and suggests that Ardipithecus ramidus is a sister species to this and all later hominids. Expand
Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya
Two new cranial fossils from the Koobi Fora Formation, east of Lake Turkana in Kenya, are described that have bearing on the relationship between species of early Homo and confirm the distinctiveness of H.’shabilis and H.erectus, independently of overall cranial size, and suggest that these two early taxa were living broadly sympatrically in the same lake basin for almost half a million years. Expand
Characterization and calibration of 40Ar/39Ar dating standards
Abstract Because 40Ar/39Ar ages are based on independent age determinations for standard minerals, it is critical that these standards be well characterized. This includes constraints both on the ageExpand
Stratigraphic placement and age of modern humans from Kibish, Ethiopia
The preferred estimate of the age of the Kibish hominids is 195 ± 5 kyr, making them the earliest well-dated anatomically modern humans yet described, and close to the older limit of Mediterranean sapropels. Expand
New hominin genus from eastern Africa shows diverse middle Pliocene lineages
New fossils discovered west of Lake Turkana, Kenya, which differ markedly from those of contemporary A. afarensis point to an early diet-driven adaptive radiation, provide new insight on the association of hominin craniodental features, and have implications for the understanding of Plio–Pleistocene hom inin phylogeny. Expand
Diffusion of 40Ar in biotite: Temperature, pressure and compositional effects
Abstract The measured radiogenic 40Ar loss from sized biotite (56% annite) samples following isothermalhydrothermal treatment have provided model diffusion coefficients in the temperature intervalExpand
Precise 40Ar/39Ar geochronology for the upper Koobi Fora Formation, Turkana Basin, northern Kenya
The Plio-Pleistocene Koobi Fora Formation, about 560 m thick, crops out east of Lake Turkana and is part of the much larger depositional system of the Omo–Turkana Basin. The upper half of the KoobiExpand
The geochronology and evolution of the young volcanic island of Réunion, Indian Ocean
Abstract A detailed K-Ar study of subaerial lavas from Reunion, using whole rock samples, shows that the measured ages are fully consistent with the excellent stratigraphic control available. TheExpand