A Field Guide to Finding Fossils on Mars.

Area of Science:

• Astrobiology
• Planetary Science
• Paleontology

Background:

• The Martian surface is currently inhospitable, but past geological evidence suggests warmer, wetter conditions.
• These past habitable environments on Mars are key targets for the search for extraterrestrial life.
• National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) missions prioritize searching for biosignatures.

Purpose of the Study:

• To evaluate potential preservation sites for fossils and isotopic biosignatures on early Mars.
• To identify the most promising depositional environments and mineralizing media for astropaleontology.
• To guide future astrobiological missions in their search for signs of ancient Martian life.

Main Methods:

• Analysis of stratigraphic, mineralogical, and geochemical data from Martian missions.
• Comparison with Earth's fossil record and studies of organic matter decay.
• Experimental investigations into organic preservation in simulated Martian conditions.

Main Results:

• Fe-bearing clay-rich fluvio-lacustrine siliciclastic deposits from the Noachian-Hesperian period are highly promising targets.
• Silica-enriched deposits within these formations offer excellent potential for fossil preservation.
• Siliceous sinters are also considered excellent targets, pending confirmation of their presence on Mars.

Conclusions:

• Noachian-Hesperian clay-rich deposits, particularly those with silica, represent the best-understood astropaleontological targets for current and future missions.
• Further research is needed to understand fossil preservation in other Martian environments, such as evaporative salts and subsurface minerals.
• Identifying and characterizing these ancient depositional environments is crucial for the successful detection of past Martian life.