Geologists combine both field and laboratory analysis to unravel the geological history of a region. In the field, they identify the different rocks types and geological structures which then get used to create a geological map. In the lab, geologists can use a wide range of techniques to further examine the rocks they have collected. This can include slicing the rocks into thin sections only 30 µm thick for use in optical microscopy where individual minerals can be identified, isotope analysis to work out how old certain minerals are, and electron microscopy analysis to investigate microscale structures as well as detailed elemental compositions.
This case study features a sample of a schist from Omeo in east Victoria, Australia, which sits at the southern end of the Wagga-Omeo Metamorphic Belt and is part of the 200,000 km2 Lachlan Fold Belt. Schists are metamorphic rocks that are produced when sedimentary rocks experience low-temperature and low-pressure metamorphism. This causes the platy minerals in them to align and wrap around larger, more rigid crystals. However, because these platy minerals are often very small it is difficult to fully understand the features of the rock without microscopic analysis.