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Expedition 316 Site C00071

Expedition 316 Scientists2

Background and objectives

Integrated Ocean Drilling Program (IODP) Site C0007 (proposed Site NT1-03A; Kimura et al., 2007) targets the main frontal thrust at the seaward edge of the accretionary prism (Figs. F1, F2). This site was drilled during IODP Expedition 316 after hole conditions at IODP Site C0006 precluded reaching the main frontal thrust fault. Based on seismic data and submersible studies, this thrust was interpreted to have placed moderately consolidated (and presumably older) clastic rocks over weak and unlithified late Quaternary trench section clastic sediments (Ashi et al., 2002). Site C0007 is located trenchward of Site C0006. At this location, a thrust fault is observed in the seismic section at ~200 meters below seafloor (mbsf), and the frontal thrust is interpreted to occur at ~400 mbsf. The scientific objectives of drilling at Site C0007 are the same as those at Site C0006: to clarify the evolution of the frontal thrust from its birth to death, the function of the frontal thrust with respect to large earthquakes, and the relationship between fluid behavior, slip, and deformation within this fault zone.

Hole C0007D was located ~185 m northwest (upslope) of Hole C0007C to avoid thick gravels encountered in Hole C0007C. The last core recovered from Hole C0007C reached 166.59 m core depth below seafloor (CSF). Because of its upslope position, initiation of coring at 175.00 m CSF in Hole C0007D allowed overlap with equivalent horizons from Hole C0007C, as identified in seismic profiles (Fig. F2).

Core samples from Expedition 316 drilling at this site will be integrated with the existing three-dimensional (3-D) seismic and Site C0006 results to characterize physical properties, strength, composition, and structure of the hanging wall, frontal thrust, and footwall at this site. In situ temperature data were also collected to assess the thermal gradient and heat flow in this area.

1 Expedition 316 Scientists, 2009. Expedition 316 Site C0007. In Kinoshita, M., Tobin, H., Ashi, J., Kimura, G., Lallemant, S., Screaton, E.J., Curewitz, D., Masago, H., Moe, K.T., and the Expedition 314/315/316 Scientists, Proc. IODP, 314/315/316: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/​iodp.proc.314315316.135.2009

2 Expedition 314/315/316 Scientists’ addresses.

Publication: 11 March 2009
MS 314315316-135