Magnetic field intensity study of the 1960 Kilauea lava flow, Hawaii, using the microwave palaeointensity technique

It is extremely valuable to study historic lava flows where the geomagnetic field at their time of extrusion is well known. In this study, two vertica l sections, 16 m apart, have been sampled from the approximately 1 m thick 1960 Kilauea lava flow, Hawaii. Variations are seen in the rock-magnetic an d palaeomagnetic properties between and within the two sections, indicating that there are small-scale lateral and vertical variations in the lava flo w. The two sections showed different responses to microwave palaeointensity analysis. Section H6001 generally gave ideal linear behaviour on plots of natural remanent magnetization (NRM) lost against microwave-induced thermor emanent magnetization (TMRM) gained, whilst the majority of samples from H6 002 showed anomalous two-slope behaviour. When all plots were interpreted b y taking the best-fitting line through all points, the flow mean intensity for H6001 was 31.6 +/- 3.6 mu T and that for H6002 was 37.1 +/- 6.4 mu T, c ompared with the expected intensity of 36 mu T. Additional historic flows n eed to be studied in order to ascertain whether this behaviour is typical o f all lava, and whether it is best to always interpret NRM lost/TMRM gained plots by taking the line of best fit regardless of shape.