Biosignature Detection and Preservation in Lake Salda Microbialites Under Simulated Martian Conditions

The alteration of martian deposits under extreme surface conditions remains a key challenge for their mineral-organic interpretation and paleoenvironmental reconstruction. This study investigates the spectral detection and alteration of mineral-organic signatures in Lake Salda hydromagnesite microbialites under martian sublimation and radiation (UV) conditions. Samples were analyzed using visible near-infrared and Fourier transform infrared (FTIR) spectroscopy, then sublimated via lyophilization and exposed to UV radiation in the Planetary Atmospheres and Surfaces Simulation Chamber. Sublimation reduced the intensity of water and carbonate vibrations and enhanced CH₂ ν₃ and PO₂^- ν₃ organic features; this demonstrated that interstitial water sublimation may reduce O-H spectral noise, improve organic visibility, and reveal volatile sublimation patterns for future Mars rovers, such as Rosalind Franklin. In a three-sol (74 h) simulation of martian UV radiation (200-400 nm) under 7 mbar of CO₂, FTIR spectral intensity was reduced, and organic CH₂ ν₃ and PO₂^- features were significantly degraded. These findings reveal spectral alterations under martian surface conditions and highlight organic biosignature vulnerability at equatorial latitudes, informing preservation protocols for future missions.