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| Titel |
Evolution of a Subduction Zone |
| VerfasserIn |
Lena Noack, Tim Van Hoolst, Veronique Dehant |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098881
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| Publikation (Nr.) |
 EGU/EGU2014-14599.pdf |
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| Zusammenfassung |
| The purpose of this study is to understand how Earth’s surface might have evolved with time
and to examine in a more general way the initiation and continuance of subduction zones and
the possible formation of continents on an Earth-like planet. Plate tectonics and continents
seem to influence the likelihood of a planet to harbour life, and both are strongly influenced
by the planetary interior (e.g. mantle temperature and rheology) and surface conditions (e.g.
stabilizing effect of continents, atmospheric temperature), but may also depend on the
biosphere.
Employing the Fortran convection code CHIC (developed at the Royal Observatory of
Belgium), we simulate a subduction zone with a pre-defined weak zone (between oceanic and
continental crust) and a fixed plate velocity for the subducting oceanic plate (Quinquis et al.
in preparation).
In our study we first investigate the main factors that influence the subduction process. We
simulate the subduction of an oceanic plate beneath a continental plate (Noack et al.,
2013). The crust is separated into an upper crust and a lower crust. We apply mixed
Newtonian/non-Newtonian rheology and vary the parameters that are most likely to influence
the subduction of the ocanic plate, as for example density of the crust/mantle, surface
temperature, plate velocity and subduction angle.
The second part of our study concentrates on the long-term evolution of a subduction zone.
Even though we model only the upper mantle (until a depth of 670km), the subducted
crust is allowed to flow into the lower mantle, where it is no longer subject to our
investigation. This way we can model the subduction zone over long time spans, for
which we assume a continuous inflow of the oceanic plate into the investigated
domain.
We include variations in mantle temperatures (via secular cooling and decay of radioactive
heat sources) and dehydration of silicates (leading to stiffening of the material). We
investigate how the mantle environment influences the subduction of the oceanic crust in
terms of subduction velocity and subduction angle over time.
We develop scaling laws combining the subduction velocity and angle depending on the
mantle environment (and thus time). These laws can then be applied to continental growth
simulations with 1D parameterized models (Höning et al., in press) or 2D/3D subduction
zone simulations at specific geological times (using the correct subduction zone
setting).
References:
Quinquis, M. et al. (in preparation). A comparison of thermo-mechanical
subduction models. In preparation for G3.
Noack, L., Van Hoolst, T., Dehant, V., and Breuer, D. (2013). Relevance of
continents for habitability and self-consistent formation of continents on early
Earth. XIII International Workshop on Modelling of Mantle and Lithosphere
Dynamics, Hønefoss, Norway, 31. Aug. - 5. Sept. 2013.
Höning, D., Hansen-Goos, H., Airo, A., and Spohn, T. (in press). Biotic vs.
abiotic Earth: A model for mantle hydration and continental coverage. Planetary
and Space Science. |
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