title: Time-resolved 2-million-year-old supernova activity discovered in Earth's microfossil record.
abstract: Massive stars ([Formula: see text]), which terminate their evolution as core-collapse supernovae, are theoretically predicted to eject [Formula: see text] of the radioisotope (60)Fe (half-life 2.61 Ma). If such an event occurs sufficiently close to our solar system, traces of the supernova debris could be deposited on Earth. Herein, we report a time-resolved (60)Fe signal residing, at least partially, in a biogenic reservoir. Using accelerator mass spectrometry, this signal was found through the direct detection of live (60)Fe atoms contained within secondary iron oxides, among which are magnetofossils, the fossilized chains of magnetite crystals produced by magnetotactic bacteria. The magnetofossils were chemically extracted from two Pacific Ocean sediment drill cores. Our results show that the (60)Fe signal onset occurs around 2.6 Ma to 2.8 Ma, near the lower Pleistocene boundary, terminates around 1.7 Ma, and peaks at about 2.2 Ma.
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Peter
authors: P
authors: Ludwig
authors: Physik Department, Technische Universität München, 85748 Garching, Germany; shawn.bishop@tum.de.
authors: Shawn
authors: S
authors: Bishop
authors: Geomagnetism and Gravimetry, Central Institute for Meteorology and Geodynamics, 1190 Vienna, Austria;
authors: Ramon
authors: R
authors: Egli
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Valentyna
authors: V
authors: Chernenko
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Boyana
authors: B
authors: Deneva
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Thomas
authors: T
authors: Faestermann
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Nicolai
authors: N
authors: Famulok
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Leticia
authors: L
authors: Fimiani
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: José Manuel
authors: JM
authors: Gómez-Guzmán
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Karin
authors: K
authors: Hain
authors: Physik Department, Technische Universität München, 85748 Garching, Germany;
authors: Gunther
authors: G
authors: Korschinek
authors: Chemie Department, Fachgebiet Elektronenmikroskopie, Technische Universität München, 85748 Garching, Germany;
authors: Marianne
authors: M
authors: Hanzlik
authors: Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, 01328 Dresden, Germany.
authors: Silke
authors: S
authors: Merchel
authors: Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, 01328 Dresden, Germany.
authors: Georg
authors: G
authors: Rugel
mesh_terms: D001256:Astronomy; D018534:Earth, Planet; D005118:Extraterrestrial Environment / Q000737:chemistry*; D052203:Ferrosoferric Oxide; D005580:Fossils
chemical_list: D052203:Ferrosoferric Oxide
keywords: accelerator mass spectrometry; magnetofossils; supernova