Earth’s rock record holds great potential for decoding the origin and early diversification of life on our planet. However, the interpretation of the Precambrian (older than ~541 million years ago) fossil record is fraught with difficulties. Distinguishing between true signs of life and non-biological artefacts requires analytical techniques with excellent spatial resolution in two and three dimensions, in order to accurately analyse key features of putative cells such as cell wall ultrastructure, biochemistry, and interaction of cell walls with the minerals that have fossilised them.
Traditional approaches involving light microscopy and Raman spectroscopy provide important information but leave vital questions unanswered that could potentially be resolved with higher resolution analytical techniques. At UWA, we have developed a multi-scale, multi-technique approach where the traditional methods are supplemented by nanoscale isotopic, structural, crystallographic, and chemical information obtained through techniques such as NanoSIMS, scanning electron microscopy (SEM), focused ion beam (FIB-SEM), and transmission electron microscopy (TEM). This correlative microscopy approach provides new insights into the development and preservation of Earth’s earliest life, demonstrating that the application of multiple techniques in a coordinated fashion can provide significantly more information than each technique in isolation.