同位素历史上Cenozoic海水:在酸盐气候变化和逆气候变化的变化
Sambuddha Misra1, Philip N Froelich
1National High Magnetic Field Laboratory, and Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL 32310, USA. sm929@cam.ac.uk
Science (New York, N.Y.)
|January 28, 2012
概括
一个6800万年的同位素记录揭示了由构造上升驱动的大陆气候变化如何影响海洋化学和气候. 这项研究将地质力量与地球联系起来.
科学领域:
- 地质化学 地质化学
- 古气候学 古气候学
- 同位素地球化学 同位素地球化学
背景情况:
- 大陆岩石的气候变化消耗大气中的二氧化碳,并将离子转移到海洋,影响海水化学和全球气候.
- 海水的化学变化可以反映出构造力量的变化,但直接档案很少.
- 海水中的同位素 (δ(7) Li(SW)) 为跟踪这些地球海洋气候过程提供了潜在的代理.
研究的目的:
- 重建海水同位素的长期 (6800万年) 记录.
- 在地质时间尺度上研究构造升起,大陆风化和海水化学之间的关系.
- 了解二氧化碳减少的驱动因素及其与地球地质演变的联系.
主要方法:
- 使用浮游生物类植物为档案的海水同位素组成 (δ(7) Li(SW)) 的重建.
- 对从古世到今天的同位素变异的分析.
- 对气候变化过程和构造影响进行建模,以解释同位素变化.
主要成果:
- 一个6800万年记录的δ(7)Li(SW) 显示,从古世到现在,每毫升 (‰) 增加了9个.
- 这种上升表明大陆气候变化和海底逆气候变化的显著变化.
- 在白纪-古纪的边界上,石南值明显下降了5‰,这表明大规模的大陆脱皮,不能归因于冲击事件或火山活动.
结论:
- 在过去的6800万年中,不断增加的构造上升和大陆脱落导致了大陆气候强度和二氧化碳吸收的重大变化.
- 海水同位素作为一种有价值的档案,用于理解构造学,气候变化和气候之间的相互作用.
- 纪-古纪边界同位素转移指向影响地球地质化学循环的重大地质事件.
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