Terrestrial Submarine Discontinuous Systems as Analogs for Similar Martian Channel Morphologies.

   Channel systems on both Earth and Mars present several morphological similarities suggesting that they are the results of relatively similar mechanisms in the spatial and temporal contexts. Our research focuses on investigating discontinuous channels, morphologically defined as channel segments interrupted by unchanneled reaches or as a set of streams interrupted over space. These systems are unfrequently found on Mars or Earth [1], therefore signify an indication of special topographic, hydrologic or lithologic conditions.

   A draft classification takes into account that discontinuities can be classified into major groups according to their origin and geological setting: 1) Arid region discontinuities. 2) Sinking streams in lava and karsts terrains. 3) Fluvio-lacustrine, continental shelves, and deep-sea discontinuities. 4) Other types as post fluvial effects that obliterate channel sections by impact cratering, Sediment covers, mudflows intersecting and filling in the channel in addition to the selective channel material removal.

   We characterized such drainage systems on Mars, in the Navua Valles paleo drainage system [2], and near Saheki crater, both situated in the northern flank of Hellas Basin. While on Earth, we identified a number of similar settings as analogs to those identified on Mars, in arid regions such as in Mojave river (USA), and the Sahara Desert (Algeria).

   Furthermore, an unusual type of martian analog on Earth was identified in the subsea using bathymetric maps, as we located discontinuous segments in various continental shelf locations to the western coast of North America [3] and to the northwest African margin in Mauritania [4]. Our preliminary investigation suggests that discontinuous channel morphologies in terrestrial dryland may be similar to those in the seafloor on a larger scale.

   The West African continental shelf confines a discontinuity in the paleo drainage rivers system flowing from the Tamanrasset paleo drainage river to Cap Timiris submarine canyon system [4]. That unmapped channel segments are believed to occur due to the change of kinetic energy on the sea bottom at relatively less sloping, then the channels reappear at the edge of continental shelves as a result of slope change. The topographic profile of a selected site southeast to Saheki crater on Mars manifested a similar topography to a continental shelf- submarine canyon system. The martian site is suggested to be a paleolake.

   As a preliminary result of our study, we emphasize that the discontinuous behavior of submarine channels on terrestrial continental shelves might be a relevant analog for understanding similar martian drainage systems and further expand geomorphological studies for a new branch of martian-terrestrial analogs in the subsea.

References:

[1] Hargitai H. et al. 2017. Discontinuous Drainage Systems Formed by Precipitation and Ground-Water Outflow in the Navua Valles and Southwest Hadriacus Mons, Mars. [2] Ettahri M.A & Hargtiai H. 2019. Discontinuous valley networks on Mars: A comparative survey. EPSC-DPS2019-1565-2. [3] Maier K.L. et al. 2011. The elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California. [4] Skonieczny C. et al. 2015. African humid periods triggered the reactivation of a large river system in Western Sahara.