Investigating the Lake Bosumtwi impact structure: Insight from numerical modeling
Investigating the Lake Bosumtwi impact structure: Insight from numerical modeling
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DOI：
10.1029/2004gc000733
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发表时间：
2004-11
期刊：
影响因子：
3.7
通讯作者：
N. Artemieva;T. Karp;B. Milkereit
中科院分区：
文献类型：
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作者：
N. Artemieva;T. Karp;B. Milkereit
目前的地形波苏姆特维湖火山口和它的一些结构尺寸已确定的地球物理方法。我们将联合收割机这些数据与复杂的数值模型相结合，以评估陨石坑形成过程本身（例如，熔融和玻璃陨石生成）以及测试建模代码。地球物理图在平面图上显示出一些不对称性，主要异常位于陨石坑中心以北。早期阶段的模拟只在喷出物和玻璃陨石分布中显示出不对称的图案，而后期阶段则模拟了垂直撞击，没有任何不对称。我们估计弹丸的大小，从比例定律，然后，不同的材料性能，重现一个陨石坑，这是类似的Bosumtwi，但太深。膨胀使我们能够调和模型结果和观察到的地形之间的差异。冲击熔化的估计是在很好的协议与Bosumtwi磁签名。玻璃陨石的模拟分布假设撞击角度为30°-45°，撞击方向为N-NE。数值模型和现场证据的结合不仅为即将进行的结构科学钻探提供了必要的信息，而且还提出了有趣且合适的钻探地点。除了中央隆起和环形护城河以及建议的厚角砾岩覆盖层之外，在地球物理异常位置的钻探以及向下和横向位置的比较将为撞击前和撞击引起的不对称性提供新的见解。
The current topography of the Lake Bosumtwi crater and some of its structural dimensions have been determined by geophysical methods. We combine these data with sophisticated numerical models to evaluate the cratering process itself (for example, melt and tektite generation) as well as to test the modeling code. The geophysical maps show some asymmetry in plan view, with the main anomaly north of the crater center. The simulations of the early stage show asymmetric patterns only in ejecta and tektite distributions, while the late stage is modeled for the vertical impact without any asymmetry. We estimate the projectile size from scaling laws and then, varying material properties, reproduce a crater, which is similar to the Bosumtwi, but too deep. Bulking allows us to reconcile differences between the model results and the observed topography. Shock melt estimates are in good agreement with the Bosumtwi magnetic signature. Modeled distribution of tektites assumes an impact angle of 30°–45° and an impact direction from the N‐NE. The combination of numerical models and field evidence not only provides necessary information for upcoming scientific drilling of the structure but also suggests interesting and well‐suited drill sites. Besides the central uplift and the annular moat with a suggested thick breccia cover, drilling at the location of the geophysical anomalies and comparison of downrange and transversal locations will provide new insight into preimpact and impact‐induced asymmetries.