Deformation structures in the frontal prism near the Japan Trench; insights from sandbox models

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doi: 10.1016/j.jog.2015.06.002
Author(s): Bose, Santanu; Saha, Puspendu; Mori, James J.; Rowe, Christie; Ujiie, Kohtaro; Chester, Frederick M.; Conin, Marianne; Regalla, Christine; Kameda, Jun; Toy, Virginia; Kirkpatrick, James; Remitti, Francesca; Moore, J. Casey; Wolfson-Schwehr, Monica; Nakamura, Yasuyuki; Gupta, Anchit
Author Affiliation(s): Primary:
University of Calcutta, Department of Geology, Experimental Tectonic Laboratory, Calcutta, India
Other:
Kyoto University Gokasho, Japan
McGill University, Canada
University of Tsukuba, Japan
Texas A&M University, United States
Universite de Lorraine, France
Hokkaido University, Japan
University of Otago, New Zealand
Universita di Modena e Reggio Emilia, Italy
University of California, Santa Cruz, United States
University of New Hampshire, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Indian Institute of Technology, India
Volume Title: Journal of Geodynamics
Source: Journal of Geodynamics, Vol.89, p.29-38. Publisher: Elsevier, Oxford, United Kingdom. ISSN: 0264-3707
Note: In English. 38 refs.; illus., incl. sects., 1 table, sketch map
Summary: We have used sandbox experiments to explore the mechanics of the frontal prism structures documented by seismic reflection data and new borehole from IODP Expedition 343 (JFAST). This study investigated the effects of down-dip (normal to trench axis) variations in frictional resistance along a decollement on the structural development of the frontal wedges near subduction zones. Interpretation of seismic reflection images indicates that the wedge has been effected by trench-parallel horst-and-graben structures in the subducting plate. We performed sandbox experiments with down-dip patches of relatively high and low friction on the basal decollement to simulate the effect of variable coupling over subducting oceanic plate topography. Our experiments verify that high frictional resistance on the basal fault can produce the internal deformation and fault-and-fold structures observed in the frontal wedge by the JFAST expedition. Subduction of patches of varying friction caused a temporal change in the style of internal deformation within the wedge and gave rise to two distinctive structural domains, separated by a break in the surface slope of the wedge: (i) complexly deformed inner wedge with steep surface slope and (ii) shallow taper outer wedge, with a sequence of imbricate thrusts. Our experiments further demonstrate that the topographic slope-break in the wedge develops when the hinterland part of the wedge essentially stops deforming internally, leading to in-sequence thrusting with the formation of an outer wedge with low taper angle. For a series of alternate high and low frictional conditions on the basal fault the slope of the wedge varies temporally between a topographic slope-break and uniformly sloping wedge. Abstract Copyright (2015) Elsevier, B.V.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 16 Structural Geology; 20 Geophysics, Applied; Accretionary wedges; Asia; Decollement; Deformation; Earthquakes; Expeditions 343/343T; Far East; Faults; Geophysical methods; Geophysical profiles; Geophysical surveys; Honshu; Horsts; IODP Site C0019; Integrated Ocean Drilling Program; Japan; Japan Trench; Japan Trench Fast Drilling Project; North Pacific; Northwest Pacific; Pacific Ocean; Physical models; Plate boundaries; Plate tectonics; Reflection; Sandbox models; Seismic methods; Seismic profiles; Structural analysis; Subduction; Surveys; Systems; Thrust faults; Tohoku-Oki earthquake 2011; Topography; West Pacific
Coordinates: N375619 N375620 E1435449 E1435447
N370000 N400000 E1450000 E1400000
Record ID: 2017014869
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands