Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS) as an Analytical Tool in the Geosciences

Secondary ion mass spectrometry (SIMS) is one of the most versatile microbeam techniques for studying geological and environmental processes, with the ability to detect the majority of elements within a wide range of materials. The limitation with SIMS has previously been the lateral resolution, with a range of microns to tensofmicrons. Nanoscale secondary ion mass spectrometry (NanoSIMS) allows for submicron elemental and isotopic characterisation of materials. NanoSIMS has applications within several geoscientific fields, including biogeoscience, palaeontology, mineralogy and petrology, and cosmochemistry. NanoSIMS can correlate nano- to microscale morphological features with chemical and isotopic signals characteristic of biology, making it suitable for studying iron oxide concretions, ooids, microbialites, bio-alteration of volcanic rocks, and biomineralization and palaeoenvironmental indicators. Palaeontologists have a better understanding of Earth's earliest life following analysis of microfossils and trace fossils, stromatalites, and biominerals, as NanoSIMS enables elemental mapping on the nanometre scale. NanoSIMS has been used to study diffusion in minerals and map ‘invisible gold’ in pyrite, i.e.gold present in concentrations below the sensitivity of other surface analytical techniques. The highspatial resolution and imaging capabilities of NanoSIMS has also enabled cosmochemists to locate individual micron-sized, presolar dust grains within a background of millions of interplanetary dust particles.