Opal-CT in chert beneath the toe of the Tohoku margin and its influence on the seismic aseismic transition in subduction zones

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doi: 10.1002/2016GL071784
Author(s): Kameda, Jun; Okamoto, Atsushi; Sato, Kiminori; Fujimoto, Koichiro; Yamaguchi, Asuka; Kimura, Gaku
Author Affiliation(s): Primary:
Hokkaido University, Graduate School of Science, Sapporo, Japan
Other:
Tohoku University, Japan
Tokyo Gakugei University, Japan
University of Tokyo, Japan
Tokyo University of Marine Science and Technology, Japan
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 44(2), p.687-693. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. 22 refs.; illus.
Summary: Thick accumulation of chert is a ubiquitous feature of old oceanic plates at convergent margins. In this study, we investigate chert fragments recovered by the Integrated Ocean Drilling Program expedition 343 at the Japan Trench where the 2011 Tohoku-Oki earthquake (Mw 9.0) occurred. This sample provides a unique opportunity to investigate in situ chert diagenesis at an active subduction margin and its influence on the kinematics of megathrust faulting. Our mineralogical analyses revealed that the chert is characterized by hydrous opal-CT and may therefore be highly deformable via pressure solution creep and readily accommodate shear strain between the converging plates at driving stresses of kilopascal order. As chert diagenesis advances, any further deformation requires stresses of >100 MPa, given the increasing transport distances for solutes as represented in cherts on land. The chert diagenesis is thus related to the mechanical transition from a weakly to strongly coupled plate interface at this margin. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 17 Geophysics, General; 19 Geophysics, Seismology; Aseismic margins; Asia; Chemically precipitated rocks; Chert; Continental margin; Diagenesis; Earthquakes; Expedition 343; Expeditions 343/343T; Far East; Framework silicates; Geologic hazards; Great earthquakes; Honshu; Integrated Ocean Drilling Program; Japan; Japan Trench; Japan Trench Fast Drilling Project; Magnitude; Natural hazards; North Pacific; Northwest Pacific; Opal; Opal-CT; Pacific Ocean; Plate tectonics; Sedimentary rocks; Seismicity; Seismotectonics; Silica minerals; Silicates; Subduction zones; Tectonics; Tohoku-Oki earthquake 2011; Tsunamis; West Pacific
Coordinates: N375619 N375620 E1435449 E1435447
Record ID: 2018015666
Copyright Information: GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom