Fission-Track, K-Ar Age Determinations and Palaeomagnetic Measurements of Miocene Volcanic Rocks in the Western Area of Baragoi, Northern Kenya: Ages of Hominoids

Abstract

Miocene rocks in the west of Baragoi, northern Kenya, consist of the Nachola, Aka Aiteputh, Namurungule and Kongia Formations in ascending order. Two kinds of hominoids, Kenyapithecus and a large hominoid (Samburu hominoid), were found from the Nachola and Namurungule Formations, respectively, in summer 1982. Two fission-track and six K-Ar ages were determined on the volcanic rocks to clarify the ages of the hominoid fossils. Paleomagnetic reconnaissance was also conducted for the sake of magnetostratigraphic correlation. The ages of the Nachola, Aka Aiteputh, Namurungule and Kongia Formations were around 11, 13, 7 and 6.4 Ma, respectively. The ages of Kenyapithecus and Samburu hominoid are considered to be the Middle Miocene and Late Miocene, respectively.