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| Titel |
Stabilizing planetary evolution through the coupling of magnetic field, surface tectonics, and atmosphere |
| VerfasserIn |
P. Driscoll, D. Bercovici |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064217
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| Zusammenfassung |
| We present a method for coupling the evolution of Earth's surface (atmosphere, tectonics) to the interior (mantle convection, core dynamo) by treating the layers as boundary-coupled one dimensional boxes. Initially atmospheric volatiles (H2O and CO2) are degassed from the mantle and remain in the atmosphere until the H2O liquid-vapor (T-P) saturation curve is intersected by the greenhouse surface temperature, at which point precipitation and weathering begins, accumulating a water ocean and buffering atmospheric CO2. Surface plate motion, a critical component of the carbon buffering cycle, is driven by mantle convection as long as the surface temperature remains below a critical value as predicted by numerical experiments using damage rheology. Active surface tectonics also allows for efficient cooling of the mantle and core, driving the core dynamo and maintaining a strong surface magnetic field. We demonstrate that this coupled model self-stabilizes as a strong magnetic field provides shielding against atmospheric erosion by the solar wind, allowing for the retention of a large water-rich atmosphere that is critical to stabilizing a temperate surface environment, surface tectonics, and whole planet cooling. Such a stabilizing feedback is consistent with observations of Earth's roughly constant surface temperature, plate speeds, and magnetic field intensity going back ~3.5 Ga. The model produces a history of Venus with initially active surface tectonics and strong magnetic field before a runaway greenhouse prevents lithospheric damage and subduction, limiting interior cooling and ultimately leading to a decay of the dynamo magnetic field. |
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