Timing and magnitude of shortening within the inner fore arc of the Japan Trench

Christine Regalla, Donald Myron Fisher, Eric Kirby

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

New structural data and kinematic modeling provide evidence for Plio-Quaternary, inner fore-arc shortening inboard of the Japan Trench, northeastern Honshu, accommodated by the Futaba fault, a high-angle, basement-involved fault that bounds the Abukuma massif on the east. Significant throw along the Futaba fault associated with exhumation of the massif is implied by a regionally extensive footwall syncline, the absence of Neogene sediments in the hanging wall, and high relief in the hanging wall adjacent to the fault. Kinematic fault-related fold modeling best reproduces fold geometry with 2.0-3.1 km of dip slip along a 40°-55° west dipping reverse fault. At the southern tip of the fault, tephra horizons of known age within units that predate and postdate deformation bracket the onset of deformation to 3.95-5.6 Ma and are used to calculate an average slip rate of 0.5-0.7 mm/yr, a throw rate of 0.3-0.5 mm/yr, and a shortening rate of 0.3-0.5 mm/yr. The northeastern Japan subduction zone is viewed as a classic example of an erosive margin, where offshore subsidence records have been used to argue for Neogene basal erosion of the upper plate. Tectonic erosion rates have been estimated from reconstructions of the paleomargin that assume no upper plate deformation and temporally constant fore-arc taper. Evidence presented here for Neogene fore-arc shortening, however, suggests that the upper plate is deformable and implies that that offshore subsidence records may reflect a combination of tectonic erosion and upper plate shortening.

Original languageEnglish (US)
Article numberB03411
JournalJournal of Geophysical Research: Solid Earth
Volume115
Issue number1
DOIs
StatePublished - Mar 1 2010

Fingerprint

trench
Erosion
Japan
arcs
time measurement
Subsidence
Tectonics
erosion
subsidence
Kinematics
Neogene
tectonics
slip
kinematics
hanging wall
synclines
Prednisolone
Sediments
brackets
tapering

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

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abstract = "New structural data and kinematic modeling provide evidence for Plio-Quaternary, inner fore-arc shortening inboard of the Japan Trench, northeastern Honshu, accommodated by the Futaba fault, a high-angle, basement-involved fault that bounds the Abukuma massif on the east. Significant throw along the Futaba fault associated with exhumation of the massif is implied by a regionally extensive footwall syncline, the absence of Neogene sediments in the hanging wall, and high relief in the hanging wall adjacent to the fault. Kinematic fault-related fold modeling best reproduces fold geometry with 2.0-3.1 km of dip slip along a 40°-55° west dipping reverse fault. At the southern tip of the fault, tephra horizons of known age within units that predate and postdate deformation bracket the onset of deformation to 3.95-5.6 Ma and are used to calculate an average slip rate of 0.5-0.7 mm/yr, a throw rate of 0.3-0.5 mm/yr, and a shortening rate of 0.3-0.5 mm/yr. The northeastern Japan subduction zone is viewed as a classic example of an erosive margin, where offshore subsidence records have been used to argue for Neogene basal erosion of the upper plate. Tectonic erosion rates have been estimated from reconstructions of the paleomargin that assume no upper plate deformation and temporally constant fore-arc taper. Evidence presented here for Neogene fore-arc shortening, however, suggests that the upper plate is deformable and implies that that offshore subsidence records may reflect a combination of tectonic erosion and upper plate shortening.",
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Timing and magnitude of shortening within the inner fore arc of the Japan Trench. / Regalla, Christine; Fisher, Donald Myron; Kirby, Eric.

In: Journal of Geophysical Research: Solid Earth, Vol. 115, No. 1, B03411, 01.03.2010.

Research output: Contribution to journalArticle

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