Experimental Studies of Early Differentiation and Evolution of the Earth

地球早期分化和演化的实验研究

基本信息

批准号：
05102003
负责人：
ITO Eiji
金额：
$ 168.96万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Specially Promoted Research
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1996
项目状态：
已结题

项目摘要

In order to simulate the core segregation in a magma ocean (MO) extended deeper than 1000 km depth, we aimed to examine experimentally reactions and elemental partitioning between molten iron (MI) and silicates at ultrahigh pressures. Melting experiment at pressures higher than 30 GPa can be carried out by utilizing sintered diamond as anvil material of the splitsphere multi-anvil apparatus. Innovation of analytical method using a secondary ion mass spectrometer has made it possible to determine concentration of elements less than 1ppm over an area of 5mum diameter. Based on these newly developed methods, melting relations of silicate and iron silicate systems have been examined and the partitioning of major and trace elements between MI and silicate liquid (SL) or coexisting solid phases has been determined as function of pressure. Important results obtained in the present research are summarized as follows : (1) Liquidus phase of the primary Earth's material is magnesiow ustite (Mw) … More at the bottom of MO with depths of 600-1000 km. However, a very narrow temperature interval of the SL+Mw field suggests that perovskite (Pv) would also have coexisted with MI prior to core formation. (2) At higher than 20 GPa, dissolution of Si and O in MI from SL proceeds noticeably with pressure. Thus Mg/Si ratio of the mantle could remarkably be increased by the core segregation in a deep MO.(3) Partition co efficients of Mn, Ni, and Co between MI and SL,Mw, and Pv to 26 GPa indicate that Ni and Co abundance of the mantle can be explained if the core material would have been equilibrated with SL and Mw at the bottom of MO deeper than 900 km. However, the coexistence of Pv demands a much deeper MO.(4) It has been found that appreciable amounts of rare earth elements (REE) dissolve in MI from SL at pressures higher than 20 GPa with a remarkable fractionation between light and heavy REE,resulting in depletion in light REE in the primitive mantle after the core formation. The results are of crucial importance for the mantle chemistry because the relative abundace of REE for the primitive mantle have intuitively assumed so far to be same as those of chondrites. Less

为了模拟岩浆海洋（MO）中的核心隔离，深度深度延长了1000公里，我们旨在检查以超大压力下的熔融铁（MI）和硅酮之间的实验反应和元素分配。可以通过使用烧结的钻石作为拆分多孔仪的砧材料来进行超过30 GPA的压力实验。使用二级离子质谱仪对分析方法的创新使得在5MUM直径的面积上确定小于1ppm的元素的浓度成为可能。基于这些新开发的方法，已经检查了有机硅和铁硅胶系统的熔融关系，并确定了MI和有机硅液体（SL）之间的主要和痕量元件或共存实心相之间的分配，这是压力函数。在本研究中获得的重要结果总结如下：（1）原发地材料的液相阶段是Magnesiow ustite（MW）…更多在MO底部，深度为600-1000 km。但是，SL+MW场的非常狭窄的温度间隔表明，钙钛矿（PV）也将在核心形成之前与MI共存。（2）在高于20 GPA的情况下，Si和O中的Si和O从SL中溶解，并随着压力而明显进行。核心隔离在深莫（3）MI和SL，SL，MW，MW，MW，MW和PV之间的分区系数中，可以显着提高地幔的Mg/Si比。但是，PV的共存需要更深的mo。（4）发现，可欣赏的稀土元素（REE）在MI中溶于MI中，从SL中溶于MI中，在高于20 GPA的压力下，光线和沉重的REE之间的明显分数，导致核心形成后的光线内深度REE的深度REE。结果对于地幔化学具有至关重要的重要性，因为原始地幔的REE的相对抽象直观地假定与软骨的相同。