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Detailed Reference Information |
Rochette, P., Hood, L., Fillion, G., Ballou, R. and Ouladdiaf, B. (2004). Reply [to “Comment on ‘Impact demagnetization by phase transition on Mars’” by P. Surdas Mohit]. Eos, Transactions American Geophysical Union 85: doi: 10.1029/2004EO220007. issn: 0096-3941. |
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We welcome the comment of P. S. Mohit on our recent Eos article as a useful contribution to the understanding of the complex question of impact demagnetization of Mars. We disagree that the map shown in our Figure 1 was deceptive. It is a simple plot of the magnetic field magnitude at the MGS mapping orbit altitude (360--400 km). Adding additional contours down to 10 nT, for example, does not change the basic character of the map. Our point was that magnetic fields are significantly weaker within several radii of the Hellas and Argyre basins than they are in the adjacent southern highlands. Specifically, fields near the basins are typically of the order of 20 nT or less, while fields in the adjacent highlands are in the range of 40--200 nT. This distribution suggests that impact shock demagnetization may have significantly weakened pre-existing crustal magnetization within several basin radii. The author's Figure 1 is based on spherical harmonic model fields at much lower altitudes (120 km) and is not a true average intensity of magnetic anomalies as a function of radius. As described by Mohit and Arkani-Hamed <2004>, the average for each basin excludes large azimuthal sectors containing very low fields. This enhances the increase of field with radial distance shown in the figure. |
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Abstract |
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Keywords
Forum, Planetology, Solid Surface Planets, Magnetic fields and magnetism, Planetology, Solid Surface Planets, Impact phenomena (includes cratering) |
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Journal
Eos, Transactions American Geophysical Union |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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