SERPENTINIZATION-RELATED MICROBE-MINERAL RELATIONSHIPS WITH µFTIR-SPECTROSCOPY

The water-rock reaction known as serpentinization is well known for co-occurring abiotic generation of molecular hydrogen, methane, and other simple carbon compounds, with documented ability to support microbial life (Mayhew et al. 2013; Schrenk et al. 2013; McCollom & Seewald 2013). Serpentinization has caught the attention of scientists working at the interface of geology and biology due to its potentially widespread occurrence in the subsurface Earth and in the wider solar system. Though much work has been performed concerning the serpentinization microbiome (Schrenk et al. 2013), the manner in which microbes and biosignatures may be spatially distributed and preserved relative to the mineral substrate remain largely unexplored. In a search for better definition of potential microbe-mineral relationships in serpentinites, this investigation will generate maps profiling spectroscopic signatures of mineral background and biological material across a variety of mineral and whole rock samples. Complimentary sample analyses will be performed with micro-FTIR spectroscopy (ThermoFischer Scientific Nicolet Continuum infrared microscope, University of Rhode Island) and Raman spectroscopy (Horiba LabRAM HR Evolution Raman microscope-spectrometer, University of Colorado-Boulder). Samples span serpentinite core fragments from drilling of the Coast Range Ophiolite Microbial Observatory (CROMO, Cardace et al., 2011) and single mineral standards, observed pre- and post-incubation experiments in natural waters. Observations of incubated samples are of particular importance as they allow documentation of the progressive formation of biofilms, and discern changing spectroscopic signatures as organic-rich material is overlain on a mineral substrate. For all materials studied, we identify characteristic patterns for (a) mineral background and (b) changing organic loading on sample surfaces; any fine scale biomineral production will also be noted. This study will inform efforts to understand biologically-driven alteration of serpentinite minerals and mineral biocorrosion in general, and will also assess the feasibility of discrimination of/characterization of biological debris sealed inside serpentinite-associated secondary minerals.