Reevaluating the earliest traces of life on Earth

• Applicant: Professor Dr. Christian Hallmann, Ph.D.
• Subject Area: Palaeontology ; Mineralogy, Petrology and Geochemistry
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258478382

Exceedingly little is known about the nature and diversity of the earliest life on Earth. In the absence of unambiguous microfossils, any such information can only be gained from the sedimentary hydrocarbon remnants of biological lipids. The oldest rocks whose metamorphic grade could allow the preservation of fossil biomarkers are found in the ca. 2.7 to 2.8 Ga Fortescue Group of the Pilbara craton, Australia, but due to low concentrations and a consequently high contamination risk, the originality of such ancient biomarkers is highly debated. This has overshadowed previous reports of Archean molecular fossils and resultant reconstructions of organismic diversity, thereby leaving a knowledge-vacuum. In 2012 we drilled three holes into the Fortescue sequence under unprecedented hydrocarbon-free conditions and collected ultra-clean core samples. Preliminary analyses show that these Archean rocks are the most pristine ever recovered, and indicate that all previous studies hitherto suffered from some contamination. I here propose the comprehensive analysis of these unique samples with specifically-developed methods to study Earths oldest uncontaminated hydrocarbons. The results will reveal all organismic and environmental information that can be extracted from these ancient samples and undoubtedly set a new paradigm for our understanding of the early Precambrian.

• DFG Programme: Research Grants