Cenozoic oil-shale deposits in southeastern-central Queensland: palynostratigraphic age determinations and correlations for the Biloela Formation (Biloela Basin) in GSQ Monto 5

Abstract

Fossil pollen and spores recovered from core chips of the Biloela Formation between 41.5 and 219.0m in GSQ Monto 5: Confirm that freshwater, lacustrine sediments infilling the inland Biloela Basin c. 110km southwest of Gladstone are a correlative of the oil-shale-rich Rundle Formation in the Narrows Graben near Gladstone on the central Queensland coast. Provide, within the resolution achieved by using palynostratigraphic-dating criteria, the first known evidence that the upper part of the Biloela Formation is Late Eocene–Early Oligocene. At present, the strongest evidence that the section is Late Eocene is the close similarity of the microflora to Late Eocene assemblages in the offshore Gippsland Basin in southeastern Australia. An Early (earliest?) Oligocene age is equally probable if age-range data from the Murray Basin, southeastern Australia, are used. Differences in the age range of fossil species shared with southeastern Australia emphasise caution is needed when using zonation schemata developed for the continental margin Gippsland Basin and/or epicontinental Murray Basin to date Cenozoic deposits in central QueenslandThis report was commisioned by Queensland Department of Natural Resources and Mine