BOSEMENA: Borehole- and Sediment physical properties Measurements in the Nankai Accretionary complex, Japan

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NanTroSEIZE (Nankai Trough Seismogenic Zone Experiment) is a multi-expedition IODP project that studies subduction zone dynamics down to the seismogenic zone. While the wealth of the cruises, which span the incoming plate, toe and slope of the prism and central forearc (Kumano Basin) and mainly aim at coring sediments and faults, Exp332 set out to deploy borehole observatories at two sites in 2010 (Kopf et al., 2011a). Both of them acquired data successfully, and one of them - the GeniusPlug - was recovered during Exp365 (March/April 2016) for data download (Kopf et al., in prep.). The proponent served as co-chief scientist onboard CHIKYU for both of these cruises, and was accompanied during Exp365 by a Univ. Bremen Master student (A. Rösner).As a consequence of the time efficient recovery of the GeniusPlug and the seamless installation of a CORK system in the C0010A borehole there was ample time during Exp365 to drill additional holes that recovered close to 100m of core at this site. The material recovered originated from the hangingwall, fault zone and footwall to the splay fault. Since the onboard science party comprised solely geophysicists and observatory specialists, the cores remained unopened on board CHIKYU and await splitting, description and subsequent analyses in August 2016 during Exp365. A. Rösner is invited to participate into the second part of Exp365 as physical properties specialist.In the BOSEMENA project we propose for a short (3 months) funding period to tackle three key tasks as part of the Exp365 scientific research: (1) Measurement of sediment physical properties such as moisture and density, shear strength and thermal conductivity on all core materials recovered during Exp365. These data will complement and help evaluate the observatory data and will be acquired on board CHIKYU in Japan during part 2 of Exp365 (August 2016). (2) Create data plots and write the relevant Physical properties chapters (Methods, Results, Initial interpretation) for the Exp365 Proceedings volume. (3) Write a chapter on the first results of the GeniusPlug temporary observatory, which was recovered successfully during part 1 of Exp365 and which hosted 5 ½ years worth of physical data. In analogy to Kopf et al. (2011b), such a chapter will also be a crucial part of the proceedings volume. For each of the three tasks we have reserved appx. one month.