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| Titel |
Giant impacts on early Mars and the cessation of the Martian dynamo |
| VerfasserIn |
J. Roberts, R. Lillis, M. Manga |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020334
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| Zusammenfassung |
| Although Mars currently has no global dynamo-driven magnetic field,
widespread crustal magnetization provides strong evidence that such
a field existed in the past. The absence of magnetization in the younger
large Noachian basins suggest that a dynamo operated early in Martian
history, but stopped in the mid-Noachian. Within a 100 Ma period,
15 giant impacts occurred coincident with the disappearance of the
global magnetic field (Lillis et al., GRL 2008). Here we investigate a possible causal link
between the giant impacts during the early and mid-Noachian and the
cessation of the Martian dynamo at about the same time. Using 3D spherical
mantle convection models, we find that impact heating associated with
the largest basins (D $>$ 2500 km) can cause the global heat flow at
the core-mantle boundary to decrease significantly (10-40\%). We suggest
that such a reduction in core heat flow may have to the cessation
of the Martian dynamo. |
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