Accretionary mechanics with properties that vary in space and time

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doi: 10.1029/GM096p0039
Author(s): Davis, Dan M.
Author Affiliation(s): Primary:
State University of New York, Department of Earth and Space Sciences, Stony Brook, NY, United States
Volume Title: Subduction top to bottom
Volume Author(s): Bebout, Gray E., editor; Scholl, David W.; Kirby, Stephen H.; Platt, John P.
Source: Subduction top to bottom, edited by Gray E. Bebout, David W. Scholl, Stephen H. Kirby and John P. Platt. Geophysical Monograph, Vol.96, p.39-48. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0065-8448. ISBN: 978-1-118-66457-5 CODEN: GPMGAD
Note: In English with English summary. 44 refs.; illus., incl. 1 plate, sects.
Summary: Sediments in accretionary wedges undergo a series of physical and chemical changes that eventually yield rocks whose mechanical behavior has changed greatly since the time of their accretion. These transitions in the shear localization, yielding, and seismic behavior of accreted sediments are all part of the evolution of a sedimentary packet from its initial accretion to its burial to the deeper parts of the accretionary forearc. The loss of fluid from pore spaces and the development of high fluid pressures appear to be the common factors linking several distinct aspects of the tectonics of forearcs. These factors appear to control the initial ability of strain to become concentrated on discrete faults. The transition to fully shear-localized, dilatant behavior is a necessary (but not sufficient) condition for the onset of seismic slip and is a prerequisite for the thrust-ramp geometry of the shortening in many accretionary wedges. Some other important factors, such as dewatering reactions and cementation are also intimately tied to the flow of fluids within the forearc. In addition, the variations of yield strength created by these same fluid-related processes of compaction, cementation, and failure mode evolution all exert important controls on the overall shape of and strain distribution within the forearc, as well as on the magnitudes, vergences, and loci of large-slip thrusts. Sharp lateral contrasts in strength, whatever their origin, lead to the formation of backstops different from those made by arc basement, which can dominate the structural geology of a forearc.
Year of Publication: 1996
Research Program: ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Accretionary wedges; Basins; Burial; Fluid pressure; Fore-arc basins; Leg 131; Leg 132; Mechanics; Nankai Trough; North Pacific; Northwest Pacific; Numerical models; ODP Site 808; Ocean Drilling Program; Ocean floors; Pacific Ocean; Physical models; Plate tectonics; Sandbox models; Sedimentary rocks; Subduction; Subduction zones; Trenches; West Pacific
Coordinates: N322105 N322111 E1345646 E1345634
N310326 N322524 E1575045 E1345630
N322105 N322111 E1345646 E1345634
Record ID: 1997021962
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