Hydrothermal evolution in the interior of a large hydrous planetesimal in the early solar system

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K18779
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 17:Earth and planetary science and related fields
• Research Institution: Tohoku University
• Principal Investigator: Nakamura Tomoki 東北大学, 理学研究科, 教授 (20260721)
• Co-Investigator(Kenkyū-buntansha): 三部 賢治 東京大学, 地震研究所, 助教 (10372426)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: 炭素質隕石 / 超臨界水 / 熱水反応

Outline of Final Research Achievements

In order to understand the chemical and mineralogical evolution in the interior of large hydrous planetesimals, hydrothermal experiments must be performed using carbonaceous chondrites and super-critical water. The purpose of this study is to develop the experimental procedure such hydrothermal experiments. We carried out a preliminary experiment using terrestrial serpentine and a hydrothermal experiment using carbonaceous chondrite with conditions of 600°C for temperature, 250atm for pressure,　50hours for experimental duration、and water/rock ratio of 1. The experimental product was analyzed by using synchrotron X-ray radiation for CT and XRD. The results indicate that hydrous phases in carbonaceous chondrite was decomposed and partially dehydrated. In this study, we developed the procedures of hydrothermal experiments using carbonaceous chondrites and super-critical water.

Free Research Field

惑星科学

Academic Significance and Societal Importance of the Research Achievements

惑星形成の初期段階で巨大化した含水微小天体では、天体内部の温度が上昇し、超臨界水が存在する状態での加熱現象が起こっていたと考えられる。この現象における解明すべき重要なポイントは、超臨界水により太陽系始原物質（小惑星由来の炭素質隕石）がどのように物質変化するかを理解することである。本研究では、この現象を調べるための熱水実験の手法を確立することができた。