Mud flow levitation on Mars: Insights from laboratory simulations

Abstract

Sediment mobilisation occurring at depth and ultimately manifesting at the surface, is a process which may have operated on Mars. However, the propagation behaviour of this mixture of water and sediments (hereafter simply referred to as mud) over the martian surface, remains uncertain. Although most of the martian surface is below freezing today, locally warmer surface temperatures do occur, and our current knowledge suggests that similar conditions prevailed in the recent past. Here, we present the results of experiments performed inside a low pressure chamber to investigate mud propagation over a warm (~295 K) unconsolidated sand surface under martian atmospheric pressure conditions (~7 mbar). Results show that the mud boils while flowing over the warm surface. The gas released during this process can displace the underlying sand particles and hence erode part of the substrate. This "entrenched" flow can act as a platform for further mud propagation over the surface. The escaping gas causes intermittent levitation of the mud resulting in enhanced flow rates. The mud flow morphologies produced by these phenomena differ from those produced when mud flows over a frozen martian surface as well as from their terrestrial counterparts. The intense boiling removes the latent heat both from the mud and the subsurface, meaning that the mud flow would eventually start to freeze and hence changing again the way it propagates. The diverse morphology expressed by our experimental mudflows implies that caution should be exercised when interpreting flow features on the surface of Mars and other celestial bodies.

Multiple sites of recent wet-based glaciation identified from eskers in western Tempe Terra, Mars

“…2 and 5A), which we interpret as an erosive feature that has undergone some degree of induration and back-wasting. The flows could alternatively be mud flows as these could produce similar morphologies to lava under Martian surface conditions, according to laboratory experiments (Brož et al, 2020a(Brož et al, , 2020b. For example, the observed raised outer margin of the upper flow unit (Fig.…”

Volumetric Changes of Mud on Mars: Evidence From Laboratory Simulations

“…At larger scales, different deformation mechanisms associated with flow movement are likely to alter the resulting morphologies. It is difficult to predict this type of alterations since only centimeter‐scale experiments have been attempted to so far to study mud movements under low atmospheric pressure (e.g., Brož, Krýza, Conway, et al., 2020; Brož, Krýza, Wilson, et al., 2020). Moreover, the various mechanisms involved may scale with the value of gravity differently.…”

“…(2020) and Brož, Krýza, Conway, et al. (2020). Similarly, we also used the same type of clay described by Brož, Krýza, Wilson, et al.…”

“…(2020) and Brož, Krýza, Conway, et al. (2020) experimentally investigated the propagation of water‐rich mud in a low‐pressure chamber partly simulating the current environmental conditions of Mars. The authors discovered that low viscosity mud flows could propagate over cold (<273 K) and warm (>273 K) surface at current martian atmospheric pressure.…”

An overview of sedimentary volcanism on Mars

“…As a consequence, mud remains liquid inside the crust for prolonged periods of time and propagates via mud tubes (analogous to lava tubes; Calvari and Pinkterton, 1999). In contrast, low viscosity mud propagating over a warm surface boils and levitates above the surface (Brož et al, 2020b). As the water content within martian mud flows might have varied, mud flows may have had different viscosities.…”