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在普莱斯托时代中期过渡时期的热环流危机和影响
Leopoldo D Pena1, Steven L Goldstein2
1Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, USA. leopoldo@ldeo.columbia.edu.
概括
普莱斯托时代中期的过渡 (MPT) 破坏了海洋热环流 (THC),使其显著减弱. 这种循环危机促进了冰盖的增长,稳定了10万年的冰川周期.
科学领域:
- 古气候学 古气候学
- 海洋学 海洋学 海洋学
- 地质化学 地质化学
背景情况:
- 普莱斯托时代中期的过渡 (MPT) 将冰川 - 间冰川周期从~41kyr转移到~100kyr周期.
- 这种转变在米兰科维奇强迫中没有发生显著变化,这表明其他地球系统反也参与其中.
研究的目的:
- 在MPT期间调查海洋热环流 (THC) 的作用.
- 为了确定与100-kyr周期的出现相关的THC变化.
主要方法:
- 在海洋沉积物中分析 (Nd) 同位素.
- 过去海洋循环模式的重建.
主要成果:
- 在MPT期间发生了THC的重大破坏和削弱,特别是在海洋同位素阶段 (MISs) 25和21 (~950860 ka) 之间.
- 在23年间冰川期 (~900万年前) 观察到THC的异常减弱.
- 在MPT后的THC恢复的特点是冰川时期的持续疲软.
结论:
- 标志着THC减弱的MPT海洋循环危机是过渡到100kyr周期的关键因素.
- 这场危机促进了大气二氧化碳的吸收和高度冰盖的增长,稳定了更长的周期.
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