Chronostratigraphy of the Cambrian Series 2-Miaolingian boundary, western Stansbury Basin, South Australia

The GSSP of the Series 2–Miaolingian (= traditional lower–middle Cambrian) boundary was ratified in South China based on the first appearance of the trilobite Orychtocephalus indicus coincident with a major negative δ13C excursion (Redlichiid–Olenellid Extinction Carbon isotope Excursion; ROECE). Unfortunately, O. indicus has not been recovered in Australian Cambrian successions and lack of isotopic data means definition of the Series 2–Miaolingian boundary has been problematic. This study integrates multiproxy data (δ13C and δ18O chemostratigraphy and biostratigraphy) along with lithostratigraphy to recognise the Series 2–Miaolingian boundary in the western Stansbury Basin, South Australia. Distinct faunal assemblages within drill cores CURD-9 and Port Julia-1A reveal range extensions of key taxa including Pagetia sp indet. within the Stansbury Limestone, below the interpreted ROECE event, which is consistent with occurrences in the GSSP. A -2.2 ‰ δ13C peak in the Ramsay Limestone in CURD-9 and coeval Wirrealpa Limestone (Arrowie Basin) represent the Archaeocyathid Extinction Carbon isotope Excursion event. The -5.3 ‰ δ13C peak in the Stansbury Limestone in CURD-9 and the ~ -2.7 ‰ δ13C in Port Julia-1A, represents the global ROECE event. Similar lithologies observed within the Stansbury Limestone of both cores reveal the same ROECE event.