A preliminary Scanning Electron Microscope (SEM) study of magnetite surface microtextures from the Wahianoa moraines, Mt Ruapehu, New Zealand.

Abstract

Scanning electron microscope (SEM) of quartz micro‐textures has routinely been used to identify the depositional environment of sediments in areas of former ice‐sheet glaciation. On volcanic mountains, where the geomorphic origin of ridge deposits is often poorly understood, quartz is much less abundant, so SEM analysis has not been used as a depositional discriminator. Preliminary research on surface micro‐textures of abundant magnetite grains from the Wahianoa moraines, south‐eastern Mt Ruapehu, suggests that SEM of magnetite may be useful in determining the process‐origin of deposits. We describe micro‐textures and surface characteristics of samples of magnetite, and our study shows that many of the micro‐textures visible on quartz, thought to be diagnostic of glacial transport, are present on magnetite too. However, evaluating whether SEM analysis of magnetite is an applicable technique will require a better understanding of the microtextures occurring on known glacial, fluvioglacial and aeolian deposits on volcanic mountains.