Experimental study on the melting relation of silicate under the lowermost mantle condition

下地幔条件下硅酸盐熔融关系的实验研究

基本信息

批准号：
16340164
负责人：
KONDO Tadashi
金额：
$ 10.56万
依托单位：
Osaka University (2006)Tohoku University (2004-2005)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

In this research project, we investigated the phase relation of the minerals under the lowermost mantle condition and the chemical reaction between those minerals and molten iron up to the condition corresponding to the earth's core-mantle boundary. For realizing such extreme conditions, we newly designed a symmetrical diamond anvil cell with a wide conical window for laser-heating and optical spectroscopy. The laser-heating system was also refined for stable heating and optimal temperature measurement from the hot sample by a spectroradiometric method. Experiments were performed using these techniques at SPring-8 and Photon Factory for in-situ X-ray diffraction measurements at high P-T, and also at laboratory for recovery runs to check the quenched samples. Thanks for the recent advances in micro-processing technologies such as laser cutting, focused ion beam, we successfully prepared the thin section of the recovered samples for analytical transmission electron microscopy. Finally we … More obtained the following results. (1) The chemical reaction between molten iron and perovskite and post-perovskite phase and wetting property at the core-mantle boundary condition was examined, and silicon and oxygen turned to be important candidates as light elements in the outer core. The wetting angle between post-perovskite phase and molten iron was slightly higher than the critical angle of 60°, which means 2wt% of the core material can be trapped in the D" layer. (2) Magnesiowustite is the heaviest minerals overall the mantle based on the iron partitioning experiments between magnesium oxide and silicate perovskite and post-perovskite phase. No evidence for the effect of a high-spin to low-spin transition was found in these minerals. (3) Potassium can be dissolved into molten iron significantly at core-mantle boundary condition, and the element may work as a heat source in the core. (4) The hydrous mineral, delta-AIOOH, has a wide stability field over 100GPa and 2000K, therefore this phase at relatively low temperature condition in descending slab possibly survive to the lowermost mantle to supply the water to core-mantle boundary. (5) Potassium bearing silicate with post-hollandite structure can be stably exist at the lowermost mantle condition. Less

在这个研究项目中，我们研究了最低地幔条件下矿物的相关系以及这些矿物与铁水之间的化学反应，直到对应于地球核心-地幔边界的条件，为了实现这种极端条件，我们重新设计了。具有用于激光加热和光学光谱的宽锥形窗口的对称金刚石砧池还对激光加热系统进行了改进，以通过光谱辐射方法进行热样品的稳定加热和最佳温度测量。这些技术在 SPring-8 和 Photon Factory 中用于高 P-T 下的原位 X 射线衍射测量，并且在实验室中用于恢复运行以检查淬火样品，这要归功于激光切割等微加工技术的最新进展。聚焦离子束，我们成功地制备了回收样品的薄片用于分析透射电子显微镜，最终我们得到了以下结果：（1）铁水与钙钛矿和后钙钛矿相之间的化学反应。并考察了核幔边界条件下的润湿特性，硅和氧成为外核中轻元素的重要候选者，后钙钛矿相与铁水之间的润湿角略高于60°的临界角。 °，这意味着 2wt% 的核心物质可以被困在 D" 层中。 (2) 根据氧化镁和氧化镁之间的铁分配实验，镁方铁矿是整个地幔中最重的矿物。在这些矿物中没有发现高自旋到低自旋转变的影响的证据。（3）钾可以在核幔边界条件下显着溶解到铁水中，并且该元素。 (4) 含水矿物 delta-AlOOH 具有超过 100GPa 和 2000K 的宽稳定场，因此该相处于相对较低的温度。下降板片的温度条件可能存留到最下地幔，为核幔边界提供水。 (5) 含钾硅酸盐可以在最下地幔条件下稳定存在。