Magnetic anomalies, layered intrusions and Mars

Studies of remanence-controlled magnetic anomalies on Earth provide possibilities to interpret the nature of crustal rocks that cause the large remanent anomalies on Mars. What types of conditions on Earth can create large remanent magnetic anomalies? Such an anomaly, extending for 20 km centered over a norite layer in the Bjerkreim-Sokndal (BKS) Intrusion, shows a minimum -13000 nT below background in the helicopter survey. Modeling of the anomaly requires a natural remanent magnetization (NRM) value of 24 A/m, similar to values measured in norite samples and to values invoked to explain the anomalies on Mars. Preliminary magnetic assessment considers the roles of hemo-ilmenite, magnetite, and oxide exsolution in clino- and orthopyroxene, and high-temperature ductilely induced lattice-preferred orientation.