Abstract

Detecting life evidence in other planetary bodies requires deep knowledge of the variety of biomarkers (i.e. with different chemical nature, preservation potential, or biological specificity) that we could ever find there. On the planetary search of life, carbonates are of special interest to scientists due to often being associated to life. On Earth, they are valuable paleogeochemical archives containing fossils of up to billions of years. Here, we investigate the biomarkers profile on three Chilean Triassic-Jurassic sedimentary records searching for signs of past and present life over ~200 Ma. A multianalytical platform combining lipid biomarkers, metaproteomics, and a life detector chip (LDChip) aimed to detect biomolecules with different perdurability and source-diagnosis potential. The combined identification of preserved proteins plus positive LDChip immunodetection provided metabolic information and taxonomic affiliation of modern/subrecent biosignatures. Molecular and isotopic analysis of more perdurable lipids allowed identifying general biosources and dominant autotrophic pathways further back in time, as well as recreating prevailing redox conditions over ~200 Ma. We demonstrate how extraterrestrial life detection can benefit from using different biomarkers to overcome diagnosis limitations due to lack of specificity and/or alteration over time. This finding has implications for defining future astrobiological missions to Mars.