SYNCHROTRON-BASED INSIGHTS INTO CHEMICAL TRANSFORMATIONS MEDIATED BY ENDOILTHIC MICROORGANISMS IN SEAFLOOR AND SUBSEAFLOOR ROCKS

Synchrotron-radiation (SR) based x-ray scattering and spectroscopic techniques are increasingly utilized to gain insights into the mechanisms of bioerosion and biomineralization processes. One of the key reasons to use SR approaches is the need to spatially resolve the redistribution of trace elements during biologically-mediated mineral dissolution and precipitation processes at the microbe/rock interface. SR-based approaches are particularly powerful when used to also identify changes in the mineralogy and speciation of redox-sensitive elements, such as Fe, Mn and S, that may sustain microbial metabolisms while leaving diagnostic biosignatures. To explore these ideas, this talk will present some recent advances in using SR-based techniques to determine mechanisms of bioalteration within the oceanic crust. In particular, we will present nano-scale and micro-scale x-ray fluorescence, diffraction and x-ray absorption spectroscopy data that helps constrain modern and ancient bioerosion processes mediated by microbial communities hosted within seafloor and subseafloor volcanic glasses.