Melting Relations in the System, CaO-MgO-Al_2O_3-SiO_2, at Ultra-high Pressure

超高压下CaO-MgO-Al_2O_3-SiO_2体系的熔融关系

• 批准号: 02452069
• 负责人: FUJII Toshitsugu
• 金额: $ 1.34万
• 依托单位: Earthquake Research Institute, University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02452069/
• 关键词: ultra-high pressure experiments; CaO-MgO-Al_2O_3-SiO_2 System; komatiite; generation of magmas; マントル物質

Melting relations of the mantle materials in the system, CaO-MgO-Al_2O_3-SiO_2, have been investigated with high pressure apparatus of MA-8 type. The compositions of melt coexisting with olivine, pyroxenes and garnet were estimated in the pressure range from 3 to 8 GPa based on the above experiments. CaO/Al_2O_3 ratio of the melt coexisting with the above four phases is almost unity up to 4 GPa and increases with increasing of pressure. This result indicates that komatiite magmas with CaO/Al_2O_3 ratio larger than unity can be formed by partial melting of peridotite or chondritic materials which are supposed to be primary materials for Earth and have CaO/Al_2O_3 ratio of unity.In order to apply the above results to the natural system, it is necessary to know the effect of other components on the partitioning of elements between melt and major mineral phases. From this view point, melting experiments on natural basalt system were also performed. The partitioning of major elements between garnet and melt does not change even the composition of garnet changes with increasing pressure. The partitioning of minor elements such as Na, however, changes drastically with increasing pressure. This may indicate that melting experiments should be done in the Nabering system addition to the above simple system.

用MA-8型高压装置研究了CaO-MgO-Al_2O_3-SiO_2系统地幔物质的熔融关系。在此基础上，估算了3 ~ 8 GPa压力范围内与橄榄石、辉石和石榴石共存的熔体的成分。在4GPa以下，与上述四种相共存的熔体的CaO/Al_2O_3比值几乎为1，并随压力的升高而增大。这一结果表明，CaO/Al_2O_3大于1的科马提岩岩浆可能是由CaO/Al_2O_3为1的橄榄岩或橄榄岩类物质部分熔融而形成的，为了将上述结果应用于自然体系，有必要了解其他组分对熔体与主要矿物相之间元素分配的影响。从这一角度出发，对天然玄武岩体系进行了熔融实验。即使石榴石的成分随着压力的增加而改变，主量元素在石榴石和熔体之间的分配也不会改变。然而，Na等微量元素的分配随着压力的增加而急剧变化。这可能表明，除了上述简单系统外，熔化实验还应在Nabering系统中进行。

项目成果

Yasuda,A.,Fujii,T.and Kurita,K.: "A fate of subducted oceanic crust:(I)Implications for the genesis of continental flood basalts." P.E.P.I.

安田，A.，藤井，T.和栗田，K.：“俯冲洋壳的命运：(I)对大陆溢流玄武岩成因的影响。”

Yasuda, A., Fujii, T. and Kurita, K.: "A fate of subducted oceanic crust : (I) Implications for the genesis of continental flood basalts." Phys. Earth Planet. Int.

Yasuda, A.、Fujii, T. 和 Kurita, K.：“俯冲洋壳的命运：(I) 对大陆溢流玄武岩成因的影响。”

Fujii,T.,Yasuda,A.and Kurita,K.: "Compositions of incipient melt in the system,CaOーMgOーAl_2O_3ーSiO_2,at ultraーhigh pressure" E.P.S.L.

Fujii, T., Yasuda, A. 和 Kurita, K.：“超高压下体系中初熔体的成分，CaO－MgO－Al_2O_3－SiO_2” E.P.S.L.

Yasuda,A.,Fujii,T.and K.Kurita: "A New technique for in situ oxygen fugacity measurement at higt pressure" American Mineralogist.

Yasuda,A.、Fujii,T. 和 K.Kurita：“高压下原位氧逸度测量新技术”美国矿物学家。

Fujii,T.,Yasuda,A.and Kurita,K.: "Compositions of incipient melt in the system,CaO-MgO-Al_2O_3-SiO_2,at ultra-high pressure" E.P.S.L.

Fujii，T.，Yasuda，A.和Kurita，K.：“超高压下体系中初熔体的成分CaO-MgO-Al_2O_3-SiO_2”E.P.S.L。