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Abstract
Siliceous sinters were collected from two high temperatures, disaerobic, reducing terrestrial hot springs from the Uzon Caldera, Kamchatka, Russia for the purpose of characterizing microbe-mineral interactions, and biomineralization of the sinters, associated microbial mats, and underlying rocks. X-Ray Diffraction (XRD) and Thermogravimetric Analysis (TGA) were used to determine the major mineral phases present within the rocks. High resolution analysis through electron microscopy was used to characterize minor mineral phases present within the rocks and microbial mats, and to analyze microbe-mineral interactions and biomineralization of prokaryotes. Opal-A was the dominant mineral phase comprising the siliceous sinter. Clay alteration of the underlying rocks of vent 1 was due to the sulfate-type waters not found in vent 2. Microbe-mineral interactions were most commonly associated with iron-bearing mineral phases since the can be directly used for metabolic processes. Biological induced mineralization through extracellular silicification was the only form of biomineralization with the exception ferrihydrite and pyrite mineralized cells. These microbial signatures offer clues to how the earliest microorganism on Earth may have preserved and where they derived their energy.