Numerical simulations of the Mjlnir marine impact crater
Numerical simulations of the Mjlnir marine impact crater
复制标题
Mjlnir 海洋撞击坑的数值模拟
DOI：
10.1029/2001je001698
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发表时间：
2002
影响因子：
--
通讯作者：
F. Tsikalas
中科院分区：
文献类型：
--
作者：
V. Shuvalov;H. Dypvik;F. Tsikalas
[1]巴伦支海直径40公里的Mjolnir陨石坑是由流星体撞击到400米的浅海中造成的，大约142 Ma。我们已经使用了一个多材料流体动力学代码与深度依赖的目标强度的Mjolnir影响的成坑和早期修改阶段的数字模型。我们的模型受到所观察到的陨石坑形态和结构的限制。复合目标强度结构获得了最佳结果：沉积岩上部3公里的强度非常低，从3公里到6.5公里深度逐渐增加，然后使用更深处花岗岩的典型强度值。浅层目标沉积物的强度低，导致异常强烈的滑塌和重力塌陷，约为2.0-2.5，远远大于典型陆地陨石坑的平均预期值。因此，我们得到了一个介于简单和复杂之间的火山口塌陷，其中滑塌和重力塌陷抵消了火山口底部的隆起，并导致中央高压的抑制和掩埋。Mjolnir在浅海中的撞击造成了水柱的重大扰动。在撞击引发的向外水涌之后，形成了大幅度的海啸，海水迅速回流到挖掘出的火山口中，将大量的喷出物和火山口壁材料送回火山口，这是喷出物材料的再沉积和广泛填充的原因。
[1] The 40-km-diameter Mjolnir crater in the Barents Sea was created by a meteoroid impact into a 400 m shallow sea about 142 Ma. We have used a multimaterial hydrocode with depth-depending target strength to model numerically the cratering and early modification stages of the Mjolnir impact. Our models are constrained by the observed crater morphology and structure. The best results were obtained for a composite target strength structure: very low strength for the upper 3 km of sedimentary rocks and gradual increase from 3 to 6.5 km depth before using strength values typical for granitic rocks at greater depths. The low strength of the target sediments at shallow depths led to exceptionally intensive slumping and gravitational collapse of the order of 2.0–2.5, considerably larger than the average expected values for typical terrestrial craters. As a result, we obtain a crater collapse in between simple and complex, where slumping and gravitational collapse counteract the crater floor uplift and lead to suppression and burial of the central high. The Mjolnir impact in a shallow sea was responsible for a major disturbance of the water column. Following the impact-induced outward water surge, large-amplitude tsunamis were formed, and the rapid resurge of seawater into the excavated crater transported large amounts of ejecta and crater wall material back into the crater, accounting for the redestribution of ejecta material and extensive infilling.