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doi:10.2204/iodp.proc.314315316.210.2012

Introduction

Integrated Ocean Drilling Program (IODP) Expedition 316 is a part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) complex drilling project, a coordinated multiexpedition drilling project with the purpose of investigating fault mechanics and seismogenesis along subduction megathrusts in the Nankai Trough (see the “Expedition 316 summary” chapter [Screaton et al., 2009]). During Expedition 316, four sites (C0004, C0006, C0007, and C0008) were drilled in the Nankai Trough (Fig. F1). IODP Site C0004 is located along the slope of the accretionary prism and landward of the inferred intersection of the megasplay fault zone with the seafloor (see the “Expedition 316 Site C0004” chapter [Expedition 316 Scientists, 2009a]). Drilling at this site was conducted to examine the youngest sediments on the slope overlying the accretionary prism, which consist of slowly deposited marine sediments and redeposited material from upslope (Fig. F2). IODP Site C0008 is located ~1 km seaward of Site C0004 (Fig. F2) and was selected to examine the basin seaward of the splay fault penetrated at Site C0004 (see the “Expedition 316 Site C0008” chapter [Expedition 316 Scientists, 2009b]). The drilling results from Sites C0004 and C0008 also provided information necessary to explore the splay fault’s origin and evolution and its relation to the structural evolution of the Nankai margin through time (Strasser et al., 2009).

The objective of this study is to provide detailed data regarding the occurrence of age-diagnostic calcareous nannofossils and to obtain better resolved biostratigraphic datums for these two sites, through reexamining shipboard nannofossil slides and data and analyzing additional samples during the postcruise study.