Magnetic anomalies resulting from baked sediments over burnt coal seams in southern New Zealand

Abstract

Abstract Baked and fused sediments over burnt lignite seams in Southland and Otago have total magnetic intensities of up to 8 A/m, and the edges of seams having residual clinker can thus be located by magnetic surveys if the seams are covered by colluvium. Minerals causing the magnetisation of the clinkers appear to include both pyrrhotite and solid solutions of the ulvospinel‐magnetite series.