Junction magnetic anomaly north of Waikato River

Abstract

A linear magnetic anomaly is traced northwards from Waikato through North Auckland and Northland until it meets the Tasman Sea west of Kaitaia. The anomaly, which has amplitudes up to 700 gammas and half-widths of 5–15 km, is believed to be due to serpentinite and probably represents the extension of the ultramafic belt which separates the principal facies of the New Zealand Geosyncline. If the serpentine pods within the Onerahi Chaos Breccia are derived from this body, flow from the west is indicated as an emplacement mechanism for the Breccia.