Depth of Martian Magnetization From Localized Power Spectrum Analysis
Shengxia Gong, M. A. Wieczorek
Abstract
Abstract Magnetic field measurements show that Mars possesses strong crustal magnetic anomalies that formed when the planet had an active dynamo. To investigate the origin of this magnetization, we used localized power spectrum analyses to constrain the equivalent depths of thin magnetic layers in the crust. Using a new martian magnetic field model that incorporates data from both the Mars Atmosphere and Volatile EvolutioN and Mars Global Surveyor missions, we found that the equivalent magnetization depths on Mars vary from the surface to 72 km. In the northern hemisphere the magnetization depths are found to be on average 9 km, whereas in the southern hemisphere the depths are on average 32 km. If these depths are interpreted in terms of a thick magnetic layer, magnetization in the northern lowlands could extend from the surface to about 18 km depth, whereas for the southern highlands the magnetic layer could extend from about 20 km depth to the base of the crust. The strongest magnetic anomalies are, in general, associated with deep source depths. Our results are consistent with the hypothesis where strong primordial magnetic materials of the northern hemisphere were excavated from the Borealis impact basin, leaving only strong deep remanent magnetization in the southern hemisphere.