在终点II期间直接确定海平面变化的时间
Christina D Gallup1, H Cheng, F W Taylor
1Department of Geological Sciences, University of Minnesota Duluth, Duluth, MN 55812, USA. cgallup@d.umn.edu
概括
珊瑚年代测定揭示了海平面在1.36万年前大幅上升,挑战了米兰科维奇理论对冰川周期的预测. 这一发现为过去的海平面变化和气候动态提供了新的见解.
科学领域:
- 海洋地质 海洋地质学
- 古气候学 古气候学
- 四分学科学 四分学科学
背景情况:
- 巴巴多斯的珊瑚化石提供了对过去海平面的洞察力.
- 最后的间冰期和前最后的脱冰期 (终结II) 是关键的研究领域.
- 了解冰川周期和海平面波动对于气候建模至关重要.
研究的目的:
- 准确地测定巴巴多斯珊瑚的年龄,以便在终结II期间重建海平面.
- 将重建的海平面与米兰科维奇理论的预测进行比较.
- 为了研究过去的冰川时期的深水温度.
主要方法:
- 化石珊瑚的联合230Th和231Pa放射测年法.
- 在珊瑚骨中分析氧同位素比率 (delta18O).
- 与现有的深海沉积物核心记录进行比较 (V19-30/V19-28).
主要成果:
- 135.8 +/- 0.8万年前的珊瑚石显示,海平面比现在低18 +/- 3米.
- 海平面已经上升到136,000年前的最后一个冰期间的峰值水平的20%之内.
- 来自氧同位素子阶段6e (168.0万年前) 的珊瑚显示海平面比现在低38 +/- 5米.
结论:
- 海平面上升13万6000年前与米兰科维奇理论的预测相矛盾.
- 轨道强迫和同静态调整可能影响了脱冰.
- 珊瑚数据证实冰川时期的深水温度较低,将这一结论扩展到之前的冰川周期.
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