Molecular-isotopic studies of carbon turnover and microbial processes in an active subduction zone (Nan TroSEIZE)

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We hereby apply for a 1-year extension to successfully conclude project C-Nankai; this project is currently funding the research by Dr. Verena Heuer who recently participated in IODP Exp. 322 (September 1 – October 10, 2009) and returned samples for further post-cruise research. Our results obtained to date demonstrate both the importance of microbial processes for the carbon cycling in the megasplay fault and the subduction input of the Nankai Trough as well as the influence of deep-sourced fluids for stimulating microbial activity. In the final stage of the project, we aim to characterize the dissolved organic carbon pool influencing sediments in the megasplay fault (Site C0004) and in incoming sediments (Sites C0011 and C0012), analyze microbial lipids in selected horizons (Exp. 322), conduct laboratory incubations to constrain the microbial carbon cycling (Exp. 322), and publish our results. Specifically we seek to further constrain the role of dissolved organic matter transported through the megasplay fault for stimulating microbial activity. We seek to differentiate the influence of a deeply buried organic-rich layer from that of laterally transported fluids on the carbon cycling at Site C0012. The extension and completion of C-Nankai is required for fully exploiting the potential of the recently obtained samples set and would bring us a significant step closer towards constraining the interplay between geological and biological processes at an active plate-boundary system.