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Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
Mechanisms for oscillatory true polar wander
J R Creveling1, J X Mitrovica, N-H Chan
1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA. jcrevel@gps.caltech.edu
Nature
|November 9, 2012
Summary
True polar wander (TPW) events may be linked by Earth's elastic lithosphere. New geodynamic models show TPW paths consistent with paleomagnetic data, suggesting a mechanism for past TPW oscillations.
Area of Science:
- Geophysics
- Earth Science
- Plate Tectonics
Background:
- Palaeomagnetic studies suggest large, rapid true polar wander (TPW) events throughout Earth's history.
- These TPW excursions may follow an oscillatory pattern around supercontinents.
- Existing geodynamic models require opposing loading phases to explain oscillatory TPW.
Purpose of the Study:
- To extend rotational stability theory by including lithospheric elastic stresses.
- To investigate geodynamic mechanisms driving oscillatory TPW.
- To reconcile palaeomagnetic evidence with theoretical models of Earth's rotation.
Main Methods:
- Developed a nonlinear rotational stability theory.
- Incorporated TPW-induced elastic stresses in the lithosphere.
- Utilized geodynamic models with convectively driven inertia perturbations on a non-hydrostatic Earth.
Main Results:
- Demonstrated that an effective elastic lithospheric thickness of ~10 km can produce oscillatory TPW paths matching palaeomagnetic data.
- Showed that TPW-induced elastic stresses stabilize the rotation axis.
- Found that excess ellipticity can reduce the required elastic thickness, even to zero.
Conclusions:
- TPW-induced elastic stresses offer a stabilizing mechanism for oscillatory TPW.
- A time-varying mantle flow field, combined with stabilization, can link distinct TPW events over billions of years.
- The proposed mechanism provides a viable explanation for observed palaeomagnetic TPW patterns.
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