Abstract
Magnetic susceptibility, hysteresis parameters, thermomagnetic curves and IRM acquisition behavior have been measured for a suite of proximal Recent tephra horizons whose source is the Taupo Volcanic Centre, New Zealand. All of the layers appear to contain (i) a TM40 titanomagnetite phase with grainsize about 50 μm and concentration about 0.1 wt% and (ii) a pure magnetite phase about 1 μm in grainsize, constituting about 0.08 wt% of the tephra and dispersed throughout the glass shards. The 1RM acquisition curves can be fitted well by two superposed cumulative log gaussian functions, each corresponding to one of the titanomagnetite phases. IRM spectra for thick distal deposits of the Taupo Ignimbrite (tephra) indicate that the same titanomagnetite phases are present but in smaller concentrations and smaller sizes. Finally, IRM spectra have been determined for samples from a soil profile in the Hunua Hills and the result is consistent with the uppermost three coloured zones having formed within one Plio-Pleistocene tephra horizon overlying further zones formed within a different tephra.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
