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UP: Umweltphysik
UP 13: Physikalische Altersbestimmung
UP 13.5: Talk
Friday, March 19, 1999, 17:30–17:45, KO
Alpha-R"uckstoss-Spuren in Glimmer als Grundlage der Datierung junger Vulkanite — •K. G"ogen —
Forschungsstelle Arch"aometrie
am Max-Planck-Institut f"ur Kernphysik
Postfach 10 39 80
D-69029 Heidelberg
Alpha-recoil track (ART) dating is based on the accumulation of nuclear tracks produced by the alpha-decay of uranium, thorium and their daughter nuclei. After emitting an alpha-particle, the nucleus recoils 30-40 nm, leaving behind a trail of radiation damage, which can be revealed by etching and observed under a phase-contrast microscope. If all tracks produced since the formation of a crystal have been preserved their density is a measure for the sample’s age. This dating technique was proposed over three decades ago, but has hardly progressed since then. We describe a methodology by which reliable ART ages of dark mica can be obtained. The technique is applicable to single mica flakes in the 102 to 106 years age-range. It was tested on Quaternary volcanics from the Eifel region in Germany.