Geobiology of modern and ancient endolithic microorganisms within ultramafic rocks on the Mid-Atlantic Ridge

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The major goal of the proposed project is the geobiological description of active and fossil deep endolithic organisms, their organic remains and mineral precipitates within pore space of basaltic and other ultramafic rocks from the Mid-Atlantic Ridge (between 14°45´N and 15°15´N) which will be recovered during cruise M60/3 of R/V Meteor in early 2004. These results will be compared with other basaltic rocks, predominately pillow basalts from different localities (e.g. ODP Leg 200). For this purpose, thin sections of the basaltic rock samples will be used for a comprehensive, multiphase experimental approach. The active endolithic "deep" bioshere will be investigated microscopically using histological staining prodedures, fluorescent in situ hybridization (FISH), and further culture independent molecular biological methods (e.g. DGGE). Lipid biomarker signatures and macromolecular investigations will provide further knowledge on the distribution of microorganisms and generally of organic matter. Geochemical and isotope proxies will be used to describe newly formed minerals in the former gas bubbles and fractures of pillow and other ultramafic rock tpyes (e.g. d13C, d18O, d34S, 87/86Sr, major and minor elements, REE). We anticipate, that the analyses will show that the inner pore space of degassed basaltic rocks and fractures is a well developed microbial ecosystem which presumably is found everywhere where oceanic crust forms the seafloor. Therefore, microbial-mediated process mineralisations within pillow basalt pore space may have a significant impact on geochemical element budgets.