爆发岩石中的稀有气体系统学:在上层地幔中的同位素和元素组成
1Universite Denis Diderot-Paris 7, Laboratoire de Geochimie et Cosmochimie, Institut de Physique du Globe de Paris, CNRS Unite de Recherche Associee Number 1758, 4 Place Jussieu, 75252 Paris Cedex 05, France.
概括
关于爆发岩石中稀有气体同位素的新研究表明,地球上层地幔具有较低的40Ar/36Ar比率 (<44,000) 和129Xe/130Xe比率 (<8.2). 这表明地球是由行星体形成的,它们改变了它们的气体成分.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 行星科学 行星科学
背景情况:
- 了解地球大气层和地幔组成的起源和演变至关重要.
- 高贵气体 (,,) 为行星形成过程提供了独特的标记物.
- 以前的模型建议地球原始大气的不同同位素组成.
研究的目的:
- 为了研究在爆裂岩石中稀有气体的同位素和元素丰度模式.
- 为了限制地球上层地幔的40Ar/36Ar比率.
- 推断地球构成块的性质及其气体演变.
主要方法:
- 对,和的同位素变异的分析.
- 测量稀有气体的元素丰度.
- 在行星积累模型的背景下解释数据.
主要成果:
- 据估计,上层地幔中的40Ar/36Ar比率小于44,000.
- 确定129Xe/130Xe比率小于8.2. 这一比率不等于8.2.
- 稀有气体的元素丰富性模式是象形状的,与太阳模式有很大不同.
结论:
- 地球很可能来自行星体,它们在稀有的气体预算中经历了转变.
- 这种转变使气体成分从类似太阳的转变为类似体的.
- 尽管发生了这种转变,地幔中稀有气体的同位素组成可能与太阳模式基本保持不变.
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