Study on deep structure and dynamics of the mantle by calorimetric measurements of high pressure silicates

高压硅酸盐量热测量研究地幔深层结构和动力学

• 批准号: 03453058
• 负责人: AKAOGI Masaki
• 金额: $ 5.18万
• 依托单位: Gakushuin University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03453058/
• 关键词: Mantle; High pressure; Calorimetry; Phase transition; Element Partition; Enthalpy; Heat capacity; Perovskite; 相転〓; オリビン; MgSiO_3ペロブスカイト; ホランダイト; カルシウムフェライト; 転移エンタルピ-; MgSiO_3ザクロ石; Mantle; High pressure; Calorimetry; Phase transition; Element Partition; Enthalpy; Heat capacity; Perovskite; 相転〓; オリビン; MgSiO_3ペロブスカイト; ホランダイト; カルシウムフェライト; 転移エンタルピ-; MgSiO_3ザクロ石

Main research results of this project are as follows.1. Heat capacity and enthalpy of MgSi0_3 perovskite were mesured, using the perovskite sample synthesized at very high pressure and high temperature. Based on the measured thermo dynamic properties, phase boundary of dissoication of Mg_2SiO_4 spinel to MgSiO_3 perovskite plas MgO was precisely determined. The slope of the boundry suggests that the upper mantle and lower mantle convect separatery but intermittant convection occurs between them. An adiabatic geotherm in the lower mantle and the temperature at the lowermost mantle were estimated, using the heat capacity of MgSiO_3 perovskite.2. Transition enthalpy of MgSiO_3 garnet was measured using the sampie synthesized at very high pressure and high temperature, and the phase equiliblium boundar were calculated. It eas suggetsed from the phase diagram that the garnet-perovskite transition which occurs in the descending lithoshere promotes the subduction.3. Effect of pressure was observed on the partition coefficients of Ni, Mn and Co between metallic iron and silicates at high pressure and hgih temparature. This result suggests that the pressure effect should be incoporated in geochemical model of the core-mantle separation.Enthalpy measurements of MgSio_4-Fe_2SiO_4 olivine solid solution showed that nonideality of the olivine solid solution was symmteric with to respect to composition and the nonideality parameter was detemined.5. Stability fields of hollandite solid solution in the system KAISi_3O_8-NaAISi_3O_8 and of a new hexagonal(Mg, Ca)AI_2O_4 phase were detemined at high pressure and high temparature.These aluminous phases may be stable in the transition zone and the lower mantle.

该项目的主要研究结果如下1。使用在非常高的压力和高温下合成的钙钛矿样品，将MGSI0_3钙钛矿的热容量和焓固定。基于测得的热动态特性，精确确定了MG_2SIO_4尖晶石对MGSIO_3的溶液的相边界。边界的斜率表明，上地幔和下地幔对流分隔板，但它们之间发生了间歇对流。使用MGSIO_3 Perovskite的热容量，估算了下地幔中的绝热地理和最低地幔的温度。2。使用在非常高压和高温下合成的Sampie测量MGSIO_3石榴石的过渡焓，并计算了相位平衡边界。从相图中可以看出，发生在降岩石岩石中的石榴石 - 栖息地过渡会促进俯冲3。在高压和HGIH温度下，在金属铁和硅酸盐之间观察到压力的影响对Ni，Mn和CO的分区系数的影响。该结果表明，压力效应应在核心掩体分离的地球化学模型中不合同。MGSIO_4-FE_2SIO_4橄榄石固体溶液的触觉测量表明，橄榄石固体溶液的非理想性与成分和非理想参数相对。荷兰石固体溶液在系统KAISI_3O_8-NAAISI_3O_8和新的六角形（MG，CA）AI_2O_4相的稳定场在高压和高温下被victement。