Measurements of iridium concentration in the oldest rock sample, ISUA.

2010 Fiscal Year Final Research Report

• Project/Area Number: 20540478
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geochemistry/Astrochemistry
• Research Institution: Japan Atomic Energy Agency
• Principal Investigator: HATSUKAWA Yuichi Japan Atomic Energy Agency, 量子ビーム応用研究部門, 研究主幹 (40343917)
• Co-Investigator(Kenkyū-buntansha): NOGUCHI Takaaki 茨城大学, 理学部, 教授 (40222195)
• Project Period (FY): 2008 – 2010
• Keywords: 放射化分析 / イスア / イリジウム / 多重ガンマ線放射化分析 / 後期重爆撃(LHB)

Research Abstract

Non-destructive ultra-sensitive elemental analyses method using gamma-gamma coincidence detection technique combined with neutron activation analysis was developed by JAEA group. In this study, iridium concentrations in the geological samples were measured using the multiple gamma detection with neutron activation analysis method. The ISUA samples from Greenland were analyzed. The ISUA is recognized as which was formed at 3.8 billion years ago, almost same age with the Late Heavy Bombardments. By the iridium measurements of the ISUA samples, we proved that Late Heavy Bombardments were caused by impacts of comets, not asteroids.

Research Products

• [Journal Article] The Earth-Moon system during the late heavy bombardment period-Geochemical support for impacts dominated by comets (2009)
  • Author(s): U.Jorgensen, P.Appel, Y.Hatsukawa, R.Frei, M.Oshima, Y.Toh, A.Kimura
  • Journal Title: Icarus 204 Pages: 368-380
  • Peer Reviewed
• [Journal Article] Iridium concentration and noble gas composition of Cretaceous-Tertiary boundary clay from Stevns Klint, Denmark (2009)
  • Author(s): T.Osawa, Y.Hatsukawa, K.Nagao, M.Koizumi,M.Oshima, Y.Toh, A.Kimura, K.Furutaka
  • Journal Title: Geological Geochemical Journal Vol.43 (No.6) Pages: 415-422
  • Peer Reviewed
• [Journal Article] High Sensitive Iridium Measurement using Neutron Activation Analysis with γ-γ Coincidence Detection (2008)
  • Author(s): Y.Hatsukawa, M.Oshima, Y.Toh, A.Kimura, M.Koizumi, K.Furutaka, M.Segawa
  • Journal Title: TRANSACTION (American Nuclear Society) 99 Pages: 53
  • Peer Reviewed
• [Journal Article] Measurement of Ir concentration in Geological Standard Samples using Neutron Activation Analysis with Multiple Gamma coincidence Mehtod
  • Author(s): Y.Hatsukawa, T.Osawa, M.Oshima, Y.Toh, A.Kimura, K.Furutaka
  • Journal Title: J.Radioalyt.Nucl.Chem. (Accepted)
  • Peer Reviewed
• [Presentation] Measurements of Iridium Concentration in Geological Standard Samples using Neutron Activation Analysis with Gamma-Gamma Coincidence Method (2011)
  • Author(s): Y.Hatsukawa, T.Osawa, M.Oshima, Y.Toh, A.Kimura, M.Koizumi, K.Furutaka
  • Organizer: MTAA-13
  • Place of Presentation: Collage Station, TX, USA
  • Year and Date: 2011-03-15
• [Presentation] Measuement of Geological Samples using Neutron Activation Analysis with Gamma-Gamma coincidence (2009)
  • Author(s): Y.Hatsukawa, T.Osawa, M.Segawa, M.Koizumi, M.Oshima, Y.Toh, A.Kimura, K.Furutaka
  • Organizer: APSORC
  • Place of Presentation: Napa, CA, USA
  • Year and Date: 2009-12-04
• [Presentation] Feasibility study of isotope measurements using activation analysis with multiple gamma-ray detection (2009)
  • Author(s): Yuichi Hatsukawa, Yutaka Miyamoto, Takahito Osawa, Takehito Hayakawa, Masumi Oshima, Yosuke Toh, Atsushi Kimura, Mitsuo Koizumi, Kazuyoshi Furutaka, Mariko Segawa, Hideaki Matsue
  • Organizer: 22nd Seminar Activation Analysis and Gamma-Spectroscopy, SAAGAS-22
  • Place of Presentation: Vienna、Austria
  • Year and Date: 2009-02-26
• [Presentation] High Sensitive Iridium Measurement using Neutron Activation Analysis with γ-γ Coincidence Detection (2008)
  • Author(s): Y.Hatsukawa, M.Oshima, Y.Toh, A.Kimura, M.Koizumi, K.Furutaka, M.Segawa
  • Organizer: American Nuclear Society Meeting
  • Place of Presentation: Reno, Nevada USA
  • Year and Date: 2008-11-11