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Topography of the Overriding Plate During Progressive Subduction: A Dynamic Model to Explain Forearc Subsidence
Author(s) -
Chen Zhihao,
Schellart Wouter P.,
Duarte João C.,
Strak Vincent
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl074672
Subject(s) - geology , subduction , forearc , slab , trench , seismology , slab window , geodynamics , mantle (geology) , ocean surface topography , subsidence , discontinuity (linguistics) , geophysics , mantle wedge , plate tectonics , wedge (geometry) , petrology , tectonics , geodesy , oceanic crust , geomorphology , geometry , chemistry , organic chemistry , layer (electronics) , structural basin , mathematical analysis , mathematics
Overriding plate topography provides constraints on subduction zone geodynamics. We investigate its evolution using fully dynamic laboratory models of subduction with techniques of stereoscopic photogrammetry and particle image velocimetry. Model results show that the topography is characterized by an area of forearc dynamic subsidence, with a magnitude scaling to 1.44–3.97 km in nature, and a local topographic high between the forearc subsided region and the trench. These topographic features rapidly develop during the slab free‐sinking phase and gradually decrease during the steady state slab rollback phase. We propose that they result from the variation of the vertical component of the trench suction force along the subduction zone interface, which gradually increases with depth and results from the gradual slab steepening during the initial transient slab sinking phase. The downward mantle flow in the nose of the mantle wedge plays a minor role in driving forearc subsidence.