Terrace Width Variations in Complex Mercurian Craters, and the Transient Strength of Cratered Mercurian and Lunar Crust
Terrace Width Variations in Complex Mercurian Craters, and the Transient Strength of Cratered Mercurian and Lunar Crust
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复杂水星陨石坑的台地宽度变化，以及有陨石坑的水星和月地壳的瞬态强度
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发表时间：
1991
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通讯作者：
W. McKinnon
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作者：
A. Leith;W. McKinnon
复杂环形山的滑塌阶地宽度可以用来确定环形山塌陷过程中环形山区的有效凝聚力。我们已经测量了水星上复杂陨石坑的阶地宽度：对于一个给定的陨石坑，这些阶地通常会向边缘向外增加，最外面的主要阶地的宽度通常是陨石坑直径的递增函数。类似的观测结果也适用于月球复合陨石坑，但水星复合陨石坑的最外塌陷阶地的宽度小于类似大小的月球复合陨石坑。使用水星上的阶地宽度和重力驱动的滑塌模型，我们估计撞击后立即（特别是在陨石坑形成的修改阶段）的陨石坑区域的强度为10.1 - 2 MPa。与皮尔斯和Melosh以前对月球复杂环形山的研究相比，水星环形山地壳的瞬态强度并不大于月球。强度估计值仅略有不同的几何模型，用于恢复最外面的主要阶地，其崩溃前的配置，并与独立的强度估计值从简单到复杂的陨石坑深度/直径的过渡，特别是最近的深度/直径的研究水星陨石坑派克是一致的。因此，与先前的研究相反，水星和月球之间的“目标特性”差异可能很小，两个世界上陨石坑之间的系统形态差异可能主要是由表面重力差异的2倍造成的。
Widths of slump terraces of complex craters can be used to determine the effective cohesion of the cratered region during crater collapse. We have measured terrace widths for complex craters on Mercury: these generally increase outward toward the rim for a given crater, and the width of the outermost major terrace is generally an increasing function of crater diameter. Similar observations apply to lunar complex craters, but the widths of the outermost slump terraces of Mercurian complex craters are less than those of similarly sized lunar complex craters. Using the terrace widths on Mercury and a gravity-driven slump model, we estimate the strength of the cratered region immediately after impact (specifically, during the modification stage of crater formation) to be ∼1–2 MPa. Comparison with the previous study of lunar complex craters by Pearce and Melosh indicates that the transient strength of cratered Mercurian crust is no greater than that of the Moon. The strength estimates only vary slightly with the geometric model used to restore the outermost major terrace to its precollapse configuration and are consistent with independent strength estimates from the simple-to-complex crater depth/diameter transition, in particular, the most recent depth/diameter study of Mercurian craters by Pike. Thus, contrary to previous work, the difference in “target properties” between Mercury and the Moon may be small, and systematic morphological differences between craters on the two worlds may be largely caused by the factor of 2 difference in surface gravity.