Magnetization of the Martian crust

Abstract

This paper presents the lateral variations of the vertically averaged magnetization model of the Martian crust determined from the degree 50 spherical harmonic model of the magnetic potential. The model potential is derived using the Mars Global Surveyor low-altitude magnetic data acquired within elevations of 85-200 km. The potential model is first verified by comparing the three orthogonal components of the corresponding vector field with the observed high-altitude (∼380 km) data. Using the paleopole positions calculated through modeling 10 isolated, small magnetic anomalies, the model potential is inverted to determine the vertically averaged magnetization of a nominal 50 km thick crust. The crust is highly magnetic, with a magnetization contrast (peak-to-trough) as high as 35 A/m. The lack of distinct magnetic signatures for the giant impact basins, Hellas, Argyre and Isidis, and the absence of a magnetic anomaly associated with the north-south topographic dichotomy indicate that the upper parts of the crust are low magnetic and that the strong magnetic source bodies are in the lower parts.