Preservation of Organic Matter Within Primary Fluid Inclusions in Late Middle Pleistocene Halite From the Mars‐Analog Qaidam Basin

Abstract Halite minerals, widespread across Mars, have captured significant attention from geologists and astrobiologists for their potential to preserve biosignatures. Here, we report the preservation of organic matter within primary fluid inclusions in a halite duricrust, dated to 197.8 ± 36.2 ∼ 226.0 ± 29.0 ka BP, obtained from the Mars‐analog Qaidam Basin, NW China. Employing transmitted and fluorescent light microscopy alongside Raman spectroscopy, we identified abundant β‐carotene, lipids, and kerogen within these fluid inclusions. Notably, lipids were detected in situ and non‐destructively within fluid inclusions in salts. The presence of genes associated with microbial synthesis of carotenoids, such as β‐carotene, across diverse prokaryotes suggests that these microorganisms could be a potential source of β‐carotene preserved in halite salts. The consistent spatial co‐occurrence of β‐carotene and anhydrite within all identified anhydrite‐containing inclusions in this study implies potential interactions between carotenoid‐producing microorganisms and sulfate minerals. This study underscores the significance of the preservation of biosignatures in near‐surface salts in the search for life on Mars.