Open AccessImpact demagnetization by phase transition on Mars
Author(s) -
Rochette Pierre,
Hood Lon,
Fillion Gerard,
Ballou Rafik,
Ouladdiaf Bachir
Publication year - 2003
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/2003eo500001
Subject(s) - impact crater , martian , geology , noachian , crust , tharsis , mars exploration program , dynamo , thermoremanent magnetization , geophysics , astrobiology , earth science , magnetization , petrology , physics , magnetic field , remanence , quantum mechanics
Recent solar system exploration has revealed the presence of a complex pattern of strong crustal magnetization on Mars [ Acuña et al ., 1999; Figure l]. The north‐south dichotomy of the magnetization might be interpreted in terms of shutdown of the Martian dynamo before the formation or reworking of the younger and/or thinner northern crust, as well as the Tharsis dome. On the other hand, there is no apparent difference in the older, southern “Noachian” heavily‐cratered terrane between the magnetized and non‐magnetized crust. One could invoke the proximity of the Hellas and Argyre giant impact craters (Figure 1) if impacts occurred after dynamo shutdown, and if a mechanism is available to demagnetize the crust at distances of several crater radii. This mechanism cannot be thermal, as the thermal effect is very limited at such distance; thus, the mechanism must be pressure‐related.