East–west trending magnetic anomalies in the Southern Hemisphere of Mars: Modeling analysis and interpretation

Hood, L. L.; Richmond, N. C.; Harrison, K. P.; Lillis, Robert J.

doi:10.1016/j.icarus.2007.04.025

Cited by 20 publications

(21 citation statements)

References 41 publications

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“…Admissible paleopole locations for P1 only extend to 60°S, indicating that TPW (Bouley et al, ; Kite et al, ) of about 30° must have occurred on Mars. TPW has previously been suggested by Arkani‐Hamed (), Hood and Zakharian (), Arkani‐Hamed and Boutin (), Frawley and Taylor (), Hood et al (), Boutin and Arkani‐Hamed (), Langlais and Purucker (), Quesnel et al (), Hood et al (), and Milbury et al (), and Bouley et al () constrained the amount of TPW associated with the Tharsis rise to 20° to 25°. This is only slightly smaller than the amount of TPW estimated here and may be consistent considering that rotational axis and dipole axis do not necessarily need to coincide.…”

Section: Discussionmentioning

confidence: 80%

“…Stereographic projections of the northern and southern hemispheres are shown in the top row, while a global map in Robinson projection is shown at the bottom. Evidence for true polar wander has been reported by Boutin and Arkani-Hamed (2006), Frawley and Taylor (2004), Arkani-Hamed (2001b), Arkani-Hamed and Boutin (2004), Hood et al (2007), Hood and Zakharian (2001), Hood et al (2005), Langlais and Purucker (2006), Milbury et al (2012), and Quesnel et al (2007), while Boutin and Arkani-Hamed (2006), Frawley and Taylor (2004), Arkani-Hamed (2001b), Arkani-Hamed and Boutin (2004), and Milbury et al (2012) in addition argue for at least one polar reversal event. (Plattner & Simons, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Paleopole Reconstruction of Martian Magnetic Field Anomalies

et al. 2018

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The crust of Mars shows strong remanent magnetization, which was likely acquired during the early phases of planetary evolution when a core dynamo still operated. The direction of the field responsible for magnetizing the crust holds clues to the working of the dynamo and the rotational dynamics of the planet. By analyzing individual crustal magnetic field anomalies and with the aid of additional assumptions, the field orientations can be reconstructed. We have implemented an Equivalent Source Dipole method to determine the main field orientation during magnetization, assuming that the considered anomalies are unidirectionally magnetized without making specific assumptions about the source geometry. The available data are fit in a least squares sense, and the method yields confidence intervals for the admissible paleopole locations. The method was applied to six crustal magnetic field anomalies, two of which require a south pole in the northern hemisphere, while three indicate a south pole in the southern hemisphere. This implies that polar reversals took place at least once in Martian history. Furthermore, one of the investigated anomalies requires a south pole at equatorial to midlatitudes, indicating that a significant amount of true polar wander must have occurred on Mars. Finally, tests with synthetic data indicate that admissible paleopole locations typically spread across at least 25% of the planet, which may partially explain the scatter found in previously published paleopole studies.

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Section: Discussionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Paleopole Reconstruction of Martian Magnetic Field Anomalies

et al. 2018

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“…Assuming that Mars once possessed a dipolar main field, several authors used either crustal magnetic field models or the data directly to estimate paleopole locations [e.g., Sprenke and Baker , ; Arkani‐Hamed , ; Hood and Zakharian , ; Arkani‐Hamed and Boutin , ; Frawley and Taylor , ; Boutin and Arkani‐Hamed , ; Hood et al , ; Langlais and Purucker , ; Quesnel et al , ; Hood et al , ; Milbury and Schubert , ; Milbury et al , ]. From their paleopole locations, Arkani‐Hamed [], Arkani‐Hamed and Boutin [], Hood et al [], Milbury and Schubert [], and Milbury et al [] concluded that the ancient Martian dynamo underwent at least one polar reversal, and that true polar wander occurred.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution local magnetic field models for the Martian South Pole from Mars Global Surveyor data

Plattner

Simons

2015

JGR Planets

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We present two high-resolution local models for the crustal magnetic field of the Martian south polar region. Models SP130 and SP130M were derived from three-component measurements made by Mars Global Surveyor at nighttime and at low altitude (<200 km). The availability area for these data covers the annulus between latitudes −76 ∘ and −87 ∘ and contains a strongly magnetized region (southern parts of Terra Sirenum) adjacent to weakly magnetized terrains (such as Prometheus Planum). Our localized field inversions take into account the region of data availability, a finite spectral bandlimit (spherical harmonic degree L = 130), and the varying satellite altitude at each observation point. We downward continue the local field solutions to a sphere of Martian polar radius 3376 km. While weakly magnetized areas in model SP130 contain inversion artifacts caused by strongly magnetized crust nearby, these artifacts are largely avoided in model SP130M, a mosaic of inversion results obtained by independently solving for the fields over individual subregions. Robust features of both models are magnetic stripes of alternating polarity in southern Terra Sirenum that end abruptly at the rim of Prometheus Planum, an impact crater with a weak or undetectable magnetic field. From a prominent and isolated dipole-like magnetic feature close to Australe Montes, we estimate a paleopole with a best fit location at longitude 207 ∘ and latitude 48 ∘ . From the abruptly ending magnetic field stripes, we estimate average magnetization values of up to 15 A/m.

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“…Provided that the magnetizing field was axially centered and dipolar, these source parameters (location and magnetization direction) can be converted into a paleopole location, which are then used to constrain the behavior of the paleodynamo. Typically these studies model a small number of magnetic anomalies (fewer than ten) that are sparsely distributed over the globe and do not use gravity or consider geologic information in the analysis [ Hood and Zakharian , 2001; Arkani‐Hamed , 2001; Frawley and Taylor , 2004; Arkani‐Hamed , 2004b; Hood et al , 2005; Boutin and Arkani‐Hamed , 2006; Quesnel et al , 2007; Hood et al , 2007]. Particular anomalies are selected because they are isolated or because they are relatively strong.…”

Section: Introductionmentioning

confidence: 99%

The history of Mars' dynamo as revealed by modeling magnetic anomalies near Tyrrhenus Mons and Syrtis Major

et al. 2012

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The lack of magnetic anomalies within the major impact basins (Hellas, Argyre, and Isidis) has led many investigators to the conclusion that Mars' dynamo shut down prior to the time when these basins formed (∼4.0 Ga). We test this hypothesis by analyzing gravity and magnetic anomalies in the regions surrounding Tyrrhenus Mons and Syrtis Major, two volcanoes that were active during the late Noachian and Hesperian. We model magnetic anomalies that are associated with gravity anomalies and generally find that sources located below Noachian surface units tend to favor paleopoles near the equator and sources located below Hesperian surface features favor paleopoles near the geographical poles, suggesting polar wander during the Noachian‐Hesperian. Both paleopole clusters have positive and negative polarities, indicating reversals of the field during the Noachian and Hesperian. Magnetization of sources below Hesperian surfaces is evidence that the dynamo persisted beyond the formation of the major impact basins. The demagnetization associated with the volcanic construct of Syrtis Major implies dynamo cessation occurred while it was geologically active approximately 3.6 billion years ago. Timing of dynamo activity is fundamentally linked to Mars' climate via the stability of its atmosphere, and is coupled to the extent and duration of surface geologic activity. Thus, the dynamo history is key for understanding both when Mars was most geologically active and when it may have been most hospitable to life.

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East–west trending magnetic anomalies in the Southern Hemisphere of Mars: Modeling analysis and interpretation

Cited by 20 publications

References 41 publications

Paleopole Reconstruction of Martian Magnetic Field Anomalies

Paleopole Reconstruction of Martian Magnetic Field Anomalies

High‐resolution local magnetic field models for the Martian South Pole from Mars Global Surveyor data

The history of Mars' dynamo as revealed by modeling magnetic anomalies near Tyrrhenus Mons and Syrtis Major

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