Large outflow channels on ancient terrains of Mars have been interpreted as the products of catastrophic flood events. The rapid burial of water-rich sediments after such flooding could have led to sedimentary volcanism, in which mixtures of sediment and water (mud) erupt to the surface. Tens of thousands of volcano-like landforms populate the northern lowlands and other local sedimentary depocentres on Mars. However, it is difficult to determine whether the edifices are related to igneous or mud extrusions, partly because the behaviour of extruded mud under Martian surface conditions is poorly constrained. Here we investigate the mechanisms of mud propagation on Mars using experiments performed inside a low-pressure chamber at cold temperatures. We found that low viscosity mud under Martian conditions propagates differently from that on Earth, because of a rapid freezing and the formation of an icy crust. Instead, the experimental mud flows propagate like terrestrial pahoehoe lava flows, with liquid mud spilling from ruptures in the frozen crust, and then refreezing to form a new flow lobe. We suggest that mud volcanism can explain the formation of some lava-like flow morphologies on Mars, and that similar processes may apply to cryovolcanic extrusions on icy bodies in the Solar System.

火星古代地形上的大量流出通道被解释为灾难性洪水事件的产物。洪水后迅速掩埋富含水的沉积物可能导致沉积火山作用，其中沉积物和水（泥）的混合物喷发到地表。北部低地和火星上其他当地的沉积沉积中心遍布着数以万计的火山状地貌。但是，很难确定建筑物是与火成岩还是泥浆挤压有关，部分原因是在火星表面条件下，挤压泥浆的行为受到的约束较弱。在这里，我们使用低温在低压室内进行的实验研究了火星上泥浆传播的机理。我们发现火星条件下的低粘度泥浆与地球上的泥浆传播方式不同，因为迅速冻结并结冰。取而代之的是，实验性泥浆流像陆地上的泥hoe熔岩流一样传播，液态泥浆从破裂的地壳破裂处溢出，然后重新冻结形成新的流瓣。我们认为泥火山作用可以解释火星上某些熔岩样流动形态的形成，并且类似的过程可能适用于太阳系中冰冷体上的冰冷挤压。