Palynological-age determination of Early Cretaceous vertebrate-bearing beds along the south Victorian coast of Australia, with implications for the spore-pollen biostratigraphy of the region

Abstract

Palynology is used to provide new age controls for the coastal exposures yielding Early Cretaceous vertebrate faunas in the Otway and Gippsland basins, southeast Australia. This work shows all vertebrate-bearing deposits in the Otway Basin are Albian in age. On the eastern margin of Cape Otway, vertebrate-bearing deposits are attributed to the early Albian Crybelosporites striatus Zone, except for one in the younger Coptospora paradoxa Zone. To the west of Cape Otway, the sampled deposits range from the oldest zone in the Albian, the C. striatus Zone, to the C. paradoxa and Phimopollenites pannosus zones, providing a complete section of the Albian stage. In the Gippsland Basin, the structural setting of vertebrate deposits is more complicated and large portions of the coastal exposures consist of repeated sections controlled by small-scale faults. Sites in this region lie below or above the Barremian/Aptian boundary. However, owing to the paucity of age indicator species, some sampled deposits remain undated. In this basin, the ranges of certain key palynomorph species (e.g., Pilosisporites notensis and Pilosisporites parvispinosus) differed from those outlined in some previously published biostratigraphic schemes. The discovery of the angiosperm pollen Clavatipollenites hughesii in the lowermost Aptian deposits of the Gippsland Basin is consistent with its first occurrence elsewhere in Australia and shows it is a reliable indicator for the Aptian stage. This study shows that there is currently a collection bias towards vertebrate assemblages that are latest Barremian and early Albian in age.Barbara E. Wagstaff [wagstaff@unimelb.edu.au], The School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; Stephen J. Gallagher [sjgall@unimelb.edu.au], The School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; W. Michael Hall [mike.hall@monash.edu], School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia; Vera A. Korasidis [korasidisv@si.edu], Smithsonian Institution, National Museum of Natural History, Department of Paleobiology, NHB121, 10th and Constitution Avenue, NW, Washington, DC20013-7012, USA; Thomas H. Rich [trich@museum.vic.gov.au], Melbourne Museum, 11 Nicholson Street, Carlton, Victoria 3053, Australia; Doris E. Seegets-Villiers [doris.seegets-villiers@monash.edu], School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia; Patricia A. Vickers-Rich [pat.rich@monash.edu], School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia and Swinburne University of Technology, Department of Chemistry and Biotechnology, Faculty of Science, Hawthorn, Victoria 3122, Australia.