Site C0002

Abstract

This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Contents 1 Introduction and operations 8 Lithology 25 Structural geology 37 Biostratigraphy and paleomagnetism 42 Geochemistry 48 Physical properties 55 Logging 75 References

The stabilizing effect of high pore-fluid pressure along subduction megathrust faults: Evidence from friction experiments on accretionary sediments from the Nankai Trough

“…Only cuttings from this depth interval were used in this study as we intend to investigate the role of varying pore-fluid pressure and effective normal stress on frictional stability, therefore we want to minimise the effects of any sample variability that might occur by using samples recovered from different depth intervals. Although it should be noted that these lithologies are typical of those found throughout the accretionary wedge system (Tobin et al, 2020) and we expect similar lithologies to be present along the main megathrust at seismogenic depths. Tobin et al, (2020)) showing the NanTroSEIZE transect and drill sites of previous expeditions (white dots).…”

“…Although it should be noted that these lithologies are typical of those found throughout the accretionary wedge system (Tobin et al, 2020) and we expect similar lithologies to be present along the main megathrust at seismogenic depths. Tobin et al, (2020)) showing the NanTroSEIZE transect and drill sites of previous expeditions (white dots). The location of Site C0002 is shown as a black dot.…”

“…The location of Site C0002 is shown as a black dot. b) Interpreted cross-section of the NanTroSEIZE transect (modified from Tobin et al, (2020)) showing Site C0002 which penetrated through the Kumano Basin and into the inner accretionary prism above the plate boundary megathrust fault.…”

“…The Nankai Trough subduction zone lies off the coast of southwest Japan, with records of creep, slow-slip events and megathrust earthquakes occurring on the fault dating back over 1000 years (Ando, 1975). In the winter of 2018-19 the accretionary complex that overlies the Nankai megathrust was drilled, with cuttings and core samples collected, to a maximum depth of 3262.5 mbsf (meters below seafloor) at Integrated Ocean Discovery Program (IODP) Site C0002 during Expedition 358 (Tobin et al, 2020), as part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) (Tobin and Kinoshita, 2006). Here we experimentally test the frictional properties of the materials recovered during Expedition 358.…”

A new method for the empirical conversion of logging data to clay mineral fraction in the Nankai accretionary prism

“…However, XRD data is limited by the fact that data cannot be acquired when core samples are not recovered. This is especially true in the accretionary prism, which is composed of easily collapsible sediment, and coring has sometimes been difficult due to poor hole conditions throughout the NanTroSEIZE project (Expedition 315 Scientists 2009b, Expedition 316 Scientists 2009aKitajima et al 2020). In difficult drilling conditions, logging while drilling (LWD) techniques are more promising than coring.…”