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Evaporation Experiments on Planetary Materials.

行星材料的蒸发实验。

基本信息

批准号：
07454132
负责人：
TSUCHIYAMA Akira
金额：
$ 4.48万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454132/
关键词：
evaporation condensation metallic iron troilite solicate melts chondrules primordial solar nebula kinetics 鉱物脱水

项目摘要

It has been believed that evaporation and condensation processes playd important roles in differentiation of materials during the formation of the solar system. The following results were obtained in the present project in relation to the above topics.(1) Experimental techniques for exactly obtaining time variation in the amounts of evaporation and condensation by using ultra-high temperature thermal balance to discuss their kinetics strictly were developed. First of all, dehydration experiments on hydrous silicate minerals and glass were carried out, and it was confirmed that kinetics of dehydration, wthich is regarded as incongruent evaporation of water, can be discussed by time variation in the amouts of dehydration. Evaporation experiments of alkalies (Na and K) on silicate melts were carried out at low pressures, and the evaporation rates were successfully obtained.(2) A new model on evaporation of Na from silicate melts and origin of chondrules was proposed. It was shown that chondrule formation is possible not only by open-system flash heating mechanism which has been proposed previously but by closed-system gradual heating. This gave a new viewpoint on the chondrule formation issue.(3) Evaporation experiments on Fe-S minerals (metallic iron and troilite) were done, and their kinetics (modes and rates) were obtained. Evaporation rates of these minerals in the primordial solar nebula were estimated based on the present results, and the Fe/S fractionation in the primordial solar nebula was discussed by combining a model for formation of a protoplanetary disk with the evaporation data.

人们一直认为，在太阳系的形成过程中，蒸发和凝结过程在物质分化过程中起着重要的作用。(1)发展了利用超高温热天平对蒸发量和冷凝量的时间变化进行精确测量的实验技术，并对其动力学进行了严格的讨论。首先，对含水硅酸盐矿物和玻璃进行了脱水实验，证实了脱水动力学可以用脱水量随时间的变化来讨论，该动力学可以看作是水的不一致蒸发。在低压下进行了碱(Na、K)在硅酸盐熔体上的蒸发实验，成功地获得了蒸发速率。(2)提出了钠在硅酸盐熔体中蒸发的新模型和球粒陨石的成因。结果表明，球粒陨石的形成不仅可以通过先前提出的开放系统闪蒸加热机制，也可以通过闭合系统的逐步加热来实现。对铁质S矿物(金属铁和铁闪锌矿)进行了蒸发实验，得到了它们的蒸发动力学(模式和速率)。在此基础上估算了这些矿物在原始太阳星云中的蒸发速率，并结合原行星盘形成模型和蒸发数据讨论了原始太阳星云中的Fe/S分馏。