JpGU-AGU Joint Meeting 2017

講演情報

[JJ] ポスター発表

セッション記号 S (固体地球科学) » S-MP 岩石学・鉱物学

[S-MP44] [JJ] 鉱物の物理化学

2017年5月21日(日) 10:45 〜 12:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:大藤 弘明(愛媛大学地球深部ダイナミクス研究センター)、鎌田 誠司(東北大学学際科学フロンティア研究所)

[SMP44-P01] Melting relations in the system of MgSiO3 – SiO2 at high pressures

*森口 拓弥1米田 明1伊藤 英司1 (1.岡山大学惑星物質研究所)

キーワード:エンスタタイトコンドライト、溶融関係、マグマオーシャン、マントル分化、高圧

Melting relations in the MgO–SiO2 system at high pressures have been extensively studied to simulate chemical differentiation in a deep magma ocean formed in the early stage of the Earth (e.g. Kato and Kumazawa, 1985; Ito and Katsura, 1992). Almost all of these works have been carried out on the compositions ranging from MgO to MgSiO3, assuming that the bulk mantle composition is peridotitic or close to that derived from CI chondrite. Recently enstatite chondrite (E-chondrite) was proposed as the bulk earth source material (Javoy et al., 2010) because the isotope systematics over O, N, Mo, Re, Os, and Cr for the Earth and Moon are almost identical to that of E-chondrite. In E-chondrite, the silicate composition is characterized by MgO/SiO2 = 0.5 (in weight ratio) which is substantially lower than that of the peridotitic mantle (~0.85).
In this context, melting relations on compositions more SiO2 enriched than MgSiO3 are indispensable to clarify the mantle fraction. However, available information regarding phase relations in the system MgSiO3–SiO2 is so far limited to 1 GPa. In the present study, therefore, we would determine the melting relations at pressures 5 to 20 GPa, focusing on the compositions of MgO-xSiO2 (x = 0.8 to 1.2). We expect to present some new results.