Magnetic anomalies off the west coast of Northland, New Zealand

Abstract

Total force magnetic measurements have shown the existence of a series of isolated positive magnetic anomalies off the west coast of Northland, New Zealand. These anomalies have amplitudes of 800 nT to 1800 nT and lie, in general, along a line parallel to the postulated ultramafic belt running through Northland. They are interpreted as being caused by a series of andesitic volcanoes which are correlated with the Manukau Breccia of lower Miocene age.