大气中二氧化碳水平的稳定性跨越了特里亚斯纪/罗纪的边界
L H Tanner1, J F Hubert, B P Coffey
1Department of Geography and Geosciences, Bloomsburg University, Bloomsburg, Pennsylvania 17815, USA. lhtann@sunlink.net
Nature
|June 8, 2001
概括
大气中的二氧化碳水平在纪/纪灭绝事件期间保持相对稳定. 这表明火山二氧化碳释放并不是大规模灭绝的主要驱动因素.
科学领域:
- 古气候学 古气候学
- 地质化学 地质化学
- 古生物学的古生物学
背景情况:
- 三叠纪/罗纪的边界 (在2.08亿年前) 标志着海洋和陆地大量灭绝的时期.
- 中亚大西洋岩地带 (CAMP) 泛滥的玄武岩喷发被假设是通过大规模的二氧化碳 (CO2) 释放和随后的温室气体变暖引起这些灭绝的原因.
- 证据将二氧化碳引起的变暖与这些物种灭绝联系在一起仍然是不确定的.
研究的目的:
- 为了重建大气中的二氧化碳度跨越三叠纪/罗纪边界.
- 评估火山二氧化碳排放在驱动观测到的灭绝中的作用.
主要方法:
- 从古岩石中获得的pedogenic石中碳同位素组成的分析.
- 应用标准扩散模型来解释同位素数据和估计大气二氧化碳水平.
主要成果:
- 估计大气中的二氧化碳在特里亚斯/罗纪边界上略有上升,大约为每百万分之250 (ppm).
- 这与之前的估计形成鲜明对比,这些估计表明二氧化碳增加的幅度要大得多 (2,0004,000 ppm).
- 数据表明,在这个关键时期,大气中的二氧化碳相对稳定.
结论:
- 这些发现挑战了火山二氧化碳排放是特里亚斯纪/罗纪灭绝的主要原因的假设.
- 环境退化和罗纪早期的灭绝可能是其他火山影响的结果,例如气溶释放或构造学诱导的海平面变化.
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