Neoproterozoic microfossils from the Officer Basin, Western Australia

Abstract

Microfossil assemblages are described from the early Neoproterozoic Madley and Browne Formations, western Officer Basin. One chert and eleven siliciclastic samples yielded microfossils. Myxococcoides cantabrigiensis occurs as pustular mats in the chert sample and Eomicrocystis malgica, Pterospermopsimorpha granulata, Skiagia sp. cf. S. pusilla, and undetermined species of Obruchevella, Heliconema, and Trachystrichosphaera are present in acid macerated samples. Leiosphaeridia spp. and Siphonophycus spp. are also found in fine-grained siliciclastic samples, with clusters of Synsphaeridium sp. in some samples. These findings enable a more substantial reconstruction of the palaeoenvironment of Supersequence 1 in the western Centralian Superbasin. The acanthomorph acritarchs are considered to be planktonic eucaryotes washed into environments which ranged from coastal sabkha through to tidal flats, which may be the source of the prokaryotic, benthic, matforming cyanobacteria.

Key words:

• Neoproterozoic
• cyanobacteria
• acritarchs
• Officer Basin
• Supersequence 1
• Centralian Superbasin
• Western Australia