[1] 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 BjerkreimSokndal (BKS) Intrusion, shows a minimum À13000 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 clinoand orthopyroxene, and high-temperature ductilely induced lattice-preferred orientation.
From the Palaeozoic to the Cretaceous, crustal thinning in the Mid Norway area was associated with the denudation of gneiss-cored culminations and metamorphic core complexes in the footwalls of major extensional faults. The development of the culminations led to warping and deactivation of early detachments, to the nucleation of new faults in more distal positions and to the exhumation of highgrade metamorphic rocks to more shallow levels in the crust. Some of the culminations and core complexes became part of the erosional template in Mid-Late Palaeozoic time, some were probably exhumed in the Mesozoic, whereas some may never have reached the surface. We present an overview of five types of gneiss-cored culminations and core complexes that have been identified in the field, through the interpretation of offshore, long-offset seismic reflection data. We furthermore address their mechanism(s) of formation, and their role in the progressive evolution of the Mid-Norwegian margin.
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