Despite their critical roles in Venus’s geological evolution, neither heat flow through the Venusian lithosphere nor the corresponding tectonic regime in its geological past is well constrained. However, because impact basin formation is sensitive to thermal conditions at depth, studying large basin development can provide crucial insights into the past geological conditions of a planet. Here we model the formation of Mead Basin, the largest impact structure on Venus, and its two ring faults at approximately 190 km and 270 km diameter, to determine the thermal conditions in Venus’s crust and upper mantle at the time of impact. For present-day surface temperatures, we find that lithospheric thermal gradients no higher than 14 K km⁻¹, corresponding to surface heat fluxes of 28 mW m⁻², are required to reproduce the morphology of Mead Basin. These values are less than half of what is expected for an active lid planet, implying that Venus may have had a stagnant lid when Mead Basin formed, between 0.3 and 1 billion years ago.

尽管它们在金星的地质演化中发挥着关键作用，但无论是通过金星岩石圈的热流还是其地质历史中相应的构造机制都没有受到很好的限制。然而，由于撞击盆地的形成对深度的热条件很敏感，研究大型盆地的发展可以提供对行星过去地质条件的重要见解。在这里，我们模拟了金星上最大的撞击结构米德盆地及其两个直径分别为 190 公里和 270 公里的环形断层的形成，以确定金星撞击时地壳和上地幔的热条件。对于当今的地表温度，我们发现岩石圈热梯度不高于 14 K km ^-1，对应于 28 mW m ^{-2的地表热通量}，需要重现米德盆地的形态。这些值不到活动盖行星预期值的一半，这意味着在 0.3 到 10 亿年前米德盆地形成时，金星可能有一个停滞的盖。