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Expedition 316 Site C00061

Expedition 316 Scientists2

Background and objectives

Integrated Ocean Drilling Program (IODP) Site C0006 (proposed Site NT1-03B; Kimura et al., 2007) targets the main frontal thrust at the seaward edge of the accretionary prism (Figs. F1, F2). 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). The scientific objectives of drilling at Site C0006 are 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.

Site C0006 was first drilled during IODP Expedition 314 (see the “Expedition 314 Site C0006” chapter), and logging-while-drilling (LWD) logs were obtained to 885.5 m logging depth below seafloor (LSF). During IODP Expedition 316, coring was completed to 603 m core depth below seafloor (CSF). Poor hole conditions stopped drilling at this site before the frontal thrust was reached.

During Expedition 314, four primary logging units were defined in IODP Hole C0006B based on visual inspection of the gamma ray, resistivity, and caliper log responses:

  1. Logging Unit I (0–198 m LSF) is interpreted as sandy and muddy sediments.
  2. Logging Unit II (198–428 m LSF) is interpreted as a mudstone with thick sandstone.
  3. Logging Unit III (428–711 m LSF) is interpreted as alternating beds of mudstone and sandstone (base marked by a large fault zone).
  4. Logging Unit IV (711 m LSF to total depth [TD]) is below the inferred fault zone and interpreted as sandstone.

Core samples from Expedition 316 drilling at this site will be integrated with the existing three-dimensional (3-D) seismic and LWD 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 C0006. 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.314315316.134.2009

2 Expedition 314/315/316 Scientists’ addresses.

Publication: 11 March 2009
MS 314315316-134