400万年前的马里诺亚雪球显示了多条通往脱冰的路线
Adrian R Tasistro-Hart1, Francis A Macdonald1, James L Crowley2
1Department of Earth and Planetary Science, McCone Hall, University of California, Berkeley, CA 94720.
概括
马里诺斯雪球地球冰期持续了大约400万年,比以前认为的要短. 这个短暂的时间可能对动物进化和行星可居住性至关重要.
科学领域:
- 古气候学 古气候学
- 新原生态时期的地质学.
- 星球上的可居住性.
背景情况:
- 地球经历了两次重大变化.
- 地球雪球地球的雪球.
- 在新新生态时代发生的事件:斯图尔特和马里诺冰川.
- 这些冰期涉及低度的广泛冰盖,大气中的二氧化碳 (CO2) 通过火山排气积累,最终导致脱冰.
- 斯图尔特冰期的持续时间是明确的 (56亿年),但马里诺冰期的持续时间具有显著的不确定性 (415亿年).
研究的目的:
- 为了准确地确定马里诺海冰期的持续时间.
- 为了研究在马里诺冰期期间冰的接地线的稳定性.
- 为了比较斯图尔特和马里诺的雪球地球事件之间的脱冰机制.
主要方法:
- 纳米比亚地质记录的放射性同位素测年.
- 在冰川前进-后退周期中分析冰的接地线运动.
主要成果:
- 纳米比亚的马里诺海冰期持续了大约400万年.
- 在冰川周期期间,冰的接地线运动是最小的 (<10 m).
- 短暂的持续时间表明,脱冰是由辐射扰动驱动的,与斯图尔特冰川较慢的二氧化碳积累形成鲜明对比.
结论:
- 马里诺冰川期比斯图尔蒂冰川期要短得多.
- 冰的接地线的稳定性支持一个冰的接地线.
- 一个硬的雪球.
- 一个具有强烈歇斯底里症的状态.
- 马里诺冰川短暂的持续时间可能对动物的进化至关重要,并提供了对系外行星可居住性的见解.
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