火星上的大气-表面相互作用:delta 17O测量了ALH 84001中的碳酸盐
J Farquhar1, M H Thiemens, T Jackson
1Department of Chemistry, University of California San Diego, 92093-0356, USA. jfarquha@ucsd.edu
概括
火星石ALH 84001揭示了火星大气和酸盐行星中明显的氧同位素储备. 这表明大气过程,如臭氧光分解,在碳酸盐矿物中创建了记录的同位素异常.
科学领域:
- 行星科学 行星科学
- 地质化学 地质化学
- 天体生物学 天体生物学
背景情况:
- 火星石为了解火星的地质和大气历史提供了重要的样本.
- 矿物中的氧同位素是行星过程和环境条件的敏感标记物.
研究的目的:
- 为了研究来自火星石ALH 84001的碳酸盐的氧同位素组成.
- 为了确定在碳酸盐形成期间火星上是否存在明显的氧同位素储库.
- 探索火星上大气氧同位素异常的潜在机制.
主要方法:
- 在ALH 84001的碳酸盐中分析氧同位素比率 (delta18O,delta17O,delta17O).
- 将火星碳酸盐同位素数据与已知的陆地和潜在的火星酸盐储库进行比较.
主要成果:
- 碳酸氧同位素测量 (delta18O = 18.3 ± 0.4 ‰,delta17O = 10.3 ± 0.2 ‰,Delta17O = 0.8 ± 0.05 ‰) 显示相对于矿物质的分化.
- 这些结果支持在碳酸盐形成时,火星上至少存在两个不同的氧同位素储库:大气和酸盐行星.
- 大气异常的潜在机制包括来自臭氧光分解的二氧化碳和激发氧气 (O(1D)).
结论:
- 来自ALH 84001碳酸盐的氧同位素数据表明火星大气的复杂同位素进化.
- 大气中的同位素特征可以通过CO2-H2O交换和矿物沉转移到地表矿物中.
- 为了平衡观测到的同位素成分,需要一个17O贫氧的海底,可能在火星的规流层内.
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