title: Geochronology, stratigraphy and geochemistry of Cindery Tuff in Pliocene hominid-bearing sediments of the Middle Awash, Ethiopia.
abstract: Cindery Tuff is a subalkaline, rhyolitic air-fall deposit that was probably produced by a mixed-magma eruption. It is a distinctive, datable, regional isochronous marker bed within the Pliocene sediments of the Middle Awash district, and is stratigraphically situated between two new fossil hominid discoveries. Based on 40Ar/39Ar analyses of plagioclase, rhyolitic glass and basaltic glass, as well as fission-track analyses of zircons, we estimate its age to be 3.8-4.0 Myr. This implies that associated hominid skull fragments are at least 3.9 Myr old.
mesh_terms: D000818:Animals; D001128:Argon; D005002:Ethiopia; D005580:Fossils; D055593:Geological Phenomena; D005844:Geology; D000882:Haplorhini; D006801:Humans; D010163:Paleontology; D011868:Radioisotopes
chemical_list: D011868:Radioisotopes; D001128:Argon