Origin of deformation bands in argillaceous sediments at the toe of the Nankai accretionary prism, Southwest Japan

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doi: 10.1016/j.jsg.2003.06.001
Author(s): Ujiie, Kohtaro; Maltman, Alex J.; Sanchez-Gomez, Mario
Author Affiliation(s): Primary:
Japan Marine Science and Technology Center, Institute for Frontier Research on Earth Evolution, Yokohama, Japan
University of Wales, United Kingdom
Universidad de Jaen, Spain
Volume Title: Journal of Structural Geology
Source: Journal of Structural Geology, 26(2), p.221-231. Publisher: Pergamon, Oxford, International. ISSN: 0191-8141 CODEN: JSGEDY
Note: In English. 24 refs.; illus., incl. sects., 2 tables, geol. sketch maps
Summary: Deformation bands in argillaceous sediments at the toe of the Nankai accretionary prism are roughly planar, ∼1-10 mm thick, bedding-oblique zones. The bands are typically developed as two oppositely dipping sets. A band of one set can be displaced by the slickenlined surface of the oppositely dipping band, showing a reverse slip with respect to a horizontal plane. Deformation bands commonly consist of thinner subbands that are oblique or parallel to the boundaries of the deformation bands. The subbands also display a reverse slip with respect to a horizontal plane, and particles within subbands are oriented perpendicular to the maximum principal stress (σ1), regardless of the dips of the subbands. Physical property analysis using an X-ray computed tomography scanner demonstrates that porosity reduction in the deformation bands relative to the surrounding undeformed material ranges from 1 to 6%. The deformation bands are compactive shear bands formed under subhorizontal σ1 associated with northwest-directed plate convergence, and subbands arise from a combination of reverse sense of shear and flattening perpendicular to σ1, with their geometries producing the S-C aspect observed in sheared clayey sediments or ductile metamorphic shear zones. Abstract Copyright (2004) Elsevier, B.V.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 16 Structural Geology; Accretionary wedges; Asia; Compaction; Decollement; Deformation; Far East; Faults; Japan; Leg 190; Marine sediments; Nankai accretionary prism; ODP Site 1174; Ocean Drilling Program; Planar deformation features; Sediments; Shear zones; Tectonics; Thrust faults; X-ray data
Coordinates: N320000 N340000 E1360000 E1320000
Record ID: 2004052938
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands