Products of Sedimentary Volcanism around Adamas Labyrinthus, Mars

<p>Landforms with specific flow-like morphology are characteristic for the area of Adamas Labyrinthus in the southwestern part of Utopia Planitia. These landforms have been previously described as degraded mud flows originating from a partly frozen muddy ocean. However, such interpretation remained ambiguous as lava flows observed elsewhere on Mars look quite similar. We mapped and investigated over 300 features spread across a 500 &#215; 1300 km large area in order to reveal whether they were formed by the movement of mud or lava. Based on our systematic examination of their shapes, their spatial distribution as well as geological context we conclude that they were formed due to the ejection of mud from a gradually freezing muddy body. Once exposed to the surface, the mud spread by flowing over the surface, while freezing at the same time. This limited its ability to flow and caused the resulting outflows to have an appearance similar to terrestrial lava flows. Emergent landforms differentiated based on the effusion rates and overall volumes of the source material and subsequently degraded over time as the liquid part of the compound sublimed away. These processes eventually lead to the characteristic morphology of hills, ridges, plateaus, and complexly layered units which we observe today. We propose that all the >300 studied features were formed by subsurface sediment mobilization and that the material likely originated from the same source.</p>