Experimental study of condensation process of minerals in the primodial solar nebula.

原始太阳星云矿物凝结过程的实验研究。

基本信息

批准号：
61540590
负责人：
TSUCHIYAMA Akira
金额：
$ 1.41万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540590/
关键词：
Primodial solar nebula Condensation Silicate minerals Solid planets Meteorites Ostwald ripening Vacuum furnace for vaporization and condensation Reproduction experiments of condensation Olivine VLS mechanism Whiskers Heterogeneous nu

项目摘要

Condensation of mineral grains from gas at high temperatures took place in the primodial solar nebula, and solid planets and meteorites were formed by accretion of these grains. In the present research project, the following experiments on condensation were carried out to understand the primodial solar nebula; (1) condensation experiments of forsterite, (2) reaction experiments between olivine and Si-rich gas, and (3) coarsening experiments of olivine.(1) A new vacuum furnace, in which silicates are volatilized by heating and condensation takes place from the gas, was specially designed. By using this furnace, experiments were carried out in the system Mg_2SiO_4-H_2, which mimics the solar composition. Conditions for the condensation were determined, and it was concluded that the condensation is mainly controlled by temperature and forsterite whiskers can grow by the VLS mechanism. Condensates in the system MgSIO_3-H_2 produced at Carnegie Institution, U.S.A. were also examined. It was concluded that heterogeneous nucleation would play an important role in the condensation process.(2) Reaction between condensates and residual gas is another important process during the condensation. Preliminary experiments on reaction between olivine and Si-rich gas indicate that the reaction hardly took place for olivine crystals larger than the order of 1 um.(3) The crystal size is one of the most important factor not only for the reaction kinetics but also for solid-gas fractionation. Preliminary experiments using forsterite crystals indicate that coarsening due to Ostwald ripening was not effective even in slowly cooled nebula.

原始太阳星云中气体中的矿物颗粒在高温下凝结，这些颗粒的吸积形成了固体行星和陨石。在本研究项目中，为了了解原始太阳星云，进行了以下凝结实验； (1)镁橄榄石的缩合实验，(2)橄榄石与富硅气体的反应实验，(3)橄榄石的粗化实验。(1)一种新型真空炉，其中硅酸盐通过加热挥发，发生缩合。气体是专门设计的。利用该炉在模拟太阳成分的Mg_2SiO_4-H_2体系中进行了实验。确定了缩合条件，得出缩合主要受温度控制，镁橄榄石晶须通过VLS机制生长的结论。对美国卡内基研究所生产的MgSIO_3-H_2系统中的冷凝物也进行了检测。结果表明,异相成核在冷凝过程中起重要作用。(2)冷凝液与残余气体的反应是冷凝过程中的另一个重要过程。橄榄石与富硅气体反应的初步实验表明，大于1 um量级的橄榄石晶体几乎不发生反应。(3)晶体尺寸不仅是影响反应动力学的最重要因素之一，也是影响反应动力学的重要因素之一。用于固气分馏。使用镁橄榄石晶体的初步实验表明，即使在缓慢冷却的星云中，由于奥斯特瓦尔德成熟而导致的粗化也不是有效的。