The Neoproterozoic-Cambrian record in Australia: A stable isotope study

At one site in the Amadeus Basin, diagenesis proved to have significantly modified the isotopic composition of the carbonates and the data were eliminated. Analysis of the remaining samples suggests that they reflect the global secular stable carbon isotope curve and tie well with established palaeontological timescales. In particular, key isotopic excursions can be identified in the earliest part of the Neoproterozoic succession, notably the negative excursion following the Sturtian glaciation. In the early Palaeozoic record a major excursion during Ordian-early Templetonian (509-506 Ma) time can be identified across the region as can the so-called SPICE excursion which has been associated globally with the Steptoean Stage of Laurentia (497.5-495 Ma). A smaller late Templetonian-Floran (506-503 Ma) positive excursion has also been recognized. The stable carbon isotope record provides a strong regional correlation in both fossiliferous and unfossiliferous Neoproterozoic and early Palaeozoic successions and allows a global correlation to be established.