ORGANIC-WALLED MICROFOSSILS OF THE PALEOPROTEROZOIC AND MESOPROTEROZOIC MCARTHUR AND BIRRINDUDU BASINS, NORTHERN TERRITORY, AUSTRALIA (Invited Presentation)

The record of probable eukaryotes reaches into the late Paleoproterozoic Era. The oldest known organic-walled microfossils bearing wall sculpture and external processes, characteristics associated with a sophisticated eukaryotic cytoskeleton, have been reported from several units including the rather diverse assemblages of the 1.74-1.41 Ga Ruyang Group and the 1.67-1.63 Ga Changcheng Group.

Here we present new microfossil assemblages including eukaryotic taxa such as Tappania plana, Satka favosa, Valeria lophostriata and Dictyosphaera macroreticulata from the Tawallah and McArthur groups of the McArthur Basin and the Limbunya and Bullita groups of the Birrindudu Basin, both of Northern Territory, Australia. These basins record variably anoxic and sulfide-poor, and euxinic shallow marine deposition between about 1.8 and 1.6 Ga. In addition to hosting diverse assemblages of prokaryotic and eukaryotic microfossils, these units offer the opportunity to better resolve the shallow marine ocean chemistry in these basins and the habitat preferences of certain ubiquitous and long-lived taxa.