A new integrated lower Cambrian chronostratigraphy for the Normanville Group, eastern Stansbury Basin, with definition of the oldest small shelly fossil zones in South Australia

The lower Cambrian Normanville Group in the eastern Stansbury Basin, South Australia is a pre-trilobitic succession of carbonates and siliciclastics, hosting a mix of endemic and cosmopolitan small shelly fossils. The mollusc Watsonella crosbyi and tommotiid Sunnaginia imbricata are two globally distributed taxa found in other Cambrian terranes. High resolution, systematic sampling of key formations has enabled the definition of eponymous zones based on these cosmopolitan faunas, which are the oldest Cambrian shelly fossil biozones in South Australia. Coupled with new δ¹³C and δ¹⁸O chemostratigraphy through the Fork Tree Limestone, a near complete integrated chronostratigraphic scheme for the Normanville Group is compiled. Comparisons to regional Cambrian basins suggests a Terreneuvian, Stage 2 age for most of the formations within the Normanville Group (Mount Terrible Formation, Wangkonda Formation, Sellick Hill Formation and Fork Tree Limestone), while the Heatherdale Shale has a Series 2, Stage 3 age.