在地球上巨大的硫酸盐沉积物中异常的17O成分
H Bao1, M H Thiemens, J Farquhar
1Department of Chemistry and Biochemistry, University of California San Diego, La Jolla 92093, USA. hbao@chem.ucsd.edu
Nature
|July 26, 2000
概括
氧同位素的质量独立分离,以前只在石中发现,现在在地球的大型硫酸盐沉积物中发现. 这一发现可能有助于追踪大气中的硫氧化,并了解行星同位素异常.
科学领域:
- 地质化学 地质化学
- 同位素地球化学 同位素地球化学
- 行星科学 行星科学
背景情况:
- 氧同位素 (三角洲18O和三角洲17O) 通常在陆地材料中显示质量依赖分化 (MDF).
- 质量独立分离 (MIF) 在地球上很少见,主要在石和一些大气物质中观察到.
- 从历史上看,陆地固体至少在37亿年内坚持MDF.
研究的目的:
- 为了调查在陆地巨型硫酸盐沉积物中存在质量独立分成的存在.
- 探索观察到的氧同位素异常的潜在来源和影响.
- 评估这些发现对于理解外星同位素变异的相关性.
主要方法:
- 在巨型硫酸盐矿床中分析氧同位素值 (delta 18O和delta 17O).
- 来自吉普克特 (纳米布沙漠) 和米奥森火山灰床 (北美) 的同位素数据的比较.
- 评估与预期的质量依赖分离关系的偏差.
主要成果:
- 在陆地硫酸盐沉积物中发现了显著的氧同位素异常 (多达4.6%在三角洲17O).
- 这些异常表明地球表面环境中的质量独立分离.
- 这些发现挑战了长期以来在陆地固体中普遍存在MDF的假设.
结论:
- 在地球的大型硫酸盐沉积物中存在质量独立的分化,这与以前的理解相反.
- 观察到的异常可能源于大气中的硫氧化反应.
- 这项研究提供了对行星化学过程和其他行星 (如火星) 的同位素异常的洞察.
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