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doi:10.2204/iodp.proc.333.201.2014

Introduction

Integrated Ocean Drilling Program (IODP) Expedition 333 was conducted to sample previously uncored intervals from Sites C0011 and C0012 and to drill and core Site C0018 to constrain submarine landslide history along the lower forearc slope in the vicinity of the seafloor outcrop of the megasplay fault of the Nankai subduction zone (Henry et al., 2010) (Fig. F1). This expedition was part of the larger Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), the goals of which were understanding faulting, deformation, and hydrological processes in the vicinity of the plate boundary and megasplay faults along the Nankai convergent margin (Tobin and Kinoshita, 2006).

We performed laboratory analyses of consolidation and fluid transport characteristics with the goal of constraining physical properties that influence sediment deformation and heat and fluid flow within the Nankai accretionary complex. This work complements other shore-based laboratory and modeling efforts by characterizing the physical properties of the input material to the subduction zone and helps us understand how the sediments change through time as they are subducted. We used whole-round samples for constant-rate-of-strain (CRS) consolidation experiments to determine permeability, compression index, and overconsolidation ratio (OCR). Sample trimmings from CRS specimens were used for grain size, specific surface, and mercury injection capillary pressure (MICP) measurements to compare with geotechnical properties and ultimately to understand the pore-scale controls on hydrologic properties of sediments in the accretionary margin. Our work complements other geotechnical and sedimentological work that is ongoing throughout the NanTroSEIZE project. Integration of these studies across the lifetime of the project will result in a complete data set of geotechnical and sedimentological parameters that may be used to understand interactions and feedback among sediment physical properties, hydrologic processes, and deformation within the Nankai convergent margin.

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