Fig. 3: Possible history for the Martian N-bearing organics.
From: In-situ preservation of nitrogen-bearing organics in Noachian Martian carbonates
Nitrogen-bearing organic matter was either synthesized locally or delivered meteoritically on the early Mars. The former case requires an abiotic reduction of N (e.g., N2, NOx → NH3) to start the ammonia-related chemical reactions. The latter case is also possible if adequate amounts of N-bearing components were supplied. This organic matter survived in the 4 Ga Martian (near)surface fluids and was trapped into ALH carbonates during precipitation. The carbonates resided in the subterranean system, preserving the organic components over long geological times.
