An ion microprobe study on fractionation of siderophile elements in the early solar system

2014 Fiscal Year Final Research Report

• Project/Area Number: 23540567
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Geochemistry/Astrochemistry
• Research Institution: The University of Tokyo
• Principal Investigator: HIYAGON Hajime 東京大学, 理学(系)研究科(研究院), 准教授 (70192292)
• Co-Investigator(Kenkyū-buntansha): MORISHITA Yuichi 静岡大学, 理学研究科, 教授 (90358185)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Keywords: 親鉄性元素 / 元素分別 / 初期太陽系 / SIMS / 相対感度係数 / コンドルール / 超難揮発性メタル / 白金族元素

Outline of Final Research Achievements

(1) Ultra-refractory (UR) metal grains were found in some CAIs from Murchison (CM2) chondrite, which show strong Mg-isotopic fractionation suggesting evaporative loss of Mg. Based on the PGE patterns in the UR metal grains, the evaporation temperature was estimated to be >1600C. (2) Metal standards (Fe-based alloys containing various siderophile elements) were prepared for the SIMS analysis, and relative sensitivity factors for siderophile elements and Fe were determined. (3) Siderophile element analyses were conducted for metal grains in Y-81020 (CO 3.05) chondrite. PGE concentrations were low in large metal grains in the matrix, but large variation were observed in the metal grains in chondrules. This suggests rahter heterogeneous distribution of UR metal grains in the early solar system at the time of chondrule formation.

Free Research Field

惑星科学