Much of my current work explores the nature and evolution of Earth’s early biosphere and its cause-and-effect relationships with the evolving continents, ocean and atmosphere. A corollary issue is whether the co-evolution of plate tectonics and life drove the irreversible oxidation of Earth’s surface and the establishment of an oxygenated atmosphere, leading to an explosion of bio- and mineralogical diversity. Primary methodologies lie at the intersection of geology, biology and chemistry, examining the best-preserved Precambrian rocks available. This involves fieldwork in Australia, South Africa, Brazil, Uruguay and Canada, identifying and drilling key sedimentary successions in order to track, at various scale (µm to the sedimentary  basin scale), the signals of microbially mediated cycling of carbon, sulfur, arsenic and metals as expressed in their abundances, redox state and stable isotopic compositions. I am particularly interested by in-situ approaches (SEM, electron microprobe, Raman microspectrometry, ion probes and synchrotron techniques), which allow a control on microstructures and mineral paragenesis in order to establish crystallization sequences and equilibrium/disequilibrium relations between minerals, fluids and organo-metallic compounds.