Acritarchs in the Ediacaran of Australia — Local or global significance? Evidence from the Lake Maurice West 1 drillcore

The Lake Maurice West 1 drillhole is located in the Officer Basin in South Australia and penetrates a siliciclastic rock succession of Ediacaran age (ca 635–542 Ma). Within this succession well-preserved organic-walled microfossils called acritarchs have been recovered from the Dey Dey Mudstone and Karlaya Limestone, which constitutes a major part of the Ungoolya Group. The assemblage consists of biostratigraphically useful acanthomorphic acritarchs in addition to a diverse assemblage of unornamented leiospheres, filamentous microbiota and some undetermined taxa. Here we describe eight acanthomorphic taxa belonging to three distinctive Ediacaran genera (Cavaspina, Ceratosphaeridium and Tanarium), of which one is described as a new species (Cavaspina amplitudinis sp. nov.). Similar acanthomorphic assemblages are known from Ediacaran strata worldwide and biostratigraphic subdivision of the system based on the occurrence of cosmopolitan taxa is possible in Australia, China, Siberia and Baltica (East European Platform), and perhaps in other areas. The Lake Maurice West 1 microfossil assemblage adds to the growing record of the Ediacaran acritarchs and supports a biostratigraphic scheme for the Ediacaran System at a global scale.

► We describe acanthomorphic microfossils from Australia.
► Have implications on Precambrian biostratigraphy.
► Improves local stratigraphy.
► Discusses the taxonomy of cosmopolitan taxa.