Lipid biomarker comparison of relict and active microbial mats from the McMurdo Ice Shelf, Antarctica

• Published in: Organic geochemistry Vol. 179; p. 104591
• Main Authors: Drozd, Juliana K., Evans, Thomas W., Summons, Roger E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2023
• Subjects: Bacteriohopanepolyols; Diagenesis; Intact polar lipids; Microbial mats; Quinones; Quinones; Intact polar lipids; Diagenesis; Bacteriohopanepolyols; Microbial mats
• ISSN: 0146-6380; 1873-5290
• DOI: 10.1016/j.orggeochem.2023.104591

•Substantial differences in lipid distributions found between living and fossil microbial mats.•Significant diagenetic degradation of lipid biomarkers occur within a short period.•Certain polar compound classes are selectively preserved under cold and dry conditions. Earth’s biota leave traces in the form of molecular fossils, typically from the membrane lipids of organisms, preserved in the sedimentary rock record. However, since the environmental conditions prevailing at the time can impact the nature of those remains, it is important to understand the diagenetic processes that occur under contrasting regimes. In this study, we investigated the preservation under cold and arid climatic conditions of intact polar lipids, bacteriohopanepolyols, and quinones preserved in a ∼700-year-old relict, desiccated microbial mat. We compared these to lipid signatures in actively growing counterparts from nearby meltwater ponds of McMurdo Ice Shelf in Antarctica. Substantial differences in lipid distribution were evident between active and relict mats, suggesting that significant diagenetic degradation of lipid biomarkers occurs within a short period, thereby illuminating the selective preservation of certain polar compound classes under cold and dry conditions.