SGER: An Impact Event at the Onset of the Younger Dryas: Search for Evidence from the Western United States and Europe

这项拟议的工作将测试较年轻的仙女木(大约12,900年前)的出现是否是由劳伦蒂冰盖上的彗星撞击造成的。特别是，该小组将试图确定1)在许多地点发现的年轻仙女木底部的铁球的磁性是否与彗星撞击形成的一致，2)在美国西部的湖泊序列中是否可以找到撞击事件喷出物的证据，在那里已经知道存在年轻仙女木边界，但尚未寻找撞击的证据，以及3)与年轻仙女木相关的欧洲单位底部的暗层是否包含与假设一致的物质。科学价值：有足够的物理证据证明年轻仙女木开始时的影响，因此似乎有必要进行仔细的额外工作。如果这一假设是正确的，它将使我们对气候突然变化的原因的理解发生根本性的变化。更深远的影响：大规模的全球气候变化的原因和后果仍然没有得到很好的理解。为最近一次重要的全球气候事件找到一种新的机制，将极大地促进我们对推动气候变化的过程的了解。它还将提供关于现代气候变化将如何受到类似过程影响的基本见解。

The proposed work will test whether the onset of the Younger Dryas (about 12,900 years ago) was caused by a cometary impact over the Laurentide Ice Sheet. In particular, the team will seek to determine 1) whether the magnetic properties of iron spherules found at the based of the Younger Dryas at many sites are consistent with formation from a cometary impact, 2) whether evidence for ejecta from the impact event can be found in lacustrine sequences in the western United States where the Younger Dryas boundary is already known to be present but where evidence for an impact has not yet been sought, and 3) whether a dark layer at the base of unit in Europe that has correlated with the Younger Dryas contains material that would be consistent with the hypothesis.Scientific Merit: There is enough physical evidence for an impact at the onset of the Younger Dryas that careful additional work seems warranted. If the hypothesis is correct, it will produce such a fundamental change in our understanding of the causes of abrupt climate change.Broader Implications: The causes and consequences of large-scale, global climatic change are still not well-understood. Finding a new mechanism for an important, recent, global climate event will significantly advance our knowledge of the processes that drive climatic variations. It will also provide fundamental insights into how modern climatic variations will be affected by similar processes.