The formation of antitaxial calcite veins with well-developed fibres, Oppaminda Creek, South Australia

The veins at Oppaminda Creek are about 585 Ma in age, and therefore formed at an estimated 4-6 km depth. Scanning electron microscope observations revealed about 1-μm-sized structures, which we interpret as fossils of microbes that lived inside the veins at the time of their formation, and which may even have played a role in the vein formation. These structures would represent the first finds of fossilised life forms of such a combined age and depth.