Dynamic Precesses of Material Transport and Transformation in the Earth's Interior

地球内部物质传输和转化的动态过程

• 批准号: 63114002
• 负责人: MARUMO Fumiyuki
• 金额: $ 5.76万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Special Project Research
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63114002/
• 关键词: earth's interior; high-pressure; high temperature experiment; insitu observation; high temperature transmission electron microscope; garnet; perovskite; pyroxene; 地球; 物質移動; material transport

1. The following evidences have been revealed on formations and changes of materials accompanying large scale material transport in the earth's interior.(1) Ultra-high pressure, high temperature experiments on MgSiO_3 showed that hte teteagonal garnet with ordered arrangements of Mg and Si over the octahedral sites ahs a wide stable retion ranging from 1600 C to the congruent melting temperature and from 17 GPA to the transition temperature to perovskite. The tetragonal garnet is more dense than the AL-free cubic garnets and in a higher entropy state than perovskite.(2) The density of anhydrous basalt magmas increases almost linearly with increasing pressure up to 1.2 GPa. Under such condition, even calcic plagioclase floats upwards in the fractionating magma. On the other hand, the density of basalt magma becomes smaller in the presence of 3 wt% H_2O than that of intermediate plagioclase, and the crystallizaed plagioclase woulk sink even in the lower crust.2. The following results have been obtained on crystallization and transformation of minerals with atomic scale investigations.(1) Equimpents have been developed for in-situ observation of nucleation, growth and dissolution of silicate and oxide crystals at high temperatures up to 1600 C. Employing these equipments, retes of nucleation, crystal growth and dissolution were determined on conpouns such as Di_<85>En_<15>.(2) A high temperature transmission electron microscope was constructed for in-situ observation of phase transformations. The processes of laihunite formation from olivine, and of the phase transitions of pyroxenes and cordierite were revealed at atomic scale.(3) Local structures around transition-element atoms in silicate melts and glasses were investigated, showing correlations to structures of crystals appearing from the melts.3. Non-empirical SCF-MO calculation resulted in realistic two-body central potential in SiO_2 ready to use in the molecular dynamics calculations.

1.揭示了伴随地球内部大规模物质输运的物质形成和变化的证据。(1)MgSiO_3的超高压高温实验表明，Mg、Si在八面体位置上有序排列的四方石榴石在1600 ℃至同成分熔化温度和17 GPA至钙钛矿转变温度范围内具有较宽的稳定性。四元石榴石比无铝立方石榴石更致密，并且比钙钛矿处于更高的熵态。(2)无水玄武岩岩浆的密度随压力的增加几乎呈线性增加，直到1.2 GPa。在这种条件下，即使含钙斜长石也会在岩浆的分馏中上浮。另一方面，在3wt%H_2O存在下，玄武岩岩浆的密度比中间斜长石的密度小，结晶后的斜长石即使在下地壳中也会下沉.用原子尺度研究矿物的结晶和转变，获得了下列结果。(1)已研制出用于在高达1600 ℃的高温下原位观察硅酸盐和氧化物晶体的成核、生长和溶解的装置。利用这些装置，对Di_ En_等离子体的成核速率、晶体生长速率和溶解速率进行了测定<85><15>。(2)建立了高温透射电子显微镜，用于原位观察相变。从原子尺度上揭示了橄榄石形成莱芜石的过程，以及辉石和堇青石的相变过程。(3)研究了硅酸盐熔体和玻璃中过渡元素原子周围的局域结构，发现其与熔体中出现的晶体结构之间存在相关性.非经验的SCF-MO计算得到了SiO_2中真实的二体中心势，为分子动力学计算提供了理论依据。