FLESHING OUT THE EDIACARAN PERIOD

Abstract

The Ediacaran Global Stratotype Section and Point has now been defined at the base of the Nuccaleena Formation in the Flinders Ranges National Park, South Australia. This GSSP marks the end of a major glacial epoch. In the absence of definitive biozones marking the base of the Ediacaran, the utility of this "cap carbonate' for correlation will depend on the verification of a global fingerprint based on the stratigraphic pattern, stable isotope trends and magnetostratigraphy. Even though the fossil record for the Ediacaran System is relatively sparse, it clearly characterizes this period on all continents except Antarctica. The task facing the Ediacaran Subcommission of the ICS is the correlation of the GSSP horizon around the globe and to foster biostratigraphic subdivision of the Ediacaran System. In the Flinders Ranges National Park, the well exposed, structurally uncomplicated, 3.5-km- thick Ediacaran succession is capped with a 2-km-thick, fossiliferous Early Cambrian succession (Fig. 1). The Flinders Ranges Ediacaran succession preserves an apparently primary palaeomagnetic record, distinctive stratigraphic events, and fossils of the Ediacara biota at three well-separated levels. • The palaeomagnetic record of the Elatina Formation, immediately below the Ediacaran GSSP, indicates that the Adelaide geosyncline experienced a protracted interval of glaciogenic sedimentation when the region was straddling the palaeomagnetic equator (Schmidt and Williams, 1995; Sohl, et al., 1999). New approaches to palaeomagnetic analysis promise a magnetostratigraphy for the Ediacaran succession in the Flinders Ranges.