Assessing the preservation of biosignatures in shallow marine hydrothermal systems through time

• Applicant: Dr. Eric Runge
• Subject Area: Mineralogy, Petrology and Geochemistry ; Geology ; Palaeontology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 577503435

Shallow marine hydrothermal systems (<200 m water depth) are unique environments in which chemoautotrophy and photoautotrophy coexist and support diverse microbial communities. These systems were likely widespread on early Earth, and their fossil counterparts provide some of the oldest evidence of life. Therefore, geo-biological interactions in shallow-water hydrothermal systems are crucial for understanding the origin and early evolution of microbial life. However, the geobiology of these systems is poorly understood due to the limited repertoire of geologically stable biosignatures, which complicates their interpretation in Earth history. This project aims to assess the geological record of biosignatures in shallow marine hydrothermal systems through comparative analysis of samples from the modern seafloor and their fossil counterparts. To achieve this, I will investigate minerals and their characteristics as microbial biosignatures in active shallow marine hydrothermal systems, as well as their preservation in the geological record. I hypothesize that shallow marine hydrothermal mineralization is a valuable archive of microbial biosignatures and that these biosignatures can be traced in the corresponding fossil mineralization. The work program includes petrographic and mineralogical methods, as well as major and trace element geochemistry and in situ analyses of the stable isotopes of pyrite and barite (S, Fe, O). The combination of these analyses allows the identification of microbial mineral textures, geochemical growth zoning, and robust signatures of microbial redox processes. The integration of this information makes it possible to distinguish between microbial and abiotic processes in active and fossil hydrothermal mineralization and to assess the preservation potential of microbial biosignatures. The novel approach of this project provides crucial context for the interpretation of fossil biosignatures and thus contributes to the understanding of the evolution of microbial life in hydrothermal systems.

• DFG Programme: Position