Secondary craters and ejecta across the solar system: Populations and effects on impact‐crater–based chronologies
Secondary craters and ejecta across the solar system: Populations and effects on impact‐crater–based chronologies
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DOI：
10.1111/maps.13057
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发表时间：
2018-04
影响因子：
2.2
通讯作者：
E. Bierhaus;A. McEwen;S. Robbins;K. N. Singer;L. Dones;M. Kirchoff;J.‐P. Williams
中科院分区：
文献类型：
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作者：
E. Bierhaus;A. McEwen;S. Robbins;K. N. Singer;L. Dones;M. Kirchoff;J.‐P. Williams
我们回顾了过去十年来的次生陨石坑研究，并提供了新的分析和模拟，首次将主-加-次生陨石坑群体组合的积累作为离散的陨石坑事件进行建模。我们利用比例律来生成抛射碎片，整合单个抛射碎片的轨迹，注意撞击时的位置和速度，并利用比例律来估计给定撞击条件下的次级陨石坑直径，从而开发了次级种群。我们还探讨了撞击体尺寸-频率分布（SFD）与产生的次级陨石坑SFD之间的关系。我们从这些分析中得出的结果表明，“二次效应”因地表而异，没有一个单一的结论适用于整个太阳系，也不适用于任何给定的时间点——相反，在空间和时间上都有一系列的结果，取决于目标参数和影响人口。表面重力和逃逸速度决定了二次粒子的空间分布。一个倾斜较浅的冲击器SFD会比一个倾斜较陡的SFD造成更多的二次冲击。确定次生陨石坑的相对数量及其对地表年龄的影响，必须考虑决定次生陨石坑大小和空间分布的驱动因素。
We review the secondary‐crater research over the past decade, and provide new analyses and simulations that are the first to model an accumulation of a combined primary‐plus‐secondary crater population as discrete cratering events. We develop the secondary populations by using scaling laws to generate ejecta fragments, integrating the trajectories of individual ejecta fragments, noting the location and velocity at impact, and using scaling laws to estimate secondary‐crater diameters given the impact conditions. We also explore the relationship between the impactor size–frequency distribution (SFD) and the resulting secondary‐crater SFD. Our results from these analyses indicate that the “secondary effect” varies from surface to surface and that no single conclusion applies across the solar system nor at any given moment in time—rather, there is a spectrum of outcomes both spatially and temporally, dependent upon target parameters and the impacting population. Surface gravity and escape speed define the spatial distribution of secondaries. A shallow‐sloped impactor SFD will cause proportionally more secondaries than a steeper‐sloped SFD. Accounting for the driving factors that define the magnitude and spatial distribution of secondaries is essential to determine the relative population of secondary craters, and their effect on derived surface ages.