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火星半球二分化的巨大冲击形成
Margarita M Marinova1, Oded Aharonson, Erik Asphaug
1California Institute of Technology, Division of Geological and Planetary Sciences, MC 150-21, Pasadena, California 91125, USA. mmm@caltech.edu
Nature
|June 27, 2008
概括
一次大型撞击可能会解释火星的半球二分法. 模拟显示特定的冲击条件,包括角度和能量,可以在南部高地和北部低地之间产生观察到的地差异.
科学领域:
- 行星科学 行星科学
- 地质物理学 地质物理学
- 冲击石坑的形成
背景情况:
- 火星半球二分法,半球之间的高度和地厚度的鲜明对比,仍然不太了解.
- 现有的形成模型,如内源对流或多重冲击,具有局限性或统计不可能性.
研究的目的:
- 为了研究单一的大冲击假设,探讨火星半球二分化的起源.
- 模拟可能产生与观察到二分法相一致的特征的撞击条件.
主要方法:
- 利用三维水力动力学模拟来建模单个大型撞击事件.
- 多种冲击能量,速度和角度,以评估它们对冲击后状态的影响.
主要成果:
- 模拟表明,倾斜撞击 (30-60度),能量为 (3-6) x 10(29) J,低速度 (6-10公里/秒) 可以产生与北方低地尺寸和圆度相匹配的地移除边界.
- 在这些条件下,融化的分布在很大程度上是局部的,从而保留了撞击的证据.
结论:
- 一个单一的巨大撞击事件是火星半球二分化的可行解释.
- 时间和撞击角度与早期太阳系条件和撞击物种群相一致.
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