欧克里特石的结晶年龄
G Srinivasan1, M J Whitehouse, I Weber
1Department of Geology, University of Toronto, Toronto, ON, Canada, M5S 3B1. srini@geology.utoronto.ca
概括
尤克里特石在680万年内迅速形成,这表明了早期的行星变暖. 随后的变形很可能是由冲击造成的,而不是岩流,为早期太阳系过程提供了关键的时间限制.
科学领域:
- 行星科学 行星科学
- 宇宙化学 宇宙化学
- 早期太阳系时间表
背景情况:
- 欧克里特石是火性石,为早期行星分化和地质物理过程提供了洞察力.
- 它们代表了太阳系中最早的火热活动,类似于小行星4Vesta上的过程.
- 这些事件的日期有助于限制早期行星体的热史.
研究的目的:
- 为了准确地确定矿石的结晶和变形的日期.
- 了解太阳系早期的岩母体上的热条件和地质过程.
- 为了使用短寿命的放射性核素作为早期太阳系事件的精确计时器.
主要方法:
- 使用了短命的放射性核酸哈夫-182 (182Hf) 作为相对计时器.
- 在岩石中分析了石结晶的年龄.
- 确定了与石结晶有关的后期变态事件的时间.
主要成果:
- 在金属酸盐分化后的680万年内,欧克里特石迅速结晶.
- 当有足够的放射性衰变 (例如26Al,60Fe) 的内部热量时,就会发生地幔分化.
- 在石结晶后至少有890万年发生了欧基的变形,这表明与撞击有关的加热.
结论:
- 欧基岩的形成和地幔的分化是太阳系早期的快速事件.
- 冲击,而不是广泛的岩流,很可能是后来的岩变形的主要原因.
- 这项研究为早期行星体的地球物理演变提供了关键的时间限制.
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