Automated petrography applications in Quaternary Science

Abstract

Automated petrography analysis integrates scanning electron microscopy and energy-dispersive x-ray spectroscopy (SEM-EDS) hardware with expert software to generate micron-scale compositional maps of rocks and sediments. While automated petrography solutions such as QEMSCAN® and MLA are widely used in the mining, mineral processing, and petroleum industries to characterise ore deposits and subsurface rock formations, only few Quaternary scientists have applied SEM-EDS compositional mapping to palaeo-environmental research. This paper explains the fundamentals behind the analytical method, describes the type of data that can be generated, and presents the latest advances. Potential applications in Quaternary Science are discussed, including the study of: 1) depositional and formation environments; 2) weathering and diagenetic history; 3) sediment provenancing and pathways; and, 4) the provision of complimentary data in chronostratigraphic studies. Three case studies illustrate potential applications in fluvial, aeolian and coastal research. The first case study applies automated petrography analysis to dust fingerprinting on samples collected from the ‘red dawn’ dust event that swept across eastern Australia on the 23 September 2009, and from the Icelandic Eyjafjallajökull volcanic eruptions that caused enormous disruption to air travel across Europe in April 2010. The second case study investigates flood deposits collected across Brisbane in the aftermath of the January 2011 floods. In the final case study we consider how automated petrography can aid the understanding of human impacts on the environment. Automated SEM-EDS technology was first developed by CSIRO in Australia, and made commercial by companies based in Brisbane. This proximity has proven an advantage to a wide range of researchers in Australasia pioneering innovative applications.