Precambrian Microfossils of Carpentarian Age from Bungle Bungle Dolomite of Western Australia

Abstract

I WISH to present some preliminary results and interpretations of the examination of a well preserved assemblage of mid-Precambrian microfossils. This previously unknown microflora of blue-green and green or red algal affinities is from chertified stromatolitic dolomites of the Bungle Bungle Dolomite which outcrops in the Osmond Range of Western Australia. There are no published radiometric ages for this formation but the Mount John Shale Member of the overlying Wade Creek Sandstone has been dated (Rb/Sr method) at 1.128±0.1 × 10⁹ yr BP¹. Regional studies and the angular unconformity between the Bungle Bungle Dolomite and Wade Creek Sandstone indicate that the former is considerably older than this minimum and that an age of about 1.5×10⁹ yr for the microbiota described here is consistent with the data available. The Bungle Bungle Dolomite consists of at least 1.3 km of dolomite, dolomitic shales, shales and sandstones. Well preserved stromatolites occur at certain levels and have been briefly described elsewhere¹. The samples used in this investigation are from the measured section in the upper part of the formation at 17° 13′ S 128° 23′ E.