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From its origins, perhaps some 4 billion years ago, life has had a profound influence on shaping the evolving Earth. Biological innovations have led to lasting environmental change, while geology feeds back on biology, creating new opportunities for evolutionary innovation. For over 80% of Earth’s living history, biological processes were driven exclusively by microorganisms. Because microorganisms are ubiquitous in environments where the temperature is below <100, the field of Geomicrobiology thus studies the relationships between the microbial life forms and their environment, from localised niches, that occur on the order of micrometres, to global elemental cycles. On each of these scales, there exists a complex interplay of biogeochemical processes that are based on the nutritional and energy requirements of co-dependent species living in juxtaposition to one another. These include the sorption and uptake of metals, the formation of authigenic mineral phases (termed biomineralisation), the weathering and dissolution of minerals and rock surfaces, and chemical and mineralogical transformations that take place during the burial and lithification of sediments. My research programme integrates geochemical, microbiological and genetic experimental studies with field-based research in modern surface environments to investigate the mechanisms by which microbes interact with their environment, and whether unique biological features may be recognisable. These studies are then linked to the analyses of the rock record, spanning nearly 4 billion years, as a means to test the usefulness of those modern biosignatures, with the ultimate aim being to gain a better understanding for the evolution of early Earth’s geosphere, hydrosphere, biosphere and atmosphere. Seven of my current research interests are briefly outlined below. They include (1) surface reactivity of biomass, (2) microbial silicification, (3) modern microbialites, (4) sediment diagenesis and the effects of infaunal burrowing, (5) understanding the mechanisms for Precambrian banded iron formation, (6) using Precambrian sediments as paleo-seawater proxies, and (7) Neoproterozoic environment and evolution of animal life.

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