Non-uniqueness of the Modeled Magnetization Vectors Used in Determining Paleopoles on Mars

This study investigates the non-uniqueness of current magnetization models derived from magnetic anomalies on Mars observed by the Mars Global Surveyor spacecraft and modeling of magnetic anomalies on Earth. In place of elliptical and circular prismatic models of Arkani-Hamed (2001, GRL, v.28, no. 17, p. 3409-3412) and Hood and Zakharian (2001, JGR, v. 106, no. E7, p. 14601-14619), alternative, smaller, multiple source configurations developed in this study explain the anomalies designated as M10 and M3 on Mars equally well and suggest that coalescence of anomalies at high altitude might be an important effect ignored in the previous studies. The coalescence effect might have affected magnetization directions derived from other isolated anomalies in other studies. The scatter in paleopole locations computed from the alternative configurations of sources M3 and M10 covers nearly 40% of the surface of Mars and, hence, the utility of these paleopole locations in deciphering the ancient tectonics is questioned. On Earth, a 2D model of the near-surface anomaly over northeast America and neighboring Atlantic ocean near Newfoundland and the 3D models of the satellite altitude anomaly over the same region demonstrated that magnetic models based on the Amplitude of Analytic Signal (AAS) field allowed more realistic complexity similar to the near-surface magnetic anomaly patterns, which closely reflect the geology, whereas, the model deciphered from the Z-component magnetic field alone was unrealistic. This suggests on Mars the magnetic model based on the AAS field is likely to yield better source characteristics than modeling of Z-component magnetic field.