Project GB6

S. Kasten, J. Peckmann and H. Schulz-Vogt
G.L. Arnold, D. Birgel, B. Brunner, B.B. Jørgensen, M.M.M. Kuypers, C. Vogt

The precipitation and dissolution of minerals is a chemical process resulting from the over- or under-saturation of solutes in the water with respect to this mineral. Nevertheless, the concentration of solutes driving precipitation or dissolution can be influenced by the metabolic activity of microorganisms. In this project we combine geochemical, microbiological and geobiological approaches to study the interaction between microbes and mineral formation (phosphates, carbonates, sulfates and sulfides) and mineral dissolution (e.g., carbonates, barite). We particularly aim at unraveling how geochemical environment, solute fluxes and prokaryotes influence the formation and preservation of the various authigenic minerals at cold seeps and in sediments of high productivity areas. Understanding and quantifying the controls that microbial activity and geochemical conditions have on mineral formation and preservation will significantly enhance the potential of authigenic minerals to reconstruct geochemical environments and fluxes of elements from fossil sediments and rocks and thus also contribute to a better understanding of the evolution of biogeochemical cycles and processes in Earth history.

Earlier studies performed in B5 on a bacterial culture (Brock and Schulz-Vogt, 2011) and on phosphogenic sediments (Arning et al., 2008) let us to the new hypothesis, that a high sulfide flux together with a shift from oxic to anoxic conditions is the crucial parameter inducing bacterially mediated apatite formation. This finding is in agreement with geochemical observations but contradicts the present view of microbiologists that derived mainly from the study of freshwater polyphosphate accumulating bacteria.