Structure and lithology of the Japan Trench subduction plate boundary fault

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doi: 10.1002/2014TC003695
Author(s): Kirkpatrick, James D.; Rowe, Christie D.; Ujiie, Kohtaro; Moore, J. Casey; Regalla, Christine; Remitti, Francesca; Toy, Virginia; Wolfson-Schwehr, Monica; Kameda, Jun; Bose, Santanu; Chester, Frederick M.
Author Affiliation(s): Primary:
Colorado State University, Department of Geosciences, Fort Collins, CO, United States
McGill University, Canada
University of Tsukuba, Japan
University of California, Santa Cruz, United States
Pennsylvania State University, United States
Universita di Modena e Reggio Emilia, Italy
University of Otago, New Zealand
University of New Hampshire, United States
Hokkaido University, Japan
University of Calcutta, India
Texas A&M University, United States
Volume Title: Tectonics
Source: Tectonics, 34(1), p.53-69. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0278-7407 CODEN: TCTNDM
Note: In English. 58 refs.; illus., incl. sketch map
Summary: The 2011 Mw9.0 Tohoku-oki earthquake ruptured to the trench with maximum coseismic slip located on the shallow portion of the plate boundary fault. To investigate the conditions and physical processes that promoted slip to the trench, Integrated Ocean Drilling Program Expedition 343/343T sailed 1 year after the earthquake and drilled into the plate boundary ∼7 km landward of the trench, in the region of maximum slip. Core analyses show that the plate boundary decollement is localized onto an interval of smectite-rich, pelagic clay. Subsidiary structures are present in both the upper and lower plates, which define a fault zone ∼5-15m thick. Fault rocks recovered from within the clay-rich interval contain a pervasive scaly fabric defined by anastomosing, polished, and lineated surfaces with two predominant orientations. The scaly fabric is crosscut in several places by discrete contacts across which the scaly fabric is truncated and rotated, or different rocks are juxtaposed. These contacts are inferred to be faults. The plate boundary decollement therefore contains structures resulting from both distributed and localized deformation. We infer that the formation of both of these types of structures is controlled by the frictional properties of the clay: the distributed scaly fabric formed at low strain rates associated with velocity-strengthening frictional behavior, and the localized faults formed at high strain rates characterized by velocity-weakening behavior. The presence of multiple discrete faults resulting from seismic slip within the decollement suggests that rupture to the trench may be characteristic of this margin. Abstract Copyright (2014), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 16 Structural Geology; Active faults; Biostratigraphy; Boundary faults; Cenozoic; Clay minerals; Coseismic processes; Cretaceous; Decollement; Deformation; Earthquakes; Expeditions 343/343T; Fabric; Faults; Friction; Integrated Ocean Drilling Program; Japan Trench; Japan Trench Fast Drilling Project; Lineation; Marine sediments; Mesozoic; Microfossils; Mineral composition; North Pacific; Northwest Pacific; Ocean floors; Pacific Ocean; Pacific Plate; Pelagic sedimentation; Plate boundaries; Plate tectonics; Rotation; Rupture; Sedimentary structures; Sedimentation; Sediments; Seismicity; Seismotectonics; Sheet silicates; Silicates; Slip rates; Smectite; Strain; Structural analysis; Subduction zones; Tectonics; Tertiary; Textures; Tohoku-Oki earthquake 2011; Trenches; West Pacific
Coordinates: N375619 N375620 E1435449 E1435447
Record ID: 2015057217
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom