Geophysical Signatures of Subsurface Microbial Processes



Microbes are found in almost every conceivable part of the Earth, from hydrothermal vents in the deep ocean basins [Huber et al., 2007] to the cold subglacial lakes of Antarctic ice sheets [Mikucki et al., 2009]. The role of microorganisms in transforming Earth systems (e.g., accelerating mineral weathering) by mediating different biogeochemical cycles over the past 4 billion years has been well documented in many studies [e.g., Banfield et al., 1999]. However, microbial processes are challenging to investigate in situ. Direct (e.g., microbial composition and population density) and indirect (e.g., alteration of mineral phases by microbial activity) evidence for microbial activity requires sampling from boreholes, which is costly and invasive and provides poor spatial coverage.