Self‐Reversed Magnetization in Sediments Caused by Greigite Alteration

Multipolarity remanence in greigite-bearing sediments has long been recognized, but the cause of this anomalous behavior is not well understood. Here, we use electron microscopic and magnetic analyses to investigate origin such multipolarity Miocene from Pannonian Basin (Hungary). We find a softening partial transformation iron sulfides magnetite pyrrhotite “single-polarity” “multi-polarity” samples. The inward alteration sulfide grains topotactic size-dependent with higher smaller grains. propose multi-phase self-reversal chemical remanent magnetization (CRM) mechanism altered greigite: neoformed magnetite/pyrrhotite shell acquires CRM coupled opposite direction primary greigite core, likely through magnetostatic interactions or interfacial exchange between closely contacting core shell. This new model can explain commonly observed antiparallel polarities broad geochronological, tectonic paleoenvironmental implications.