Pressure demagnetization of the Martian crust: Ground truth from SNC meteorites

We performed hydrostatic pressure demagnetization experiments up to 1.3 GPa on Martian meteorites: nakhlite NWA998 (magnetite‐bearing), basaltic shergottites NWA1068 (pyrrhotite‐bearing) and Los Angeles (titanomagnetite‐bearing) as well as terrestrial rocks: rhyolite (hematite‐bearing) and basalt (titanomagnetite‐bearing), using a new non‐magnetic high‐pressure cell. The detailed description of measuring techniques and experimental set‐up is presented. We found that under 1.3 GPa the samples lost up to 54% of their initial saturation isothermal remanent magnetization (IRM). Repeated loading resulted in a further decrease of magnetization of the samples. Our experiments show that the resistance of IRM to hydrostatic pressure is not exclusively controlled by the remanent coercivity of the sample, but is strongly dependant on its magnetic mineralogy. There is no simple equivalence between pressure demagnetization and alternating field demagnetization. The extrapolation of these results of pressure demagnetization of IRM of Martian meteorites to the demagnetization of the Martian crust by impacts is discussed.