This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The immediate goals of this project are to acquire and build two instrument packages that will be interfaced with IODP borehole observatories, known as CORKs, as part of the Mid-Atlantic Ridge Microbiological Experiments (MARME) program. This international program utilizes novel interdisciplinary approaches to elucidate the linkages and rates of exchange between the hydrological, geochemical and microbiological components of the oceanic subsurface. The instrument packages are essential for achieving the over-arching goals of MARME to determine the origin and nature of microbial communities in situ within basaltic basement of 7-8Ma age below an isolated sediment "pond" on the western flank of the Mid-Atlantic Ridge at 22N, known as North Pond. The microbial communities of North Pond will be characterized in the context of their hydrogeochemical environment. This site was chosen because 1) the basaltic basement is suitably young (< 10 Ma) to harbor active microorganisms, 2) the sediment cover over the basement rock is sufficiently deep to permit good penetration of the drill bit, 3) the site has been drilled several times before during DSDP and ODP legs, thus information exists regarding the hydrology and geochemistry of the system. This project feeds into a much larger multi-disciplinary study of the deep biosphere within crystalline rocks that addresses important questions such as 1) nature of microbial communities in young ridge flanks? 2) mechanisms of microbial growth in such environments? 3) What is the role of microbes in mineral weathering under oxidizing and reducing conditions? 4) source of inoculum for this bacterial community? 5) How microbial community composition and physiology is affected by the subseafloor hydrogeology? Questions as these are most effectively addressed through the use of long term subseafloor observatories, which permit in situ fluid, thermal, and chemical conditions to re-establish after the initial disturbance from drilling. This project is one part of a much larger research effort that is divided into three major phases, including a site survey as the first phase, which was completed in January, 2009. The drilling expedition will be the second phase, during which 3 sealed borehole observatories will be installed as part of an IODP-sponsored cruise (IODP 677 Proposal, Full). This project will directly support the third phase, which is to deploy and recover seafloor instrumental packages to be interfaced with the CORKs that will 1) measure fluid flow in the system by monitoring formation fluid pressures and temperatures, and 2) deploy a GeoMICROBE Sled for collecting fluid samples from specified depth horizons within the CORKs for microbiological and geochemical analyses over 1 ? 5 year time scales. The pressure and temperature measurements provide the basic constraints of the in situ hydrological and thermal conditions from which all of the in situ microbiological and modeling experiments are designed.
Broader Impacts: The MARME project and associated IODP drilling would be the largest coordinated investigation of the deep marine biosphere since IODP leg 201, which focused on marine sediments. This project will utilize novel and multidisciplinary approaches that will significantly advance our understanding of the deep marine biosphere in the basement rocks of the Mid Atlantic Ridge. Relative to marine sediments, the basaltic basement poses more challenges for obtaining quality samples for microbiological analysis, and the use of CORK observatories for such studies is essential to move this discipline forward. As such, this project meets many of the primary scientific objectives of the IODP. The foundation laid by this project will provide the necessary infrastructure and momentum for future observatory-based investigations of the deep biosphere. It will support numerous undergraduate and graduate research projects, and foster collaborative research and educational exchange across three continents, Asia, North America and Europe.
