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Subsurface structure of oblique impact craters

倾斜撞击坑的地下结构

基本信息

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

项目摘要

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，平均撞击角度为45°。撞击矢量可以通过喷射物的不均匀分布来分析。在地球上，陨石坑的喷出物覆盖层非常罕见，而且保存不完整，但不同程度的侵蚀通常可以详细研究陨石坑的底部。这一提议的工作假设是，陨石坑底部流场能够通过从弹丸到目标的动量传递提供斜撞击的直接证据。目的是根据地下陨石坑结构确定陆地陨石坑的撞击矢量，并推断斜向撞击的结构清单。为此目的，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斜向撞击形成的。在彻底的结构分析中，将推导出陨石坑底部结构径向对称的偏差，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与弹丸矢量重建相关的主要流动轨迹。该分析将与倾斜撞击场景下陨石坑底部流动的3D数值模拟相关联，计划将Spider结构与其他陨石坑进行比较，以测试指示倾斜撞击的结构元素是否可以普遍应用，并推断撞击的发生率。