Planetary crusts undergo viscous closure of pores at depth; if the thickness of this porous layer can be measured, constraints on crustal thermal evolution can be derived. We apply a pore closure model developed for the Moon to Mars and take into account the geological processes that may alter the depth of this transition region. If the 8–11 km deep discontinuity in seismic wave speed detected by the InSight lander marks the base of the porous layer, the heat flux at the time the porosity was created must have exceed 60mW m, probably indicating a time prior to 4 Ga. Plain Language Summary On long timescales, and with enough heat or pressure, rocks in the crust of a planet can flow. This viscous deformation allows the empty pore spaces in a rock to close up. The history of the temperature at depth plays an important role in how deep one may expect porosity to exist. One can use a computational model to calculate the thickness of this porous layer as a function of the crust's thermal history. If the InSight Mars lander detects the thickness of such a porous layer, we can estimate the necessary temperature structure of the Martian crust and when porosity in the crust was generated. From a potential measurement of this porous layer at around 10 km thick, we predict the last significant pore formation event to have occurred at least 4 Gyr before present.

中文翻译：

---

InSight 下孔隙闭合深度对火星热历史的限制

行星地壳在深处经历孔隙的粘性闭合；如果可以测量这个多孔层的厚度，就可以推导出地壳热演化的约束条件。我们将为月球开发的孔隙闭合模型应用于火星，并考虑到可能改变该过渡区域深度的地质过程。如果洞察号着陆器探测到的 8-11 公里深的地震波速度不连续性标志着多孔层的底部，那么孔隙形成时的热通量必定超过 60mW·m，可能表明时间早于 4Ga。简单的语言总结 在很长的时间尺度上，如果有足够的热量或压力，行星地壳中的岩石可以流动。这种粘性变形使岩石中的空孔空间闭合。深度温度的历史在人们预期孔隙度存在的深度方面起着重要作用。人们可以使用计算模型来计算这个多孔层的厚度，作为地壳热历史的函数。如果洞察号火星着陆器探测到这样一个多孔层的厚度，我们就可以估计火星地壳的必要温度结构以及地壳中的孔隙何时产生。通过对该约 10 公里厚的多孔层的潜在测量，我们预测最后一次重要的孔隙形成事件至少在 4 Gyr 之前发生。我们可以估计火星地壳的必要温度结构以及地壳中的孔隙何时产生。通过对该约 10 公里厚的多孔层的潜在测量，我们预测最后一次重要的孔隙形成事件至少在 4 Gyr 之前发生。我们可以估计火星地壳的必要温度结构以及地壳中的孔隙何时产生。通过对该约 10 公里厚的多孔层的潜在测量，我们预测最后一次重要的孔隙形成事件至少在 4 Gyr 之前发生。