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Three‐dimensional necking during viscous slab detachment
Author(s) -
Tscharner M.,
Schmalholz S. M.,
Duretz T.
Publication year - 2014
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 - 10.1002/2014gl060075
Subject(s) - slab , geology , lithosphere , necking , trench , mantle (geology) , seismology , deflection (physics) , deformation (meteorology) , power law , geophysics , optics , tectonics , physics , materials science , layer (electronics) , oceanography , statistics , mathematics , composite material , thermodynamics
We study the three‐dimensional (3‐D) deformation during detachment of a lithospheric slab with simple numerical models using the finite element method. An initially vertical layer of power law viscous fluid mimics the slab and is surrounded by a linear or power law viscous fluid representing asthenospheric mantle. We quantify the impact of slab size and shape (symmetric/asymmetric) on slab detachment and identify two processes that control the lateral (i.e., along‐trench) slab deformation: (1) the horizontal deflection of the lateral, vertical slab sides (> 100 km with velocities up to 16 mm/yr) and (2) the propagation of localized thinning (necking) inside the slab (with velocities >9 cm/yr). The lateral propagation velocity is approximately constant during slab detachment. Larger slabs (here wider than approximately 300 km) detach with rates similar to those predicted by 2‐D models, whereas smaller slabs detach slower. Implications for geodynamic processes and interpretations of seismic tomography are discussed.