The effect of the oceans on the terrestrial crater size-frequency distribution: Insight from numerical modeling
The effect of the oceans on the terrestrial crater size-frequency distribution: Insight from numerical modeling
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DOI：
10.1111/j.1945-5100.2007.tb00550.x
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发表时间：
2007-11-01
影响因子：
2.2
通讯作者：
Collins, Gareth S.
中科院分区：
文献类型：
--
作者：
Davison, Thomas;Collins, Gareth S.
在地球上，海洋撞击发生的可能性是大陆撞击的两倍，然而，在估计陆地陨石坑的大小-频率分布时，海洋的影响尚未被考虑在内。尽管最近通过新颖的实验室实验、详细的数值模拟以及对地质和地球物理数据的解释，在理解水层对撞击过程的定性和定量影响方面取得了进展，但撞击物属性、水深和最终陨石坑直径之间没有确定的关系。在本文中，我们利用数值撞击模型的结果确定了最终（和瞬态）陨石坑直径与水深与撞击体直径之比之间的关系。这种关系适用于石质小行星以15公里/秒（-1）的速度撞击水覆盖的结晶海洋地壳的正常发生率。我们利用这些关系构建了陆地陨石坑大小-频率分布（过去1亿年）的第一个估计，其中考虑了地球上海洋的深度分布。我们发现，海洋使直径小于1公里的陨石坑数量减少了约三分之二，使直径类似于30公里的陨石坑数量减少了约三分之一，而对于直径大于类似于100公里的陨石坑，海洋几乎没有影响。直径超过12公里的陨石坑在海底比在陆地上多；在这个直径以下，陆地上形成的陨石坑比海洋中多。我们还估计，在过去的1亿年里，该地区发生了150次撞击事件，形成了与撞击相关的复苏特征，或对海底的扰动，而不是陨石坑。
On Earth, oceanic impacts are twice as likely to occur as continental impacts, yet the effect of the oceans has not been previously considered when estimating the terrestrial crater size-frequency distribution. Despite recent progress in understanding the qualitative and quantitative effect of a water layer on the impact process through novel laboratory experiments, detailed numerical modeling, and interpretation of geological and geophysical data, no definitive relationship between impactor proper-ties, water depth, and final crater diameter exists. In this paper, we determine the relationship between final (and transient) crater diameter and the ratio of water depth to impactor diameter using the results of numerical impact models. This relationship applies for normal incidence impacts of stoney asteroids into water-covered, crystalline oceanic crust at a velocity of 15 km s(-1). We use these relationships to construct the first estimates of terrestrial crater size-frequency distributions (over the last 100 million years) that take into account the depth-area distribution of oceans on Earth. We find that the oceans reduce the number of craters smaller than I kin in diameter by about two-thirds, the number of craters similar to 30 km in diameter by about one-third, and that for craters larger than similar to 100 km in diameter, the oceans have little effect. Above a diameter of similar to 12 km, more craters occur on the ocean floor than on land; below this diameter more craters form on land than in the oceans. We also estimate that there have been in the region of 150 impact events in the last 100 million years that formed an impact-related resurge feature, or disturbance on the seafloor, instead of a crater.