Development of robust LA-ICP-MS U-Pb zircon dating with an annealing technique

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14573
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Kyoto University (2022); The University of Tokyo (2020-2021)
• Principal Investigator: Asanuma Hisashi 京都大学, 人間・環境学研究科, 講師 (90852525)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: ジルコン / ウラン(U)-鉛(Pb)放射年代測定 / アニール / メタミクト / レーザーアブレーション / ICP質量分析計

Outline of Final Research Achievements

In this study, an annealing technique was applied to control the recovery from radiation damages in zircon samples, which leads to improve a geochronological analysis using a laser ICP mass spectrometer. As a result, it was confirmed that the zircon grain became more crystalline through the annealing process, but an Archean zircon subjected to heavy radiation damage showed an incomplete damage recovery. These findings indicate the need for a laser source that achieves minimized elemental fractionation in order to position laser ICP mass spectrometry as an absolute age constraint technique.

Free Research Field

地質学

Academic Significance and Societal Importance of the Research Achievements

ジルコン年代学は地球史研究における一つの絶対基軸を提供できる一方で，日頃から我々の感心の高い地震や火山噴火といった地質現象の年代解析にも活用される．そのため，本研究が目指すジルコン年代学の高確度化は地質現象の高時間解像度解析へと貢献し，学術研究のみならず火山学，地震学を内包する防災研究分野において高い波及効果を示すことが期待される．