Integrated Ocean Drilling Program Expedition 322 scientific prospectus; NanTroSEIZE Stage 2; subduction inputs

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doi: 10.2204/iodp.sp.322.2009
Author(s): Saito, Saneatsu; Underwood, Michael B.; Kubo, Yu'suke
Author Affiliation(s): Primary:
Japan Agency for Marine-Earth Science and Technology, Institute for Research on Earth Evolution, Yokosuka, Japan
Other:
University of Missouri, United States
Source: Scientific Prospectus (Integrated Ocean Drilling Program), Vol.322, 62p. Publisher: IODP Management International, College Station, TX, United States. ISSN: 1932-9415
Note: In English. 72 refs.
Summary: Integrated Ocean Drilling Program (IODP) Expedition 322 is part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). This multiexpedition drilling project was designed to investigate fault mechanics and seismogenesis along subduction megathrusts through direct sampling, in situ measurements, and long-term monitoring in conjunction with laboratory studies and numerical modeling. The primary goal for Expedition 322 is to characterize the composition, architecture, and state of sediments and upper igneous crust entering the subduction system offshore the Kii Peninsula, Japan. Proposed drilling Site NT1-07A will penetrate ∼1200 meters below seafloor through an important interval of turbidite-rich strata overlying the flanks of an oceanic basement high. If time and borehole conditions permit, we will also core and log up to 40 m of basement. The data will provide much-needed constraints on the initial conditions for the "subduction conveyor", which transports the incoming sediments and igneous crust to higher pressure-temperature (P-T) conditions. Ultimately, according to the overarching hypotheses of NanTroSEIZE, the changes imparted on rocks and fluids by those higher P-T conditions drive the onset of seismogenic fault behavior. The architecture of the incoming sediment is also important as a potential control on spatial heterogeneities in permeability, pore pressure, fluid chemistry, and mechanical strength. We will test how and to what extent sandy turbidites in the lower Shikoku Basin facies serve as permeable conduits for draining deeper sections of the underthrust sequence as they pass beneath the accretionary wedge. Focused fluid flow may lead to the development of overpressured compartments, thereby modulating shear strength. In this Scientific Prospectus we present the scientific background and objectives, the drilling operations designed to achieve them, a contingency plan strategy, the currently understood risks and steps taken to mitigate them, and the coordinated stages of the NanTroSEIZE research plan.
Year of Publication: 2009
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Accretionary wedges; Aqueous solutions; Asia; Basement; Boreholes; Continental margin; Crust; Decollement; Downhole methods; Drilling; Expedition 322; Expeditions; Far East; Faults; Fluid phase; Geophysical methods; Geophysical profiles; Geophysical surveys; Honshu; Integrated Ocean Drilling Program; Japan; Kii Peninsula; Marine drilling; Marine sediments; NanTroSEIZE; Nanai Trough Seismogenic Zone Experiment; Nankai Trough; North Pacific; Northwest Pacific; Pacific Ocean; Permeability; Planning; Plate convergence; Plate tectonics; Pore pressure; Programs; Sampling; Sediments; Seismic methods; Seismic profiles; Subduction; Subduction zones; Surveys; Upper crust; Well-logging; West Pacific
Coordinates: N323000 N350000 E1390000 E1360000
Record ID: 2009098240
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