Decoding organic compounds in lava tube sulfates to understand potential biomarkers in the Martian subsurface

This study investigated sulfate speleothems from Lanzarote lava tubes as Mars analogs to understand potential biomarkers in the Martian subsurface. Molecular, isotopic, and mineralogical characterization revealed primarily calcium and sodium sulfates. Sulfur isotope analyses indicated volcanic and oceanic origins, while carbon isotope composition and pyrolysis analyses suggested vegetation and microbial influences. Lipid profiles, including branched and *n*-alkanes and palmitic and stearic acid methyl esters, suggested microbial origins. These findings contribute to understanding lava tube dynamics and recognizing potential biosignatures on Earth and other planets.

Vera Palma, José María De la Rosa, Bogdan Petroniu Onac, Francesco Sauro, Jesús Martínez-Frías, Ana Teresa Caldeira, José Antonio González-Pérez, Nicasio Tomás Jiménez-Morillo, Ana Zélia Miller