Subsurface structure of oblique impact craters

倾斜撞击坑的地下结构

• 批准号: 18879389
• 负责人: Professor Dr. Thomas Kenkmann
• 金额: --
• 依托单位: Lehrstuhl Allgemeine Geologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/18879389?language=en
• 关键词: Subsurface; structure; oblique; impact; craters

Impacts of asteroids on planetary surfaces usually occur obliquely with an average impact angle of 45°. The impact vector can be analysed by the uneven distribution of ejecta. On Earth ejecta blankets of meteorite craters are very rare and incompletely preserved, but different degrees of erosion often allow to study the crater floor in detail. The working hypothesis of this proposal is that the crater floor flow field is capable to provide direct evidence for oblique impacts via momentum transfer from projectile to the target. The objective is to determine the impact vector of terrestrial craters from the subsurface crater structure and to infer the structural inventory of oblique impacts. For this purpose a field study is planned at the Spider impact crater in Western Australia, which is believed to have been formed by an oblique impact. In a thorough structural analysis deviations from a radial symmetry of the crater floor structure including a study on shock and damaging in different sectors of the crater will be deduced. A kinematic analysis will be performed to quantify dominant flow trajectories which are relevant for reconstruction of the projectile s vector. The analysis will be linked to 3D numerical modeling of the crater floor flow in an oblique impact scenario, A comparison of the Spider structure with other craters is planned to test if structural elements indicative for oblique impacts can be generally applied and to infer the incidence of impact.

小行星对行星表面的撞击通常是倾斜的，平均撞击角为45°，撞击矢量可以通过喷射物分布不均匀来分析。地球上陨石坑的喷射物覆盖层非常罕见，且保存不完整，但受到不同程度的侵蚀。该提案的工作假设是，弹坑底部流场能够通过从弹丸到目标的动量传递来提供倾斜撞击的直接证据。目的是从地下陨石坑结构确定陆地陨石坑的撞击矢量，并推断倾斜撞击的结构清单。为此，计划在西澳大利亚的蜘蛛陨石坑进行实地研究，该陨石坑被认为是由陨石坑形成的。在彻底的结构分析中，将推断出陨石坑底部结构径向对称性的偏差，包括对陨石坑不同部分的冲击和破坏的研究，将进行运动学分析以量化主要流动。与弹丸矢量重建相关的轨迹该分析将与倾斜撞击场景中弹坑底部流动的 3D 数值模型相关联，计划将蜘蛛结构与其他弹坑进行比较，以测试结构元素是否表明通常可以应用倾斜撞击并推断撞击的发生率。