Origin and dynamics of depositionary subduction margins

Geochemistry, Geophysics, Geosystems
By: , and 

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Abstract

Here we propose a new framework for forearc evolution that focuses on the potential feedbacks between subduction tectonics, sedimentation, and geomorphology that take place during an extreme event of subduction erosion. These feedbacks can lead to the creation of a “depositionary forearc,” a forearc structure that extends the traditional division of forearcs into accretionary or erosive subduction margins by demonstrating a mode of rapid basin accretion during an erosive event at a subduction margin. A depositionary mode of forearc evolution occurs when terrigenous sediments are deposited directly on the forearc while it is being removed from below by subduction erosion. In the most extreme case, an entire forearc can be removed by a single subduction erosion event followed by depositionary replacement without involving transfer of sediments from the incoming plate. We need to further recognize that subduction forearcs are often shaped by interactions between slow, long-term processes, and sudden extreme events reflecting the sudden influences of large-scale morphological variations in the incoming plate. Both types of processes contribute to the large-scale architecture of the forearc, with extreme events associated with a replacive depositionary mode that rapidly creates sections of a typical forearc margin. The persistent upward diversion of the megathrust is likely to affect its geometry, frictional nature, and hydrogeology. Therefore, the stresses along the fault and individual earthquake rupture characteristics are also expected to be more variable in these erosive systems than in systems with long-lived megathrust surfaces.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Origin and dynamics of depositionary subduction margins
Series title Geochemistry, Geophysics, Geosystems
DOI 10.1002/2016GC006259
Volume 17
Issue 6
Year Published 2016
Language English
Publisher AGU Publications
Contributing office(s) Pacific Coastal and Marine Science Center
Description 9 p.
First page 1966
Last page 1974
Online Only (Y/N) N
Additional Online Files (Y/N) N
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