114-3 Arctic Deltas as a Potential Astrobiological Analog for Early Mars

Session: Geomorphology and Surface Processes Across the Solar System (Poster)

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Abstract:

Results from NASA’s two most recent rovers, the Mars Science Laboratory Curiosity and Mars 2020 Perseverance rovers, have revealed evidence of likely habitable surface environments recorded in ancient deltaic sedimentary deposits from early in Mars’ history (>3.5 Ga). Yet it remains unknown whether ancient Mars ever harbored life, and whether such life is preserved in the martian rock record. Guiding the search for potential biosignatures on Mars is our understanding of biosignature preservation in various depositional environments on Earth. From this, delta deposits, and in particular the distal bottomset portions of delta deposits, are often thought to be an ideal location for the concentration and preservation of organic matter, based on analogy with primarily temperate deltas on Earth. However, recent work on the climate and surface environment of early Mars suggests that a colder environment, such as the Earth’s Arctic, may be a more relevant environmental analog. Even in the case of a more temperate, Earth-like climate, early Mars was likely to have ice-covered lakes and deltas at higher latitudes. Although neither the Curiosity nor Perseverance rovers have identified evidence for an ice-rich surface environment, these study sites are at relatively low latitudes (<20°). Therefore, we suggest the relevance of Arctic deltas as astrobiological analogs for early Mars remains under-considered.

Here we explore the astrobiology of Arctic delta systems through a summary and assessment of the literature to better understand whether a search for preserved biosignatures might differ in an Arctic, vs. temperate, deltaic depositional environment. Arctic deltas have many unique sediment transport characteristics compared to temperate deltas, and we suggest that the two most important for biosignature preservation are flow damming from ice that amplifies upstream overbank flooding, and the formation of numerous thermokarst lakes on the delta plain. Combined, these processes act to enhance storage of sediment, and especially fine-grained sediment, on the delta plain, as opposed to transport of that sediment to offshore portions of the delta. Given the tendency for fine-grained deposits to concentrate and preserve organic matter, we hypothesize that any ice-influenced deltas on early Mars may be equally, or more, likely to preserve biosignatures in proximal delta plain deposits compared to distal delta bottomset deposits.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10344

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