Structural glaciology of the Martian ice caps unveils conduits for fluid migrations

• DOI: 10.5194/epsc2022-844
• Publication Date: 2022-09-23T12:06:09Z
• Authors: Paola Cianfarra; Francesco Salvini; Evandro Balbi; Matteo Maggi
• Keywords: 13. Climate action; 15. Life on land

<p>The increasing availability of radar sub-surface/surface imaging the terrestrial planets allowed to highlight structural architecture buried geological structures. The reconstruction 3D subsurface geometries, besides supporting classic geologic mapping planetary surfaces, allows constrain models unravel 4D evolution a region. This is utmost importance in key regions where trapped fluids and their (possible) migration surface might impact local/global climate conditions , atmospheric composition,  as well as presence water close maritan surface.</p> <p>Shallow Subsurface Radar (SHARAD) data [1] revealed that Martian caps are composed primarily ice was deposited layers contain varying amount dust. They referred martian Polar Layered Deposits (PLD). internal stratigraphy these deposits strongly resemble layering sites East Antarctic Ice Sheet, tectonics (e.g. faulting) dynamics, be causes observed architecture.</p> <p>Mechanisms responsible for formation PLD still under debate exogenous processes considered among best candidates [2]. Steep troughs dissecting polar with spiral shapes provide an optimal view layered reflectors interpretations suggested accompanied by katabatic winds produce erosion/sublimation at exposed accumulation/deposition opposite slopes Nevertheless, SHARAD profiles crosscutting canyons lateral change thickness layers, thickening they approach canyon structures (Fig.1). It known from analogues/structures such geometry may result activity normal faults sintectonic sedimentation (ice dust deposition case).</p> <p><img src="" alt="" width="436" height="368" /></p> <p><strong>Figure 1.</strong> Sharad Image showing examples stratigraphic North  through cap.</p> <p>In this work we present results forward numerical modeling HCA technique [3] structure evolution.. simulated mesh cells whose links replicate physical rheological characteristics material ruptures faults. PLD, variations, vertical offset successfully shear discontinuities series listric displacements (Fig.2).</p> width="421" height="459" 2.</strong> model Mars north Subset radargram 1294501 [3]</p> kinematic thus existence size order hundreds km within caps. Faults similar displacement several kms associated developed extended fault core damaged zones, characterized strong variation permeability due secondary fracturing. In way cap corridors brittle deformation dissect entire cap, conduits fluid migration, enhance development troughs.</p> width zones meters core, attitude fault-related fractures (synthetic fractures, antithetic extensional pressure solutions seams) spatial distribution frequency volume affected damage zone has been quantified analytical-numerical  performed FRAP software using found [4]. takes into account modeled fault, properties environmental parameters acting stresses, gravity, …) which influence computation (Fig 3).</p> width="561" height="361" 3</strong>. Schematic sketch (example output).</p> <p>Results study represent contribute better understand hitherto underestimated tectonic setting Highlighting  hydraulic pivotal enhanced pathway both base Fluids biological can atmosphere easily detectable/sampled improve success future onland missions.</p> <p>References</p> <p>[1] Seu, R., Biccari, D., Orosei, Lorenzoni, L. V., Phillips, R. J., Marinangeli, L., ... & Zampolini, E. (2004). SHARAD: MRO 2005 shallow radar. <em>Planetary Space Science</em>, <em>52</em>(1-3), 157-166.</p> <p>[2] Smith, Holt, Spiga, Howard, Parker (2013). cyclic steps. Journal Of Geophysical Research: Planets, 118, 1835–1857.</p> <p>[3] Salvini F. Storti F., McClay K (2001)) Self-determining compressional</p> <p>fault-bend folding. Geology, 29,  839-842.</p> <p>[4] (2005). – Fault-Related fracturing Analytic-numerical aPpproach. Inhouse application GEoQuTe Lab, Roma Tre University.</p>