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| Titel |
Using open sidewalls for modelling self-consistent lithosphere subduction dynamics |
| VerfasserIn |
M. V. Chertova, T. Geenen, A. Berg, W. Spakman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 3, no. 2 ; Nr. 3, no. 2 (2012-10-09), S.313-326 |
| Datensatznummer |
250000990
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| Publikation (Nr.) |
 copernicus.org/se-3-313-2012.pdf |
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| Zusammenfassung |
| Subduction modelling in regional model domains, in 2-D or 3-D, is commonly
performed using closed (impermeable) vertical boundaries. Here we investigate
the merits of using open boundaries for 2-D modelling of lithosphere
subduction. Our experiments are focused on using open and closed (free slip)
sidewalls while comparing results for two model aspect ratios of 3:1 and 6:1.
Slab buoyancy driven subduction with open boundaries and free plates
immediately develops into strong rollback with high trench retreat velocities
and predominantly laminar asthenospheric flow. In contrast, free-slip
sidewalls prove highly restrictive on subduction rollback evolution, unless
the lithosphere plates are allowed to move away from the sidewalls. This
initiates return flows pushing both plates toward the subduction zone
speeding up subduction. Increasing the aspect ratio to 6:1 does not change
the overall flow pattern when using open sidewalls but only the flow
magnitude. In contrast, for free-slip boundaries, the slab evolution does
change with respect to the 3:1 aspect ratio model and slab evolution does not
resemble the evolution obtained with open boundaries using 6:1 aspect ratio.
For models with open side boundaries, we could develop a flow-speed scaling
based on energy dissipation arguments to convert between flow fields of
different model aspect ratios. We have also investigated incorporating the
effect of far-field generated lithosphere stress in our open boundary models.
By applying realistic normal stress conditions to the strong part of the
overriding plate at the sidewalls, we can transfer intraplate stress to
influence subduction dynamics varying from slab roll-back, stationary
subduction, to advancing subduction. The relative independence of the flow
field on model aspect ratio allows for a smaller modelling domain. Open
boundaries allow for subduction to evolve freely and avoid the adverse
effects (e.g. forced return flows) of free-slip boundaries. We conclude that
open boundaries in combination with intraplate stress conditions are to be
preferred for modelling subduction evolution (rollback, stationary or
advancing) using regional model domains. |
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