15. Evolution of Sedimentary Environments in the Subduction Zone v of Southwest Japan: Recent Results from the NanTroSEIZE Kumano Transect

  1. Cathy Busby3 and
  2. Antonio Azor4
  1. Michael B. Underwood3 and
  2. Gregory F. Moore4

Published Online: 30 JAN 2012

DOI: 10.1002/9781444347166.ch15

Tectonics of Sedimentary Basins: Recent Advances

Tectonics of Sedimentary Basins: Recent Advances

How to Cite

Underwood, M. B. and Moore, G. F. (2011) Evolution of Sedimentary Environments in the Subduction Zone v of Southwest Japan: Recent Results from the NanTroSEIZE Kumano Transect, in Tectonics of Sedimentary Basins: Recent Advances (eds C. Busby and A. Azor), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9781444347166.ch15

Editor Information

  1. 3

    Department of Earth Science, University of California, Santa Barbara CA 93106, USA

  2. 4

    Departamento de Geodinámica, Universidad de Granada, Campus de Fuentenueva, s/n, 18071 Granada, Spain

Author Information

  1. 3

    Department of Earth Science, University of California, Santa Barbara CA 93106, USA

  2. 4

    Departamento de Geodinámica, Universidad de Granada, Campus de Fuentenueva, s/n, 18071 Granada, Spain

Publication History

  1. Published Online: 30 JAN 2012
  2. Published Print: 30 DEC 2011

ISBN Information

Print ISBN: 9781405194655

Online ISBN: 9781444347166

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Keywords:

  • Integrated Ocean Drilling Program;
  • Nankai Trough;
  • forearc basin;
  • accretionary prism;
  • lithostratigraphy

Summary

The Nankai Trough is located off the coast of southwest Japan, where the Philippine Sea plate is subducting beneath the Eurasian plate. The margin's Kii Peninsula or Kumano Basin corridor is the focal area for the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). This multi-disciplinary, multi-stage, multi-expedition project was designed to improve our understanding of seismogenic processes along the plate interface. Drilling Stage 1 of NanTroSEIZE included Expeditions 314, 315, and 316 of the Integrated Ocean Drilling Program. Coring and logging during those three expeditions generated a wealth ofnewinformation about the stratigraphic and structural evolution of the margin. Our summary descriptions are organized into three broad domains: the Kumano (forearc) Basin; the megasplay fault zone, which is a significant out-of-sequence thrust within the accretionary prism; and the frontal thrust zone of the accretionary prism. For the most part, drilling results validate structural interpretations of 3D seismic-reflection data, but they also place invaluable constraints on the timing of such events as the initiation of forearc-basin sedimentation and the history of slip on the megasplay fault. Weseemany types of interaction between tectonics and sedimentation. The frontal thrust zone is dominated by packets of sand and gravel that probably accumulated within trench-floor axial channel systems prior to their accretion in the early Pleistocene. The accretionary prism becomes progressively older toward land, and a time-transgressive unconformity separates the prism from the overlying slope apron. Turbidite sedimentation within the Kumano Basin did not begin until the early Pleistocene, after a succession of precursor events: formation of the underlying accretionary prism during the late Miocene and early Pliocene; erosion of an unconformity above the accretionary prism, with an associated hiatus of ∼1.2 My; a long phase of unusually slow hemipelagic sedimentation, lasting from ∼3.8 Myr to ∼1.67 Myr; acceleration of uplift along the megasplay fault at ∼1.55 Myr, which enhanced accommodation space; and organization of a robust sediment-delivery system, which was achieved through uplift and erosion of the hinterland and incision of canyons and gullies into the upper trench slope.